IPAC2017 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOXAA1	Commissioning of the European XFEL Accelerator	linac, operation, undulator, emittance	1
	W. Decking, H. Weise DESY, Hamburg, Germany
	The European XFEL uses the world's largest superconducting RF installation to drive three independent SASE FELs. After eight years of construction the facility is now brought into operation. First experience with the superconducting accelerator as well as beam commissioning results will be presented. The path to the first user experiments will be laid down.
	Slides MOXAA1 [22.967 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOXAA1
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MOZA1	Electron Cloud Effects at the LHC and LHC Injectors	operation, simulation, emittance, dipole	30
	G. Rumolo, H. Bartosik, E. Belli, P. Dijkstal, G. Iadarola, K.S.B. Li, L. Mether, A. Romano, M. Schenk, F. Zimmermann CERN, Geneva, Switzerland E. Belli University of Rome La Sapienza, Rome, Italy P. Dijkstal TU Darmstadt, Darmstadt, Germany M. Schenk EPFL, Lausanne, Switzerland
	Electron cloud effects are one of the main limitations of the performance of the LHC and its injectors. Enormous progress has been done in the simulation of the electron cloud build-up and of the effects on beam stability while mitigation measures have been identified and implemented (scrubbing, low secondary electron yield coatings, etc.). The above has allowed reaching nominal beam parameters in the LHC during Run 2. A review of the studies and results obtained and the strategy and expected performance for the High Luminosity operation of the LHC will be presented.
	Slides MOZA1 [12.855 MB]
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MOOCA1	High Efficiency Klystrons Using the COM Bunching Technique	klystron, cavity, simulation, bunching	37
	D.A. Constable Lancaster University, Lancaster, United Kingdom A.Yu. Baikov Moscow University of Finance & Law, Moscow, Russia G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R.D. Kowalczyk L-3, Williamsport, Pennsylvania, USA I. Syratchev CERN, Geneva, Switzerland
	Future large-scale particle accelerators, for example, the Future Circular Collider (FCC), the Compact Linear Collider (CLIC) and the International Linear Collider (ILC), will require significant RF drive power on the order of 100 MW. Thus, an RF source with high efficiency is preferable to minimise the overall power required. Klystrons represent an attractive RF source, with the current state of the art operating at efficiencies of up to 70%. Such devices feature monotonic bunching, where at the output cavity, a number of electrons will not be in the main bunch, and instead will be present in the anti-bunch, and therefore not contributing to the output power. Therefore, novel bunching methods, such as the Core Oscillation Method (COM), are worthy of investigation. By allowing the core of the electron beam to bunch and de-bunch between successive cavities, the number of electrons contained in the final bunch can increase, and therefore improve the efficiency of the device. Numerical simulation of klystrons featuring COM will be presented, with efficiencies of up to 85% being predicted thus far.
	Slides MOOCA1 [12.765 MB]
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MOOCA3	Amorphous Carbon Thin Film Coating of the SPS Beamline: Evaluation of the First Coating Implementation	vacuum, cathode, proton, operation	44
	M. Van Gompel, P. Chiggiato, P. Costa Pinto, P. Cruikshank, C. Pasquino, J. Perez Espinos, A. Sapountzis, M. Taborelli, W. Vollenberg CERN, Geneva, Switzerland
	As part of the LHC Injector Upgrade (LIU) project, the Super Proton Synchrotron (SPS) must be upgraded in order to inject in the LHC 25 ns bunch spaced beams of higher intensity. To mitigate the Electron Multipacting (EM) phenomenon in the SPS, CERN developed thin film carbon coatings with a low Secondary Electron Yield (SEY). The development went from coating small samples, up to coating of 6 m long vacuum chambers directly installed in the magnets. To deposit the low SEY amorphous carbon (aC) film on the vacuum chamber inner wall of SPS ring components, a modular hollow cathode train was designed. The minimization of the logistical impact requires a strategy combining in-situ and ex-situ coating, depending on the type of components. To validate the implementation strategy of the aC thin films and the in-situ coating process along the 7 km long SPS beamline, approximately 2 cells of B-type bending dipoles and 9 focussing quadrupoles are foreseen to be treated with the aC coating during the Extended Year End Technical Stop (EYETS) 2016-2017. We will discuss the coating technique and evaluate both the implementation process and the resulting coating performance.
	Slides MOOCA3 [71.421 MB]
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MOZB1	First Results with the Novel Peta-Watt Laser Acceleration Facility in Dresden	laser, target, plasma, acceleration	48
	U. Schramm, D. Albach, C. Bernert, S. Bock, F. Brack, J. Branco, M.H. Bussmann, J.P. Couperus, A.D. Debus, C. Eisenmann, M. Garten, R. Gebhardt, S. Grams, U. Helbig, A. Huebl, A. Irman, A. Köhler, J.M. Krämer, S. Kraft, F. Kroll, J. Metzkes, L. Obst, R.G. Pausch, M. Rehwald, H.P. Schlenvoigt, M. Siebold, K. Steiniger, O. Zarini, K. Zeil Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany T. Kluge, M. Kuntzsch, U. Lehnert, M. Löser, P. Michel, R. Sauerbrey HZDR, Dresden, Germany
	Applications of laser plasma accelerated particle beams ranging from driving of light sources to radiation therapy require the scaling of beam energy and charge as well as reproducible operating conditions. Both issues have motivated the development of novel table-top class Petawatt laser systems (e.g., 30J pulse energy in 30fs) with unprecedented pulse control, here represented by the Draco-PW system recently commissioned at HZDR Dresden. First results will be presented on laser wakefield electron acceleration where in the beam loading regime high bunch charges in the nC range could be efficiently accelerated with good beam quality, and on proton acceleration where pulsed magnet beam transport ensured depth dose distributions allowing for tumor irradiation in animal models.
	Slides MOZB1 [4.059 MB]
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MOOCB3	Intensity Interferometer to Measure Bunch Length at SPEAR3	photon, detector, optics, storage-ring	60
	W.J. Corbett SLAC, Menlo Park, California, USA T.M. Mitsuhashi KEK, Ibaraki, Japan
	Electron bunch length in a storage ring is typically measured with streak cameras, electro-optic devices or non-linear cross-correlation techniques with a range of system complexity, signal-to-noise ratios and cost. Another straight-forward method is to construct an 'intensity interferometer' utilizing a coincidence detector to record simultaneous photon arrival events. In this configuration, visible SR light is passed through a narrow bandpass filter followed by a small pinhole to generate a stream of single-mode monochromatic wavepackets. As the interferometer delay is scanned across an electron bunch, two-photon events occurring within the longitudinal coherence time of the light cause a reduction in the measured coincidence rate. The resulting autocorrelation of the optical pulse duration reveals the electron bunch length, independent of synchrotron oscillation motion. In this paper we comment on the theory and report on preliminary measurements carried out at SPEAR3.
	Slides MOOCB3 [2.606 MB]
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MOPAB013	Recent Development and Results With the Merlin Tracking Code	collimation, proton, simulation, collider	104
	S.C. Tygier, R.B. Appleby, H. Rafique UMAN, Manchester, United Kingdom R.J. Barlow, S. Rowan IIAA, Huddersfield, United Kingdom J. Molson LAL, Orsay, France
	Funding: Work supported by High Luminosity LHC : UK (HL-LHC-UK), grant number ST/N001621/1 MERLIN is an high performance accelerator simulation code which is used for modelling the collimation system at the LHC. It is written in extensible object-oriented C++ so new physics processes can be easily added. In this article we present recent developments needed for the Hi-Lumi LHC and future high energy colliders including FCC, such as hollow electron lenses and composite materials. We also give an overview of recent simulation work, validation against LHC data from run 1 and 2, and loss maps for Hi-Lumi LHC.
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MOPAB016	Beam Diagnostic and Control Systems for AREAL 50 MeV Linac	controls, emittance, diagnostics, linac	114
	V. Sahakyan, G.A. Amatuni, A. Azatyan, B. Grigoryan, N. Martirosyan, A. Sargsyan, V.M. Tsakanov, G.S. Zanyan CANDLE SRI, Yerevan, Armenia
	Advanced Research Electron Accelerator Laboratory (AREAL) is an electron linear accelerator project with a laser driven RF gun that has been constructed at CANDLE Synchrotron Research Institute. After the completion of the first phase, which implies the operation of a 5 MeV gun section, the second phase of facility development (energy enhancement up to 50 MeV) is in progress. In the present paper the description of corresponding upgrades for diagnostic and control systems is given.
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MOPAB022	Fabrication Studies of a 650 MHz Superconducting RF Deflecting Mode Cavity for the ARIEL Electron Linac	cavity, niobium, linac, impedance	120
	D.W. Storey, R.E. Laxdal, B. Matheson, N. Muller TRIUMF, Vancouver, Canada D.W. Storey Victoria University, Victoria, B.C., Canada
	A 650 MHz RF deflecting mode cavity is required for the ARIEL electron Linac to separate interleaved beams bound for either rare isotope production or a recirculation loop containing a Free Electron Laser. An RF separator will allow both modes to run simultaneously by imparting opposite transverse deflection to adjacent bunches at 1.3 GHz. The SRF cavity has been designed to provide up to 0.6 MV transverse voltage for operation with up to a 50 MeV CW electron beam. The design was optimised for compact geometry with high shunt impedance. Due to the low dissipated power, the cavity will operate at 4 K and allows for investigations into low cost fabrication techniques. The cavity is being machined from bulk reactor grade ingot Niobium and welds will be performed using TIG welding in an ultra-pure Argon chamber. Results of fabrication studies will be presented as well as measurements performed on a copper prototype cavity.
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MOPAB024	Proposal to Observe Half-Bare Electrons on a 40-MeV LINAC	radiation, experiment, laser, linac	126
	N. Delerue, S. Jenzer, V. Khodnevych, A. Migayron LAL, Orsay, France N.F. Shul'ga NSC/KIPT, Kharkov, Ukraine S. Trofymenko KhNU, Kharkov, Ukraine
	Funding: CNRS/IN2P3 and Joint Laboratory France-Ukraine IDEATE In different processes of relativistic electron interaction with substance and external fields, the electron loses part of its Coulomb field and becomes half-bare. Such state of electron significantly modifies the characteristics of its electromagnetic radiation during further interaction of the particle with substance. We propose to study the influence of the half-bare state of electron upon its transition radiation (TR). The existence of such influence for the case of electron undressing at its scattering was theoretically predicted. We intend to obtain the electrons in half-bare state in the result of their crossing of a conducting screen such as a TR screen. We propose to investigate the influence of the half-bare state of electron in this process upon TR generated by such electron on a downstream TR screen situated on some distance from the upstream screen which undresses the particle. Calculations are presented for the case of a 45-MeV linac and the distance between the screens in the region between 100 mm and 300 mm. The proposed experiment is expected to reveal new features of TR signal in such process comparing to previous measurements. N.F. Shul'ga, S.V. Trofymenko, V.V. Syshchenko, JETP Lett. 93 (2011) 1. Y. Shibata, K. Ishi, T. Tokahashi et al., Phys. Rev. E 49 (1994) 785.
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MOPAB026	Study of a Smith-Purcell Radiation-Based Longitudinal Profile Monitor at the CLIO Free Electron Laser	radiation, laser, free-electron-laser, detector	132
	V. Khodnevych, N. Delerue, S. Jenzer, H. Roesch LAL, Orsay, France J.P. Berthet, F. Glotin, J.-M. Ortega, R. Prazeres LCP/CLIO, Orsay, Cedex, France N. Jestin CLIO/ELISE/LCP, Orsay, France
	Funding: CNRS and ANR (contract ANR-12-JS05-0003-01) We report on measurements of Coherent Smith-Purcell radiation at the CLIO Free Electron Laser. Smith-Purcell radiation is emitted when a grating is brought close from a bunch of relativistic particles. When the bunch is sufficiently short coherent radiation is emitted. This coherent radiation encodes the longitudinal form factor of the bunch and can therefore be used as a longitudinal profile monitor. With its short pulses and high charge the 45 MeV Linac of CLIO is a good location to test advanced longitudinal profile diag- nostics. The results will be compared with measurements using the RF dephasing. induced energy dispersion.
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MOPAB028	Estimation of Longitudinal Dimensions of Sub-Picosecond Electron Bunches with the 3-Phase Method	booster, space-charge, simulation, gun	139
	H. Purwar, C. Bruni, A. Gonnin LAL, Orsay, France T. Vinatier DESY, Hamburg, Germany
	An estimation of the longitudinal dimensions for short electron bunches in an accelerating field is an important diagnostic and can be extremely helpful in evaluating the performance of an accelerator. We investigate a method for close estimation of bunch length for sub-picosecond electron bunches from the measurement of their energy spreads. Three or more measurements for the bunch energy spread are made by varying the phase of the accelerating structure and later a reconstruction of the bunch longitudinal dimensions, namely bunch length, initial energy spread and chirp at the entrance of the accelerating structure are obtained using the least square method. A comparison of the obtained results with ASTRA simulations is also included to validate the 3-phase method for sub-ps electron bunches. It is a simple method from both understanding (easy reconstruction using transport matrices) and experimental point of views (multiple measurements of energy spread with varying phase of the accelerating structure).
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MOPAB029	Experimental Study of Halo Formation at ATF2	vacuum, simulation, scattering, detector	142
	R.J. Yang, P. Bambade, A. Faus-Golfe, V. Kubytskyi, S. Wallon LAL, Orsay, France A. Aryshev, T. Naito KEK, Ibaraki, Japan N. Fuster-Martínez IFIC, Valencia, Spain
	For Accelerator Test Facility 2 (ATF2), as well as other high-intensity accelerators, beam halo has been an important aspect reducing the machine performance and activating the components. It is imperative to clearly understand the mechanisms that lead to halo formation and to test the avail- able theoretical models with an adequate experiment setup. In this paper, the experimental measurement of the beam halo formation from beam gas scattering is presented. The upgrading of an OTR/YAG screen monitor for future halo study is also introduced.
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MOPAB038	Research and Development of Diamond Based Beam Monitoring and Diagnostics Systems at the S-DALINAC	detector, monitoring, simulation, FPGA	163
	A. Rost, T. Galatyuk TU Darmstadt, Darmstadt, Germany T. Galatyuk, J. Pietraszko GSI, Darmstadt, Germany
	Funding: This work has been supported by the DFG through GRK 2128 and VH-NG-823. For future experiments with the HADES and CBM detectors at FAIR in Darmstadt, a radiation hard and fast beam detector is required. The beam detector has to perform precise T0 measurements (σ_T0 < 50 ps) and should also offer beam monitoring capabilities. These tasks can be fulfilled by utilizing single-crystal Chemical Vapor Deposition (scCVD) diamond based detectors. For research and development of such detectors, a test set-up will be installed at the Superconducting Darmstadt Electron Linear Accelerator (S-DALINAC) of TU Darmstadt. A read-out system for a beam monitoring and diagnostics system is currently under development. It is based on the already well established TRB3 platform, which can provide FPGA based signal discriminators and high precision FPGA-TDCs with on-line monitoring capabilities. In this contribution the concept and the performance of a prototype beam monitoring system will be discussed. Furthermore the preparatory work, with particular focus on the beam-line simulations, for a multipurpose beam detector test set-up at the S-DALINAC will be addressed.
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MOPAB039	Development of a Control System Based on Experimental Data for Space Charge Lenses	plasma, operation, ion, space-charge	166
	S. Klaproth, C. Beberweil, M. Droba, O. Meusel, H. Podlech, B.E.J. Scheible, K. Schulte, K.I. Thoma, C. Wagner IAP, Frankfurt am Main, Germany
	Space charge lenses use a confined electron cloud for the focusing of ion beams. The electron density gives the focusing strength whereas the density distribution influences the mapping quality of the space charge lens and is related to the confinement. The major role of the electron density with respect to the focusing quality has been pointed out many times in the past ,. With an automated measurement system the radial light density profile, plasma stability and mean value of the electron density have been measured in respect to the confining fields and the pressure. The results are summarized in 3D-maps. The theoretical model approximations for space charge lenses predicts high electron densities then measured. With the automated system the realistic 3D-maps can be considered instead of an approximation of a theoretical density including knowledge of the most stable electron cloud achievable within the parameter range of the lens. The experimental results of the automated measurement system will be presented here and a concept of a control system for this type of space charge lenses will be explained. O. Meusel, 'Focussing and transport of ion beams using space charge lenses', PhD thesis, 2006
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MOPAB043	Very First Experience with the Standard Diagnostics at the European XFEL	diagnostics, operation, cavity, electronics	180
	D. Lipka DESY, Hamburg, Germany
	The whole European XFEL becomes in operation this year. Dedicated standard diagnostics systems are installed and almost all types are tested at the injector before. Now the standard diagnostics are used to commission the facility. In this contribution the very first results and the operation experiences of the standard beam diagnostics of the entire European XFEL are reported.
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MOPAB044	X-Band TDS Project	polarization, experiment, diagnostics, cavity	184
	B. Marchetti, R.W. Aßmann, B. Beutner, J. Branlard, F. Christie, R.T.P. D'Arcy, W. Decking, U. Dorda, J. Herrmann, M. Hoffmann, M. Hüning, O. Krebs, G. Kube, S. Lederer, F. Ludwig, F. Marutzky, D. Marx, J. Osterhoff, I. Peperkorn, S. Pfeiffer, F. Poblotzki, J. Rönsch-Schulenburg, J. Rothenburg, H. Schlarb, M. Scholz, S. Schreiber, M. Vogt, A. Wagner, T. Wilksen, K. Wittenburg DESY, Hamburg, Germany M. Bopp, H.-H. Braun, P. Craievich, M. Pedrozzi, E. Prat, S. Reiche, K. Rolli, R. Zennaro PSI, Villigen PSI, Switzerland N. Catalán Lasheras, A. Grudiev, G. McMonagle, W. Wuensch CERN, Geneva, Switzerland
	Based on the success of the X-Band Transverse Deflecting Structure (TDS) diagnostic at LCLS, a collaboration between DESY, PSI and CERN has formed with the aim of developing and building an advanced modular X-Band TDS system. The designed TDS has the new feature of providing variable polarization of the deflecting field. The possibility of changing the orientation of the streaking field of the TDS to an arbitrary azimuthal angle allows for 3D characterization of the phase space using tomographic methods. Moreover the complete 6D characterization of the beam phase space is possible by combining this technique with quadrupole scans and a dipole spectrometer. As this new cavity design requires very high manufacturing precision to guarantee highest azimuthal symmetry of the structure to avoid the deterioration of the polarization of the streaking field, the high precision tuning-free assembly procedures developed at PSI for the SwissFEL C-band accelerating structures will be used for the manufacturing*. The high-power rf system is based on the CERN-based X-band test stands. We summarize in this work the status of the projects and its main technical parameters. C. Behrens et al. , Nat. Comm. 4762 (2014). A. Grudiev, CLIC-note-1067 (2016). * D. Marx et al., contribution to this conference proceedings. **** U. Ellenberger et al., FEL 2013, TUPS017.
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MOPAB045	Reconstruction of the 3D Charge Distribution of an Electron Bunch Using a Novel Variable-Polarization Transverse Deflecting Structure (TDS)	simulation, experiment, space-charge, laser	188
	D. Marx, R.W. Aßmann, U. Dorda, U. Dorda, B. Marchetti DESY, Hamburg, Germany P. Craievich PSI, Villigen PSI, Switzerland A. Grudiev, A. Grudiev, A. Grudiev CERN, Geneva, Switzerland
	A TDS is a well-known device for the characterization of the longitudinal properties of an electron bunch in a linear accelerator. So far, the correlation of the slice properties in the horizontal/vertical planes of the electron bunch distribution has been characterized by using a TDS system deflecting in the vertical/horizontal directions respectively and analysing the image on a subsequent screen. Recently, an innovative design for a TDS structure has been proposed, which includes the possibility of continuously varying the angle of the transverse streaking field inside a TDS structure. This allows the beam distribution to be characterized in all transverse directions. By collecting measurements of bunches streaked at different angles and combining them using tomographic techniques, it is possible to retrieve 3D distributions of the charge density. In this paper, a method is proposed and simulation results are presented to show the feasibility of such an approach at the upcoming accelerator R&D facility, SINBAD, at DESY*. M. Roehrs et al., Phys. Rev. ST Accel. Beams 12, 050704 (2009). A. Grudiev, Report No. CLIC-Note-1067, 2016. * B. Marchetti et al. X-band TDS project contribution to these conference proceedings.
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MOPAB046	Lattice Considerations for the Use of an X-Band Transverse Deflecting Structure (TDS) at SINBAD	dipole, quadrupole, lattice, cavity	192
	D. Marx, R.W. Aßmann, U. Dorda, U. Dorda, B. Marchetti, F. Mayet DESY, Hamburg, Germany F. Mayet University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	An X-band TDS is a well-known device for the characterization of the longitudinal properties of an electron bunch in a linear accelerator. It is planned that a novel X-band TDS with variable polarization* will be installed within the next few years at SINBAD, an upcoming accelerator R&D facility at DESY*. There are several measurements that can be performed with the TDS, each with specific optics requirements to reach the highest possible resolution and keep induced energy spread to a tolerable level. Quadrupoles will be installed between the TDS and the screen to help satisfy these conditions. In this paper, the requirements for the bunch length measurements, a novel 3D charge density reconstruction technique and slice energy measurements are discussed and some simulation results for the slice energy measurement using example lattices are presented. A. Grudiev, CLIC-note-1067 (2016). ** B. Marchetti et al. X-band TDS project contribution to these conference proceedings.
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MOPAB047	Electron Beam Phase Space Tomography at the European XFEL Injector	emittance, quadrupole, FEL, optics	196
	M. Scholz, B. Beutner DESY, Hamburg, Germany
	The FEL process is determined by the 6D phase space distribution of relativistic electron bunches. Experimental reconstructions of these distributions are therefore a step foreward to understand the beam dynamics and to optimize FEL operation. The reconstructions of the transverse phase spaces can be acieved with tomographic methods. In the injector of the European XFEL, measurements for the reconstruction of the phase spaces were carried out using phase advance scans with multiple quadrupoles. The beam sizes were kept optimized at the measurement screen. A transversely deflecting cavity (TDS) was used to streak the beam vertically. That allows to do longitudinally slice resolved measurements of the horizontal phase space. The horizontal streak required for the slice measurements in the vertical plane was achieved with a correlated linear energy spread and dispersion. In this paper, we present measurement results showing longitudinal slice resolved reconstructions of the transverse phase spaces taken in the European XFEL injector.
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MOPAB048	Simulation of fs Bunch Length Determination with the 3-Phase Method and THz Dielectric Loaded Waveguides	injection, linac, space-charge, simulation	199
	T. Vinatier, R.W. Aßmann, U. Dorda, B. Marchetti DESY, Hamburg, Germany
	In this paper, we investigate with ASTRA simulations the capability of the 3-phase method to reconstruct the length of a fs electron bunch. We show that a standard 3 GHz travelling wave accelerating structure is not suited for this purpose, because of the too important effect of the space-charge forces and of the too small variations of the induced energy spread with the bunch injection phase. Our simulations demonstrate that the use of dielectric-loaded waveguides driven by THz pulses would allow overcoming these two limitations and possibly achieving an ultimate resolution better than 5% for the determination of a 6.25 fs rms bunch length at 100 MeV energy and 1 pC charge. The next steps of the study to better evaluate, in simulations and experiments, the possible sources of degradation of the 3-phase method resolution are also mentioned.
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MOPAB050	Reconstruction of Sub-Femtosecond Longitudinal Bunch Profile Measurement Data	laser, diagnostics, undulator, cavity	207
	M.K. Weikum, R.W. Aßmann, U. Dorda DESY, Hamburg, Germany G. Andonian RadiaBeam, Santa Monica, California, USA G. Andonian UCLA, Los Angeles, California, USA Z.M. Sheng, M.K. Weikum USTRAT/SUPA, Glasgow, United Kingdom Z.M. Sheng Shanghai Jiao Tong University, Shanghai, People's Republic of China
	With a current trend towards shorter electron beams with lengths on the order of few femtoseconds (fs) to sub-femtoseconds both in conventional and novel accelerator communities, the need for diagnostics with equivalent attosecond resolution is increasing. The proposed design for a sub-femtosecond diagnostic by Andonian et al.* is one such example that combines a laser deflector with an RF deflecting cavity to streak the electron beam in the horizontal and vertical direction. In this paper, we present a tool for the reconstruction of the longitudinal beam profile from this diagnostic data, which can be used both for the analysis of planned experiments and testing of different beam scenarios with respect to their specific setup requirements. Applying this method, the usefulness of the device for measurements in a number of example scenarios, including plasma-accelerated and ultrashort RF-accelerated electron beams, is discussed. *G. Andonian, E. Hemsing, D. Xiang, P. Mumuseci, A. Murokh, S. Tochitsky, et al, Phys. Rev. Spec. Top-Ac. 14, 072802 (2011).
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MOPAB052	A Transverse Deflection Structure with Dielectric-Lined Waveguides in the Sub-THz Regime	simulation, emittance, impedance, laser	215
	F. Lemery University of Hamburg, Hamburg, Germany R.W. Aßmann, K. Flöttmann, T. Vinatier DESY, Hamburg, Germany
	Longitudinal bunch measurements are typically done with rf-powered transverse deflection structures with operating frequencies 1-12~GHz. We explore the use of mm-scale, THz-driven, dielectric-lined cylindrical waveguides as transverse deflectors by driving the fundamental deflecting mode of the structure, the HEM₁₁. We give a brief overview of the physics, history, and provide an example with a 5~MeV beam using {\sc astra} and {\sc CST-MWS}. This work was supported by the European Research Council (ERC) under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant agreement no. 609920
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MOPAB053	Electron Bunch Streaking With Single-Cycle THz Radiation Using an NSOM-Style TIP	simulation, laser, interaction-region, diagnostics	219
	F. Lemery, A.F. Hartin University of Hamburg, Hamburg, Germany D. Zhang DESY, Hamburg, Germany D. Zhang CFEL, Hamburg, Germany
	THz wavelengths provide an excellent scale for electron-bunch acceleration and manipulation. The improvement of laser-based THz-generation efficiencies to ~1% provides a good opportunity for e.g. phase-space manipulation and diagnostics. We describe a simple technique to streak and characterize electron beams. We provide full simulation results and discuss the scaling of this technique to various regimes.
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MOPAB055	Towards Near-Field Electro-Optical Bunch Profile Monitoring in a Multi-Bunch Environment	wakefield, laser, storage-ring, radiation	227
	P. Schönfeldt, E. Blomley, E. Bründermann, M. Caselle, S. Funkner, N. Hiller, B. Kehrer, A.-S. Müller, M.J. Nasse, G. Niehues, L. Rota, M. Schedler, M. Schuh, M. Weber KIT, Karlsruhe, Germany
	Funding: This work is funded by the BMBF contract numbers: 05K13VKA and 05K16VKA. For electron accelerators, electro-optical methods in the near-field have been shown to be a powerful tool to detect longitudinal bunch profiles. In 2013, we demonstrated for the first time, electro-optical bunch profile measurements in a storage ring at the accelerator test facility and synchrotron light source ANKA at the Karlsruhe Institute of Technology (KIT). To study possible bunch-bunch interactions and its effects on the longitudinal dynamics, these measurements need to be performed in a multi-bunch environment. Up to now, due to long-ranging wake-fields the electro-optical monitoring was limited to single-bunch operation. Here, we present our new in-vacuum setup to overcome this limitation. First measurements show reduced wake-fields in particular around 2 ns, where the subsequent bunch can occur in a multi-bunch environment at ANKA.
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MOPAB057	Analysis and Correction of Geometrical Non-Linearities of ELI-NP BPMs on Position and Current Measurements	linac, laser, photon, instrumentation	235
	G. Franzini, F. Cioeta, O. Coiro, V.L. Lollo, D. Pellegrini, S. Pioli, A. Stella, A. Variola INFN/LNF, Frascati (Roma), Italy M. Marongiu INFN-Roma, Roma, Italy A. Mostacci University of Rome La Sapienza, Rome, Italy A.A. Nosych ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain L. Sabato U. Sannio, Benevento, Italy
	The advanced source of Gamma-ray photons will be soon built near Bucharest (Romania) by an European consortium (EurogammaS) led by INFN, as part of the ELI-NP (Extreme Light Infrastructure-Nuclear Physics). It will generate photons by Compton back-scattering in the collision between a multi-bunch electron beam, at a maximum energy of 720 MeV, and a high intensity recirculated laser pulse. An S-Band photo-injector and the following C-band Linac, which are under construction, will operate at 100Hz repetition rate with macro pulses of 32 electron bunches, separated by 16ns and with 250pC nominal charge. Stripline and cavity BPMs will be installed along the linac, in order to measure both the position and charge of the electron beam. Stripline BPM response can be considered linear within a limited area around the BPM origin. In order to use the full BPM acceptance area, without accuracy losses due to non-linearities, we plan to use correction algorithms, developed on the basis of simulations and measurements of BPMs response. In particular, suitable high-order surface polynomials will be used.
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MOPAB058	Optical Issues for the Diagnostic Stations for the ELI-NP Compton Gamma Source	target, diagnostics, linac, laser	238
	M. Marongiu, D. Cortis INFN-Roma, Roma, Italy E. Chiadroni, F. Cioeta, G. Di Pirro, G. Franzini, V. Shpakov, A. Stella, A. Variola INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy A. Mostacci, L. Palumbo University of Rome La Sapienza, Rome, Italy L. Sabato U. Sannio, Benevento, Italy
	A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy in order to measure very small beam (below 30 um) or to study the angular distribution of the OTR and therefore the energy of the beam. Several configurations of the optical detection line will be studied both with simulation tools (e.g. Zemax) and experimentally. The paper will deal also with the sensibility of optic system (in terms of depth of field, magnification and resolution) to systematic errors.
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MOPAB059	Energy Chirp Measurements by Means of an RF Deflector: a Case Study the Gamma Beam Source LINAC at ELI-NP	linac, brightness, detector, simulation	242
	L. Sabato U. Sannio, Benevento, Italy P. Arpaia, A. Liccardo Naples University Federico II, Science and Technology Pole, Napoli, Italy A. Mostacci, L. Palumbo University of Rome La Sapienza, Rome, Italy A. Variola INFN/LNF, Frascati (Roma), Italy
	RF Deflector (RFD) based measurements are widely used in high–brightness electron LINAC around the world in order to measure the ultra–short electron bunch length. The RFD provides a vertical kick to the particles of the electron bunch according to their longitudinal positions. In this paper, a measurement technique for the bunch length and other bunch proprieties, based on the usage of an RFD, is proposed. The basic idea is to obtain information about the bunch length, energy chirp, and energy spread from vertical spot size measurements varying the RFD phase, because they add contributions on this quantity. The case study is the Gamma Beam System (GBS), the Compton Source being built in the Extreme Light Infrastructure–Nuclear Physics (ELI–NP) facility. The ELEctron Generation ANd Tracking (ELEGANT) code is used for tracking the particles from RFD to the measurement screen.
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MOPAB060	Thermal Issues for the Optical Transition Radiation Screen for the ELI-NP Compton Gamma Source	target, radiation, simulation, laser	246
	F. Cioeta, D. Alesini, A. Falone, V.L. Lollo, L. Pellegrino, A. Variola INFN/LNF, Frascati (Roma), Italy M. Ciambrella University of Rome La Sapienza, Rome, Italy D. Cortis, M. Marongiu, V. Pettinacci INFN-Roma, Roma, Italy A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy
	A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in two interaction points. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the OTR screens must sustain the thermal and mechanical stress due to the energy deposited by the bunches. This paper is an ANSYS study of the issues due to the high energy transferred to the OTR screens. Thermal multicycle analysis will be shown; each analysis will be followed by a structural analysis in order to investigate the performance of the material. The multiphysics analysis will be extended to the mechanical contact areas with the target frame in order to evaluate the order of magnitude of the phenomena in those regions.
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MOPAB064	Photoinjector Emittance Measurement at STAR	emittance, gun, solenoid, simulation	257
	A. Bacci, C. Curatolo, I. Drebot, L. Serafini, V. Torri Istituto Nazionale di Fisica Nucleare, Milano, Italy R.G. Agostino, R. Barberi, V. Formoso, M. Ghedini, F. Martire, C. Pace UNICAL, Arcavacata di Rende, Italy D. Alesini, M. Bellaveglia, J.J. Beltrano, F.G. Bisesto, G. Borgese, B. Buonomo, G. Di Pirro, G. Di Raddo, A. Esposito, A. Gallo, A. Ghigo, F. Iungo, A. Papa, L. Pellegrino, A. Stella, C. Vaccarezza, S. Vescovi INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy G. D'Auria, A. Fabris, M. Marazzi Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy V. Petrillo Universita' degli Studi di Milano, Milano, Italy A. Policicchio UniCal & INFN CS, Arcavacata di Rende (CS), Italy E. Puppin Politecnico/Milano, Milano, Italy M. Rossetti Conti Universita' degli Studi di Milano & INFN, Milano, Italy
	STAR is an advanced Thomson source of monochromatic and tunable, ps-long, polarised X-ray beams in the 40-140 keV range. The commissioning has started at the Univ. of Calabria (Italy). The light source is driven by a high-brightness, low-emittance electron beam produced in a LINAC allowing for the source tunability and spectral density. This note reports on an emittance measurement schema based on the insertion of a slit mask in the vacuum chamber dedicated to the photocathode laser entrance. Results of the simulation of the measurement technique are reported, and the use of the data for the optimisation of the accelerator performance are detailed. The experimental setup and the application developed in EPICS for image recording and analysis are also described.
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MOPAB065	Breit-Wheeler Scattering Events Produced by Two Interacting Compton Sources	photon, scattering, laser, background	261
	I. Drebot, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy D. Micieli, E. Tassi UNICAL, Arcavacata di Rende, Italy E. Milotti INFN-Trieste, Trieste, Italy V. Petrillo Universita' degli Studi di Milano & INFN, Milano, Italy
	We present the dimensioning of a photon-photon collider based on conventional Compton gamma sources for the observation of Breit-Wheeler pair production and QED gamma-gamma generation. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two primary gamma rays through Compton back-scattering with two high-energy lasers. Tuning the system energy above the Breit-Wheeler cross section threshold, a flux of secondary electrons and positrons is generated. The process is analyzed by start-to-end simulations. The Monte Carlo code 'Rate Of Scattering Events' (ROSE) has been developed ad hoc for the counting of the QED events. Realistic numbers of the secondary particles yield, referring to existing or approved set-ups, a discussion of the feasibility of the experiment and the evaluation of the background are presented.
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MOPAB066	Development and Performance Test of the BPM System for the SPring-8 Upgrade	radiation, simulation, storage-ring, photon	265
	H. Maesaka RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan H. Dewa, T. Fujita, M. Masaki JASRI, Hyogo, Japan S. Takano Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan
	We are developing a stable and precise BPM system for the low-emittance upgrade of SPring-8. One of the essential requirements for the BPM is the long term stabilization of the photon beam by regulating the electron beam orbit. Both the single-pass resolution of 100 um rms for an injected beam charge of 100 pC and an accuracy of 100 um rms are also crucial for beam commissioning. Drift sources of the present BPM system have been investigated extensively, such as humidity-dependent drifts coming from the radiation damage of coaxial cables, and the results are fed back to the design of the new BPM system. We have optimized the design of the button BPM electrodes to reconcile reduction of trapped-mode heating and maximization of the signal intensity. Stringent machining tolerance is imposed on a BPM head to align the BPM electric center accurately. A few kinds of the BPM head prototypes were produced and the machining accuracy, RF characteristics etc. were confirmed to be sufficient. We have installed one of the prototypes in the present storage ring to test the performance of the new BPM system under development, and have been obtaining successful results satisfying the requirements.
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MOPAB067	Response of Scintillating Screens to High Charge Density Electron Beam	quadrupole, linac, diagnostics, experiment	268
	F. Miyahara, S. Kishimoto, M. Satoh, Y. Seimiya, T. Suwada KEK, Ibaraki, Japan M. Koshimizu Tohoku University, School of Science, Sendai, Japan
	Inorganic scintillating screens are very useful tool to measure transverse profile of charged particle beams. The cerium-doped yttrium:aluminum:garnet (YAG:Ce) crystal scintillator is used in many accelerating facilities. The scintillating screen shows good resolution comparable to that of OTR screen. However, response to high charge density electron beam, more than 10 nC per square millimeter, has not been clarified. In KEK e⁺/e⁻ injector linac, the charge areal density (σ) will exceed 25 nC per square mm. Thus, beam tests has been performed on YAG:Ce, LYSO, and BGO crystals for 1.5 GeV, 1 nC/bunch electron beam at the linac. Saturation of the luminescence which causes degradation of the resolution has been observed above 1 nC per square mm in those crystals. We will report the response of the scintillating screens to high charge density electron beam and discuss the degradation of the resolution due to the saturation of the light yield.
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MOPAB068	Bunch Shape Monitor Development in J-PARC Linac	vacuum, quadrupole, focusing, target	271
	A. Miura, J. Tamura JAEA/J-PARC, Tokai-mura, Japan Y. Liu KEK/JAEA, Ibaraki-Ken, Japan T. Miyao KEK, Ibaraki, Japan
	At Japan accelerator reserch complex (J-PARC), the linac, which serves as the injector for the downstream 3-GeV synchrotron, accelerates a negative-hydrogen-ion beam (H⁻) to obtain a 400-MeV beam energy. We use an accelerating frequency of 324 MHz for the accelerator cavities and of 972 MHz. Both the centroid-phase set point at the frequency jump from 324 MHz to 972 MHz and the phase-width control are key issues for suppressing the excess beam loss. In order to optimize a set point of the tuning cavities, we developed a bunch-shape monitor (BSM) to measure the phase width as well as a tuning strategy to minimize the beam loss. In the development of the BSM, the design developed in the INR, Russia. Because the BSM had first experienced to be used between accelearation cavities, we need to protect the leak-magnetic field from quadrupole magnets and outgas impacts to cavities. We installed a BSM again in the beamline, BSM started to measure the phase width and evaluated its performances with a peak-beam-current dependence. We proposed new strategy to use BSM-measurment data for the tuning cavity. This paper describes the BSM development, its modification, and new strategy.
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MOPAB072	Measurement of Three-Dimensional Distribution of Electron Bunch Using RF Transverse Deflector	experiment, laser, gun, solenoid	285
	Y. Nakazato, Y. Koshiba, T. Sasaki, M. Washio Waseda University, Tokyo, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
	We have been studying a high quality electron beam generated by a photocathode RF gun at Waseda University. The electron beam is applied to a pulse radiolysis experiment, laser Compton scattering for soft X-ray generation, and a THz imaging experiment using coherent radiation. In these applications, longitudinal parameters of the electron beam are important. For this reason, we developed the RF deflector system which can directly convert longitudinal distribution of the beam to transverse with high temporal resolution, and performed longitudinal profile measurements of an electron beam from the RF gun. During a series of experiments using an RF deflector, we found that the bunch had a horizontal angle with respect to z axis. Thus we tried to reconstruct the three-dimensional profile of the bunch by computed tomography* in order to visualize the three-dimensional distribution of the bunch. In this conference, we will report the principle of measurement, experimental results of the bunch three-dimensional measurement, and future prospects. * J. Shi, et al., Reconstruction of the three-dimensional bunch profile by tomography technique with RF deflecting cavity, Nucl. Instrum. Methods Phys. Res., A 752 (2014) 36-41
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MOPAB073	Measurement of Electron-Bunch Length Using Coherent Radiation in Infrared Free-Electron Laser Facilities	FEL, detector, radiation, laser	288
	N. Sei, H. Ogawa AIST, Tsukuba, Ibaraki, Japan K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, T. Tanaka LEBRA, Funabashi, Japan H. Ohgaki, H. Zen Kyoto University, Kyoto, Japan
	Funding: This study was financially supported by JSPS KAKENHI Grant Number JP16H03912. We have studied techniques evaluating bunch length of micropulses in an electron beam. The bunch length of the electron beam is an important parameter for free-electron laser (FEL) facilities with linear accelerators. In order to obtain high FEL gain at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University and at Kyoto University Free Electron Laser (KU-FEL), the electron-bunch length is compressed to less than 1 ps in their undulator sections. Using the compressed electron beams, intense terahertz lights were generated by coherent radiation. The power of the coherent radiation was more than 50 micro-joule per electron-beam macropulse. We can extract the information of the bunch length of the electron-beam micropulse from the intense coherent radiation by using narrow-band diode detectors. In this presentation, experimental results of the measurements of the root-mean-square electron-bunch length using the coherent radiation at LEBRA* and KU-FEL** will be reported. : N. Sei et al., J. Opt. Soc. Am. B, 31, 2150 (2014). *: N. Sei et al., Nucl. Instrum. Methods Phys. Res., Sect. A, 832, 208 (2016).
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MOPAB074	Low Intensity Electron Beam Controlling and Monitoring	detector, linac, controls, experiment	292
	L. Yu, Y. Li, Y.F. Sui, J.H. Yue IHEP, Beijing, People's Republic of China
	To calibrating a cosmic-ray detector, a low beam current accelerator has been built to generate ultra low intensity electron beams at Institute of High Energy Physics (IHEP). The minimum beam charge obtained was estimated to be about one electron/pulse. Beam commissioning has been carried out. The key technologies for achieving such low intensity electron beams are to control the beam using 8 movable slits and to measure the intensity of the beam using 9 movable current monitors based on scintillator. In this paper, principal of operation, instrumentation and programming of the movable slits and movable current monitors are discussed. Some results of beam commissioning are also presented.
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MOPAB075	Measurement of Electron Bunch Length via a Tunable-Gap Undulator	radiation, undulator, laser, acceleration	295
	X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan TUB, Beijing, People's Republic of China Y.F. Liang Tsinghua University, Beijing, People's Republic of China
	A THz undulator with widely tunable gap is constructed and installed at Tsinghua University beamline, which is applied for narrow-band THz radiation and measurements of electron bunch longitudinal structure. This is a planar electromagnetic device with 8 regular periods, each 10 cm long. The field range B=0.15- 0.99 T peak field on axis while changing the gap from 75mm to 23mm. In the experiments, we scanned the undulator gap to measure the radiation intensity at different resonant frequency, thus we can get the bunch length even form factor of the bunch. The demonstrated experimental results show that the bunch of 220pC compressed by chicane in Tsinghua beamline is about 120fs (rms), which agree well with the simulations. The resolution of bunch length measurement with this method can be attoseconds by optimized undulator. Furthermore, the form factor of electron bunch train can also be measured.
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MOPAB077	Spatial Decoding Electro-Optic Bunch Measurement at Tsinghua Thomson Scattering X-ray Source	laser, experiment, diagnostics, scattering	302
	W. Wang, Z.J. Chi, Y.-C. Du, W.-H. Huang, C.-X. Tang, L.X. Yan, Z. Zhang TUB, Beijing, People's Republic of China
	Electron bunches with duration of sub-picosecond are essential in ultraviolet and X-ray free electron laser (XFEL) to reach the desired peak current. Electro-optic (EO) technique is suitable for temporal profile measure-ment of these ultrashort bunches which is one of the key diagnostics in FELs. An electro-optic monitor based on spatial sampling has recently been designed and installed for bunch profile diagnostic at Tsinghua Thomson scat-tering X-ray source (TTX). An ultrashort laser pulse is used to detect the field induced birefringence of the bunch Coulomb field in an electro-optic crystal and the monitor allows direct time-resolved single-shot measure-ment of bunch profile with an accuracy of 135 femtosec-onds for a 40 MeV electron bunch in a non-destructive way, which can simultaneously record the relative time jitter between probe laser and electron bunch. This paper performs the layout of the setup and presents the current measurement results.
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MOPAB082	Design and Simulation of High Order Mode Cavity Bunch Length Monitor for Infrared Free Electron Laser	cavity, simulation, FEL, laser	309
	Q. Wang, X.Y. Liu, P. Lu, Q. Luo, B.G. Sun, L.L. Tang, J.H. Wei, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900, 2016YFA0401903); NSFC (11375178, 11575181); the Fundamental Research Funds for the Central Universities (WK2310000046) A bunch length monitor using resonant cavity has been designed for the NSRL Infrared Free Electron Laser (IR-FEL) facility. To avoid the restriction of working fre-quency caused by the beam pipe radius, the high order modes of the harmonic cavities are utilized. The position and orientation of coaxial probes are optimized to avoid interference modes which come from the cavity and beam tube according to the analysis formula of electro-magnetic field distribution. Based on the parameters of IR-FEL, a simulation is performed to verify the feasibility of the bunch length monitor. The simulation result shows that the design meets the requirements of IR-FEL, and the resolution can be better than 50 fs.
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MOPAB083	The New Beam Current Transformer for IR-FEL Facility at NSRL *	FEL, diagnostics, induction, electronics	312
	J.H. Wei, H. Li, X.Y. Liu, P. Lu, B.G. Sun, J.G. Wang, Q. Wang, F.F. Wu, Y.L. Yang, T.Y. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by The National Science Foundation of China (Grant No. 11575181) The beam current transformer (CT) is an important part of the beam diagnostics system as a kind of non-destructive intensity measurement. The beam CT has the strong dependence of the sensitivity and time constant on the time structure of the beam. To measure the macro-pulse beam intensity with 5-10 's length and 238 MHzμpulse repetition rate in the IR-FEL, it is necessary to find a suitable material as the CT core which can meet the measure requirement of the beam current. In this paper, three different magnetic materials were tested to find out that the laminated amorphous core owned the best performance, meanwhile, the mechanical structure was designed. The finished product passed the acceptance test.
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MOPAB098	Coronagraph Based Beam Halo Monitor Development for BERLinPro	background, dipole, linac, scattering	355
	J.G. Hwang Kyungpook National University, Daegu, Republic of Korea J. Kuszynski HZB, Berlin, Germany
	For linac based high power electron machines, beam halo induced by nonlinear space charge force and scattering of trapped ions is one of the critical issues on a machine protection system. It causes additional radiation which can be a heat source on a cryogenic system as a result of uncontrolled beam losses. During the last decades, several instruments have been newly developed for measuring the beam halo distribution. The conceptual design and optimization of the coronagraph based halo monitor were performed to measure the beam halo which has ~ 10^-3 contrast to the beam core.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB098
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MOPAB118	Cherenkov Diffraction Radiation From Long Dielectric Material: An Intense Source of Photons in the NIR-THz Range	photon, radiation, target, storage-ring	400
	T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni CERN, Geneva, Switzerland M.G. Billing, J.V. Conway, J.P. Shanks Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA L.M. Bobb DLS, Oxfordshire, United Kingdom P. Karataev Royal Holloway, University of London, Surrey, United Kingdom
	This paper presents the design on the Cornell Electron Storage Ring (CESR) of an experimental set-up to meas-ure incoherent Diffraction Cherenkov Radiation (DChR) produced in a 2 cm long SiO2 radiator by a 2.1 GeV elec-tron beam. The electron beam is circulating at a distance of few mm from the edge of the radiator and the DChR photon output power is expected to be significantly higher than the diffraction radiation power emitted from a metal-lic slit of similar aperture. The radiator design and the detection set-up are presented in detail together with sim-ulations describing the expected properties of the emitted DChR in terms of light intensity and spectral bandwidth. Finally, potential applications of DChR are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB118
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MOPAB119	Beam Instrumentation Developments for the Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN	proton, plasma, laser, electronics	404
	S. Mazzoni, M. Barros Marin, B. Biskup, A. Boccardi, T.B. Bogey, S. Burger, F.S. Domingues Sousa, E. Effinger, J. Emery, A. Goldblatt, I. Gorgisyan, E. Gschwendtner, A. Guerrero, L.K. Jensen, T. Lefèvre, D. Medina, B. Moser, G. Schneider, L. Søby, M. Turner, M. Vicente Romero, M. Wendt CERN, Geneva, Switzerland B. Biskup Czech Technical University, Prague 6, Czech Republic M. Turner TUG/ITP, Graz, Austria V.A. Verzilov TRIUMF, Vancouver, Canada
	The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) at CERN aims to develop a proof-of-principle electron accelerator based on proton driven plasma wake-field acceleration. The core of AWAKE is a 10 metre long plasma cell filled with Rubidium vapour in which single, 400 GeV, proton bunches extracted from the CERN Super Proton Synchrotron (SPS) generate a strong plasma wakefield. The plasma is seeded using a femtosecond pulsed Ti:Sapphire laser. The aim of the experiment is to inject low energy electrons onto the plasma wake and accelerate them over this short distance to an energy of several GeV. To achieve its commissioning goals, AWAKE requires the precise measurement of the position and transverse profile of the laser, proton and electron beams as well as their temporal synchronisation. This contribution will present the beam instrumentation systems designed for AWAKE and their performance during the 2016 proton beam commissioning period.
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MOPAB124	A Fast Gain Calibration Algorithm for Beam Position Monitoring at Taiwan Photon Source	pick-up, storage-ring, operation, target	419
	J.Y. Chen, C.H. Chen, M.-S. Chiu, P.C. Chiu, P.J. Chou, S. Fann, K.H. Hu, C.S. Huang, C.-C. Kuo, T.Y. Lee, C.C. Liang, Y.-C. Liu, G.-H. Luo, H.-J. Tsai, F.H. Tseng NSRRC, Hsinchu, Taiwan
	A stable, reliable and well-calibrated beam position monitor (BPM) system is essential for the operation of accelerators. At newly constructed Taiwan Photon Source (TPS), it not only helps us to determine the accelerator parameters, such as Twiss parameters and tune, but also to avoid the damage on accelerator instruments caused by high-energy particle beams or radiation. In this study, we demonstrate a new BPM calibration scheme at TPS storage ring. To excite the electron beams inside accelerator beam pipe by one horizontal or vertical corrector magnet, we measure the response of analog-to-digital converter (ADC) of each BPM pick-up electrodes with different lateral positions and beam currents. Depending on the measured ADC responses, we calibrated the beam position monitor system. Simultaneously, because of limited preparation time after every long shutdown, we are looking for a fast algorithm to ensure the measurement could be done easily and finished as quickly as possible.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB124
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MOPAB126	Applications of Metamaterials for Particle Beam Diagnostics	target, radiation, diagnostics, resonance	425
	T.G. Vaughan, P. Karataev JAI, Egham, Surrey, United Kingdom V. Antonov Royal Holloway, University of London, Surrey, United Kingdom V.V. Soboleva RASA Center in Tomsk, Tomsk, Russia
	Funding: The work was supported by the Leverhulme Trust through the International Network Grant (IN-2015-012) and the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179 and Russian Governmental Program 'Nauka', N: 0.1656.2016. Modern and future accelerators, such as linear colliders and X-ray Free Electron Lasers (X-FELs), will be capable of producing femtosecond and sub-femtosecond electron bunches with unprecedented intensity. Non-invasive beam diagnostics will be an integral component of such machines. A new non-destructive method, which employs a Left Handed Metamaterial (LHM), is promising as it provides additional flexibility in the generation and manipulation of radiation compared to techniques which use conventional materials. Simulations of the interaction of a photon beam with the LHM target have been performed using CST Microwave Studio. The range over which the frequency responce is negative can be tuned to the bunch length requirements by varying the parameters of the unit cell such as: the dimensions of the rings and the number of slits in each ring. Simulations have also been performed using Particle Studio on the interaction of an electron beam with the LHM. With a flexible resonance in the terahertz range, this material not only offers applications for ultra short bunch length measurements, but it also opens up the possibility to be used to generate coherent terahertz radiation.
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MOPAB132	Beam Size Measurement Using High Aspect Ratio LIGA Apertures in an X-Ray Pinhole Camera	radiation, synchrotron, status, emittance	445
	L.M. Bobb, G. Rehm DLS, Oxfordshire, United Kingdom
	For optimal brilliance third generation light sources operate at a low emittance and low coupling. Commonly, transverse beam profile measurements are provided by direct imaging of the electron beam using X-ray pinhole cameras. From these beam size measurements and given knowledge of the lattice parameters the emittance, coupling and energy spread are calculated. Ideally, the pinhole aperture should be formed in an infinitely thin screen. However, due to the penetration of X-rays in the keV spectral range, stacked tungsten blades are often used to form the pinhole aperture. In this arrangement the absolute size of the pinhole aperture is unknown and cannot be directly measured, which affects the spatial resolution of the imaging system. Here we investigate the use of X-ray Lithography, Electroplating and Moulding (commonly known as LIGA) to fabricate high aspect ratio pinhole apertures in a gold screen of approximately 1 mm thickness.
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MOPAB138	Comparison of Optical Transition Radiation Simulations and Theory	radiation, diagnostics, simulation, optics	455
	J. Wolfenden, R.B. Fiorito, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom M. Bergamaschi, P. Karataev, K.O. Kruchinin JAI, Egham, Surrey, United Kingdom M. Bergamaschi, P. Karataev, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom M. Bergamaschi, R. Kieffer, T. Lefèvre CERN, Geneva, Switzerland R.B. Fiorito, C.P. Welsch, J. Wolfenden The University of Liverpool, Liverpool, United Kingdom
	The majority of optical diagnostics currently used will not stand up to the requirements of the next generation of particle accelerators. Current methodologies need innovation to be able to reach the sub-micrometre resolution and sensitivity that will be required. One technique that has the potential to meet these requirements is optical transition radiation (OTR) imaging. A new algorithm is proposed which incorporates OTR theory, optical effects and beam distribution. This algorithm takes an existing method used for beam imaging and pushes the limits resolution beyond that normally attainable. In doing so, it can provide a reliable and economical diagnostic for future accelerators. A discussion on further applications of the algorithm is also presented.
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MOPAB139	A Supersonic Gas-Jet Based Beam Induced Fluorescence Prototype Monitor for Transverse Profile Determination	ion, photon, experiment, gun	458
	H.D. Zhang, E. Martin, V. Tzoganis, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom E. Barrios Diaz, N. Chritin, O.R. Jones, G. Schneider, R. Veness CERN, Geneva, Switzerland P. Forck, S. Udrea GSI, Darmstadt, Germany P. Forck IAP, Frankfurt am Main, Germany E. Martin, V. Tzoganis, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom S. Udrea TU Darmstadt, Darmstadt, Germany
	Supersonic gas jets have been used in transverse beam profile monitoring as Ionization Profile Monitors (IPMs) and Beam Induced Fluorescence (BIF) monitors. The former method images ions generated by the projectile beam, whilst the latter is based on the detection of photons. This is a promising technology for use in high energy accelerators, such as the High Luminosity Large Hadron Collider (HLLHC). In this paper, the suitability of a supersonic gas jet in combination with a BIF detection system for the measurement of the transverse beam profile of a low energy electron beam is discussed. The technical layout and experimental results from measurements at a test installation at the Cockcroft Institute are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB139
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MOPAB144	Residual-Gas Beam Profile Monitors for Intense Beams in Transfer Lines	ion, proton, synchrotron, detector	469
	R.J. Abrams, M.A. Cummings, V.G. Dudnikov, R.P. Johnson Muons, Inc, Illinois, USA M. Popovic Fermilab, Batavia, Illinois, USA
	Muons, Inc. proposes to develop a Residual-Gas Beam Profile Monitor for Transfer Lines with pulse-to-pulse precision of better than 0.1 mm in position and size that will operate over a wide range of proton beam intensities including those needed for multi-MW beams of future facilities. Traditional solid-based beam intercepting instrumentation produces unallowable levels of radiation at high powers. Our alternative approach is to use a low mass residual-gas profile monitor, where ionization electrons are collected along extended magnetic field lines and the gas composition and pressure in the beam pipe are locally controlled to minimize unwanted radiation and to improve resolution. Beam Induced Fluorescence profile monitor with mirascope light collection is proposed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB144
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MOPAB146	Electron Beam Diagnosis Using K-edge Absorption of Laser-Compton Photons	laser, photon, emittance, scattering	473
	Y. Hwang, T. Tajima UCI, Irvine, California, USA C.P.J. Barty, D.J. Gibson, R.A. Marsh LLNL, Livermore, California, USA
	Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The mean energy, energy spread and divergence of the electron beam can be deduced from laser-Compton scattered X-rays filtered by a material whose K-edge is near the energy of the X-rays. This technique, combined with a spot size measurement of the beam, can be used to measure the emittance of electron bunches, and can be especially useful in LWFA experiments where conventional methods are unavailable. The effects of the electron beam parameters on X-ray absorption images are discussed, along with experimental demonstrations of the technique using the Compact Laser-Compton X-ray Source at LLNL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB146
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MOPAB150	Imaging the Spatial Modulation of a Relativistic Electron Beam	experiment, scattering, quadrupole, emittance	480
	C. Zhang, W.S. Graves, L.E. Malin, J. Spence Arizona State University, Tempe, USA D.B. Cesar, J.M. Maxson, P. Musumeci, A. Urbanowicz UCLA, Los Angeles, USA C. Limborg, E.A. Nanni SLAC, Menlo Park, California, USA
	Funding: Work supported by NSF awards 1632780, 1415583, 1231306 and DOE award de-sc0009914 We describe Bragg diffraction of relativistic electron beams through a patterned Si crystal consisting of alternating thick and thin strips to produce nanometer scale electron density modulations. Multi-slice simulations show that a two-beam situation can be set up where, for a particular thickness of Si, nearly 100% of the electron beam is diffracted. Plans are underway to carry out experiments showing this effect in UCLA's ultrafast electron microscopy lab with 3.5 MeV electrons. We will select either the diffracted beam or the primary beam with a small aperture in the diffraction plane of a magnetic lens, and so record either the dark or bright field magnified image of the strips. Our first goal is to observe the nanopatterned beam at the image plane. We will then investigate various crystal thickness and sample orientations to maximize the contrast in the pattern and explore tuning the period of the modulation through varying magnification.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB150
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MOPAB153	R&D of a Gas-Filled RF Beam Profile Monitor for Intense Neutrino Beam Experiments	cavity, plasma, ion, experiment	491
	K. Yonehara, M. Backfish, A. Moretti, A.V. Tollestrup, A.C. Watts, R.M. Zwaska Fermilab, Batavia, Illinois, USA R.J. Abrams, M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer Muons, Inc, Illinois, USA Q. Liu Case Western Reserve University, Cleveland, USA
	Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013764. A MW-power beam facility is desired to produce an intense neutrino beam for study of fundamental particle physics. It is a critical challenge to measure beam profile in extreme radiation environments. To this end, a novel beam profile monitor based on a gas-filled multi-RF cavity is proposed. Charged particles through the gas-filled RF generate plasma that changes the gas permittivity. The modulated RF signal in the cavity due to the permittivity shift will be measured to reconstruct the flux of charged particles in the cavity. The demonstration is proposed to validate the concept of the monitor. We report the progress of the demonstration test.
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MOPIK004	Demonstration of an All-Optically Driven Sub-keV THz Gun	gun, acceleration, laser, operation	503
	W.R. Huang, K.-H. Hong, F.X. Kärtner, E.A. Nanni, KR. Ravi MIT, Cambridge, Massachusetts, USA A-L. Calendron, H. Cankaya, A. Fallahi, F.X. Kärtner, X. Wu CFEL, Hamburg, Germany D. Zhang DESY, Hamburg, Germany
	Funding: European Research Council under the European Union Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement no. 609920 Intense ultrashort THz and optical pulses with single-cycle pulse duration became possible after the recent advances in ultrafast technologies. Using such ultrashort pulses for electron acceleration offers advantages in terms of higher thresholds for material breakdown which opens up a promising path towards increased acceleration gradients. In addition, using optically generated THz pulses enable inherently synchronized acceleration schemes, since accelerating field and particle injecting field are excited by a single seed laser. In this contribution, we present the first experimental demonstration of laser-driven THz acceleration of electrons initially at rest. It is shown that strong-field, single-cycle THz fields accelerate electrons with peak energies of up to 0.8 keV in an ultracompact THz gun with bunch charge of 40 fC. The achieved energy spreads are as low as 5.8%.
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MOPIK005	Compact Electron Injectors Using Laser Driven THz Cavities	cavity, gun, laser, acceleration	506
	M. Fakhari, A. Fallahi, F.X. Kärtner, N.H. Matlis, A. Yahaghi CFEL, Hamburg, Germany R.W. Aßmann, U. Dorda, K. Galaydych, B. Marchetti, G. Vashchenko, T. Vinatier, D. Zhang, C. Zhou DESY, Hamburg, Germany
	We present ultra-small electron injectors based on cascaded cavities excited by short multi-cycle THz signals. The designed structure is a 3.5 cell normal conducting cavity operating at 300 GHz. This cavity is able to generate pC electron bunches and accelerate them up to 250 keV using less than 1 mJ THz energy. Unlike conventional RF guns, the designed cavity operates in a transient state which, in combination with the high frequency of the driving field, makes it possible to apply accelerating gradients as high as 500 MV/m. Such high accelerating gradients are promising for the generation of high brightness electron beams with transverse emittances in the nm-rad range. The designed cavity can be used as the injector for a compact accelerator of low charge bunches.
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MOPIK006	Characterization of the Electron Beam from the Thz Driven Gun for AXSIS	gun, experiment, simulation, diagnostics	509
	G. Vashchenko, R.W. Aßmann, U. Dorda, K. Galaydych, B. Marchetti, T. Vinatier DESY, Hamburg, Germany M. Fakhari, A. Fallahi, F.X. Kärtner, N.H. Matlis CFEL, Hamburg, Germany W. Qiao, C. Zhou University of Hamburg, Hamburg, Germany
	Funding: The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 609920 The AXSIS (Attosecond X-ray Science: Imaging and Spectroscopy) project aims for development of a compact, fully coherent, THz-driven, attosecond X-ray source. A compact THz driven gun was developed, produced and tested as a source of the ultra-short electron bunches required for the project. To characterize the low energy, low-charge beam produced by such a gun tailored diagnostic devices were developed and commissioned at a test-stand chamber in CFEL (DESY). Results of the first experiments on the production and characterization of the electron beam are presented.
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MOPIK007	THz Driven Electron Acceleration with a Multilayer Structure	acceleration, laser, gun, dipole	512
	D. Zhang, M. Fakhari, W. Qiao, C. Zhou DESY, Hamburg, Germany F. Ahr, A-L. Calendron, H. Cankaya, M. Fakhari, A. Fallahi, F.X. Kärtner, F. Lemery, N.H. Matlis, X. Wu CFEL, Hamburg, Germany W.R. Huang, F.X. Kärtner MIT, Cambridge, Massachusetts, USA C. Zhou University of Hamburg, Hamburg, Germany
	We present first results in THz-based electron acceleration using a novel multilayer structure which we dub a Butterfly LINAC. THz-based accelerators are mm-scale devices that bridge the gap between micron-scale, ultra-compact devices such as laser-plasma accelerators (LPAs) and dielectric laser accelerators (DLAs) and meter-scale conventional accelerators. These intermediate-scale devices are promising because they combine many of the benefits of LPAs and DLAs, such as intrinsic synchronization and high acceleration gradients with the benefits of conventional accelerators such as high charge capacity, tunability as well as the robustness, stability and simple fabrication of static, macroscopic acceleration structures. The Butterfly LINAC allows optimization of electron acceleration using transversely-coupled single-cycle THz pulses by phase-matching electrons with the driving field. Proof-of-concept experiments will be described demonstrating 10 keV energy gain of a 55 keV source, in good agreement with simulation. Scalability of this device to the MeV level and applicability towards free electron lasers and ultrafast electron diffractometers will also be discussed.
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MOPIK008	Numerical Studies on a Modified Cathode Tip for the ELBE Superconducting RF Gun	cathode, SRF, gun, simulation	515
	E.T. Tulu, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany A. Arnold HZDR, Dresden, Germany
	Future light sources such as synchrotron radiation sources driven by an Energy Recovery Linac (ERL), Free Electron Laser (FEL) or THz radiation sources have in common that they require injectors, which provide high-brilliance, high-current electron beams in almost continuous operation. Thus, the development of appropriate highly brilliant electron sources is a central factor. A promising approach for this key component is provided by superconducting radiofrequency photoinjectors (SRF guns) []. Since 2007, the free-electron laser FELBE at HZDR successfully operates such a SRF gun under real conditions and equipped with all components []. Nevertheless, there are limitations caused by multipacting which should be overcome in order to further improve the gun []. One aspect in order to reach this aim lies in studying various modifications of the cathode tip [*]. This contribution will present the effectiveness of isosceles triangular grooves with respect to MP. Arnold, et al., NIM A, 593, 57, (2008). J. Teichert, et al., 2008 NSS/MIC, Dresden, Germany. * J. Teichert, et al., J. Phys.: Conf. Ser. 298(2011), 012008. **** E. T. Tulu, et al., IPAC2014, p652, Dresden, Germany.
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MOPIK011	Electron Beam Generation From InGaN/GaN Superlattice Photocathode	laser, polarization, gun, brightness	522
	N. Yamamoto KEK, Ibaraki, Japan M. Hosaka, A. Mano, T. Miyauchi, Y. Takashima Nagoya University, Nagoya, Japan M. Katoh UVSOR, Okazaki, Japan
	GaAs-type photocathode (PC) has been used as electron spin polarization (ESP) sources for various applications. Recently, by using a strain-compensated technique for GaAs/GaAsP, the super lattice (SL) thickness of up to 720 nm could be manufactured and the quantum efficiency (QE) improvements with the thickness increases was observed. In the experiments, the ESP degradation was also observed for the thicker thickness samples than 194nm and we considered that electron spin relaxation during diffusion process in the PC caused the degradation. Therefore, we propose developing fcc-GaN based PCs instead of GaAs because a factor of ten longer spin relaxation time compared with GaAs/GaAsP SL was reported. However an fcc-GaN sample with adequate dimensions for PC applications is not available at present due to manufacturing difficulties. Then at the start of GaN-type PC development, an hcp-GaN sample has been studied. In the study, NEA-activation was made for an InGaN/GaN SL sample and QE, surface lifetime and ESP were measured. The QE and ESP values were 1.3% and 2.1% at the pump laser wavelength of 405nm.
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MOPIK013	Design and Simulation of a C-Band Photocathode RF Gun With a Coaxial Coupler for UEM	gun, cavity, coupling, impedance	525
	T. Chen, Y.J. Pei, Y. Song USTC/NSRL, Hefei, Anhui, People's Republic of China
	A ultrafast electron microscope (UEM) has been become much more important research instrument and has been widely used in many fields. As a part of the UEM, a photocathode RF gun working at C-band frequency of 5712MHz is being developed, which provides electron beam with high qualities for UEM. This paper presents the physics and structure design, including optimization of cavity shape parameter for improving shunt impedance and Q factor. We adopt a novel coaxial coupler, which could decrease the multipole field and decrease the focusing coil size, build better accelerating field in the RF gun. In this paper, we discussed the simulation process and results of the RF gun, especially the design of the coaxial input coupler was described.
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MOPIK015	Improvement of Electron Intensity Reduction System at SLRI Beam Test Facility	target, synchrotron, booster, shielding	528
	K. Kittimanapun, N. Chanlek, P. Klysubun, S. Krainara, S. Supajeerapan SLRI, Nakhon Ratchasima, Thailand
	Funding: This work is partly supported by the National Science and Technology Development Agency (NSTDA) under contract FDA-C0-2558-855-TH. Synchrotron Light Research Institute (SLRI) has been commissioning an additional experimental station, a Beam Test Facility (BTF), to the SLRI accelerator complex. SLRI BTF was constructed to provide electron test beams with energy ranging from 40 MeV up to 1.2 GeV and with tunable electron intensity from a few to millions of electrons per burst. In order to obtain low intensity of test beams, an approach using a metal target together with an energy selector has been employed. A combination of a target chamber installed at the high energy beam transport line and the existing 4-degree bending magnet that is used as an energy selector first produced low intensity test beams. However, the test beam profile was not well determined due to the insufficient bending angle of the energy selector and high primary beam energy. Another approach mounting a target chamber at the low energy beam transport line and using the synchrotron booster as an energy selector was implemented to avoid such problems. Once in operation, the facility will have the potential to service calibration and testing of high energy detectors as well as beam diagnostic instrumentations.
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MOPIK016	Sub-Picosecond Beam Production for External Injection Into Plasma Experiments	gun, plasma, linac, simulation	531
	O. Mete Apsimon, R. Apsimon, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G.X. Xia UMAN, Manchester, United Kingdom
	Funding: This work has been funded by STFC. Applications of plasmas in accelerators benefit from short probe bunches comparable to plasma wavelength due to currently achievable plasma wake profiles. In plasma acceleration case, high capture efficiency within a narrow energy spectrum can be achieved when a sub-picosecond to femtosecond witness bunch injected behind the driver pulse at the high electric field region. A start-to-end simulation study was performed for parametric optimisation of an rf photoinjector to provide a short witness bunch for plasma applications in accelerators. An rf photoinjector is a laser-driven, high brightness and robust electron source that can provide stability and flexibility provided by today's advanced laser and rf technologies.
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MOPIK018	Micro-Scale Electron Beam Generation Using Pyroelectric Crystals	acceleration, laser, injection, diagnostics	538
	R.B. Yoder, Z. Kabilova Goucher College, Baltimore, Maryland, USA
	Novel laser-powered acceleration structures currently under development, which have dimensions comparable to optical wavelengths and can be constructed on a silicon wafer, require injection of a sub-micron-scale electron bunch to achieve high-quality, monoenergetic output beams. A potential injection mechanism for such micro-scale beams relies on field emission from a nanotip array, followed by acceleration to near-relativistic energies. We demonstrate field emission of electrons from a lithium niobate crystal during heating and cooling, and describe the production of electrons within a hollow channel along the axis of a lithium niobate crystal. Measurements of emitted beam properties are compared with direct measurements of crystal fields under comparable conditions and modeled mathematically.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK018
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MOPIK019	Upgrade Options Towards Higher Fields and Beam Energies for Continuous-Wave Room-Temperature VHF RF Guns	gun, brightness, cathode, cavity	542
	F. Sannibale, J.M. Byrd, D. Filippetto, M.J. Johnson, D. Li, T.H. Luo, C.E. Mitchell, J.W. Staples, S.P. Virostek LBNL, Berkeley, California, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 Science demand for MHz-class repetition rate electron beam applications such as free electron lasers (FELs), inverse Compton scattering sources, and ultrafast electron diffraction and microscopy (UED/UEM), pushed the development of new gun schemes that could generate high brightness beams at such high rates. At the Lawrence Berkeley Lab (LBNL), we proposed a new concept room-temperature RF gun resonating in the VHF frequency range (30-300 MHz) capable of operating in continuous wave mode at the fields required for high-brightness performance. A first VHF-Gun was constructed and tested in the APEX facility at LBNL, which successfully demonstrated all design parameters and the generation of high brightness electron beams. A second version of the APEX VHF-Gun is being built at LBNL for the LCLS-II, the new SLAC X-ray FEL. Recent studies showed that a proposed LCLS-II upgrade and UED/UEM applications would greatly benefit from an increased gun brightness obtained by raising the electric field at the cathode and the beam energy at the gun exit. In this paper, we present and discuss possible upgrade options that would allow extension of the VHF-Gun performance towards these new goals.
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MOPIK022	Experimental Investigation of Field-Emission From Silicon Nano-Cone Cathodes	cathode, emittance, vacuum, ion	548
	A. Lueangaramwong, C. Buzzard, V. Korampally, O. Mohsen, P. Piot Northern Illinois University, DeKalb, Illinois, USA S. Chattopadhyay Northern Illinois Univerity, DeKalb, Illinois, USA R. Divan Argonne National Laboratory, Argonne, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA
	Funding: This work is supported by the NSF grant PHY-1535401 with Northern Illinois University Field emission cathode are capable of forming electron beam with extreme brightness via strong-field excitation from applied electrostatic, or electromagnetic (radiofrequency and laser) fields. Our group, in collaboration with the Argonne Center for Nanoscale Material, has recently developed nanocone cathode. The present paper reports on the experimental characterization of these cathodes both configured as a single-cone emitter or as large arrays of tightly-packed emitter. The tests carried in a diode setup are capable of measuring IV characteristic curves and beam distributions.
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MOPIK023	Cornell Laboratory for High Intensity, Ultra-Bright and Polarized Electron Beams	gun, simulation, cathode, ion	551
	L. Cultrera, A.C. Bartnik, I.V. Bazarov, C.M. Gulliford, P. Gupta, H. Lee, S.A. McBride, T.P. Moore Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work has been funded by the National Science Foundation (Grant No. PHY-1416318) and Department of Energy (Grants No. DE-SC0014338, No. DE-SC0011643 and No. DE-SC0016203). We report on the current activities pursued at Cornell University for the production of electron beams tailored to a wide range of applications. We have developed the expertise to grow many different type of high quantum efficiency photocathode belonging to the alkali antimonide family. Those materials are ideal candidates to produce high intensity beam with average currents in the mA range. When operated near threshold at cryogenic temperature in transmission mode they can also generate the electron beams needed to perform ultrafast electron diffraction of bio molecules. We have recently expanded our facility with a Mott polarimeter to include the capability to measure polarization of the electron beam. The photocathode lab is being complemented by a dedicated photo-gun laboratory to test the photocathode properties in a real environment and to perform measurement of the beam properties under new and yet unexplored operating conditions.
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MOPIK026	Commissioning and Operation of an Ultrafast Electron Diffraction Facility as Part of the ATF-II Upgrade at Brookhaven National Laboratory	operation, laser, photon, experiment	554
	M.G. Fedurin, M. Babzien, C. Folz, M. Fulkerson, K. Kusche, J.J. Li, R. Malone, M.A. Palmer, T.V. Shaftan, J. Skaritka, L. Snydstrup, C. Swinson, F.J. Willeke BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the US DOE under contract DE-SC0012704. The Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL) is presently carrying out an upgrade, ATF-II, which will provide significantly expanded experimental space and capabilities for its users. One of the new capabilities being integrated into the ATF-II program is an Ultrafast Electron Diffraction (UED) beam line, which was originally deployed in the BNL Source Development Laboratory. Inclusion of the UED in the ATF-II research portfolio will enable ongoing development and extension of the UED capabilities for use in materials research. We describe the design, operation and future plans for the UED beam line at the ATF-II.
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MOPIK041	Commissioning of the Stripping Foil Units for the Upgrade of the PSB H⁻ Injection System	injection, linac, controls, vacuum	595
	C. Bracco, S. Burger, V. Forte, B. Goddard, G. Guidoboni, L.O. Jorat, B. Mikulec, A. Navarro Fernandez, R. Noulibos, F. Roncarolo, P. Van Trappen, W.J.M. Weterings CERN, Geneva, Switzerland
	The PSB will be extensively upgraded during the next long shutdown of the CERN accelerator complex, to double the brightness of the stored beams. The existing multi-turn injection will be replaced by a charge exchange system designed for the 160 MeV hydrogen ions provided by Linac4. Part of the injection equipment has been temporarily installed along the Linac4-to-PSB transfer line and tested with beam. This allowed to gain experience with the system, test the related diagnostics and benchmark calculations with measurements. An additional permanent stripping foil test stand is also installed right after the Linac and will be used to characterise new foils for possible future applications. The main outcomes, issues and applied or planned mitigations are presented for both installations.
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MOPIK055	Beam by Design: Current Pulse Shaping Through Longitudinal Dispersion Control	simulation, sextupole, synchrotron, laser	644
	T.K. Charles, D.M. Paganin Monash University, Faculty of Science, Clayton, Victoria, Australia M.J. Boland The University of Melbourne, Melbourne, Victoria, Australia M.J. Boland, R.T. Dowd SLSA, Clayton, Australia
	Electron beams traversing a dispersive region, such as a bunch compressor and some transport line can form caustic lines and surfaces corresponding to regions of maximum electron density, which influence the current pulse shape. In this paper, we present a technique to manipulate the longitudinal phase space distribution to achieve an arbitrary, desired current pulse shape. We show how sextupole magnets (and in certain circumstances, octupole magnets), placed within a dispersive region can be used to generate the conditions required for a flexible technique of current pulse shaping that avoids truncation through collimation.
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MOPIK072	Recent Upgrades of the Bunch Arrival Time Monitors at FLASH and European XFEL	laser, software, controls, electronics	695
	M. Viti, M.K. Czwalinna, H. Dinter, C. Gerth, K.P. Przygoda, R. Rybaniec, H. Schlarb DESY, Hamburg, Germany
	In modern free electron laser facilities like FLASH and European XFEL a high resolution intra train bunch arrival time measurement is mandatory, providing a crucial information for the beam based feedback system. At FLASH and European XFEL a reliable arrival time detection with a resolution better than 0.1% is required for a broad range of bunch charges, from 1 nC down to 20 pC. The system developed is based on electro-optical sampling where an ultra-short pulsed laser is employed. Several bunch arrival time monitors (BAM) were developed and are since 2012 in operation at the FLASH facility. A major upgrade involved the development of new hardware and software based on the MTCA standard. Special operation mode at both facilities includes the possibility to subdivide the bunch train in up to three segments, each with different bunch energy and charge, causing variation of the time jitter within the bunch train itself. A further upgrade includes the measurement of the arrival time and application of delay correction for each of the three segments. In this poster, we describe the development, installation and commissioning of the hardware, firmware and software of the new system.
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MOPIK075	Design, Simulation and Compare of Flat Cathode Electron Guns with Spherical Cathode Electron Guns for Industrial Accelerators	cathode, gun, simulation, space-charge	702
	M. Nazari, F. Abbasi Shahid Beheshti University, Tehran, Iran S. Ahmadiannamin ILSF, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran S. Haghtalab IPM, Tehran, Iran
	In this article, electron guns with flat and spherical cathodes have been designed and simulated for industrial accelerators. After checking the different features of each cathode geometry, there has been discussed about optimum values of this features. The most important features in selecting the best cathode geometry for industrial accelerators are beam waist radius, beam waist position, current density and price. Finally after comparing the different features of both geometries with each other, suitable geometry was selected.
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MOPIK078	Narrow-Band, Wide-Range Tuneable THz Source Based on the Slotted-Foil Technique	undulator, radiation, simulation, FEL	712
	J. Pfingstner, E. Adli, H. Holmestad University of Oslo, Oslo, Norway S. Bettoni, S. Reiche PSI, Villigen PSI, Switzerland
	The FEL user community has expressed a strong interest in a THz source for the excitation of their samples in pump probe experiments. The demanded THz properties are challenging to achieve, as they include a narrow bandwidth of <5-10%, the possibility of frequency tuning between 1 and 20 THz, a THz pulse energy of about 100 uJ, and a fixed phase relation from shot-to-shot. To fulfil these specifications, an accelerator-based source is proposed in this paper. It utilises the slotted-foil technique to create a pre-bunched electron beam that is injected into a helical undulator. Detailed simulation studies presented in this paper show that the corresponding undulator radiation has the demanded properties.
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MOPIK080	Research of the Electro-Gravitational Induction by Using COD Signals in Charged Particle Storage Rings	storage-ring, induction, positron, feedback	719
	D. Dong IHEP, Beijing, People's Republic of China J.Y. Dong Binghamton University, State University of New York, Binghamton, New York, USA
	Funding: The project was supported by the National Natural Science Foundation of China under Grant No. 11575215, partly. Form the beam instability in the charged particle storage ring; researchers have known that one kinds of long term beam instability, the period of 12 hours, comes from the gravity changes, the change of acceleration of gravity g, delta g caused by the moon and sun moving relative to the earth, so called the terrestrial tidal forces. Phenomenology, we would say that the gravity changes caused by the moon and sun moving at the storage ring have caused the beam energy changes in the storage ring. If it is true, then it may be the electro-gravitational induction (EGI). In this paper, we will discuss the possibility of EGI, and estimate the maximum value of the gravity coefficient of the induced electromotive force by using the existing beam data from the storage rings.
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MOPIK103	Operation with Carbon Stripping Foils at ISIS	injection, operation, synchrotron, emittance	771
	H.V. Cavanagh, B. Jones STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The ISIS facility at the Rutherford Appleton Laboratory is a pulsed neutron and muon source for physical and life science research. Up to 3·10¹³ protons per pulse are accelerated to 800 MeV in the 50 Hz rapid cycling synchrotron that serves two spallation neutron targets. Charge exchange injection of 70 MeV H' ions into the synchrotron takes place over 130 turns. For over 30 years ISIS has used 40×120 mm aluminium oxide stripping foils, produced in-house [1]. Recently, foil preparation and installation processes have been simplified with the use of commercially available 40×60 mm carbon stripping foils. This paper summarises operational experiences with diamond-like-carbon (DLC) and graphene foils. Radiological analysis, atomic force microscope (AFM) imaging of foils and off-line irradiation with a 1.5 keV electron gun are also discussed.
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MOPIK106	Effect of Magnetic Element Alignment Errors on Electron Beam Dynamics in the Transportation Channel of the NSC KIPT Neutron Source Driven With Linear Accelerator	target, neutron, alignment, dipole	781
	A.Y. Zelinsky, P. Gladkikh, A.A. Kalamayko NSC/KIPT, Kharkov, Ukraine
	In the paper, the results of beam dynamics simulation in the transportation channel of the NSC KIPT neutron source taking into account the errors of the electromagnetic elements alignment are presented. It is show that the values of RMS alignment errors such as 100 mkm in transverse planes and 200 mkrad in angle installations lead to the essential shifts of the beam at a neutron target and, therefore, to the essential beam losses at the vacuum chamber walls. To avoid the losses one should provide additional electron beam correction and to increase the accuracy of the equipment alignment.
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MOPIK107	Injection Efficiency Simulation in the Electron Storage Ring of X-Ray Generator NESTOR	storage-ring, injection, alignment, simulation	784
	A.Y. Zelinsky, P. Gladkikh, A.A. Kalamayko NSC/KIPT, Kharkov, Ukraine
	In the paper the results of the beam dynamics and injection efficiency simulation in the storage ring of the X-ray generator NESTOR are presented.
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MOPIK111	Initial Performance Measurements of Multi-GHz Electron Bunch Trains	laser, emittance, gun, cathode	795
	D.J. Gibson, R.A. Marsh LLNL, Livermore, California, USA Y. Hwang UCI, Irvine, California, USA
	Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL's compact laser-Compton based x-ray source is currently producing up to 35 keV photons, with the capability to upgrade to 250 keV. Increasing the average brightness of such sources requires increasing the electron beam current. To avoid degradation of the narrow-bandwidth performance of the source, the per-bunch charge shouldn't increase; the effective repetition rate of the electron beams must be raised. It has been proposed* to generate bunch trains of several hundred pulses spaced by the period of X-band RF (~87 ps), which raises questions about beam-loading effects on the energy uniformity of the bunches and wakefield effects degrading the emittance of later bunches, compromising the x-ray quality. As a first test of this concept, we have installed into the electron-generating laser of our system optical pulse-stacking hardware to allow generation of 16-electron-bunch trains. Here we present the current status of our x-ray source, along with initial results using this new multi-bunch train. This includes characterization of collective electron beam energy spread and emittance growth. * D.J. Gibson, et al., IPAC2012.
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MOPIK113	Beam Phase Space Tomography for FXR LIA	emittance, space-charge, simulation, solenoid	801
	Y.H. Wu, Y.-J. Chen LLNL, Livermore, California, USA
	Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Knowing the initial beam parameters entering an accelerator or a downstream beamline allows us to select transport tunes optimized for a desired accelerator performance. In this study, we report unfolding LLNL's FXR [1] beam parameters by using the tomography technique [2, 3] to construct the beam phase space along the accelerator's downstream beamline. The unfolded phase spaces from tomography and simulations are consistent.
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MOPIK115	A Design for 10 GeV, High Peak-Current, Tightly Focused Electron Beams at FACET-II	emittance, linac, simulation, acceleration	807
	G.R. White SLAC, Menlo Park, California, USA
	Funding: This work was sponsored by the Department of Energy under Contract Number: DE-AC02-76SF00515 FACET-II will be a new test facility, starting construction in 2018 within the main SLAC Linac. Its purpose is to build on the decades-long experience developed conducting accelerator R&D at SLAC in the areas of advanced acceleration and coherent radiation techniques with high-energy electron and positron beams. The design consists of a 135-MeV high-brightness photo-injector constructed in an off-axis injection line in Sector 10 of the SLAC Linac, two new 4-bend chicane bunch compressors installed in Sectors 11 and 14, with a third compression stage provided by the existing FACET W Chicane in Sector 20. We develop a design to deliver peak currents more than 160 kA to the Sector 20 interaction region at 10 GeV, with 10 'm-rad emittances at 2 nC bunch charge and 1.4 % rms energy spread. The Sector 20 bunch compressor is re-designed for maximum peak current throughput and minimal emittance degradation via CSR, and the FACET-II compression scheme is optimized. We present 6D start-end beam tracking simulations using Lucretia including ISR, CSR, wakefields and space charge effects.
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MOPIK122	The Beam Optics of the FFAG Cell of the CBETA ERL Accelerator	quadrupole, optics, dipole, focusing	820
	N. Tsoupas, J.S. Berg, S.J. Brooks, G.J. Mahler, F. Méot, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA J.A. Crittenden Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S.C. Tygier UMAN, Manchester, United Kingdom
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The CBETA project[] is a prototype electron accelerator for the proposed eRHIC project[]. The electron accelerator is based on the Energy Recovery Linac (ERL) and the Fixed Field Alternating Gradient (FFAG) principles. The FFAG arcs and the straight section of the accelerator are comprised of one focusing and one defocusing quadrupoles which are designed as Halbach-type permanent dipole magnets with quadrupoles component[]. We will present the beam optics of the FFAG cell which is based on 3D field maps derived with the use of the OPERA computer code[*]. We will also present the electromagnetic design of the corrector magnets of the cell. http://arxiv.org/abs/1504.00588 http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf * K. Halbach, Nucl. Instrum. Meth. 169 (1980) pp. 1-10 **** http://www.scientificcomputing.com
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MOPVA001	Coherent X-Ray Radiation From Electron Beam Processed by Channeling and Emittance Exchange	photon, radiation, laser, emittance	845
	I. Lobach, A.I. Benediktovitch BSU, Minsk, Belarus
	Presented contribution theoretically studies a novel scheme of compact intense x-ray radiation source. In the scheme, longitudinally modulated electron beam emits x-rays by Inverse Compton Scattering (ICS). The setup's feature is the way how longitudinal density modulation in angstrom scale is created. There are three stages of processing of initial beam of relativistic electrons: 1. First, the electrons cross a crystal plate in channeling regime. It is shown that upon leaving the crystal, the electron beam acquires discernible transverse modulation in angstrom scale. It is taken into account that not all electrons are captured in channeling mode and that some of those that do may leave it as they travel through the crystal slab. 2. Further, the beam is transported to Emittance Exchange (EEX) line, in which the direction of modulation is tilted and the beam becomes longitudinally modulated. The scale of modulation remains the same. 3. Finally, intense quasi-coherent x-ray radiation is emitted by ICS. Numerical estimations show that coherent contribution to intensity is considerable for feasible parameters of used beam, components of EEX line and laser producing photons for ICS.
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MOPVA002	Initial Stage of Self Amplified Radiation Emission From Electron Bunches in Crystal: Linear Response Theory	radiation, brightness, polarization, undulator	848
	A.I. Benediktovitch, I. Lobach BSU, Minsk, Belarus, Belarus
	Self amplified spontaneous emission (SASE) is a key process in X-ray free electron lasers' operation. In this case the spontaneous emission is undulator radiation emission, the radiation in X-ray range being possible from electrons in GeV energy range. In the case of interaction of electrons with properly aligned crystal the channeling radiation results in X-rays from electrons with energies in tens MeV energy range. In this situation for high current densities the SASE process may take place that potentially could lead to construction of a compact bright X-ray source. In present contribution the first principle theoretical description is outlined and first order perturbation theory is used to model the initial stage of SASE. The transition from spontaneous to SASE regime is described, the requirements for bunch current and emittance are determined. By means of dispersion equation analysis and boundary condition application the intensity radiated from crystal slab is calculated and it is shown that Bragg diffraction could enhance self amplification. A numerical example for Si (001) illustrates the model.
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MOPVA004	Operating Simultaneously Two In-Vacuum Canted Undulators in Synchrotron SOLEIL	undulator, photon, vacuum, radiation	851
	L.S. Nadolski, Y.-M. Abiven, P. Brunelle, N. Béchu, M.-E. Couprie, F.J. Cullinan, X. Delétoille, M. El Ajjouri, C. Herbeaux, N. Hubert, N. Jobert, M. Labat, J.-F. Lamarre, A. Lestrade, A. Loulergue, O. Marcouillé, P. Monteiro, A. Nadji, R. Nagaoka, D. Pédeau, P. Rommeluère, K.T. Tavakoli, M. Valléau, J. Vétéran SOLEIL, Gif-sur-Yvette, France C. Benabderrahmane ESRF, Grenoble, France

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MOXAA1

Commissioning of the European XFEL Accelerator

linac, operation, undulator, emittance

1

W. Decking, H. Weise
DESY, Hamburg, Germany

The European XFEL uses the world's largest superconducting RF installation to drive three independent SASE FELs. After eight years of construction the facility is now brought into operation. First experience with the superconducting accelerator as well as beam commissioning results will be presented. The path to the first user experiments will be laid down.

Slides MOXAA1 [22.967 MB]

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MOZA1

Electron Cloud Effects at the LHC and LHC Injectors

operation, simulation, emittance, dipole

30

G. Rumolo, H. Bartosik, E. Belli, P. Dijkstal, G. Iadarola, K.S.B. Li, L. Mether, A. Romano, M. Schenk, F. Zimmermann
CERN, Geneva, Switzerland
E. Belli
University of Rome La Sapienza, Rome, Italy
P. Dijkstal
TU Darmstadt, Darmstadt, Germany
M. Schenk
EPFL, Lausanne, Switzerland

Electron cloud effects are one of the main limitations of the performance of the LHC and its injectors. Enormous progress has been done in the simulation of the electron cloud build-up and of the effects on beam stability while mitigation measures have been identified and implemented (scrubbing, low secondary electron yield coatings, etc.). The above has allowed reaching nominal beam parameters in the LHC during Run 2. A review of the studies and results obtained and the strategy and expected performance for the High Luminosity operation of the LHC will be presented.

Slides MOZA1 [12.855 MB]

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MOOCA1

High Efficiency Klystrons Using the COM Bunching Technique

klystron, cavity, simulation, bunching

37

D.A. Constable
Lancaster University, Lancaster, United Kingdom
A.Yu. Baikov
Moscow University of Finance & Law, Moscow, Russia
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R.D. Kowalczyk
L-3, Williamsport, Pennsylvania, USA
I. Syratchev
CERN, Geneva, Switzerland

Future large-scale particle accelerators, for example, the Future Circular Collider (FCC), the Compact Linear Collider (CLIC) and the International Linear Collider (ILC), will require significant RF drive power on the order of 100 MW. Thus, an RF source with high efficiency is preferable to minimise the overall power required. Klystrons represent an attractive RF source, with the current state of the art operating at efficiencies of up to 70%. Such devices feature monotonic bunching, where at the output cavity, a number of electrons will not be in the main bunch, and instead will be present in the anti-bunch, and therefore not contributing to the output power. Therefore, novel bunching methods, such as the Core Oscillation Method (COM), are worthy of investigation. By allowing the core of the electron beam to bunch and de-bunch between successive cavities, the number of electrons contained in the final bunch can increase, and therefore improve the efficiency of the device. Numerical simulation of klystrons featuring COM will be presented, with efficiencies of up to 85% being predicted thus far.

Slides MOOCA1 [12.765 MB]

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MOOCA3

Amorphous Carbon Thin Film Coating of the SPS Beamline: Evaluation of the First Coating Implementation

vacuum, cathode, proton, operation

44

M. Van Gompel, P. Chiggiato, P. Costa Pinto, P. Cruikshank, C. Pasquino, J. Perez Espinos, A. Sapountzis, M. Taborelli, W. Vollenberg
CERN, Geneva, Switzerland

As part of the LHC Injector Upgrade (LIU) project, the Super Proton Synchrotron (SPS) must be upgraded in order to inject in the LHC 25 ns bunch spaced beams of higher intensity. To mitigate the Electron Multipacting (EM) phenomenon in the SPS, CERN developed thin film carbon coatings with a low Secondary Electron Yield (SEY). The development went from coating small samples, up to coating of 6 m long vacuum chambers directly installed in the magnets. To deposit the low SEY amorphous carbon (aC) film on the vacuum chamber inner wall of SPS ring components, a modular hollow cathode train was designed. The minimization of the logistical impact requires a strategy combining in-situ and ex-situ coating, depending on the type of components. To validate the implementation strategy of the aC thin films and the in-situ coating process along the 7 km long SPS beamline, approximately 2 cells of B-type bending dipoles and 9 focussing quadrupoles are foreseen to be treated with the aC coating during the Extended Year End Technical Stop (EYETS) 2016-2017. We will discuss the coating technique and evaluate both the implementation process and the resulting coating performance.

Slides MOOCA3 [71.421 MB]

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MOZB1

First Results with the Novel Peta-Watt Laser Acceleration Facility in Dresden

laser, target, plasma, acceleration

48

U. Schramm, D. Albach, C. Bernert, S. Bock, F. Brack, J. Branco, M.H. Bussmann, J.P. Couperus, A.D. Debus, C. Eisenmann, M. Garten, R. Gebhardt, S. Grams, U. Helbig, A. Huebl, A. Irman, A. Köhler, J.M. Krämer, S. Kraft, F. Kroll, J. Metzkes, L. Obst, R.G. Pausch, M. Rehwald, H.P. Schlenvoigt, M. Siebold, K. Steiniger, O. Zarini, K. Zeil
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
T. Kluge, M. Kuntzsch, U. Lehnert, M. Löser, P. Michel, R. Sauerbrey
HZDR, Dresden, Germany

Applications of laser plasma accelerated particle beams ranging from driving of light sources to radiation therapy require the scaling of beam energy and charge as well as reproducible operating conditions. Both issues have motivated the development of novel table-top class Petawatt laser systems (e.g., 30J pulse energy in 30fs) with unprecedented pulse control, here represented by the Draco-PW system recently commissioned at HZDR Dresden. First results will be presented on laser wakefield electron acceleration where in the beam loading regime high bunch charges in the nC range could be efficiently accelerated with good beam quality, and on proton acceleration where pulsed magnet beam transport ensured depth dose distributions allowing for tumor irradiation in animal models.

Slides MOZB1 [4.059 MB]

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MOOCB3

Intensity Interferometer to Measure Bunch Length at SPEAR3

photon, detector, optics, storage-ring

60

W.J. Corbett
SLAC, Menlo Park, California, USA
T.M. Mitsuhashi
KEK, Ibaraki, Japan

Electron bunch length in a storage ring is typically measured with streak cameras, electro-optic devices or non-linear cross-correlation techniques with a range of system complexity, signal-to-noise ratios and cost. Another straight-forward method is to construct an 'intensity interferometer' utilizing a coincidence detector to record simultaneous photon arrival events. In this configuration, visible SR light is passed through a narrow bandpass filter followed by a small pinhole to generate a stream of single-mode monochromatic wavepackets. As the interferometer delay is scanned across an electron bunch, two-photon events occurring within the longitudinal coherence time of the light cause a reduction in the measured coincidence rate. The resulting autocorrelation of the optical pulse duration reveals the electron bunch length, independent of synchrotron oscillation motion. In this paper we comment on the theory and report on preliminary measurements carried out at SPEAR3.

Slides MOOCB3 [2.606 MB]

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MOPAB013

Recent Development and Results With the Merlin Tracking Code

collimation, proton, simulation, collider

104

S.C. Tygier, R.B. Appleby, H. Rafique
UMAN, Manchester, United Kingdom
R.J. Barlow, S. Rowan
IIAA, Huddersfield, United Kingdom
J. Molson
LAL, Orsay, France

Funding: Work supported by High Luminosity LHC : UK (HL-LHC-UK), grant number ST/N001621/1
MERLIN is an high performance accelerator simulation code which is used for modelling the collimation system at the LHC. It is written in extensible object-oriented C++ so new physics processes can be easily added. In this article we present recent developments needed for the Hi-Lumi LHC and future high energy colliders including FCC, such as hollow electron lenses and composite materials. We also give an overview of recent simulation work, validation against LHC data from run 1 and 2, and loss maps for Hi-Lumi LHC.

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MOPAB016

Beam Diagnostic and Control Systems for AREAL 50 MeV Linac

controls, emittance, diagnostics, linac

114

V. Sahakyan, G.A. Amatuni, A. Azatyan, B. Grigoryan, N. Martirosyan, A. Sargsyan, V.M. Tsakanov, G.S. Zanyan
CANDLE SRI, Yerevan, Armenia

Advanced Research Electron Accelerator Laboratory (AREAL) is an electron linear accelerator project with a laser driven RF gun that has been constructed at CANDLE Synchrotron Research Institute. After the completion of the first phase, which implies the operation of a 5 MeV gun section, the second phase of facility development (energy enhancement up to 50 MeV) is in progress. In the present paper the description of corresponding upgrades for diagnostic and control systems is given.

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MOPAB022

Fabrication Studies of a 650 MHz Superconducting RF Deflecting Mode Cavity for the ARIEL Electron Linac

cavity, niobium, linac, impedance

120

D.W. Storey, R.E. Laxdal, B. Matheson, N. Muller
TRIUMF, Vancouver, Canada
D.W. Storey
Victoria University, Victoria, B.C., Canada

A 650 MHz RF deflecting mode cavity is required for the ARIEL electron Linac to separate interleaved beams bound for either rare isotope production or a recirculation loop containing a Free Electron Laser. An RF separator will allow both modes to run simultaneously by imparting opposite transverse deflection to adjacent bunches at 1.3 GHz. The SRF cavity has been designed to provide up to 0.6 MV transverse voltage for operation with up to a 50 MeV CW electron beam. The design was optimised for compact geometry with high shunt impedance. Due to the low dissipated power, the cavity will operate at 4 K and allows for investigations into low cost fabrication techniques. The cavity is being machined from bulk reactor grade ingot Niobium and welds will be performed using TIG welding in an ultra-pure Argon chamber. Results of fabrication studies will be presented as well as measurements performed on a copper prototype cavity.

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MOPAB024

Proposal to Observe Half-Bare Electrons on a 40-MeV LINAC

radiation, experiment, laser, linac

126

N. Delerue, S. Jenzer, V. Khodnevych, A. Migayron
LAL, Orsay, France
N.F. Shul'ga
NSC/KIPT, Kharkov, Ukraine
S. Trofymenko
KhNU, Kharkov, Ukraine

Funding: CNRS/IN2P3 and Joint Laboratory France-Ukraine IDEATE
In different processes of relativistic electron interaction with substance and external fields, the electron loses part of its Coulomb field and becomes half-bare. Such state of electron significantly modifies the characteristics of its electromagnetic radiation during further interaction of the particle with substance. We propose to study the influence of the half-bare state of electron upon its transition radiation (TR). The existence of such influence for the case of electron undressing at its scattering was theoretically predicted. We intend to obtain the electrons in half-bare state in the result of their crossing of a conducting screen such as a TR screen. We propose to investigate the influence of the half-bare state of electron in this process upon TR generated by such electron on a downstream TR screen situated on some distance from the upstream screen which undresses the particle. Calculations are presented for the case of a 45-MeV linac and the distance between the screens in the region between 100 mm and 300 mm. The proposed experiment is expected to reveal new features of TR signal in such process comparing to previous measurements.
N.F. Shul'ga, S.V. Trofymenko, V.V. Syshchenko, JETP Lett. 93 (2011) 1.
Y. Shibata, K. Ishi, T. Tokahashi et al., Phys. Rev. E 49 (1994) 785.

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MOPAB026

Study of a Smith-Purcell Radiation-Based Longitudinal Profile Monitor at the CLIO Free Electron Laser

radiation, laser, free-electron-laser, detector

132

V. Khodnevych, N. Delerue, S. Jenzer, H. Roesch
LAL, Orsay, France
J.P. Berthet, F. Glotin, J.-M. Ortega, R. Prazeres
LCP/CLIO, Orsay, Cedex, France
N. Jestin
CLIO/ELISE/LCP, Orsay, France

Funding: CNRS and ANR (contract ANR-12-JS05-0003-01)
We report on measurements of Coherent Smith-Purcell radiation at the CLIO Free Electron Laser. Smith-Purcell radiation is emitted when a grating is brought close from a bunch of relativistic particles. When the bunch is sufficiently short coherent radiation is emitted. This coherent radiation encodes the longitudinal form factor of the bunch and can therefore be used as a longitudinal profile monitor. With its short pulses and high charge the 45 MeV Linac of CLIO is a good location to test advanced longitudinal profile diag- nostics. The results will be compared with measurements using the RF dephasing. induced energy dispersion.

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MOPAB028

Estimation of Longitudinal Dimensions of Sub-Picosecond Electron Bunches with the 3-Phase Method

booster, space-charge, simulation, gun

139

H. Purwar, C. Bruni, A. Gonnin
LAL, Orsay, France
T. Vinatier
DESY, Hamburg, Germany

An estimation of the longitudinal dimensions for short electron bunches in an accelerating field is an important diagnostic and can be extremely helpful in evaluating the performance of an accelerator. We investigate a method for close estimation of bunch length for sub-picosecond electron bunches from the measurement of their energy spreads. Three or more measurements for the bunch energy spread are made by varying the phase of the accelerating structure and later a reconstruction of the bunch longitudinal dimensions, namely bunch length, initial energy spread and chirp at the entrance of the accelerating structure are obtained using the least square method. A comparison of the obtained results with ASTRA simulations is also included to validate the 3-phase method for sub-ps electron bunches. It is a simple method from both understanding (easy reconstruction using transport matrices) and experimental point of views (multiple measurements of energy spread with varying phase of the accelerating structure).

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MOPAB029

Experimental Study of Halo Formation at ATF2

vacuum, simulation, scattering, detector

142

R.J. Yang, P. Bambade, A. Faus-Golfe, V. Kubytskyi, S. Wallon
LAL, Orsay, France
A. Aryshev, T. Naito
KEK, Ibaraki, Japan
N. Fuster-Martínez
IFIC, Valencia, Spain

For Accelerator Test Facility 2 (ATF2), as well as other high-intensity accelerators, beam halo has been an important aspect reducing the machine performance and activating the components. It is imperative to clearly understand the mechanisms that lead to halo formation and to test the avail- able theoretical models with an adequate experiment setup. In this paper, the experimental measurement of the beam halo formation from beam gas scattering is presented. The upgrading of an OTR/YAG screen monitor for future halo study is also introduced.

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MOPAB038

Research and Development of Diamond Based Beam Monitoring and Diagnostics Systems at the S-DALINAC

detector, monitoring, simulation, FPGA

163

A. Rost, T. Galatyuk
TU Darmstadt, Darmstadt, Germany
T. Galatyuk, J. Pietraszko
GSI, Darmstadt, Germany

Funding: This work has been supported by the DFG through GRK 2128 and VH-NG-823.
For future experiments with the HADES and CBM detectors at FAIR in Darmstadt, a radiation hard and fast beam detector is required. The beam detector has to perform precise T0 measurements (σ_T0 < 50 ps) and should also offer beam monitoring capabilities. These tasks can be fulfilled by utilizing single-crystal Chemical Vapor Deposition (scCVD) diamond based detectors. For research and development of such detectors, a test set-up will be installed at the Superconducting Darmstadt Electron Linear Accelerator (S-DALINAC) of TU Darmstadt. A read-out system for a beam monitoring and diagnostics system is currently under development. It is based on the already well established TRB3 platform, which can provide FPGA based signal discriminators and high precision FPGA-TDCs with on-line monitoring capabilities. In this contribution the concept and the performance of a prototype beam monitoring system will be discussed. Furthermore the preparatory work, with particular focus on the beam-line simulations, for a multipurpose beam detector test set-up at the S-DALINAC will be addressed.

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MOPAB039

Development of a Control System Based on Experimental Data for Space Charge Lenses

plasma, operation, ion, space-charge

166

S. Klaproth, C. Beberweil, M. Droba, O. Meusel, H. Podlech, B.E.J. Scheible, K. Schulte, K.I. Thoma, C. Wagner
IAP, Frankfurt am Main, Germany

Space charge lenses use a confined electron cloud for the focusing of ion beams. The electron density gives the focusing strength whereas the density distribution influences the mapping quality of the space charge lens and is related to the confinement. The major role of the electron density with respect to the focusing quality has been pointed out many times in the past *,**. With an automated measurement system the radial light density profile, plasma stability and mean value of the electron density have been measured in respect to the confining fields and the pressure. The results are summarized in 3D-maps. The theoretical model approximations for space charge lenses predicts high electron densities then measured. With the automated system the realistic 3D-maps can be considered instead of an approximation of a theoretical density including knowledge of the most stable electron cloud achievable within the parameter range of the lens. The experimental results of the automated measurement system will be presented here and a concept of a control system for this type of space charge lenses will be explained.
* O. Meusel, 'Focussing and transport of ion beams using space charge lenses', PhD thesis, 2006

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MOPAB043

Very First Experience with the Standard Diagnostics at the European XFEL

diagnostics, operation, cavity, electronics

180

D. Lipka
DESY, Hamburg, Germany

The whole European XFEL becomes in operation this year. Dedicated standard diagnostics systems are installed and almost all types are tested at the injector before. Now the standard diagnostics are used to commission the facility. In this contribution the very first results and the operation experiences of the standard beam diagnostics of the entire European XFEL are reported.

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MOPAB044

X-Band TDS Project

polarization, experiment, diagnostics, cavity

184

B. Marchetti, R.W. Aßmann, B. Beutner, J. Branlard, F. Christie, R.T.P. D'Arcy, W. Decking, U. Dorda, J. Herrmann, M. Hoffmann, M. Hüning, O. Krebs, G. Kube, S. Lederer, F. Ludwig, F. Marutzky, D. Marx, J. Osterhoff, I. Peperkorn, S. Pfeiffer, F. Poblotzki, J. Rönsch-Schulenburg, J. Rothenburg, H. Schlarb, M. Scholz, S. Schreiber, M. Vogt, A. Wagner, T. Wilksen, K. Wittenburg
DESY, Hamburg, Germany
M. Bopp, H.-H. Braun, P. Craievich, M. Pedrozzi, E. Prat, S. Reiche, K. Rolli, R. Zennaro
PSI, Villigen PSI, Switzerland
N. Catalán Lasheras, A. Grudiev, G. McMonagle, W. Wuensch
CERN, Geneva, Switzerland

Based on the success of the X-Band Transverse Deflecting Structure (TDS) diagnostic at LCLS*, a collaboration between DESY, PSI and CERN has formed with the aim of developing and building an advanced modular X-Band TDS system. The designed TDS has the new feature of providing variable polarization of the deflecting field**. The possibility of changing the orientation of the streaking field of the TDS to an arbitrary azimuthal angle allows for 3D characterization of the phase space using tomographic methods***. Moreover the complete 6D characterization of the beam phase space is possible by combining this technique with quadrupole scans and a dipole spectrometer. As this new cavity design requires very high manufacturing precision to guarantee highest azimuthal symmetry of the structure to avoid the deterioration of the polarization of the streaking field, the high precision tuning-free assembly procedures developed at PSI for the SwissFEL C-band accelerating structures will be used for the manufacturing****. The high-power rf system is based on the CERN-based X-band test stands. We summarize in this work the status of the projects and its main technical parameters.
* C. Behrens et al. , Nat. Comm. 4762 (2014).
** A. Grudiev, CLIC-note-1067 (2016).
*** D. Marx et al., contribution to this conference proceedings.
**** U. Ellenberger et al., FEL 2013, TUPS017.

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MOPAB045

Reconstruction of the 3D Charge Distribution of an Electron Bunch Using a Novel Variable-Polarization Transverse Deflecting Structure (TDS)

simulation, experiment, space-charge, laser

188

D. Marx, R.W. Aßmann, U. Dorda, U. Dorda, B. Marchetti
DESY, Hamburg, Germany
P. Craievich
PSI, Villigen PSI, Switzerland
A. Grudiev, A. Grudiev, A. Grudiev
CERN, Geneva, Switzerland

A TDS is a well-known device for the characterization of the longitudinal properties of an electron bunch in a linear accelerator. So far, the correlation of the slice properties in the horizontal/vertical planes of the electron bunch distribution has been characterized by using a TDS system deflecting in the vertical/horizontal directions respectively and analysing the image on a subsequent screen*. Recently, an innovative design for a TDS structure has been proposed, which includes the possibility of continuously varying the angle of the transverse streaking field inside a TDS structure**. This allows the beam distribution to be characterized in all transverse directions. By collecting measurements of bunches streaked at different angles and combining them using tomographic techniques, it is possible to retrieve 3D distributions of the charge density. In this paper, a method is proposed and simulation results are presented to show the feasibility of such an approach at the upcoming accelerator R&D facility, SINBAD, at DESY***.
* M. Roehrs et al., Phys. Rev. ST Accel. Beams 12, 050704 (2009).
** A. Grudiev, Report No. CLIC-Note-1067, 2016.
*** B. Marchetti et al. X-band TDS project contribution to these conference proceedings.

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MOPAB046

Lattice Considerations for the Use of an X-Band Transverse Deflecting Structure (TDS) at SINBAD

dipole, quadrupole, lattice, cavity

192

D. Marx, R.W. Aßmann, U. Dorda, U. Dorda, B. Marchetti, F. Mayet
DESY, Hamburg, Germany
F. Mayet
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

An X-band TDS is a well-known device for the characterization of the longitudinal properties of an electron bunch in a linear accelerator. It is planned that a novel X-band TDS with variable polarization* will be installed within the next few years at SINBAD, an upcoming accelerator R&D facility at DESY**. There are several measurements that can be performed with the TDS, each with specific optics requirements to reach the highest possible resolution and keep induced energy spread to a tolerable level. Quadrupoles will be installed between the TDS and the screen to help satisfy these conditions. In this paper, the requirements for the bunch length measurements, a novel 3D charge density reconstruction technique and slice energy measurements are discussed and some simulation results for the slice energy measurement using example lattices are presented.
* A. Grudiev, CLIC-note-1067 (2016).
** B. Marchetti et al. X-band TDS project contribution to these conference proceedings.

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MOPAB047

Electron Beam Phase Space Tomography at the European XFEL Injector

emittance, quadrupole, FEL, optics

196

M. Scholz, B. Beutner
DESY, Hamburg, Germany

The FEL process is determined by the 6D phase space distribution of relativistic electron bunches. Experimental reconstructions of these distributions are therefore a step foreward to understand the beam dynamics and to optimize FEL operation. The reconstructions of the transverse phase spaces can be acieved with tomographic methods. In the injector of the European XFEL, measurements for the reconstruction of the phase spaces were carried out using phase advance scans with multiple quadrupoles. The beam sizes were kept optimized at the measurement screen. A transversely deflecting cavity (TDS) was used to streak the beam vertically. That allows to do longitudinally slice resolved measurements of the horizontal phase space. The horizontal streak required for the slice measurements in the vertical plane was achieved with a correlated linear energy spread and dispersion. In this paper, we present measurement results showing longitudinal slice resolved reconstructions of the transverse phase spaces taken in the European XFEL injector.

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MOPAB048

Simulation of fs Bunch Length Determination with the 3-Phase Method and THz Dielectric Loaded Waveguides

injection, linac, space-charge, simulation

199

T. Vinatier, R.W. Aßmann, U. Dorda, B. Marchetti
DESY, Hamburg, Germany

In this paper, we investigate with ASTRA simulations the capability of the 3-phase method to reconstruct the length of a fs electron bunch. We show that a standard 3 GHz travelling wave accelerating structure is not suited for this purpose, because of the too important effect of the space-charge forces and of the too small variations of the induced energy spread with the bunch injection phase. Our simulations demonstrate that the use of dielectric-loaded waveguides driven by THz pulses would allow overcoming these two limitations and possibly achieving an ultimate resolution better than 5% for the determination of a 6.25 fs rms bunch length at 100 MeV energy and 1 pC charge. The next steps of the study to better evaluate, in simulations and experiments, the possible sources of degradation of the 3-phase method resolution are also mentioned.

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MOPAB050

Reconstruction of Sub-Femtosecond Longitudinal Bunch Profile Measurement Data

laser, diagnostics, undulator, cavity

207

M.K. Weikum, R.W. Aßmann, U. Dorda
DESY, Hamburg, Germany
G. Andonian
RadiaBeam, Santa Monica, California, USA
G. Andonian
UCLA, Los Angeles, California, USA
Z.M. Sheng, M.K. Weikum
USTRAT/SUPA, Glasgow, United Kingdom
Z.M. Sheng
Shanghai Jiao Tong University, Shanghai, People's Republic of China

With a current trend towards shorter electron beams with lengths on the order of few femtoseconds (fs) to sub-femtoseconds both in conventional and novel accelerator communities, the need for diagnostics with equivalent attosecond resolution is increasing. The proposed design for a sub-femtosecond diagnostic by Andonian et al.* is one such example that combines a laser deflector with an RF deflecting cavity to streak the electron beam in the horizontal and vertical direction. In this paper, we present a tool for the reconstruction of the longitudinal beam profile from this diagnostic data, which can be used both for the analysis of planned experiments and testing of different beam scenarios with respect to their specific setup requirements. Applying this method, the usefulness of the device for measurements in a number of example scenarios, including plasma-accelerated and ultrashort RF-accelerated electron beams, is discussed.
*G. Andonian, E. Hemsing, D. Xiang, P. Mumuseci, A. Murokh, S. Tochitsky, et al, Phys. Rev. Spec. Top-Ac. 14, 072802 (2011).

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MOPAB052

A Transverse Deflection Structure with Dielectric-Lined Waveguides in the Sub-THz Regime

simulation, emittance, impedance, laser

215

F. Lemery
University of Hamburg, Hamburg, Germany
R.W. Aßmann, K. Flöttmann, T. Vinatier
DESY, Hamburg, Germany

Longitudinal bunch measurements are typically done with rf-powered transverse deflection structures with operating frequencies 1-12~GHz. We explore the use of mm-scale, THz-driven, dielectric-lined cylindrical waveguides as transverse deflectors by driving the fundamental deflecting mode of the structure, the HEM₁₁. We give a brief overview of the physics, history, and provide an example with a 5~MeV beam using {\sc astra} and {\sc CST-MWS}.
This work was supported by the European Research Council (ERC) under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant agreement no. 609920

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MOPAB053

Electron Bunch Streaking With Single-Cycle THz Radiation Using an NSOM-Style TIP

simulation, laser, interaction-region, diagnostics

219

F. Lemery, A.F. Hartin
University of Hamburg, Hamburg, Germany
D. Zhang
DESY, Hamburg, Germany
D. Zhang
CFEL, Hamburg, Germany

THz wavelengths provide an excellent scale for electron-bunch acceleration and manipulation. The improvement of laser-based THz-generation efficiencies to ~1% provides a good opportunity for e.g. phase-space manipulation and diagnostics. We describe a simple technique to streak and characterize electron beams. We provide full simulation results and discuss the scaling of this technique to various regimes.

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MOPAB055

Towards Near-Field Electro-Optical Bunch Profile Monitoring in a Multi-Bunch Environment

wakefield, laser, storage-ring, radiation

227

P. Schönfeldt, E. Blomley, E. Bründermann, M. Caselle, S. Funkner, N. Hiller, B. Kehrer, A.-S. Müller, M.J. Nasse, G. Niehues, L. Rota, M. Schedler, M. Schuh, M. Weber
KIT, Karlsruhe, Germany

Funding: This work is funded by the BMBF contract numbers: 05K13VKA and 05K16VKA.
For electron accelerators, electro-optical methods in the near-field have been shown to be a powerful tool to detect longitudinal bunch profiles. In 2013, we demonstrated for the first time, electro-optical bunch profile measurements in a storage ring at the accelerator test facility and synchrotron light source ANKA at the Karlsruhe Institute of Technology (KIT). To study possible bunch-bunch interactions and its effects on the longitudinal dynamics, these measurements need to be performed in a multi-bunch environment. Up to now, due to long-ranging wake-fields the electro-optical monitoring was limited to single-bunch operation. Here, we present our new in-vacuum setup to overcome this limitation. First measurements show reduced wake-fields in particular around 2 ns, where the subsequent bunch can occur in a multi-bunch environment at ANKA.

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MOPAB057

Analysis and Correction of Geometrical Non-Linearities of ELI-NP BPMs on Position and Current Measurements

linac, laser, photon, instrumentation

235

G. Franzini, F. Cioeta, O. Coiro, V.L. Lollo, D. Pellegrini, S. Pioli, A. Stella, A. Variola
INFN/LNF, Frascati (Roma), Italy
M. Marongiu
INFN-Roma, Roma, Italy
A. Mostacci
University of Rome La Sapienza, Rome, Italy
A.A. Nosych
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
L. Sabato
U. Sannio, Benevento, Italy

The advanced source of Gamma-ray photons will be soon built near Bucharest (Romania) by an European consortium (EurogammaS) led by INFN, as part of the ELI-NP (Extreme Light Infrastructure-Nuclear Physics). It will generate photons by Compton back-scattering in the collision between a multi-bunch electron beam, at a maximum energy of 720 MeV, and a high intensity recirculated laser pulse. An S-Band photo-injector and the following C-band Linac, which are under construction, will operate at 100Hz repetition rate with macro pulses of 32 electron bunches, separated by 16ns and with 250pC nominal charge. Stripline and cavity BPMs will be installed along the linac, in order to measure both the position and charge of the electron beam. Stripline BPM response can be considered linear within a limited area around the BPM origin. In order to use the full BPM acceptance area, without accuracy losses due to non-linearities, we plan to use correction algorithms, developed on the basis of simulations and measurements of BPMs response. In particular, suitable high-order surface polynomials will be used.

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MOPAB058

Optical Issues for the Diagnostic Stations for the ELI-NP Compton Gamma Source

target, diagnostics, linac, laser

238

M. Marongiu, D. Cortis
INFN-Roma, Roma, Italy
E. Chiadroni, F. Cioeta, G. Di Pirro, G. Franzini, V. Shpakov, A. Stella, A. Variola
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
A. Mostacci, L. Palumbo
University of Rome La Sapienza, Rome, Italy
L. Sabato
U. Sannio, Benevento, Italy

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy in order to measure very small beam (below 30 um) or to study the angular distribution of the OTR and therefore the energy of the beam. Several configurations of the optical detection line will be studied both with simulation tools (e.g. Zemax) and experimentally. The paper will deal also with the sensibility of optic system (in terms of depth of field, magnification and resolution) to systematic errors.

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MOPAB059

Energy Chirp Measurements by Means of an RF Deflector: a Case Study the Gamma Beam Source LINAC at ELI-NP

linac, brightness, detector, simulation

242

L. Sabato
U. Sannio, Benevento, Italy
P. Arpaia, A. Liccardo
Naples University Federico II, Science and Technology Pole, Napoli, Italy
A. Mostacci, L. Palumbo
University of Rome La Sapienza, Rome, Italy
A. Variola
INFN/LNF, Frascati (Roma), Italy

RF Deflector (RFD) based measurements are widely used in high–brightness electron LINAC around the world in order to measure the ultra–short electron bunch length. The RFD provides a vertical kick to the particles of the electron bunch according to their longitudinal positions. In this paper, a measurement technique for the bunch length and other bunch proprieties, based on the usage of an RFD, is proposed. The basic idea is to obtain information about the bunch length, energy chirp, and energy spread from vertical spot size measurements varying the RFD phase, because they add contributions on this quantity. The case study is the Gamma Beam System (GBS), the Compton Source being built in the Extreme Light Infrastructure–Nuclear Physics (ELI–NP) facility. The ELEctron Generation ANd Tracking (ELEGANT) code is used for tracking the particles from RFD to the measurement screen.

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MOPAB060

Thermal Issues for the Optical Transition Radiation Screen for the ELI-NP Compton Gamma Source

target, radiation, simulation, laser

246

F. Cioeta, D. Alesini, A. Falone, V.L. Lollo, L. Pellegrino, A. Variola
INFN/LNF, Frascati (Roma), Italy
M. Ciambrella
University of Rome La Sapienza, Rome, Italy
D. Cortis, M. Marongiu, V. Pettinacci
INFN-Roma, Roma, Italy
A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in two interaction points. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the OTR screens must sustain the thermal and mechanical stress due to the energy deposited by the bunches. This paper is an ANSYS study of the issues due to the high energy transferred to the OTR screens. Thermal multicycle analysis will be shown; each analysis will be followed by a structural analysis in order to investigate the performance of the material. The multiphysics analysis will be extended to the mechanical contact areas with the target frame in order to evaluate the order of magnitude of the phenomena in those regions.

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MOPAB064

Photoinjector Emittance Measurement at STAR

emittance, gun, solenoid, simulation

257

A. Bacci, C. Curatolo, I. Drebot, L. Serafini, V. Torri
Istituto Nazionale di Fisica Nucleare, Milano, Italy
R.G. Agostino, R. Barberi, V. Formoso, M. Ghedini, F. Martire, C. Pace
UNICAL, Arcavacata di Rende, Italy
D. Alesini, M. Bellaveglia, J.J. Beltrano, F.G. Bisesto, G. Borgese, B. Buonomo, G. Di Pirro, G. Di Raddo, A. Esposito, A. Gallo, A. Ghigo, F. Iungo, A. Papa, L. Pellegrino, A. Stella, C. Vaccarezza, S. Vescovi
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
G. D'Auria, A. Fabris, M. Marazzi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
A. Policicchio
UniCal & INFN CS, Arcavacata di Rende (CS), Italy
E. Puppin
Politecnico/Milano, Milano, Italy
M. Rossetti Conti
Universita' degli Studi di Milano & INFN, Milano, Italy

STAR is an advanced Thomson source of monochromatic and tunable, ps-long, polarised X-ray beams in the 40-140 keV range. The commissioning has started at the Univ. of Calabria (Italy). The light source is driven by a high-brightness, low-emittance electron beam produced in a LINAC allowing for the source tunability and spectral density. This note reports on an emittance measurement schema based on the insertion of a slit mask in the vacuum chamber dedicated to the photocathode laser entrance. Results of the simulation of the measurement technique are reported, and the use of the data for the optimisation of the accelerator performance are detailed. The experimental setup and the application developed in EPICS for image recording and analysis are also described.

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MOPAB065

Breit-Wheeler Scattering Events Produced by Two Interacting Compton Sources

photon, scattering, laser, background

261

I. Drebot, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
D. Micieli, E. Tassi
UNICAL, Arcavacata di Rende, Italy
E. Milotti
INFN-Trieste, Trieste, Italy
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy

We present the dimensioning of a photon-photon collider based on conventional Compton gamma sources for the observation of Breit-Wheeler pair production and QED gamma-gamma generation. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two primary gamma rays through Compton back-scattering with two high-energy lasers. Tuning the system energy above the Breit-Wheeler cross section threshold, a flux of secondary electrons and positrons is generated. The process is analyzed by start-to-end simulations. The Monte Carlo code 'Rate Of Scattering Events' (ROSE) has been developed ad hoc for the counting of the QED events. Realistic numbers of the secondary particles yield, referring to existing or approved set-ups, a discussion of the feasibility of the experiment and the evaluation of the background are presented.

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MOPAB066

Development and Performance Test of the BPM System for the SPring-8 Upgrade

radiation, simulation, storage-ring, photon

265

H. Maesaka
RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
H. Dewa, T. Fujita, M. Masaki
JASRI, Hyogo, Japan
S. Takano
Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan

We are developing a stable and precise BPM system for the low-emittance upgrade of SPring-8. One of the essential requirements for the BPM is the long term stabilization of the photon beam by regulating the electron beam orbit. Both the single-pass resolution of 100 um rms for an injected beam charge of 100 pC and an accuracy of 100 um rms are also crucial for beam commissioning. Drift sources of the present BPM system have been investigated extensively, such as humidity-dependent drifts coming from the radiation damage of coaxial cables, and the results are fed back to the design of the new BPM system. We have optimized the design of the button BPM electrodes to reconcile reduction of trapped-mode heating and maximization of the signal intensity. Stringent machining tolerance is imposed on a BPM head to align the BPM electric center accurately. A few kinds of the BPM head prototypes were produced and the machining accuracy, RF characteristics etc. were confirmed to be sufficient. We have installed one of the prototypes in the present storage ring to test the performance of the new BPM system under development, and have been obtaining successful results satisfying the requirements.

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MOPAB067

Response of Scintillating Screens to High Charge Density Electron Beam

quadrupole, linac, diagnostics, experiment

268

F. Miyahara, S. Kishimoto, M. Satoh, Y. Seimiya, T. Suwada
KEK, Ibaraki, Japan
M. Koshimizu
Tohoku University, School of Science, Sendai, Japan

Inorganic scintillating screens are very useful tool to measure transverse profile of charged particle beams. The cerium-doped yttrium:aluminum:garnet (YAG:Ce) crystal scintillator is used in many accelerating facilities. The scintillating screen shows good resolution comparable to that of OTR screen. However, response to high charge density electron beam, more than 10 nC per square millimeter, has not been clarified. In KEK e⁺/e⁻ injector linac, the charge areal density (σ) will exceed 25 nC per square mm. Thus, beam tests has been performed on YAG:Ce, LYSO, and BGO crystals for 1.5 GeV, 1 nC/bunch electron beam at the linac. Saturation of the luminescence which causes degradation of the resolution has been observed above 1 nC per square mm in those crystals. We will report the response of the scintillating screens to high charge density electron beam and discuss the degradation of the resolution due to the saturation of the light yield.

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MOPAB068

Bunch Shape Monitor Development in J-PARC Linac

vacuum, quadrupole, focusing, target

271

A. Miura, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan
T. Miyao
KEK, Ibaraki, Japan

At Japan accelerator reserch complex (J-PARC), the linac, which serves as the injector for the downstream 3-GeV synchrotron, accelerates a negative-hydrogen-ion beam (H⁻) to obtain a 400-MeV beam energy. We use an accelerating frequency of 324 MHz for the accelerator cavities and of 972 MHz. Both the centroid-phase set point at the frequency jump from 324 MHz to 972 MHz and the phase-width control are key issues for suppressing the excess beam loss. In order to optimize a set point of the tuning cavities, we developed a bunch-shape monitor (BSM) to measure the phase width as well as a tuning strategy to minimize the beam loss. In the development of the BSM, the design developed in the INR, Russia. Because the BSM had first experienced to be used between accelearation cavities, we need to protect the leak-magnetic field from quadrupole magnets and outgas impacts to cavities. We installed a BSM again in the beamline, BSM started to measure the phase width and evaluated its performances with a peak-beam-current dependence. We proposed new strategy to use BSM-measurment data for the tuning cavity. This paper describes the BSM development, its modification, and new strategy.

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MOPAB072

Measurement of Three-Dimensional Distribution of Electron Bunch Using RF Transverse Deflector

experiment, laser, gun, solenoid

285

Y. Nakazato, Y. Koshiba, T. Sasaki, M. Washio
Waseda University, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan

We have been studying a high quality electron beam generated by a photocathode RF gun at Waseda University. The electron beam is applied to a pulse radiolysis experiment, laser Compton scattering for soft X-ray generation, and a THz imaging experiment using coherent radiation. In these applications, longitudinal parameters of the electron beam are important. For this reason, we developed the RF deflector system which can directly convert longitudinal distribution of the beam to transverse with high temporal resolution, and performed longitudinal profile measurements of an electron beam from the RF gun. During a series of experiments using an RF deflector, we found that the bunch had a horizontal angle with respect to z axis. Thus we tried to reconstruct the three-dimensional profile of the bunch by computed tomography* in order to visualize the three-dimensional distribution of the bunch. In this conference, we will report the principle of measurement, experimental results of the bunch three-dimensional measurement, and future prospects.
* J. Shi, et al., Reconstruction of the three-dimensional bunch profile by tomography technique with RF deflecting cavity, Nucl. Instrum. Methods Phys. Res., A 752 (2014) 36-41

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MOPAB073

Measurement of Electron-Bunch Length Using Coherent Radiation in Infrared Free-Electron Laser Facilities

FEL, detector, radiation, laser

288

N. Sei, H. Ogawa
AIST, Tsukuba, Ibaraki, Japan
K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, T. Tanaka
LEBRA, Funabashi, Japan
H. Ohgaki, H. Zen
Kyoto University, Kyoto, Japan

Funding: This study was financially supported by JSPS KAKENHI Grant Number JP16H03912.
We have studied techniques evaluating bunch length of micropulses in an electron beam. The bunch length of the electron beam is an important parameter for free-electron laser (FEL) facilities with linear accelerators. In order to obtain high FEL gain at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University and at Kyoto University Free Electron Laser (KU-FEL), the electron-bunch length is compressed to less than 1 ps in their undulator sections. Using the compressed electron beams, intense terahertz lights were generated by coherent radiation. The power of the coherent radiation was more than 50 micro-joule per electron-beam macropulse. We can extract the information of the bunch length of the electron-beam micropulse from the intense coherent radiation by using narrow-band diode detectors. In this presentation, experimental results of the measurements of the root-mean-square electron-bunch length using the coherent radiation at LEBRA* and KU-FEL** will be reported.
*: N. Sei et al., J. Opt. Soc. Am. B, 31, 2150 (2014).
**: N. Sei et al., Nucl. Instrum. Methods Phys. Res., Sect. A, 832, 208 (2016).

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MOPAB074

Low Intensity Electron Beam Controlling and Monitoring

detector, linac, controls, experiment

292

L. Yu, Y. Li, Y.F. Sui, J.H. Yue
IHEP, Beijing, People's Republic of China

To calibrating a cosmic-ray detector, a low beam current accelerator has been built to generate ultra low intensity electron beams at Institute of High Energy Physics (IHEP). The minimum beam charge obtained was estimated to be about one electron/pulse. Beam commissioning has been carried out. The key technologies for achieving such low intensity electron beams are to control the beam using 8 movable slits and to measure the intensity of the beam using 9 movable current monitors based on scintillator. In this paper, principal of operation, instrumentation and programming of the movable slits and movable current monitors are discussed. Some results of beam commissioning are also presented.

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MOPAB075

Measurement of Electron Bunch Length via a Tunable-Gap Undulator

radiation, undulator, laser, acceleration

295

X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan
TUB, Beijing, People's Republic of China
Y.F. Liang
Tsinghua University, Beijing, People's Republic of China

A THz undulator with widely tunable gap is constructed and installed at Tsinghua University beamline, which is applied for narrow-band THz radiation and measurements of electron bunch longitudinal structure. This is a planar electromagnetic device with 8 regular periods, each 10 cm long. The field range B=0.15- 0.99 T peak field on axis while changing the gap from 75mm to 23mm. In the experiments, we scanned the undulator gap to measure the radiation intensity at different resonant frequency, thus we can get the bunch length even form factor of the bunch. The demonstrated experimental results show that the bunch of 220pC compressed by chicane in Tsinghua beamline is about 120fs (rms), which agree well with the simulations. The resolution of bunch length measurement with this method can be attoseconds by optimized undulator. Furthermore, the form factor of electron bunch train can also be measured.

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MOPAB077

Spatial Decoding Electro-Optic Bunch Measurement at Tsinghua Thomson Scattering X-ray Source

laser, experiment, diagnostics, scattering

302

W. Wang, Z.J. Chi, Y.-C. Du, W.-H. Huang, C.-X. Tang, L.X. Yan, Z. Zhang
TUB, Beijing, People's Republic of China

Electron bunches with duration of sub-picosecond are essential in ultraviolet and X-ray free electron laser (XFEL) to reach the desired peak current. Electro-optic (EO) technique is suitable for temporal profile measure-ment of these ultrashort bunches which is one of the key diagnostics in FELs. An electro-optic monitor based on spatial sampling has recently been designed and installed for bunch profile diagnostic at Tsinghua Thomson scat-tering X-ray source (TTX). An ultrashort laser pulse is used to detect the field induced birefringence of the bunch Coulomb field in an electro-optic crystal and the monitor allows direct time-resolved single-shot measure-ment of bunch profile with an accuracy of 135 femtosec-onds for a 40 MeV electron bunch in a non-destructive way, which can simultaneously record the relative time jitter between probe laser and electron bunch. This paper performs the layout of the setup and presents the current measurement results.

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MOPAB082

Design and Simulation of High Order Mode Cavity Bunch Length Monitor for Infrared Free Electron Laser

cavity, simulation, FEL, laser

309

Q. Wang, X.Y. Liu, P. Lu, Q. Luo, B.G. Sun, L.L. Tang, J.H. Wei, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900, 2016YFA0401903); NSFC (11375178, 11575181); the Fundamental Research Funds for the Central Universities (WK2310000046)
A bunch length monitor using resonant cavity has been designed for the NSRL Infrared Free Electron Laser (IR-FEL) facility. To avoid the restriction of working fre-quency caused by the beam pipe radius, the high order modes of the harmonic cavities are utilized. The position and orientation of coaxial probes are optimized to avoid interference modes which come from the cavity and beam tube according to the analysis formula of electro-magnetic field distribution. Based on the parameters of IR-FEL, a simulation is performed to verify the feasibility of the bunch length monitor. The simulation result shows that the design meets the requirements of IR-FEL, and the resolution can be better than 50 fs.

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MOPAB083

The New Beam Current Transformer for IR-FEL Facility at NSRL *

FEL, diagnostics, induction, electronics

312

J.H. Wei, H. Li, X.Y. Liu, P. Lu, B.G. Sun, J.G. Wang, Q. Wang, F.F. Wu, Y.L. Yang, T.Y. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by The National Science Foundation of China (Grant No. 11575181)
The beam current transformer (CT) is an important part of the beam diagnostics system as a kind of non-destructive intensity measurement. The beam CT has the strong dependence of the sensitivity and time constant on the time structure of the beam. To measure the macro-pulse beam intensity with 5-10 's length and 238 MHzμpulse repetition rate in the IR-FEL, it is necessary to find a suitable material as the CT core which can meet the measure requirement of the beam current. In this paper, three different magnetic materials were tested to find out that the laminated amorphous core owned the best performance, meanwhile, the mechanical structure was designed. The finished product passed the acceptance test.

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MOPAB098

Coronagraph Based Beam Halo Monitor Development for BERLinPro

background, dipole, linac, scattering

355

J.G. Hwang
Kyungpook National University, Daegu, Republic of Korea
J. Kuszynski
HZB, Berlin, Germany

For linac based high power electron machines, beam halo induced by nonlinear space charge force and scattering of trapped ions is one of the critical issues on a machine protection system. It causes additional radiation which can be a heat source on a cryogenic system as a result of uncontrolled beam losses. During the last decades, several instruments have been newly developed for measuring the beam halo distribution. The conceptual design and optimization of the coronagraph based halo monitor were performed to measure the beam halo which has ~ 10^-3 contrast to the beam core.

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MOPAB118

Cherenkov Diffraction Radiation From Long Dielectric Material: An Intense Source of Photons in the NIR-THz Range

photon, radiation, target, storage-ring

400

T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni
CERN, Geneva, Switzerland
M.G. Billing, J.V. Conway, J.P. Shanks
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
L.M. Bobb
DLS, Oxfordshire, United Kingdom
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom

This paper presents the design on the Cornell Electron Storage Ring (CESR) of an experimental set-up to meas-ure incoherent Diffraction Cherenkov Radiation (DChR) produced in a 2 cm long SiO2 radiator by a 2.1 GeV elec-tron beam. The electron beam is circulating at a distance of few mm from the edge of the radiator and the DChR photon output power is expected to be significantly higher than the diffraction radiation power emitted from a metal-lic slit of similar aperture. The radiator design and the detection set-up are presented in detail together with sim-ulations describing the expected properties of the emitted DChR in terms of light intensity and spectral bandwidth. Finally, potential applications of DChR are discussed.

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MOPAB119

Beam Instrumentation Developments for the Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

proton, plasma, laser, electronics

404

S. Mazzoni, M. Barros Marin, B. Biskup, A. Boccardi, T.B. Bogey, S. Burger, F.S. Domingues Sousa, E. Effinger, J. Emery, A. Goldblatt, I. Gorgisyan, E. Gschwendtner, A. Guerrero, L.K. Jensen, T. Lefèvre, D. Medina, B. Moser, G. Schneider, L. Søby, M. Turner, M. Vicente Romero, M. Wendt
CERN, Geneva, Switzerland
B. Biskup
Czech Technical University, Prague 6, Czech Republic
M. Turner
TUG/ITP, Graz, Austria
V.A. Verzilov
TRIUMF, Vancouver, Canada

The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) at CERN aims to develop a proof-of-principle electron accelerator based on proton driven plasma wake-field acceleration. The core of AWAKE is a 10 metre long plasma cell filled with Rubidium vapour in which single, 400 GeV, proton bunches extracted from the CERN Super Proton Synchrotron (SPS) generate a strong plasma wakefield. The plasma is seeded using a femtosecond pulsed Ti:Sapphire laser. The aim of the experiment is to inject low energy electrons onto the plasma wake and accelerate them over this short distance to an energy of several GeV. To achieve its commissioning goals, AWAKE requires the precise measurement of the position and transverse profile of the laser, proton and electron beams as well as their temporal synchronisation. This contribution will present the beam instrumentation systems designed for AWAKE and their performance during the 2016 proton beam commissioning period.

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MOPAB124

A Fast Gain Calibration Algorithm for Beam Position Monitoring at Taiwan Photon Source

pick-up, storage-ring, operation, target

419

J.Y. Chen, C.H. Chen, M.-S. Chiu, P.C. Chiu, P.J. Chou, S. Fann, K.H. Hu, C.S. Huang, C.-C. Kuo, T.Y. Lee, C.C. Liang, Y.-C. Liu, G.-H. Luo, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

A stable, reliable and well-calibrated beam position monitor (BPM) system is essential for the operation of accelerators. At newly constructed Taiwan Photon Source (TPS), it not only helps us to determine the accelerator parameters, such as Twiss parameters and tune, but also to avoid the damage on accelerator instruments caused by high-energy particle beams or radiation. In this study, we demonstrate a new BPM calibration scheme at TPS storage ring. To excite the electron beams inside accelerator beam pipe by one horizontal or vertical corrector magnet, we measure the response of analog-to-digital converter (ADC) of each BPM pick-up electrodes with different lateral positions and beam currents. Depending on the measured ADC responses, we calibrated the beam position monitor system. Simultaneously, because of limited preparation time after every long shutdown, we are looking for a fast algorithm to ensure the measurement could be done easily and finished as quickly as possible.

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MOPAB126

Applications of Metamaterials for Particle Beam Diagnostics

target, radiation, diagnostics, resonance

425

T.G. Vaughan, P. Karataev
JAI, Egham, Surrey, United Kingdom
V. Antonov
Royal Holloway, University of London, Surrey, United Kingdom
V.V. Soboleva
RASA Center in Tomsk, Tomsk, Russia

Funding: The work was supported by the Leverhulme Trust through the International Network Grant (IN-2015-012) and the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179 and Russian Governmental Program 'Nauka', N: 0.1656.2016.
Modern and future accelerators, such as linear colliders and X-ray Free Electron Lasers (X-FELs), will be capable of producing femtosecond and sub-femtosecond electron bunches with unprecedented intensity. Non-invasive beam diagnostics will be an integral component of such machines. A new non-destructive method, which employs a Left Handed Metamaterial (LHM), is promising as it provides additional flexibility in the generation and manipulation of radiation compared to techniques which use conventional materials. Simulations of the interaction of a photon beam with the LHM target have been performed using CST Microwave Studio. The range over which the frequency responce is negative can be tuned to the bunch length requirements by varying the parameters of the unit cell such as: the dimensions of the rings and the number of slits in each ring. Simulations have also been performed using Particle Studio on the interaction of an electron beam with the LHM. With a flexible resonance in the terahertz range, this material not only offers applications for ultra short bunch length measurements, but it also opens up the possibility to be used to generate coherent terahertz radiation.

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MOPAB132

Beam Size Measurement Using High Aspect Ratio LIGA Apertures in an X-Ray Pinhole Camera

radiation, synchrotron, status, emittance

445

L.M. Bobb, G. Rehm
DLS, Oxfordshire, United Kingdom

For optimal brilliance third generation light sources operate at a low emittance and low coupling. Commonly, transverse beam profile measurements are provided by direct imaging of the electron beam using X-ray pinhole cameras. From these beam size measurements and given knowledge of the lattice parameters the emittance, coupling and energy spread are calculated. Ideally, the pinhole aperture should be formed in an infinitely thin screen. However, due to the penetration of X-rays in the keV spectral range, stacked tungsten blades are often used to form the pinhole aperture. In this arrangement the absolute size of the pinhole aperture is unknown and cannot be directly measured, which affects the spatial resolution of the imaging system. Here we investigate the use of X-ray Lithography, Electroplating and Moulding (commonly known as LIGA) to fabricate high aspect ratio pinhole apertures in a gold screen of approximately 1 mm thickness.

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MOPAB138

Comparison of Optical Transition Radiation Simulations and Theory

radiation, diagnostics, simulation, optics

455

J. Wolfenden, R.B. Fiorito, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Bergamaschi, P. Karataev, K.O. Kruchinin
JAI, Egham, Surrey, United Kingdom
M. Bergamaschi, P. Karataev, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
M. Bergamaschi, R. Kieffer, T. Lefèvre
CERN, Geneva, Switzerland
R.B. Fiorito, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom

The majority of optical diagnostics currently used will not stand up to the requirements of the next generation of particle accelerators. Current methodologies need innovation to be able to reach the sub-micrometre resolution and sensitivity that will be required. One technique that has the potential to meet these requirements is optical transition radiation (OTR) imaging. A new algorithm is proposed which incorporates OTR theory, optical effects and beam distribution. This algorithm takes an existing method used for beam imaging and pushes the limits resolution beyond that normally attainable. In doing so, it can provide a reliable and economical diagnostic for future accelerators. A discussion on further applications of the algorithm is also presented.

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MOPAB139

A Supersonic Gas-Jet Based Beam Induced Fluorescence Prototype Monitor for Transverse Profile Determination

ion, photon, experiment, gun

458

H.D. Zhang, E. Martin, V. Tzoganis, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
E. Barrios Diaz, N. Chritin, O.R. Jones, G. Schneider, R. Veness
CERN, Geneva, Switzerland
P. Forck, S. Udrea
GSI, Darmstadt, Germany
P. Forck
IAP, Frankfurt am Main, Germany
E. Martin, V. Tzoganis, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
S. Udrea
TU Darmstadt, Darmstadt, Germany

Supersonic gas jets have been used in transverse beam profile monitoring as Ionization Profile Monitors (IPMs) and Beam Induced Fluorescence (BIF) monitors. The former method images ions generated by the projectile beam, whilst the latter is based on the detection of photons. This is a promising technology for use in high energy accelerators, such as the High Luminosity Large Hadron Collider (HLLHC). In this paper, the suitability of a supersonic gas jet in combination with a BIF detection system for the measurement of the transverse beam profile of a low energy electron beam is discussed. The technical layout and experimental results from measurements at a test installation at the Cockcroft Institute are also presented.

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MOPAB144

Residual-Gas Beam Profile Monitors for Intense Beams in Transfer Lines

ion, proton, synchrotron, detector

469

R.J. Abrams, M.A. Cummings, V.G. Dudnikov, R.P. Johnson
Muons, Inc, Illinois, USA
M. Popovic
Fermilab, Batavia, Illinois, USA

Muons, Inc. proposes to develop a Residual-Gas Beam Profile Monitor for Transfer Lines with pulse-to-pulse precision of better than 0.1 mm in position and size that will operate over a wide range of proton beam intensities including those needed for multi-MW beams of future facilities. Traditional solid-based beam intercepting instrumentation produces unallowable levels of radiation at high powers. Our alternative approach is to use a low mass residual-gas profile monitor, where ionization electrons are collected along extended magnetic field lines and the gas composition and pressure in the beam pipe are locally controlled to minimize unwanted radiation and to improve resolution. Beam Induced Fluorescence profile monitor with mirascope light collection is proposed.

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MOPAB146

Electron Beam Diagnosis Using K-edge Absorption of Laser-Compton Photons

laser, photon, emittance, scattering

473

Y. Hwang, T. Tajima
UCI, Irvine, California, USA
C.P.J. Barty, D.J. Gibson, R.A. Marsh
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The mean energy, energy spread and divergence of the electron beam can be deduced from laser-Compton scattered X-rays filtered by a material whose K-edge is near the energy of the X-rays. This technique, combined with a spot size measurement of the beam, can be used to measure the emittance of electron bunches, and can be especially useful in LWFA experiments where conventional methods are unavailable. The effects of the electron beam parameters on X-ray absorption images are discussed, along with experimental demonstrations of the technique using the Compact Laser-Compton X-ray Source at LLNL.

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MOPAB150

Imaging the Spatial Modulation of a Relativistic Electron Beam

experiment, scattering, quadrupole, emittance

480

C. Zhang, W.S. Graves, L.E. Malin, J. Spence
Arizona State University, Tempe, USA
D.B. Cesar, J.M. Maxson, P. Musumeci, A. Urbanowicz
UCLA, Los Angeles, USA
C. Limborg, E.A. Nanni
SLAC, Menlo Park, California, USA

Funding: Work supported by NSF awards 1632780, 1415583, 1231306 and DOE award de-sc0009914
We describe Bragg diffraction of relativistic electron beams through a patterned Si crystal consisting of alternating thick and thin strips to produce nanometer scale electron density modulations. Multi-slice simulations show that a two-beam situation can be set up where, for a particular thickness of Si, nearly 100% of the electron beam is diffracted. Plans are underway to carry out experiments showing this effect in UCLA's ultrafast electron microscopy lab with 3.5 MeV electrons. We will select either the diffracted beam or the primary beam with a small aperture in the diffraction plane of a magnetic lens, and so record either the dark or bright field magnified image of the strips. Our first goal is to observe the nanopatterned beam at the image plane. We will then investigate various crystal thickness and sample orientations to maximize the contrast in the pattern and explore tuning the period of the modulation through varying magnification.

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MOPAB153

R&D of a Gas-Filled RF Beam Profile Monitor for Intense Neutrino Beam Experiments

cavity, plasma, ion, experiment

491

K. Yonehara, M. Backfish, A. Moretti, A.V. Tollestrup, A.C. Watts, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
R.J. Abrams, M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer
Muons, Inc, Illinois, USA
Q. Liu
Case Western Reserve University, Cleveland, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013764.
A MW-power beam facility is desired to produce an intense neutrino beam for study of fundamental particle physics. It is a critical challenge to measure beam profile in extreme radiation environments. To this end, a novel beam profile monitor based on a gas-filled multi-RF cavity is proposed. Charged particles through the gas-filled RF generate plasma that changes the gas permittivity. The modulated RF signal in the cavity due to the permittivity shift will be measured to reconstruct the flux of charged particles in the cavity. The demonstration is proposed to validate the concept of the monitor. We report the progress of the demonstration test.

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MOPIK004

Demonstration of an All-Optically Driven Sub-keV THz Gun

gun, acceleration, laser, operation

503

W.R. Huang, K.-H. Hong, F.X. Kärtner, E.A. Nanni, KR. Ravi
MIT, Cambridge, Massachusetts, USA
A-L. Calendron, H. Cankaya, A. Fallahi, F.X. Kärtner, X. Wu
CFEL, Hamburg, Germany
D. Zhang
DESY, Hamburg, Germany

Funding: European Research Council under the European Union Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement no. 609920
Intense ultrashort THz and optical pulses with single-cycle pulse duration became possible after the recent advances in ultrafast technologies. Using such ultrashort pulses for electron acceleration offers advantages in terms of higher thresholds for material breakdown which opens up a promising path towards increased acceleration gradients. In addition, using optically generated THz pulses enable inherently synchronized acceleration schemes, since accelerating field and particle injecting field are excited by a single seed laser. In this contribution, we present the first experimental demonstration of laser-driven THz acceleration of electrons initially at rest. It is shown that strong-field, single-cycle THz fields accelerate electrons with peak energies of up to 0.8 keV in an ultracompact THz gun with bunch charge of 40 fC. The achieved energy spreads are as low as 5.8%.

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MOPIK005

Compact Electron Injectors Using Laser Driven THz Cavities

cavity, gun, laser, acceleration

506

M. Fakhari, A. Fallahi, F.X. Kärtner, N.H. Matlis, A. Yahaghi
CFEL, Hamburg, Germany
R.W. Aßmann, U. Dorda, K. Galaydych, B. Marchetti, G. Vashchenko, T. Vinatier, D. Zhang, C. Zhou
DESY, Hamburg, Germany

We present ultra-small electron injectors based on cascaded cavities excited by short multi-cycle THz signals. The designed structure is a 3.5 cell normal conducting cavity operating at 300 GHz. This cavity is able to generate pC electron bunches and accelerate them up to 250 keV using less than 1 mJ THz energy. Unlike conventional RF guns, the designed cavity operates in a transient state which, in combination with the high frequency of the driving field, makes it possible to apply accelerating gradients as high as 500 MV/m. Such high accelerating gradients are promising for the generation of high brightness electron beams with transverse emittances in the nm-rad range. The designed cavity can be used as the injector for a compact accelerator of low charge bunches.

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MOPIK006

Characterization of the Electron Beam from the Thz Driven Gun for AXSIS

gun, experiment, simulation, diagnostics

509

G. Vashchenko, R.W. Aßmann, U. Dorda, K. Galaydych, B. Marchetti, T. Vinatier
DESY, Hamburg, Germany
M. Fakhari, A. Fallahi, F.X. Kärtner, N.H. Matlis
CFEL, Hamburg, Germany
W. Qiao, C. Zhou
University of Hamburg, Hamburg, Germany

Funding: The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 609920
The AXSIS (Attosecond X-ray Science: Imaging and Spectroscopy) project aims for development of a compact, fully coherent, THz-driven, attosecond X-ray source. A compact THz driven gun was developed, produced and tested as a source of the ultra-short electron bunches required for the project. To characterize the low energy, low-charge beam produced by such a gun tailored diagnostic devices were developed and commissioned at a test-stand chamber in CFEL (DESY). Results of the first experiments on the production and characterization of the electron beam are presented.

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MOPIK007

THz Driven Electron Acceleration with a Multilayer Structure

acceleration, laser, gun, dipole

512

D. Zhang, M. Fakhari, W. Qiao, C. Zhou
DESY, Hamburg, Germany
F. Ahr, A-L. Calendron, H. Cankaya, M. Fakhari, A. Fallahi, F.X. Kärtner, F. Lemery, N.H. Matlis, X. Wu
CFEL, Hamburg, Germany
W.R. Huang, F.X. Kärtner
MIT, Cambridge, Massachusetts, USA
C. Zhou
University of Hamburg, Hamburg, Germany

We present first results in THz-based electron acceleration using a novel multilayer structure which we dub a Butterfly LINAC. THz-based accelerators are mm-scale devices that bridge the gap between micron-scale, ultra-compact devices such as laser-plasma accelerators (LPAs) and dielectric laser accelerators (DLAs) and meter-scale conventional accelerators. These intermediate-scale devices are promising because they combine many of the benefits of LPAs and DLAs, such as intrinsic synchronization and high acceleration gradients with the benefits of conventional accelerators such as high charge capacity, tunability as well as the robustness, stability and simple fabrication of static, macroscopic acceleration structures. The Butterfly LINAC allows optimization of electron acceleration using transversely-coupled single-cycle THz pulses by phase-matching electrons with the driving field. Proof-of-concept experiments will be described demonstrating 10 keV energy gain of a 55 keV source, in good agreement with simulation. Scalability of this device to the MeV level and applicability towards free electron lasers and ultrafast electron diffractometers will also be discussed.

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MOPIK008

Numerical Studies on a Modified Cathode Tip for the ELBE Superconducting RF Gun

cathode, SRF, gun, simulation

515

E.T. Tulu, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
A. Arnold
HZDR, Dresden, Germany

Future light sources such as synchrotron radiation sources driven by an Energy Recovery Linac (ERL), Free Electron Laser (FEL) or THz radiation sources have in common that they require injectors, which provide high-brilliance, high-current electron beams in almost continuous operation. Thus, the development of appropriate highly brilliant electron sources is a central factor. A promising approach for this key component is provided by superconducting radiofrequency photoinjectors (SRF guns) [*]. Since 2007, the free-electron laser FELBE at HZDR successfully operates such a SRF gun under real conditions and equipped with all components [**]. Nevertheless, there are limitations caused by multipacting which should be overcome in order to further improve the gun [***]. One aspect in order to reach this aim lies in studying various modifications of the cathode tip [****]. This contribution will present the effectiveness of isosceles triangular grooves with respect to MP.
* Arnold, et al., NIM A, 593, 57, (2008).
** J. Teichert, et al., 2008 NSS/MIC, Dresden, Germany.
*** J. Teichert, et al., J. Phys.: Conf. Ser. 298(2011), 012008.
**** E. T. Tulu, et al., IPAC2014, p652, Dresden, Germany.

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MOPIK011

Electron Beam Generation From InGaN/GaN Superlattice Photocathode

laser, polarization, gun, brightness

522

N. Yamamoto
KEK, Ibaraki, Japan
M. Hosaka, A. Mano, T. Miyauchi, Y. Takashima
Nagoya University, Nagoya, Japan
M. Katoh
UVSOR, Okazaki, Japan

GaAs-type photocathode (PC) has been used as electron spin polarization (ESP) sources for various applications. Recently, by using a strain-compensated technique for GaAs/GaAsP, the super lattice (SL) thickness of up to 720 nm could be manufactured and the quantum efficiency (QE) improvements with the thickness increases was observed. In the experiments, the ESP degradation was also observed for the thicker thickness samples than 194nm and we considered that electron spin relaxation during diffusion process in the PC caused the degradation. Therefore, we propose developing fcc-GaN based PCs instead of GaAs because a factor of ten longer spin relaxation time compared with GaAs/GaAsP SL was reported. However an fcc-GaN sample with adequate dimensions for PC applications is not available at present due to manufacturing difficulties. Then at the start of GaN-type PC development, an hcp-GaN sample has been studied. In the study, NEA-activation was made for an InGaN/GaN SL sample and QE, surface lifetime and ESP were measured. The QE and ESP values were 1.3% and 2.1% at the pump laser wavelength of 405nm.

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MOPIK013

Design and Simulation of a C-Band Photocathode RF Gun With a Coaxial Coupler for UEM

gun, cavity, coupling, impedance

525

T. Chen, Y.J. Pei, Y. Song
USTC/NSRL, Hefei, Anhui, People's Republic of China

A ultrafast electron microscope (UEM) has been become much more important research instrument and has been widely used in many fields. As a part of the UEM, a photocathode RF gun working at C-band frequency of 5712MHz is being developed, which provides electron beam with high qualities for UEM. This paper presents the physics and structure design, including optimization of cavity shape parameter for improving shunt impedance and Q factor. We adopt a novel coaxial coupler, which could decrease the multipole field and decrease the focusing coil size, build better accelerating field in the RF gun. In this paper, we discussed the simulation process and results of the RF gun, especially the design of the coaxial input coupler was described.

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MOPIK015

Improvement of Electron Intensity Reduction System at SLRI Beam Test Facility

target, synchrotron, booster, shielding

528

K. Kittimanapun, N. Chanlek, P. Klysubun, S. Krainara, S. Supajeerapan
SLRI, Nakhon Ratchasima, Thailand

Funding: This work is partly supported by the National Science and Technology Development Agency (NSTDA) under contract FDA-C0-2558-855-TH.
Synchrotron Light Research Institute (SLRI) has been commissioning an additional experimental station, a Beam Test Facility (BTF), to the SLRI accelerator complex. SLRI BTF was constructed to provide electron test beams with energy ranging from 40 MeV up to 1.2 GeV and with tunable electron intensity from a few to millions of electrons per burst. In order to obtain low intensity of test beams, an approach using a metal target together with an energy selector has been employed. A combination of a target chamber installed at the high energy beam transport line and the existing 4-degree bending magnet that is used as an energy selector first produced low intensity test beams. However, the test beam profile was not well determined due to the insufficient bending angle of the energy selector and high primary beam energy. Another approach mounting a target chamber at the low energy beam transport line and using the synchrotron booster as an energy selector was implemented to avoid such problems. Once in operation, the facility will have the potential to service calibration and testing of high energy detectors as well as beam diagnostic instrumentations.

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MOPIK016

Sub-Picosecond Beam Production for External Injection Into Plasma Experiments

gun, plasma, linac, simulation

531

O. Mete Apsimon, R. Apsimon, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
G.X. Xia
UMAN, Manchester, United Kingdom

Funding: This work has been funded by STFC.
Applications of plasmas in accelerators benefit from short probe bunches comparable to plasma wavelength due to currently achievable plasma wake profiles. In plasma acceleration case, high capture efficiency within a narrow energy spectrum can be achieved when a sub-picosecond to femtosecond witness bunch injected behind the driver pulse at the high electric field region. A start-to-end simulation study was performed for parametric optimisation of an rf photoinjector to provide a short witness bunch for plasma applications in accelerators. An rf photoinjector is a laser-driven, high brightness and robust electron source that can provide stability and flexibility provided by today's advanced laser and rf technologies.

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MOPIK018

Micro-Scale Electron Beam Generation Using Pyroelectric Crystals

acceleration, laser, injection, diagnostics

538

R.B. Yoder, Z. Kabilova
Goucher College, Baltimore, Maryland, USA

Novel laser-powered acceleration structures currently under development, which have dimensions comparable to optical wavelengths and can be constructed on a silicon wafer, require injection of a sub-micron-scale electron bunch to achieve high-quality, monoenergetic output beams. A potential injection mechanism for such micro-scale beams relies on field emission from a nanotip array, followed by acceleration to near-relativistic energies. We demonstrate field emission of electrons from a lithium niobate crystal during heating and cooling, and describe the production of electrons within a hollow channel along the axis of a lithium niobate crystal. Measurements of emitted beam properties are compared with direct measurements of crystal fields under comparable conditions and modeled mathematically.

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MOPIK019

Upgrade Options Towards Higher Fields and Beam Energies for Continuous-Wave Room-Temperature VHF RF Guns

gun, brightness, cathode, cavity

542

F. Sannibale, J.M. Byrd, D. Filippetto, M.J. Johnson, D. Li, T.H. Luo, C.E. Mitchell, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
Science demand for MHz-class repetition rate electron beam applications such as free electron lasers (FELs), inverse Compton scattering sources, and ultrafast electron diffraction and microscopy (UED/UEM), pushed the development of new gun schemes that could generate high brightness beams at such high rates. At the Lawrence Berkeley Lab (LBNL), we proposed a new concept room-temperature RF gun resonating in the VHF frequency range (30-300 MHz) capable of operating in continuous wave mode at the fields required for high-brightness performance. A first VHF-Gun was constructed and tested in the APEX facility at LBNL, which successfully demonstrated all design parameters and the generation of high brightness electron beams. A second version of the APEX VHF-Gun is being built at LBNL for the LCLS-II, the new SLAC X-ray FEL. Recent studies showed that a proposed LCLS-II upgrade and UED/UEM applications would greatly benefit from an increased gun brightness obtained by raising the electric field at the cathode and the beam energy at the gun exit. In this paper, we present and discuss possible upgrade options that would allow extension of the VHF-Gun performance towards these new goals.

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MOPIK022

Experimental Investigation of Field-Emission From Silicon Nano-Cone Cathodes

cathode, emittance, vacuum, ion

548

A. Lueangaramwong, C. Buzzard, V. Korampally, O. Mohsen, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
S. Chattopadhyay
Northern Illinois Univerity, DeKalb, Illinois, USA
R. Divan
Argonne National Laboratory, Argonne, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by the NSF grant PHY-1535401 with Northern Illinois University
Field emission cathode are capable of forming electron beam with extreme brightness via strong-field excitation from applied electrostatic, or electromagnetic (radiofrequency and laser) fields. Our group, in collaboration with the Argonne Center for Nanoscale Material, has recently developed nanocone cathode. The present paper reports on the experimental characterization of these cathodes both configured as a single-cone emitter or as large arrays of tightly-packed emitter. The tests carried in a diode setup are capable of measuring IV characteristic curves and beam distributions.

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MOPIK023

Cornell Laboratory for High Intensity, Ultra-Bright and Polarized Electron Beams

gun, simulation, cathode, ion

551

L. Cultrera, A.C. Bartnik, I.V. Bazarov, C.M. Gulliford, P. Gupta, H. Lee, S.A. McBride, T.P. Moore
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work has been funded by the National Science Foundation (Grant No. PHY-1416318) and Department of Energy (Grants No. DE-SC0014338, No. DE-SC0011643 and No. DE-SC0016203).
We report on the current activities pursued at Cornell University for the production of electron beams tailored to a wide range of applications. We have developed the expertise to grow many different type of high quantum efficiency photocathode belonging to the alkali antimonide family. Those materials are ideal candidates to produce high intensity beam with average currents in the mA range. When operated near threshold at cryogenic temperature in transmission mode they can also generate the electron beams needed to perform ultrafast electron diffraction of bio molecules. We have recently expanded our facility with a Mott polarimeter to include the capability to measure polarization of the electron beam. The photocathode lab is being complemented by a dedicated photo-gun laboratory to test the photocathode properties in a real environment and to perform measurement of the beam properties under new and yet unexplored operating conditions.

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MOPIK026

Commissioning and Operation of an Ultrafast Electron Diffraction Facility as Part of the ATF-II Upgrade at Brookhaven National Laboratory

operation, laser, photon, experiment

554

M.G. Fedurin, M. Babzien, C. Folz, M. Fulkerson, K. Kusche, J.J. Li, R. Malone, M.A. Palmer, T.V. Shaftan, J. Skaritka, L. Snydstrup, C. Swinson, F.J. Willeke
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US DOE under contract DE-SC0012704.
The Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL) is presently carrying out an upgrade, ATF-II, which will provide significantly expanded experimental space and capabilities for its users. One of the new capabilities being integrated into the ATF-II program is an Ultrafast Electron Diffraction (UED) beam line, which was originally deployed in the BNL Source Development Laboratory. Inclusion of the UED in the ATF-II research portfolio will enable ongoing development and extension of the UED capabilities for use in materials research. We describe the design, operation and future plans for the UED beam line at the ATF-II.

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MOPIK041

Commissioning of the Stripping Foil Units for the Upgrade of the PSB H⁻ Injection System

injection, linac, controls, vacuum

595

C. Bracco, S. Burger, V. Forte, B. Goddard, G. Guidoboni, L.O. Jorat, B. Mikulec, A. Navarro Fernandez, R. Noulibos, F. Roncarolo, P. Van Trappen, W.J.M. Weterings
CERN, Geneva, Switzerland

The PSB will be extensively upgraded during the next long shutdown of the CERN accelerator complex, to double the brightness of the stored beams. The existing multi-turn injection will be replaced by a charge exchange system designed for the 160 MeV hydrogen ions provided by Linac4. Part of the injection equipment has been temporarily installed along the Linac4-to-PSB transfer line and tested with beam. This allowed to gain experience with the system, test the related diagnostics and benchmark calculations with measurements. An additional permanent stripping foil test stand is also installed right after the Linac and will be used to characterise new foils for possible future applications. The main outcomes, issues and applied or planned mitigations are presented for both installations.

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MOPIK055

Beam by Design: Current Pulse Shaping Through Longitudinal Dispersion Control

simulation, sextupole, synchrotron, laser

644

T.K. Charles, D.M. Paganin
Monash University, Faculty of Science, Clayton, Victoria, Australia
M.J. Boland
The University of Melbourne, Melbourne, Victoria, Australia
M.J. Boland, R.T. Dowd
SLSA, Clayton, Australia

Electron beams traversing a dispersive region, such as a bunch compressor and some transport line can form caustic lines and surfaces corresponding to regions of maximum electron density, which influence the current pulse shape. In this paper, we present a technique to manipulate the longitudinal phase space distribution to achieve an arbitrary, desired current pulse shape. We show how sextupole magnets (and in certain circumstances, octupole magnets), placed within a dispersive region can be used to generate the conditions required for a flexible technique of current pulse shaping that avoids truncation through collimation.

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MOPIK072

Recent Upgrades of the Bunch Arrival Time Monitors at FLASH and European XFEL

laser, software, controls, electronics

695

M. Viti, M.K. Czwalinna, H. Dinter, C. Gerth, K.P. Przygoda, R. Rybaniec, H. Schlarb
DESY, Hamburg, Germany

In modern free electron laser facilities like FLASH and European XFEL a high resolution intra train bunch arrival time measurement is mandatory, providing a crucial information for the beam based feedback system. At FLASH and European XFEL a reliable arrival time detection with a resolution better than 0.1% is required for a broad range of bunch charges, from 1 nC down to 20 pC. The system developed is based on electro-optical sampling where an ultra-short pulsed laser is employed. Several bunch arrival time monitors (BAM) were developed and are since 2012 in operation at the FLASH facility. A major upgrade involved the development of new hardware and software based on the MTCA standard. Special operation mode at both facilities includes the possibility to subdivide the bunch train in up to three segments, each with different bunch energy and charge, causing variation of the time jitter within the bunch train itself. A further upgrade includes the measurement of the arrival time and application of delay correction for each of the three segments. In this poster, we describe the development, installation and commissioning of the hardware, firmware and software of the new system.

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MOPIK075

Design, Simulation and Compare of Flat Cathode Electron Guns with Spherical Cathode Electron Guns for Industrial Accelerators

cathode, gun, simulation, space-charge

702

M. Nazari, F. Abbasi
Shahid Beheshti University, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
S. Haghtalab
IPM, Tehran, Iran

In this article, electron guns with flat and spherical cathodes have been designed and simulated for industrial accelerators. After checking the different features of each cathode geometry, there has been discussed about optimum values of this features. The most important features in selecting the best cathode geometry for industrial accelerators are beam waist radius, beam waist position, current density and price. Finally after comparing the different features of both geometries with each other, suitable geometry was selected.

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MOPIK078

Narrow-Band, Wide-Range Tuneable THz Source Based on the Slotted-Foil Technique

undulator, radiation, simulation, FEL

712

J. Pfingstner, E. Adli, H. Holmestad
University of Oslo, Oslo, Norway
S. Bettoni, S. Reiche
PSI, Villigen PSI, Switzerland

The FEL user community has expressed a strong interest in a THz source for the excitation of their samples in pump probe experiments. The demanded THz properties are challenging to achieve, as they include a narrow bandwidth of <5-10%, the possibility of frequency tuning between 1 and 20 THz, a THz pulse energy of about 100 uJ, and a fixed phase relation from shot-to-shot. To fulfil these specifications, an accelerator-based source is proposed in this paper. It utilises the slotted-foil technique to create a pre-bunched electron beam that is injected into a helical undulator. Detailed simulation studies presented in this paper show that the corresponding undulator radiation has the demanded properties.

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MOPIK080

Research of the Electro-Gravitational Induction by Using COD Signals in Charged Particle Storage Rings

storage-ring, induction, positron, feedback

719

D. Dong
IHEP, Beijing, People's Republic of China
J.Y. Dong
Binghamton University, State University of New York, Binghamton, New York, USA

Funding: The project was supported by the National Natural Science Foundation of China under Grant No. 11575215, partly.
Form the beam instability in the charged particle storage ring; researchers have known that one kinds of long term beam instability, the period of 12 hours, comes from the gravity changes, the change of acceleration of gravity g, delta g caused by the moon and sun moving relative to the earth, so called the terrestrial tidal forces. Phenomenology, we would say that the gravity changes caused by the moon and sun moving at the storage ring have caused the beam energy changes in the storage ring. If it is true, then it may be the electro-gravitational induction (EGI). In this paper, we will discuss the possibility of EGI, and estimate the maximum value of the gravity coefficient of the induced electromotive force by using the existing beam data from the storage rings.

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MOPIK103

Operation with Carbon Stripping Foils at ISIS

injection, operation, synchrotron, emittance

771

H.V. Cavanagh, B. Jones
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The ISIS facility at the Rutherford Appleton Laboratory is a pulsed neutron and muon source for physical and life science research. Up to 3·10¹³ protons per pulse are accelerated to 800 MeV in the 50 Hz rapid cycling synchrotron that serves two spallation neutron targets. Charge exchange injection of 70 MeV H' ions into the synchrotron takes place over 130 turns. For over 30 years ISIS has used 40×120 mm aluminium oxide stripping foils, produced in-house [1]. Recently, foil preparation and installation processes have been simplified with the use of commercially available 40×60 mm carbon stripping foils. This paper summarises operational experiences with diamond-like-carbon (DLC) and graphene foils. Radiological analysis, atomic force microscope (AFM) imaging of foils and off-line irradiation with a 1.5 keV electron gun are also discussed.

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MOPIK106

Effect of Magnetic Element Alignment Errors on Electron Beam Dynamics in the Transportation Channel of the NSC KIPT Neutron Source Driven With Linear Accelerator

target, neutron, alignment, dipole

781

A.Y. Zelinsky, P. Gladkikh, A.A. Kalamayko
NSC/KIPT, Kharkov, Ukraine

In the paper, the results of beam dynamics simulation in the transportation channel of the NSC KIPT neutron source taking into account the errors of the electromagnetic elements alignment are presented. It is show that the values of RMS alignment errors such as 100 mkm in transverse planes and 200 mkrad in angle installations lead to the essential shifts of the beam at a neutron target and, therefore, to the essential beam losses at the vacuum chamber walls. To avoid the losses one should provide additional electron beam correction and to increase the accuracy of the equipment alignment.

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MOPIK107

Injection Efficiency Simulation in the Electron Storage Ring of X-Ray Generator NESTOR

storage-ring, injection, alignment, simulation

784

A.Y. Zelinsky, P. Gladkikh, A.A. Kalamayko
NSC/KIPT, Kharkov, Ukraine

In the paper the results of the beam dynamics and injection efficiency simulation in the storage ring of the X-ray generator NESTOR are presented.

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MOPIK111

Initial Performance Measurements of Multi-GHz Electron Bunch Trains

laser, emittance, gun, cathode

795

D.J. Gibson, R.A. Marsh
LLNL, Livermore, California, USA
Y. Hwang
UCI, Irvine, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
LLNL's compact laser-Compton based x-ray source is currently producing up to 35 keV photons, with the capability to upgrade to 250 keV. Increasing the average brightness of such sources requires increasing the electron beam current. To avoid degradation of the narrow-bandwidth performance of the source, the per-bunch charge shouldn't increase; the effective repetition rate of the electron beams must be raised. It has been proposed* to generate bunch trains of several hundred pulses spaced by the period of X-band RF (~87 ps), which raises questions about beam-loading effects on the energy uniformity of the bunches and wakefield effects degrading the emittance of later bunches, compromising the x-ray quality. As a first test of this concept, we have installed into the electron-generating laser of our system optical pulse-stacking hardware to allow generation of 16-electron-bunch trains. Here we present the current status of our x-ray source, along with initial results using this new multi-bunch train. This includes characterization of collective electron beam energy spread and emittance growth.
* D.J. Gibson, et al., IPAC2012.

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MOPIK113

Beam Phase Space Tomography for FXR LIA

emittance, space-charge, simulation, solenoid

801

Y.H. Wu, Y.-J. Chen
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Knowing the initial beam parameters entering an accelerator or a downstream beamline allows us to select transport tunes optimized for a desired accelerator performance. In this study, we report unfolding LLNL's FXR [1] beam parameters by using the tomography technique [2, 3] to construct the beam phase space along the accelerator's downstream beamline. The unfolded phase spaces from tomography and simulations are consistent.

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MOPIK115

A Design for 10 GeV, High Peak-Current, Tightly Focused Electron Beams at FACET-II

emittance, linac, simulation, acceleration

807

G.R. White
SLAC, Menlo Park, California, USA

Funding: This work was sponsored by the Department of Energy under Contract Number: DE-AC02-76SF00515
FACET-II will be a new test facility, starting construction in 2018 within the main SLAC Linac. Its purpose is to build on the decades-long experience developed conducting accelerator R&D at SLAC in the areas of advanced acceleration and coherent radiation techniques with high-energy electron and positron beams. The design consists of a 135-MeV high-brightness photo-injector constructed in an off-axis injection line in Sector 10 of the SLAC Linac, two new 4-bend chicane bunch compressors installed in Sectors 11 and 14, with a third compression stage provided by the existing FACET W Chicane in Sector 20. We develop a design to deliver peak currents more than 160 kA to the Sector 20 interaction region at 10 GeV, with 10 'm-rad emittances at 2 nC bunch charge and 1.4 % rms energy spread. The Sector 20 bunch compressor is re-designed for maximum peak current throughput and minimal emittance degradation via CSR, and the FACET-II compression scheme is optimized. We present 6D start-end beam tracking simulations using Lucretia including ISR, CSR, wakefields and space charge effects.

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MOPIK122

The Beam Optics of the FFAG Cell of the CBETA ERL Accelerator

quadrupole, optics, dipole, focusing

820

N. Tsoupas, J.S. Berg, S.J. Brooks, G.J. Mahler, F. Méot, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA
J.A. Crittenden
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.C. Tygier
UMAN, Manchester, United Kingdom

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The CBETA project[*] is a prototype electron accelerator for the proposed eRHIC project[**]. The electron accelerator is based on the Energy Recovery Linac (ERL) and the Fixed Field Alternating Gradient (FFAG) principles. The FFAG arcs and the straight section of the accelerator are comprised of one focusing and one defocusing quadrupoles which are designed as Halbach-type permanent dipole magnets with quadrupoles component[***]. We will present the beam optics of the FFAG cell which is based on 3D field maps derived with the use of the OPERA computer code[****]. We will also present the electromagnetic design of the corrector magnets of the cell.
* http://arxiv.org/abs/1504.00588
** http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf
*** K. Halbach, Nucl. Instrum. Meth. 169 (1980) pp. 1-10
**** http://www.scientificcomputing.com

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MOPVA001

Coherent X-Ray Radiation From Electron Beam Processed by Channeling and Emittance Exchange

photon, radiation, laser, emittance

845

I. Lobach, A.I. Benediktovitch
BSU, Minsk, Belarus

Presented contribution theoretically studies a novel scheme of compact intense x-ray radiation source. In the scheme, longitudinally modulated electron beam emits x-rays by Inverse Compton Scattering (ICS). The setup's feature is the way how longitudinal density modulation in angstrom scale is created. There are three stages of processing of initial beam of relativistic electrons: 1. First, the electrons cross a crystal plate in channeling regime. It is shown that upon leaving the crystal, the electron beam acquires discernible transverse modulation in angstrom scale. It is taken into account that not all electrons are captured in channeling mode and that some of those that do may leave it as they travel through the crystal slab. 2. Further, the beam is transported to Emittance Exchange (EEX) line, in which the direction of modulation is tilted and the beam becomes longitudinally modulated. The scale of modulation remains the same. 3. Finally, intense quasi-coherent x-ray radiation is emitted by ICS. Numerical estimations show that coherent contribution to intensity is considerable for feasible parameters of used beam, components of EEX line and laser producing photons for ICS.

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MOPVA002

Initial Stage of Self Amplified Radiation Emission From Electron Bunches in Crystal: Linear Response Theory

radiation, brightness, polarization, undulator

848

A.I. Benediktovitch, I. Lobach
BSU, Minsk, Belarus, Belarus

Self amplified spontaneous emission (SASE) is a key process in X-ray free electron lasers' operation. In this case the spontaneous emission is undulator radiation emission, the radiation in X-ray range being possible from electrons in GeV energy range. In the case of interaction of electrons with properly aligned crystal the channeling radiation results in X-rays from electrons with energies in tens MeV energy range. In this situation for high current densities the SASE process may take place that potentially could lead to construction of a compact bright X-ray source. In present contribution the first principle theoretical description is outlined and first order perturbation theory is used to model the initial stage of SASE. The transition from spontaneous to SASE regime is described, the requirements for bunch current and emittance are determined. By means of dispersion equation analysis and boundary condition application the intensity radiated from crystal slab is calculated and it is shown that Bragg diffraction could enhance self amplification. A numerical example for Si (001) illustrates the model.

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MOPVA004

Operating Simultaneously Two In-Vacuum Canted Undulators in Synchrotron SOLEIL

undulator, photon, vacuum, radiation

851

L.S. Nadolski, Y.-M. Abiven, P. Brunelle, N. Béchu, M.-E. Couprie, F.J. Cullinan, X. Delétoille, M. El Ajjouri, C. Herbeaux, N. Hubert, N. Jobert, M. Labat, J.-F. Lamarre, A. Lestrade, A. Loulergue, O. Marcouillé, P. Monteiro, A. Nadji, R. Nagaoka, D. Pédeau, P. Rommeluère, K.T. Tavakoli, M. Valléau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France
C. Benabderrahmane
ESRF, Grenoble, France

Each long SOLEIL beamline, ANATOMIX and Nanoscopium, takes a photon beam from an in-vacuum undulator with a minimum gap of 5.5 mm. The canted radiation sources are installed in a long straight section of the storage ring. The first closure of both undulators led to the severe damage of the downstream undulator in 2011. The reason for this incident has been investigated and clearly identified. A long-term project has enabled us to find a technical solution for a simultaneous operation of both undulators. A special angle fast interlock was designed and a dedicated photon absorber has been introduced at the entrance of the second undulator while keeping the impact on the beam performance as low as possible. The main technical steps will be reported with an interim solution put in place in spring 2015 and a final solution deployed and validated in May 2016.

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MOPVA012

The Dedicated Accelerator R&D Facility Sinbad at DESY

linac, laser, experiment, acceleration

869

U. Dorda, R.W. Aßmann, K. Galaydych, W. Kuropka, B. Marchetti, D. Marx, F. Mayet, G. Vashchenko, T. Vinatier, P.A. Walker, J. Zhu
DESY, Hamburg, Germany
A. Fallahi, F.X. Kärtner, N.H. Matlis
CFEL, Hamburg, Germany

We present an overview of the dedicated R\&D facility SINBAD which is currently under construction at DESY. The facility will host multiple independent experiments on the acceleration of ultra-short electron bunches and advanced acceleration schemes. In its initial phase, SINBAD will host two experiments: AXSIS and ARES. The AXSIS collaboration aims to accelerate fs-electron bunches to 15 MeV in a THz driven dielectric structure and subsequently create X-rays by inverse Compton scattering. The first stage of the ARES experiment is to set up a 100 MeV S-band electron linac to produce ultra-short electron bunches with excellent beam arrival time stability. Once this is achieved, the electrons will be ideally suited to be injected into experiments for testing advanced accelerator concepts e.g. DLA experiments in the context of the ACHIP collaboration. In the long term, external injection into a laser driven plasma acceleration stage is targeted as well.

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MOPVA013

Application of Non-Isochronous Beam Dynamics in ERLs for Improving Energy Spread and Beam Stability

linac, acceleration, operation, recirculation

873

F. Hug
IKP, Mainz, Germany

Funding: Work supported by DFG through the PRISMA cluster of excellence EXC 1098/2014 and Research Training Group GRK 2128
Non-isochronous recirculation is the common operation mode for synchrotrons or microtrons. In such a non-isochronous recirculation scheme the recirculation paths provide a non-zero longitudinal dispersion while the accelerating field is operated at a certain phase off-crest with respect to the maximum. In few turn linacs like ERLs and in microtrons non-isochronous beam dynamics can be used to reduce the energy spread by cancelling out any rf-jitters coming from the linac cavities. To do so the longitudinal phase advance needs to be tuned to a half-integer number of oscillations in longitudinal phase space. Then the total energy spread after main linac acceleration conserves the value at injection. In addition to the improved energy spread the beam stability of few-turn recirculators can be increased as well using such a system. Such concept provides an inherent beam stability and has been introduced many years ago [*] and proven to work successfully in a few-turn recirculator already [**]. We will present beam dynamics calculations for the application of nonisochronous beam dynamics in single- and multi-turn energy recovery linacs at different longitudinal working points.
[*] H. Herminghaus, NIM. A 314 (1992) 209.
[**] F. Hug et al., Proc. of LINAC '12 (2012) 531.

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MOPVA014

Injector Linac Stability Requirements for High Precision Experiments at MESA

experiment, linac, operation, acceleration

876

F. Hug, R.G. Heine
IKP, Mainz, Germany

Funding: Work supported by DFG through the PRISMA cluster of excellence EXC 1098/2014 and Research Training Group GRK 2128
MESA is a recirculating superconducting accelerator under construction at Johannes Gutenberg-Universität Mainz. It will be used for high precision particle physics experiments in two different operation modes: external beam (EB) mode and energy recovery (ERL) mode. The operating beam current and energy in EB mode is 0.15 mA with polarized electrons at 155 MeV. In ERL mode an unpolarized beam of 1 mA at 10⁵ MeV will be available. In a later construction stage of MESA the beam current in ERL-mode shall be upgraded to 10 mA. In order to achieve high beam stability and low energy spread in recirculating operation the acceleration in the main linac sections will be done on edge of the accelerating field while the return arcs provide longitudinal dispersion. On certain longitudinal working points this can result in a setting where rf jitters from main linac do not contribute to the resulting energy spread of the final beam at all [*,**]. Then the resulting energy spread is only determined by the energy spread provided by the inector linac. Within this contribution we will investigate the requirements on the stability of the MESA injector linac MAMBO for achieving the experimental goals.
[*] H. Herminghaus, NIM. A 314 (1992) 209.
[**] F. Hug et al., Proc. of LINAC '12 (2012) 531.

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MOPVA016

ELI-NP GBS Status

laser, linac, gun, collimation

880

A. Giribono, M. Marongiu, A. Mostacci, V. Pettinacci
INFN-Roma, Roma, Italy
S. Albergo
INFN-CT, Catania, Italy
D. Alesini, M. Bellaveglia, B. Buonomo, F. Cioeta, E. Di Pasquale, G. Di Pirro, A. Esposito, A. Falone, G. Franzini, O. Frasciello, A. Gallo, S. Guiducci, S. Incremona, F. Iungo, V.L. Lollo, L. Pellegrino, L. Piersanti, S. Pioli, R. Ricci, U. Rotundo, L. Sabbatini, A. Stella, S. Tomassini, C. Vaccarezza, A. Variola
INFN/LNF, Frascati (Roma), Italy
A. Bacci, C. Curatolo, I. Drebot, V. Petrillo, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
N. Bliss, C. Hill
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
G. Campogiani
Rome University La Sapienza, Roma, Italy
P. Cardarelli, M. Gambaccini
INFN-Ferrara, Ferrara, Italy
F. Cardelli, A. Mostacci, L. Palumbo, A. Vannozzi
University of Rome La Sapienza, Rome, Italy
F. Cardelli, L. Palumbo
INFN-Roma1, Rome, Italy
K. Cassou, K. Dupraz, A. Martens, C.F. Ndiaye, Z.F. Zomer
LAL, Orsay, France
G. D'Auria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
L. Sabato
U. Sannio, Benevento, Italy
M. Veltri
INFN-FI, Sesto Fiorentino, Italy

New generation of Compton sources are developing in different countries to take advantage of the photon energy amplification given by the Compton backscattering effect. In this framework the Eurogammas international collaboration is producing a very high brilliance gamma source for the Nuclear Pillar of the Exterme Light Infrastructure program (ELI). At present there is a lot of effort in the mass production of all the components and in the developments and tests of the different high technology devices that will operate in the gammas beam source, like the optical recirculator and the high gradient - high average current warm C band accelerating sections. In this paper we will provide a general overview of the GBS status and of the perspectives for the future integration phase.

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MOPVA020

S2E Simulation of an ERL-Based High-Power EUV-FEL Source for Lithography

FEL, linac, simulation, injection

894

N. Nakamura, R. Kato, T. Miyajima, M. Shimada
KEK, Ibaraki, Japan
R. Hajima
QST, Tokai, Japan
T. Hotei
Sokendai, Ibaraki, Japan

An energy recovery linac(ERL)-based free electron laser(FEL) is a possible candidate of a high-power EUV source for lithography. The ERL can provide a high-current and high-quality electron beam for the high-power FEL and also greatly reduce the dumped beam power and activation compared to ordinary linacs. An ERL-based EUV-FEL source has been designed using available technologies and resources*. For this design, we perform Start-to-End(S2E) simulation from the electron gun to the exit of the decelerating main linac to track the electron beam parameters and to evaluate the FEL performance. The electron bunches from the injector are off-crest accelerated to 800 MeV and compressed in the 1st arc and/or chicane to obtain a high-peak current for high FEL output. After the undulator section for SASE FEL, they are decompressed in the 2nd arc and then decelerated in the main linac to optimize the energy spread or the energy recovery efficiency. This paper will present the S2E simulation for the designed EUV-FEL source.
* N. Nakamura et al., Proc. of ERL2015, Stony Brook, NY, USA, pp.4-9.

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MOPVA023

Luminosity Increase in Laser-Compton Scattering by Crab Crossing Method

laser, luminosity, photon, scattering

902

Y. Koshiba, D. Igarashi, S. Ota, T. Takahashi, M. Washio
RISE, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

In collider experiments such as KEKB, crab crossing method is a promising way to increase the luminosity. We are planning to apply crab crossing to laser-Compton scattering, which is a collision of electron beam and laser, to gain a higher luminosity leading to a higher flux X-ray source. It is well known that the collision angle between electron beam and laser affects the luminosity. It is the best when the collision angle is zero, head-on collision, to get a higher luminosity but difficult to construct such system especially when using an optical cavity for laser. Concerning this difficulty, we are planning crab crossing by tilting the electron beam using an rf-deflector. Although crab crossing in laser-Compton scattering has been already proposed*, nowhere has demonstrated yet. We are going to demonstrate and conduct experimental study at our compact accelerator system in Waseda University. In this conference, we will report about our compact accelerator system, laser system for laser-Compton scattering, and expected results of crab crossing laser-Compton scattering.
*Variola Alessandro, et al. Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators. Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.

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MOPVA024

Investigation of the Coherent Cherenkov Radiation Using Tilted Electron Bunch

radiation, target, laser, gun

905

K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Brameld, M. Nishida, T. Toida, M. Washio, R. Yanagisawa
Waseda University, Tokyo, Japan
R. Kuroda, Y. Taira
AIST, Tsukuba, Ibaraki, Japan
J. Urakawa
KEK, Ibaraki, Japan

Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083.
Cherenkov radiation can be produced when the velocity of the charged particles are faster than the light in some medium. We investigated the coherent Cherenkov radiation using electron bunch tilting for matching the wave front of the Cherenkov radiation. The electron bunch was tilted by using rf transverse deflecting cavity. We tested several materials for the Cherenkov target which has enough transmittance at the wavelength of THz region. As a result, high peak power THz was achieved using this novel technique. We will report the principle of this technique, the experimental results and future prospects at the conference.

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MOPVA027

Measurement of High Power Terahertz with Dielectric Loaded Waveguide at Tsinghua University

radiation, wakefield, experiment, extraction

914

D. Wang, Y.-C. Du, W. Gai, W.-H. Huang, X.L. Su, C.-X. Tang, Q.L. Tian, L.X. Yan
TUB, Beijing, People's Republic of China
S.P. Antipov
Euclid Beamlabs LLC, Bolingbrook, USA
Y.F. Liang
Tsinghua University, Beijing, People's Republic of China

Funding: Work supported by the National Nature Science Foundation of China (NSFC Grants No.11475097) and the National Key Scientific Instrument and Equipment Development Project of China (Grants No. 2013YQ12034504)
We have measured an intense THz radiation produced by a sub-picosecond, relativistic electron bunch passing through a dielectric loaded waveguide (DLW) at Tsinghua University accelerator beamline. The DLW was 3 cm long quartz tube with 900 'm inner diameter and 100 'm wall thickness metallized on the outside. Radiated energy of the THz pulse was measured to be proportional to the square of the effective charge. The end of the DLW was cut at an angle for efficient THz pulse extraction. Tens of 'J THz energy per pulse were measured outside the vacuum chamber with a calibrated Golay cell in the experiment.
*wangdan16@mail.tsinghua.edu.cn
*yanlx@mail.tsinghua.edu.cn

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MOPVA031

Low Energy Compact Storage Ring Design for Compton Gamma-Ray Light Source

emittance, laser, storage-ring, scattering

921

Z. Pan, J.M. Byrd, C. Sun
LBNL, Berkeley, USA
H. Hao, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China

Gamma-ray sources with high flux and spectral densities are highly demanded by many nuclear experiments. We design a low energy compact storage ring to produce gamma-ray with energy in the range of 4-20 MeV based on Compton backscattering technique. The storage ring energy is 500-800 MeV with the circumference of about 59 m and natural emittance of about 3 nmrad at 500 MeV. In this paper, we present the storage ring lattice design and propose two collision configurations for Compton gamma-ray generation. Intrabeam scattering has been investigated which can increase emittance from 3 nmrad to 6 nmrad horizontally for 500 MeV ring. We also discuss how Compton scattering affects longitudinal and transverse beam dynamics by tracking macro particles using our parallel simulation code. Based on this study, we can further optimize our storage ring lattice design for the higher gamma-ray flux production.

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MOPVA033

A Compact Thermionic RF Injector with RF Bunch Compression fed by a Quadrupole-Free Mode Launcher

gun, cathode, undulator, linac

924

F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
We present a design for a compact X-Band RF thermionic injector consisting of two iris-loaded accelerator structures. Both structures are fed by a single quadrupole-free TM01 mode launcher. In the first structure the electron bunches are extracted from a thermionic cathode. The second structure creates an energy chirp in the bunch for its further ballistic compression. This injector can produce short electron bunches without the need for a magnetic bunch compressor. We are developing this injector as part of a linac-based 91.392 GHz RF power source, which further comprises a booster linac and a mm-wave decelerator structure that extracts 91.392 GHz RF power from the electron beam. This source will be used to power a short-period RF undulator with 1.75 mm period*.
* F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.

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MOPVA034

A Compact EUV Light Source Using a mm-Wave Undulator

undulator, gun, impedance, quadrupole

928

F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
We are building an Extreme Ultra Violet (EUV) light source based on a 1.75 mm period RF undulator*. We will use a thermionic X-Band injector which utilizes RF bunch compression. The beam is accelerated using an X-Band traveling wave accelerating structure followed by a high shunt impedance standing wave accelerating structure up to 129 MeV. The beam then goes through a 91.392 GHz RF undulator with a period of 1.75 mm, producing EUV radiation around 13.5 nm. The RF undulator is powered by a 91.392 GHz decelerating structure, which extracts the RF power from the spent electron beam. The length of the entire beam line from the cathode to the beam dump is approximately 6 m. We describe the design and projected operating parameters for this EUV light source.
* F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.

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MOPVA036

High Average Brilliance Compact Inverse Compton Light Source

SRF, gun, brilliance, laser

932

K.E. Deitrick, J.R. Delayen, G.A. Krafft
ODU, Norfolk, Virginia, USA
J.R. Delayen, G.A. Krafft
JLab, Newport News, Virginia, USA

Funding: Partially authored by Jefferson Science Associates, LLC under U.S. DOE contract NO. DE-AC05-6OR23177.
There exists an increasing demand for compact Inverse Compton Light Sources (ICLS) capable of producing substantial fluxes of narrow-band X-rays. While multiple design proposals have been made, compared to typical bremsstrahlung sources, most of these have comparable fluxes and improve on the brilliance within a 0.1% bandwidth by only a few orders of magnitude. By applying cw superconducting rf beam acceleration and rf focusing to produce a beam of small emittance and magnetic focusing to produce a small spot size on the order of a few microns at collision, the source presented here provides a 12 keV X-ray beam which outperforms other compact designs and bremsstrahlung sources. Compared to a bremsstrahlung source, the flux is improved by at least an order of magnitude and the average brilliance by six orders of magnitude. Surpassing other compact ICLS designs, the source presented here is attractive to a wide variety of potential users.

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MOPVA055

Upgrade of the Capture Section of the S-DALINAC Injector

cavity, SRF, operation, accelerating-gradient

993

D.B. Bazyl, H. De Gersem, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This work is supported by the DFG through GRK 2128.
In order to reduce the energy spread of the recirculated beam, the injector of the S-DALINAC needs to be optimized, because the non-isochronous recirculation cannot correct for errors originating from the injector linac. For the S-DALINAC, spatial restrictions suggest the use of SRF technology for the capture section. In this work, we consider various SRF cavities with an operating frequency of 3 GHz for a possible upgrade of the capture section of the S-DALINAC. The first results of the RF and beam dynamics simulations for the proposed options are presented in this paper.

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MOPVA061

Quench and Field Emission Diagnostics for the ESS Medium-Beta Prototypes Vertical Tests at LASA

cavity, radiation, detector, diagnostics

1007

M. Bertucci, A. Bellandi, A. Bignami, A. Bosotti, J.F. Chen, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
S. Pirani
ESS, Lund, Sweden

In order to investigate the possible causes of premature thermal breakdown and performance degradation, several diagnostic techniques have been employed during the vertical tests of the Fine and Large Grain ESS Medium Beta prototypes cavities. The whole equipment, which includes second sound, fast thermometry, photodiode x ray detectors and an external NaI scintillator, is here described and the results so far obtained during the vertical tests presented.

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MOPVA064

Multipacting Study in INFN-LASA ESS Medium-Beta Cavity

cavity, simulation, SRF, site

1019

J.F. Chen, M. Bertucci, A. Bosotti, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
S. Pirani
ESS, Lund, Sweden

We present Multipacting studies in ESS Medium-Beta cavities of INFN-LASA design with both simulation and experimental results. The simulation on the ideal cavity shape with both FishPact and MultiPac2.1 codes shows that multipacting appears in a very small region near equator where the weld seam exists. A simulation with more realistic cavity shape considering the weld seam at cell equators has also been done out showing similar results for end cell but a remarkable mitigation for inner cell. During the vertical tests at LASA, Multipacting is frequently observed but with no limitation to the cavity performance, which well confirms the MP predicted by the simulations.

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MOPVA073

Development of Peak Hold Module for Electron Emission in STF-Type Power Coupler for the ILC

operation, vacuum, cryomodule, monitoring

1034

Y. Yamamoto, E. Kako, T. Shishido
KEK, Ibaraki, Japan

In STF, the RF conditioning for power coupler is done in several steps from 10 to 1650 μs as specified in TDR for the ILC. The most important signals during the RF conditioning are vacuum level, and electron emission by multipacting. The vacuum level changes continuously, and electron emission has pulse-like behavior, which has much faster response. Therefore, it was necessary to develop the peak hold and isolation modules to evaluate electron emission in short pulse width. This module has two kinds of feature. One is pulse height detection, and the other is total charge detection (integrated signal). During the RF conditioning for power couplers in STF-2 cryomodule, this module perfectly worked, and detected different trend between the pulse height and the total charge. In this paper, the detailed result for the peak hold module will be presented.

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MOPVA106

Experimental Studies of Asymmetric Dual Axis Cavity for Energy Recovery LINAC

cavity, luminosity, linac, radiation

1105

I.V. Konoplev, A.J. Lancaster, K. Metodiev, A. Seryi
JAI, Oxford, United Kingdom
R. Ainsworth
Fermilab, Batavia, Illinois, USA
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Funding: The Leverhulme Trust via International Network Grant (IN-2015-012).
Increasing the beam charge and repetition rate leads to appearance of beam break-up instabilities in conventional ERLs. At this stage the highest current, from the SRF ERL, is around 300mA. A single turn, dual axis, compact Asymmetric Energy Recovery LINAC (AERL) was proposed. The concept assumes the use of electron beams with energies up to 300 MeV and peak currents >1A, enabling the generation of high flux EUV/X-rays and THz radiation using conventional approaches. System allows beam to be transported through each stage i.e. the acceleration, interaction and deceleration only once partially removing the feedback thus increasing the instability start current. This further improved by tuning the individual cells allowing only operating mode to be uniform inside the cavity. We present the studies of 7 cells, aluminium alloy prototype of the cavity and discuss the experimental results. We show that HOMs excited on the different axis have different R/Q factors and show the field structures of operating mode and HOMs. The experimental results observed are in good agreement with theoretical predictions and the full scale copper prototype is demonstrated.

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MOPVA114

Materials Characterization for SRF Cavities: Gaining Insight Into Nb3Sn

ion, SRF, interface, cavity

1111

J. Tuggle
Virginia Polytechnic Institute and State University, Blacksburg, USA
G.V. Eremeev, A.D. Palczewski, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley, U. Pudasaini
The College of William and Mary, Williamsburg, Virginia, USA

Funding: JLab work supported by U.S. DOE Contract No. DE-AC05-06OR23177. Work at William & Mary and Virginia Tech supported by the Office of High Energy Physics, U.S. Department of Energy grant DE-SC-0014475
Although SRF accelerators are an invaluable research tool they can be painfully expensive to construct and operate at the current level of SRF technology. This cost is significantly due to the necessity to operate at a temperature of only 2K. Considerable research is currently underway into next generation SRF cavity technologies such as Ndoping and Nb3Sn coating. Both of these technologies will lower the cryogenic load of accelerators, correspondingly lowering both construction and operating costs. However, current understanding of either technology is incomplete and in order to elucidate the underlying mechanisms there is a need to push current characterization methods forward. In this work, ion beam techniques (e.g. focused ion beam (FIB)), and electron backscatter diffraction (EBSD) were applied to help understand Nb3Sn coating mechanisms. This presentation will focus on characterization, providing examples of EBSD work, along with discussion of some of the issues encountered while trying to produce high quality EBSD data.

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MOPVA123

Cornell Sample Host Cavity: Recent Results

cavity, niobium, SRF, operation

1142

J.T. Maniscalco, D.L. Hall, M. Liepe, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V.M. Arrieta, S.R. McNeal, W.E. Williams
Ultramet, Pacoima, California, USA

Funding: NSF-PHY 1416318 NSF-PHY 1549132
The Cornell sample host cavity is a 3.9~GHz testing system for RF analysis of novel superconducting surfaces. The cavity applies fields up to 100~mT on a removable and replaceable 5-inch sample plate in order to measure the surface resistance of the material under investigation. The cavity also includes a temperature-mapping system for localization of quench events and surface defects. In this paper, we present recent experimental results from the host cavity of niobium deposited onto molybdenum and copper substrates using chemical vapor deposition, in collaboration with industry partner Ultramet. The results indicate low BCS resistance and good adhesion but also areas of high residual resistance due to chemical and morphological defects.

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MOPVA133

Optimization of the RF Cavity Heat Load and Trip Rates for CEBAF at 12 GeV

linac, cavity, operation, SRF

1170

H. Zhang, A. Freyberger, G.A. Krafft, Y. Roblin
JLab, Newport News, Virginia, USA
B. Terzić
ODU, Norfolk, Virginia, USA

Funding: Work supported by the Department of Energy under Contract No. DE-AC05-06OR23177
The Continuous Electron Beam Accelerator Facility at JLab has 200 RF cavities in the north linac and the south linac respectively after the 12 GeV upgrade. The purpose of this work is to simultaneously optimize the heat load and the trip rate for the cavities and to reconstruct the pareto-optimal front in a timely manner when some of the cavities are turned down. By choosing an efficient optimizer and strategically creating the initial gradients, the pareto-optimal front for no more than 15 cavities down can be re-established within 20 seconds.

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MOPVA136

Higher Order Multipole Analysis for 952.6 Mhz Superconducting Crabbing Cavities for Jefferson Lab Electron-Ion Collider

cavity, multipole, dipole, proton

1177

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
H. Park
JLab, Newport News, Virginia, USA

The proposed electron ion collider at Jefferson Lab requires a crabbing cavity system to increase the luminosity in the colliding beams. Currently several superconducting crabbing cavity designs are being reviewed as the design option for the crabbing cavity. Knowledge of higher order mode multipole field effects is important for accurate beam dynamics study for the crabbing system, in selecting the design that meets the design specifications. The multipole components can be accurately determined numerically using the electromagnetic field data in the rf structure. This paper discusses the detailed analysis of higher order multipole components for the operating crabbing mode and design modifications in reducing those components.

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MOPVA140

Multipacting Behavior Study for the 112 MHz Superconducting Photo-Electron Gun

cavity, gun, SRF, cathode

1180

I. Petrushina
SUNY SB, Stony Brook, New York, USA
V. Litvinenko, G. Narayan, I. Pinayev, F. Severino, K.S. Smith
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Superconducting 1.2 MV 112 MHz quarter-wave photo-electron gun (SRF gun) is used as a source of electron beam for the Coherent electron Cooling experiment (CeC) at BNL. During the CeC commissioning we encountered a number of multipacting zones in the gun. It was also observed that introduction of CsK2Sb photocathode creates additional multipacting zone. This paper presents numerical and experimental study of the multipactor discharge in the SRF gun. We also discuss ways of crossing the multipacting levels to the operational voltage. Finally, we compare the results of our numerical simulations of the multipactor discharge using ACE3P with experimental data.

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TUXA1

Towards Diffraction Limited Storage Ring Based Light Sources

emittance, storage-ring, lattice, undulator

1203

L. Liu, H. Westfahl Jr.
LNLS, Campinas, Brazil

Experimental x-ray techniques that benefit from the great increase in brightness and coherent flux provided by the fourth generation of synchrotron light sources, based on recent advances in accelerator design and technology, are widely expanding nowadays. The basic ingredient to higher brightness is a further reduction of the electron beam emittance in storage rings dedicated to light sources. However, to fully explore the potential of these new sources, it is necessary to optimize other variables as well, such as the proper matching of electrons and photons phase-space and the possibility of using new kinds of insertion devices. Equally important is to try new ways to improve the integration between the light source capabilities and the experiment needs. In this work, recent progress of low emittance rings will be reviewed and the efforts to improve transverse coherent flux and source-to-beamline integration at the Brazilian Sirius project will be described.

Slides TUXA1 [11.984 MB]

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TUOAA2

A Soft X-Ray Free-Electron Laser Beamline of SACLA

FEL, undulator, photon, laser

1209

K. Togawa, T. Asaka, N. Azumi, T. Hara, T. Hasegawa, N. Hosoda, T. Inagaki, T. Ishikawa, R. Kinjo, C. Kondo, H. Maesaka, S. Matsui, T. Ohshima, Y. Otake, S. Owada, H. Tanaka, T. Tanaka, M. Yabashi
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Bizen, H. Kimura, S. Matsubara, K. Nakajima, T. Sakurai, T. Togashi, K. Tono
JASRI/SPring-8, Hyogo, Japan
T. Fukui
RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan

At the Japanese x-ray free-electron laser (FEL) facility, SACLA, the beamline-1 has been upgraded from a spontaneous radiation to a soft x-ray FEL beamline, which generates FEL lights over a wide wavelength range from the extreme-ultraviolet to the soft x-ray regions. We started operation for users in July 2016. A dedicated accelerator, which is a refinement of the SCSS test accelerator operated in 2005-2013, was installed beside the XFEL beamlines in the SACLA undulator hall. The SCSS concept to make an FEL facility compact was continuously adopted. In the 2016 summer shutdown period, the beam energy was upgraded from 500 MeV to 800 MeV by adding two C-band rf units. The maximum K-value of the undulator magnet is 2.1. The available wavelengths of the FEL lights were extended to the range from 8 to 50 nm with pulse energies between a few to few tensμJ at an operational repetition rate of 60 Hz. In this conference, we will report an overview of the upgraded SACLA-beamline-1 and characteristics of the FEL light pulse.

Slides TUOAA2 [15.457 MB]

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TUOAA3

Progress of Pr2Fe14B Based Hybrid Cryogenic Undulators at SOLEIL

undulator, cryogenics, radiation, photon

1213

A.M. Ghaith, P. Berteaud, F. Blache, F. Briquez, N. Béchu, M.-E. Couprie, J. Da Silva Castro, J.M. Dubuisson, C. Herbeaux, C.A. Kitegi, A. Lestrade, O. Marcouillé, F. Marteau, M. Sebdaoui, G. Sharma, A. Somogyi, K.T. Tavakoli, M. Tilmont, M. Valléau
SOLEIL, Gif-sur-Yvette, France
C. Benabderrahmane
ESRF, Grenoble, France

Cryogenic Permanent Magnet Undulators (CPMUs) take advantage of the enhanced field performance of permanent magnets when cooled down to low temperature, enabling shorter period with sufficient magnetic field to achieve high brightness radiation in the X-ray domain. Several CPMUs have been manufactured at SOLEIL. The first CPMU of period 18 mm (U18), optimized with a phase error of 3.2° at temperature of 77 K, has been installed and operated for the past 5 years at SOLEIL for the NANOSCOPIUM beamline. We report on photon beam based alignment enabling for a better adjustment of the vertical position offset of the undulator with a precision of 50 μm, and on the correction of the taper with a precision of 5 μrad to enhance the radiation flux. A second U18 cryo-ready undulator, with a new mechanical and magnetic sorting of module shimming, has attained a phase error of 2.3° at CT without any further adjustments after the assembly. Currently, two more CPMUs are being built; a 2 m long U18 for the SOLEIL ANATOMIX beamline, and a 3 m long U15 undulator reaching a magnetic gap of 3 mm. The new challenges encountered with magnetic measurements and mechanical designs for U15 are presented.

Slides TUOAA3 [3.491 MB]

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TUXB1

Non-destructive Beam Profile Monitors

ion, photon, vacuum, focusing

1234

C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

This paper will present an overview and comparison between beam induced fluorescence, residual gas ionization and gas jet based beam profile monitors, based on recent experimental and theoretical results at different labs. The achievable image/profile quality and resolution limits will be discussed, along with design consideration for different particle species and primary beam energies. Details may be provided about different classic and novel approaches to gas jet shaping, including nozzle-skimmer and Freznel Zone Plate configurations. Finally, particular challenges such as those arising from monitoring multiple beams in parallel (e.g. proton and electron beam in HLLHC) and solutions for targeting the energy limit within the HLLHC project will be presented.

Slides TUXB1 [12.557 MB]

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TUYB1

First Measurements of Trojan Horse Injection in a Plasma Wakefield Accelerator

plasma, laser, wakefield, injection

1252

B. Hidding, A. Beaton, A.F. Habib, T. Heinemann, G.G. Manahan, P. Scherkl, A. Sutherland, D. Ullmann
USTRAT/SUPA, Glasgow, United Kingdom
E. Adli, C.A. Lindstrøm
University of Oslo, Oslo, Norway
E. Adli, S.J. Gessner
CERN, Geneva, Switzerland
G. Andonian, A. Deng, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
G. Andonian
RadiaBeam, Santa Monica, California, USA
A. Beaton, A.F. Habib, T. Heinemann, B. Hidding, G.G. Manahan, P. Scherkl, A. Sutherland, D. Ullmann
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D.L. Bruhwiler
RadiaSoft LLC, Boulder, Colorado, USA
J.R. Cary
Tech-X, Boulder, Colorado, USA
C.I. Clarke, S.Z. Green, M.J. Hogan, B.D. O'Shea, V. Yakimenko
SLAC, Menlo Park, California, USA
M. Downer, R. Zgadzaj
The University of Texas at Austin, Austin, Texas, USA
T. Heinemann, A. Knetsch
DESY, Hamburg, Germany
T. Heinemann, G. Wittig
University of Hamburg, Hamburg, Germany
O.S. Karger
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
M.D. Litos
Colorado University at Boulder, Boulder, Colorado, USA
J.D.A. Smith
TXUK, Warrington, United Kingdom

Funding: Work supported in part by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
Plasma accelerators support accelerating fields of 100's of GV/m over meter-scale distances and routinely produce femtosecond-scale, multi-kA electron bunches. The so called Trojan Horse underdense photocathode plasma wakefield acceleration scheme combines state-of-the-art accelerator technology with laser and plasma methods and paves the way to improve beam quality as regards emittance and energy spread by many orders of magnitude. Electron beam brightness levels exceeding 10²⁰ Am^-2 rad^-2 may be reached, and the tunability allows for multi-GeV energies, designer bunches and energy spreads <0.05% in a single plasma accelerator stage. The talk will present results of the international E210 multi-year experimental program at SLAC FACET, which culminated in successful first demonstration of the Trojan Horse method during FACET's final experimental run in 2016. Enabling implications for applications, including high performance plasma-based 5th generation light sources such as hard x-ray FEL's, for which start-to-end simulations are presented, and for high energy physics are discussed.

Slides TUYB1 [19.089 MB]

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TUOBB1

Experimental Demonstration of Energy-Chirp Reduction by a Plasma Dechirper

plasma, laser, experiment, linac

1258

Y.P. Wu, Z. Cheng, Y.-C. Du, J.F. Hua, W. Lu, C.H. Pai, J. Zhang, S.Y. Zhou, Z. Zhou
TUB, Beijing, People's Republic of China

The first experimental study is presented using a low density plasma dechirper to reduce a correlated energy chirp from the 41.5-MeV, 500-fs (RMS) beam at the linac in Tsinghua University. The plasma dechirper operates through the interaction of the electron bunch with its near linear self-wake to dechirp itself, leading to a reduction in energy spread. The experimental results demonstrate that the projected FWHM energy spread of the beam can be reduced from 1.2% to 0.9% with a 12 mm long plasma dechirper, which are in good agreement with full 3D PIC simulations. Theoretical analyses and simulations indicate that by optimizing the plasma density and length, the plasma dechirper can also be used to completely remove the characteristic energy chirp of the ultra-short high-current bunch generated from plasma based accelerator, such that its energy spread can be reduced from one percent level to 0.1 percent level[*]. Application of such a simple and effective method can significantly improve the beam quality and provide the path to realize the future compact free electron lasers and colliders driven by plasma based accelerators.
[*] Y. P. Wu. A plasma dechirper for electron and positron beams in plasma-based accelerators, to be submitted to Scientific Reports

Slides TUOBB1 [10.555 MB]

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TUOBB2

Starting Up the AWAKE Experiment at CERN

proton, plasma, laser, experiment

1261

E. Gschwendtner
CERN, Geneva, Switzerland

AWAKE, the Advanced Proton Driven Plasma Wake-field Acceleration Experiment at CERN was approved in 2013. The facility was commissioned in 2016 to perform first experiments to demonstrate the self-modulation in-stability (SMI) of a 400 GeV/c SPS proton bunch in a 10 m long Rubidium plasma cell. The plasma is created in Rb vapor via field ionization by a TW laser pulse. In the second phase starting late 2017, the proton driven plasma wakefield will be probed with an externally injected 10 ' 20 MeV/c electron beam. This paper gives an overview of the AWAKE facility, describes the successful commissioning of the laser and proton beam line, the plasma cell and diagnostics and shows the successful synchronization of the proton beam with the laser at the few ps level so that the facility is ready for the SMI physics runs. In addition the status of the electron acceleration exper-iment for late 2017 will be presented.

Slides TUOBB2 [3.513 MB]

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TUOBB3

HORIZON 2020 EuPRAXIA Design Study

plasma, laser, acceleration, radiation

1265

P.A. Walker, R.W. Aßmann, J. Bödewadt, R. Brinkmann, J. Dale, U. Dorda, A. Ferran Pousa, A.F. Habib, T. Heinemann, O. S. Kononenko, C. Lechner, B. Marchetti, A. Martinez de la Ossa, T.J. Mehrling, P. Niknejadi, J. Osterhoff, K. Poder, E.N. Svystun, G.E. Tauscher, M.K. Weikum, J. Zhu
DESY, Hamburg, Germany
D. Alesini, M.P. Anania, F.G. Bisesto, E. Chiadroni, M. Croia, M. Ferrario, F. Filippi, A. Gallo, A. Mostacci, R. Pompili, S. Romeo, J. Scifo, C. Vaccarezza, F. Villa
INFN/LNF, Frascati (Roma), Italy
A.S. Alexandrova, R.B. Fiorito, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom
A.S. Alexandrova, R.B. Fiorito, C.P. Welsch, J. Wolfenden
Cockcroft Institute, Warrington, Cheshire, United Kingdom
N.E. Andreev, D. Pugacheva
JIHT RAS, Moscow, Russia
T. Audet, B. Cros, G. Maynard
CNRS LPGP Univ Paris Sud, Orsay, France
A. Bacci, D. Giove, V. Petrillo, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
I.F. Barna, M.A. Pocsai
Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
A. Beaton, P. Delinikolas, B. Hidding, D.A. Jaroszynski, F.Y. Li, G.G. Manahan, P. Scherkl, Z.M. Sheng, M.K. Weikum
USTRAT/SUPA, Glasgow, United Kingdom
A. Beck, A. Specka
LLR, Palaiseau, France
A. Beluze, M. Mathieu, D.N. Papadopoulos
LULI, Palaiseau, France
A. Bernhard, E. Bründermann, A.-S. Müller
KIT, Karlsruhe, Germany
S. Bielawski
PhLAM/CERLA, Villeneuve d'Ascq, France
F. Brandi, G. Bussolino, L.A. Gizzi, P. Koester, B. Patrizi, G. Toci, M. Vannini
INO-CNR, Pisa, Italy
O. Bringer, A. Chancé, O. Delferrière, J. Fils, D. Garzella, P. Gastinel, X. Li, A. Mosnier, P.A.P. Nghiem, J. Schwindling, C. Simon
CEA/IRFU, Gif-sur-Yvette, France
M. Büscher, A. Lehrach
FZJ, Jülich, Germany
M. Chen, L. Yu
Shanghai Jiao Tong University, Shanghai, People's Republic of China
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
J.A. Clarke, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.-E. Couprie
SOLEIL, Gif-sur-Yvette, France
G. Dattoli, F. Nguyen
ENEA C.R. Frascati, Frascati (Roma), Italy
N. Delerue
LAL, Orsay, France
J.M. Dias, R.A. Fonseca, J.L. Martins, L.O. Silva, U. Sinha, J. Vieira
IPFN, Lisbon, Portugal
K. Ertel, M. Galimberti, R. Pattathil, D. Symes
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Fils
GSI, Darmstadt, Germany
A. Giribono
INFN-Roma, Roma, Italy
L.A. Gizzi
INFN-Pisa, Pisa, Italy
F.J. Grüner, A.R. Maier
CFEL, Hamburg, Germany
F.J. Grüner, T. Heinemann, B. Hidding, O.S. Karger, A. Knetsch, A.R. Maier
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
C. Haefner
LLNL, Livermore, California, USA
B.J. Holzer
CERN, Geneva, Switzerland
S.M. Hooker
University of Oxford, Clarendon Laboratory, Oxford, United Kingdom
S.M. Hooker, R. Walczak
JAI, Oxford, United Kingdom
T. Hosokai
Osaka University, Graduate School of Engineering, Osaka, Japan
C. Joshi
UCLA, Los Angeles, California, USA
M. Kaluza
HIJ, Jena, Germany
S. Karsch
LMU, Garching, Germany
E. Khazanov, I. Kostyukov
IAP/RAS, Nizhny Novgorod, Russia
D. Khikhlukha, D. Kocon, G. Korn, A.Y. Molodozhentsev, L. Pribyl
ELI-BEAMS, Prague, Czech Republic
L. Labate, P. Tomassini
CNR/IPP, Pisa, Italy
W. Leemans, C.B. Schroeder
LBNL, Berkeley, California, USA
A. Lifschitz, V. Malka, F. Massimo
LOA, Palaiseau, France
V. Litvinenko
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
W. Lu
TUB, Beijing, People's Republic of China
V. Malka
Ecole Polytechnique, Palaiseau, France
S. P. D. Mangles, Z. Najmudin, A. A. Sahai
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
A. Marocchino, A. Mostacci
University of Rome La Sapienza, Rome, Italy
K. Masaki, Y. Sano
JAEA/Kansai, Kyoto, Japan
U. Schramm
HZDR, Dresden, Germany
M.J.V. Streeter, A.G.R. Thomas
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
C.-G. Wahlstrom
Lund Institute of Technology (LTH), Lund University, Lund, Sweden
R. Walczak
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
G.X. Xia
UMAN, Manchester, United Kingdom
M. Yabashi
JASRI/SPring-8, Hyogo, Japan
A. Zigler
The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel

The Horizon 2020 Project EuPRAXIA ('European Plasma Research Accelerator with eXcellence In Applications') aims at producing a design report of a highly compact and cost-effective European facility with multi-GeV electron beams using plasma as the acceleration medium. The accelerator facility will be based on a laser and/or a beam driven plasma acceleration approach and will be used for photon science, high-energy physics (HEP) detector tests, and other applications such as compact X-ray sources for medical imaging or material processing. EuPRAXIA started in November 2015 and will deliver the design report in October 2019. EuPRAXIA aims to be included on the ESFRI roadmap in 2020.

Slides TUOBB3 [9.269 MB]

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TUZB2

Commissioning Status of High Luminosity Collider Rings for SuperKEKB

solenoid, emittance, quadrupole, positron

1275

H. Koiso
KEK, Ibaraki, Japan

SuperKEKB project aims to obtain the world's highest luminosity of 8x10³⁵/cm/s, in order to discover new particle physics beyond the Standard Model. Key technologies for the high luminosity are nano-beam scheme at the collision point and high positron and electron stored current with low emittance, which require the significant upgrade of both the injector and the collider rings. Recently commissioning of the renewal collider rings has been performed without final focus magnets and the Belle II detector (Phase 1). This talk gives results of the Phase 1 commissioning and construction status toward the first beam collisions (Phase 2).

Slides TUZB2 [64.509 MB]

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TUOCB3

CBETA - Cornell University Brookhaven National Laboratory Electron Energy Recovery Test Accelerator

linac, permanent-magnet, acceleration, gun

1285

D. Trbojevic, S. Bellavia, J.S. Berg, M. Blaskiewicz, S.J. Brooks, K.A. Brown, W. Fischer, F.X. Karl, C. Liu, G.J. Mahler, F. Méot, R.J. Michnoff, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
BNL, Upton, Long Island, New York, USA
N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, B.M. Dunham, R.G. Eichhorn, S.J. Full, F. Furuta, R.E. Gallagher, M. Ge, B.K. Heltsley, G.H. Hoffstaetter, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, C.E. Mayes, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D. Douglas
JLab, Newport News, Virginia, USA
D. Jusic, J.R. Patterson
Cornell University, Ithaca, New York, USA

Funding: New York State Energy Research and Development Authority (NYSERDA)
Cornell's Lab of Accelerator-based Sciences and Education (CLASSE) and the Collider Accelerator Department (BNL-CAD) are developing the first SRF multi-turn energy recovery linac with Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) racetrack. The existing injector and superconducting linac at Cornell University are installed together with a single NS-FFAG arcs and straight section at the opposite side of the the linac to form an Electron Energy Recovery (ERL) system. Electron beam from the 6 MeV injector is injected into the 36 MeV superconducting linac, and accelerated by four successive passes: from 42 MeV up to 150 MeV using the same NS-FFAG structure made of permanent magnets. After the maximum energy of 150 MeV is reached, the electron beam is brought back to the linac with opposite Radio Frequency (RF) phase. Energy is recovered and reduced to the initial value of 6 MeV with 4 additional passes. There are many novelties: a single NS-FFAG structure, made of permanent magnets, brings electrons with four different energies back to the linac. A new adiabatic NS-FFAG arc-to-straight section merges 4 separated orbits into a single orbit in the straight section.

Slides TUOCB3 [41.888 MB]

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TUPAB002

Material Tests for the ILC Positron Source

target, positron, photon, operation

1293

A. Ushakov, G.A. Moortgat-Pick
University of Hamburg, Hamburg, Germany
K. Aulenbacher, Th. Beiser, P. Heil, V. Tioukine
IKP, Mainz, Germany
A. Ignatenko, S. Riemann
DESY Zeuthen, Zeuthen, Germany
A.L. Prudnikava, Y. Tamashevich
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

The positron source is a vital system of the ILC. The conversion target that yields 10¹⁴ positrons per second will undergo high peak and cyclic load during ILC operation. In order to ensure stable long term operation of the positron source the candidate material for the conversion target has to be tested. The intense electron beam at the Mainz Microtron (MAMI) provides a good opportunity for such tests. The first results for Ti6Al4V are presented which is the candidate material for the positron conversion target as well as for the exit window to the photon beam absorber.

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TUPAB003

High Energy Density Irradiation With MAMI LINAC

target, positron, radiation, photon

1296

P. Heil, K. Aulenbacher, Th. Beiser
IKP, Mainz, Germany
A. Ignatenko, G.A. Moortgat-Pick, A. Ushakov
DESY, Hamburg, Germany
S. Riemann
DESY Zeuthen, Zeuthen, Germany

In order to build a positron source for the ILC, a high energy density irradiation is needed to test the used materials. At the MAMI linear accelerator such a radiation can be provided at different electron energies. With a macro pulsed source it is possible to imitate a yearlong radiation at the ILC within several hours. Small transversal beam sizes need to be provided with the focusing system and be measured at high beam currents using transition radiation and current measurements.

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TUPAB004

Progress of 7-GeV SuperKEKB Injector Linac Upgrade and Commissioning

positron, gun, injection, linac

1300

K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, H. Ego, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funahashi, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, D. Satoh, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimoto, H. Sugimura, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
KEK, Ibaraki, Japan

KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It is being upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of new physics beyond the standard model of elementary particle physics. SuperKEKB asymmetric electron and positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. Electron beams will be generated by a new type of RF gun, that will provide a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 micron to 20 micron in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The recent status of the upgrade and beam commissioning is reported.

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TUPAB005

Investigation of Beam Variation and Emittance Growth Simulation With Both Misalignments and the Beam Jitter for SuperKEKB Injector Linac

emittance, linac, simulation, quadrupole

1304

Y. Seimiya, K. Furukawa, T. Higo, F. Miyahara, M. Satoh, T. Suwada
KEK, Ibaraki, Japan

Funding: This work was supported by JSPS KAKENHI Grant Number 16K17545.
The SuperKEKB is e⁺/e⁻ circular collider for high luminosity, 8Â¥times10³⁵ as a target value. For the high luminosity, the injector linac is required to transport low emittance high-charged electron beam and positron beam to the ring. A charged beam with an offset from a center of cavity is affected by the wakefield depending on both the offset size in the cavity and longitudinal particle position in the beam. The wakefield causes emittance growth. This growth can be suppressed by appropriate orbit control so as to cancel the wakefield effect of the cavities in total. On the other hands, the beam variation in 6-dimensional phase space also induces the emittance growth. Emittance growth by both misalignments and 6-dimensional beam jitter was evaluated by particle tracking simulation. Investigation of beam jitter and drift was also performed by correlation analysis between beam position and measured parameter, charge or temperature.

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TUPAB008

CEPC Linac Design and Beam Dynamics

positron, linac, target, quadrupole

1315

C. Meng, Y.L. Chi, X.P. Li, G. Pei, S. Pei, D. Wang, J.R. Zhang
IHEP, Beijing, People's Republic of China

Circular Electron-Positron Collider (CEPC) is a 100 km ring e⁺ e⁻ collider for a Higgs factory, which is organized and led by the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences (CAS) in collaboration with a number of institutions from various countries. The linac of CEPC is a normal con-ducting S-band linac with frequency in 2856.75 MHz and provide electron and positron beam at an energy up to 10 GeV with bunch charge in 1.0 nC and repetition frequency in 100 Hz. The linac scheme will be detailed discussed in this paper, including electron bunching system, positron source design, and main linac. Positrons are generated using a 4 GeV electron beam with bunch charge 10 nC hit tungsten target and the positron source design are presented. The beam dynamic results with longitudinal short Wakefield, transverse Wakefield and errors are presented.

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TUPAB011

Beam Dynamics Simulation in Two Versions of New Photogun for FCC-ee Electron Injector Linac

linac, injection, simulation, beam-loading

1326

S.M. Polozov, T.V. Bondarenko
MEPhI, Moscow, Russia

New high-energy frontier project FCC is now under development at CERN. The project includes three modes: ee, hh and eh interactions for FCC. New injection system for FCC-ee is planned to consist of new ~ 2-14 GeV electron linac and electron-positron converter. Injector linac should provide two regimes: ~250 pC bunches for injection and ~6 nC bunches for e⁻/e⁺ conversion. Two possible schemes of photogun are comprised and results of beam dynamics simulation in both FCC-ee injection linac photoguns are discussed.

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TUPAB018

Initial Data From an Electron Cloud Detector in a Quadrupole Magnet at CesrTA

quadrupole, detector, positron, storage-ring

1352

J.P. Sikora, S.T. Barrett, M.G. Billing, J.A. Crittenden, K.A. Jones, Y. Li, T.I. O'Connell
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505
In September 2016, we installed a detector in a quadrupole magnet that measures the electron cloud density using two independent techniques. Stripline electrodes collect cloud electrons which pass through holes in the beam-pipe wall. The array of small holes shields the striplines from the beam-induced electromagnetic pulse. The beam-pipe chamber has also been designed so that microwave measurements of the electron cloud density can be performed. The resonant microwaves are confined to be within the 56 cm length of the quadrupole. The detector is placed in a newly installed quadrupole that is adjacent to an existing lattice quadrupole of the same polarity. Since they are powered independently, their relative strengths can be varied with stored beam – allowing electron cloud measurements to be made as a function of gradient. This paper presents the first data obtained with this detector with trains of positron bunches at 5.3 GeV. The detector is installed in the Cornell Electron Storage Ring and is part of the test accelerator program for the study of electron cloud build-up using electron and positron beams from 2 to 5 GeV.

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TUPAB020

AREAL 50 MeV Electron Accelerator Project for THz and Middle IR FEL

radiation, emittance, gun, FEL

1355

G.A. Amatuni, Z.G. Amirkhanyan, V.S. Avagyan, A. Azatyan, V. Danielyan, H. Davtyan, S.G. Dekhtiarov, N. Ghazaryan, B. Grigoryan, L. Hakobyan, M. Ivanyan, V.G. Khachatryan, E.M. Laziev, T. Markosyan, N. Martirosyan, Sh.A. Mehrabyan, T. Melkumyan, T.H. Mkrtchyan, V.H. Petrosyan, V. Sahakyan, A. Sargsyan, A.S. Simonyan, A.V. Tsakanian, V.M. Tsakanov, A. Vardanyan, Ta.S. Vardanyan, T.L. Vardanyan, V. V. Vardanyan, A.S. Yeremyan, G.S. Zanyan
CANDLE SRI, Yerevan, Armenia
P.S. Manukyan
SEUA, Yerevan, Armenia
A.V. Tsakanian
HZB, Berlin, Germany

Advanced Research Electron Accelerator Laboratory (AREAL) is an electron accelerator project based on photo cathode RF gun. First phase of the facility is a 5 MeV energy RF photogun, which is currently under operation. The facility development implies energy upgrade to 50 MeV with further delivery of the electron beam to the undulator sections for Free Electron Laser and coherent undulator radiation generation in MIR and THz frequency ranges respectively. In this report the design study of AREAL 50 MeV facility main systems along with the beam dynamics and characteristics of expected radiation are presented.

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TUPAB021

The Study of Focus-Dependent Dark Current for AREAL RF Photogun

gun, solenoid, experiment, simulation

1358

L. Hakobyan, H. Davtyan, B. Grigoryan, A. Vardanyan
CANDLE SRI, Yerevan, Armenia

AREAL (Advanced Research Electron Accelerator Laboratory) is a project of linear accelerator based facility aimed to produce ultra-short electron bunches with small emittance. In the first phase of AREAL project an electron beam with energy up to 5 MeV is produced by the electron RF photogun and used for irradiation experiments in biology, microelectronics and accelerator technology development. For such experiments the exact calculation of absorbed dose and electron bunch peak current is one of important conditions. The presence of a dark current in electron gun affects the electron emission from photocathode, the exact absorbed dose calculation, and in general harms the machine performance. In this paper the estimation of dark current amount, produced in the electron gun, the ways to avoid its influence on experiments are discussed. The dark current measurements are compared with the simulation results. The electron beam separation from a dark current is discussed.

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TUPAB022

TRIUMF ARIEL e-Linac Ready for 30 MeV

cavity, linac, cryomodule, TRIUMF

1361

S.R. Koscielniak, Z.T. Ang, K. Fong, J.J. Keir, O.K. Kester, M.P. Laverty, R.E. Laxdal, Y. Ma, A.K. Mitra, T. Planche, D.W. Storey, E. Thoeng, B.S. Waraich, Z.Y. Yao, V. Zvyagintsev
TRIUMF, Vancouver, Canada

Funding: TRIUMF is funded under a contribution agreement with the National Research Council of Canada.
The ARIEL electron linac (e-linac) in its present configuration has a 10 mA electron gun and a single-cavity 10 MeV injector cryomodule followed by the accelerator cryomodule intended to house two 10-MeV-capable SRF cavities. There are momentum analysis stations at 10 MeV and 30 MeV. In October 2014, using a total of two cavities, the e-linac demonstrated 22.9 MeV acceleration. In 2017 an additional SRF cavity was installed in the accelerator cryomodule, thereby completing its design specification; and leading to 30 MeV acceleration capability. The 9-cell 1.3 GHz cavities are a variant of the TESLA type, modified for c.w. operation and recirculation. An unusual feature of the module is the power feed of two cavities by one klystron through a wave-guide type power divider, and closed loop control of the combined voltage from the cavities. Initial operation of the two-cavity control, including power and phase balancing, is reported.

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TUPAB023

Commissioning of the 10MeV Electron Injector Cryomodule for VECC at TRIUMF

cavity, cryomodule, TRIUMF, linac

1365

R.E. Laxdal, Y. Ma, R.R. Nagimov, D.W. Storey, E. Thoeng, Z.Y. Yao, V. Zvyagintsev
TRIUMF, Vancouver, Canada
U. Bhunia, A. Chakrabarti, S. Dechoudhury, V. Naik
VECC, Kolkata, India

TRIUMF (Vancouver) and VECC (Kolkata) have been engaged in a collaboration on superconducting electron linacs since 2008. The motivation for the collaboration was to support initiatives at both labs, ARIEL at TRIUMF and ANURIB at VECC, to augment the respective radioactive ion beam (RIB) programs with the addition of a high intensity electron linac driver to produce RIBs through photo-fission. The common linac architecture is based on five 1.3GHz nine-cell SRF cavities housed in three cryomodules; a single cavity injector (ICM) and a pair of two cavity accelerating modules (ACM). Final design goals are 50MeV and 10mA/3mA at TRIUMF/VECC respectively. A ARIEL e-linac demonstrator with two cold cavities in two modules successfully accelerated beam to 20MeV. Recently the VECC 10MeV injector cryomodule was commissioned with beam. A summary of the ICM design and results of the commissioning will be presented.

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TUPAB025

Experimental Results for Multiphoton Nonlinear Photoemission Processes on Phil Test Line

laser, photon, gun, cathode

1369

H. Purwar, C. Bruni, V. Chaumat, N. ElKamchi, V. Soskov
LAL, Orsay, France
D. Garzella
CEA, Gif-sur-Yvette, France
B. Lucas
CNRS LPGP Univ Paris Sud, Orsay, France
M. Pittman
CLUPS, Orsay, France
T. Vinatier
DESY, Hamburg, Germany

One of the prerequisites for the next generation high luminosity light sources is the availability of the short electron bunches. It also has several applications in other domains, including medical diagnostics and high-resolution imaging. In principle, using photoelectric effect a short electron bunch can initially be generated by illuminating a photocathode with an ultra-short light pulse of appropriate wavelength. Strong EM fields from a RF gun or similar accelerating structures, synchronized with the incoming laser pulses, are then used to accelerate these electron bunches initially up to an energy of tens of MeV. We present our preliminary results on the experimental investigation of two-photon nonlinear photoemission processes for the generation of picosecond, low-charge electron bunches conducted at PHIL photoinjector facility. A comparison of the emission efficiency and bunch characteristics with the single photon emission process is also made.
*PHIL is an acronym for Photo-injector at Linear Accelerator Laboratory (LAL).

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TUPAB028

Measuring the Spectral Response of Cs-K-Sb Photocathodes for BERLinPro

SRF, cathode, linac, emittance

1378

H. Kirschner, A. Jankowiak, T. Kamps, J. Kühn, M.A.H. Schmeißer
HZB, Berlin, Germany

A spectral response setup was commissioned at the Cs-K-Sb photocathode preparation and analysis system developed for the BERLinPro project. The setup is designed to measure the spectral quantum efficiency from 370 to 700 nm and to monitor the photocurrent during the photocathode growth process and the photocathode lifetime at 515 nm.

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TUPAB031

Status and Perspectives of the S-DALINAC Polarized-Electron Injector

gun, cathode, experiment, laser

1388

M. Herbert, J. Enders, M. Espig, Y. Fritzsche, N. Kurichiyanil, M. Wagner
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by the Deutsche Forschungsgemeinschaft through grants GRK 2128 and SFB 1245
The S-DALINAC Polarized Injector (SPIn) uses GaAs photocathodes to provide pulsed and/or polarized electron beams for nuclear-structure investigations. Recently, a test facility for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen \mbox{(Photo-CATCH)} has been developed. This setup uses an inverted-insulator geometry for the photo-electron gun. Currently, tests and optimizations are conducted at \mbox{Photo-CATCH} in order to implement this new gun design at SPIn. We will present the current status of \mbox{Photo-CATCH}, the planned upgrade of SPIn (aimed at an operational voltage of 200 kV) and future measurements.

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TUPAB032

Development of a Cryogenic GaAs DC Photo-Gun for High-Current Applications

cathode, cryogenics, vacuum, ion

1391

S. Weih, T. Eggert, J. Enders, M. Espig, Y. Fritzsche, N. Kurichiyanil, M. Wagner
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG (GRK 2128) and BMBF (05H15RDRB1)
For high-current applications of GaAs photocathodes it is necessary to maximize the charge lifetime of the cathode material to ensure reliable operation. By means of cryogenic cooling of the electrode, the local vacuum conditions around the source can be improved due to cryogenic adsorption of reactive rest-gas molecules at the surrounding walls. Furthermore, the cooling also allows a higher laser power deposited in the material, resulting in higher currents that can be extracted from the cathode. Ion-backbombardment is expected to be reduced using electrostatic bending of the electrons behind the cathode. To measure the characteristics of such an electron source, a dedicated set-up is being developed at the Photo-CATCH test facility in Darmstadt.

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TUPAB033

Design of a Stripline Kicker for the ELBE Accelerator

kicker, emittance, neutron, laser

1393

Ch. Schneider, A. Arnold, J. Hauser, P. Michel, G.S. Staats
HZDR, Dresden, Germany

ELBE is a linac based cw electron accelerator serving different secondary beams one at a time. Depending on the user demand the bunch repetition rate may vary from single pulse up to 13 MHz. For the future different end stations should be served simultaneously, hence specific bunch patterns have to be kicked to other beam-lines. To use e.g. one bunch out of the bunch train very short kicking durations have to be realized. The variability of the bunch pattern and the frequency resp. switching time are one of the main arguments for a stripline-kicker combined with HV-switches as basic concept. A nearly homogenous field in the kicker has to be realized for uniform deflection of the electron bunch and emittance grow of the bunch has to be kept as low as possible. Furthermore the fast switching ability of the kicker demands for a fast decay of the HV-pulse resp. its reflections in the structure implying a specific design of the kicker elements. For this reason a design with two tapered active electrodes and two ground fenders was optimized in time and frequency domain with the software package CST. Additionally a first prototype was manufactured for laboratory and first beam-line tests.

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TUPAB037

An Optimized Lattice for a Very Large Acceptance Compact Storage Ring

lattice, storage-ring, laser, sextupole

1402

A.I. Papash, E. Bründermann, A.-S. Müller
KIT, Eggenstein-Leopoldshafen, Germany

Combining a circular storage ring and a laser wakefield accelerator (LWFA) might be the basis for future compact light sources and advancing user facilities to different commercial applications. Meanwhile the post-LWFA beam is not directly suitable for storage and accumulation in conventional storage rings. New generation rings with adapted features are required. Different geometries and ring lattices of very large-acceptance compact storage ring operating between 50 to 500 MeV energy range were studied. The main objective was to create a model suitable to store the post-LWFA beam with a wide momentum spread (2% to3%) and ultra-short electron bunches of fs range. The DBA-FDF lattice with relaxed settings, split elements and optimized parameters allows to open the dynamic aperture up to 20 mm while dispersion is limited and sextupole strength is high. The proposed machine model could be a basis for further, more detailed design studies.

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TUPAB038

Electron Acceleration With a Ultrafast Gun Driven by Single-Cycle Terahertz Pulses

gun, acceleration, timing, laser

1406

C. Zhou, F. Ahr, A-L. Calendron, H. Cankaya, M. Fakhari, A. Fallahi, F.X. Kärtner, N.H. Matlis, W. Qiao, X. Wu, D. Zhang
CFEL, Hamburg, Germany
R.W. Aßmann, U. Dorda, K. Galaydych, B. Marchetti, G. Vashchenko, T. Vinatier
DESY, Hamburg, Germany

Funding: This work was supported by the European Research Council under the European Union Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement no. 609920.
We present results on an improved THz-driven electron gun using transversely-incident single-cycle THz pulses using a horn-coupler. Intrinsic synchronization between the electrons and the driving field was achieved by using a single laser system to create electrons by UV photoemission and to create THz radiation by difference frequency generation in a tilted-pulse front geometry. Details of the optical setups for the UV and THz pulses will be described as well as preliminary results showing evidence of electron acceleration.

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TUPAB039

Installation Management for the European XFEL Main Accelerator

Ethernet, cryogenics, status, controls

1409

M. Bousonville, S. Choroba, F. Eints
DESY, Hamburg, Germany

By end of 2016, the main accelerator of the European XFEL was completed. To build this complex machine in a minimum of time, certain management methods were introduced in mid 2015, which accelerated the installation process substantially. In the following 64 weeks additional 84 % of the main accelerator were set up. This was possible due to an improved planning, the reinforcement of two teams as well as a permanent controlling and optimizing of the installation process. In this paper, the installation process from July 2015 to end 2016 and the measures which speeded up the workflow are described.

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TUPAB040

Status Update of the SINBAD-ARES Linac Under Construction at DESY

linac, diagnostics, laser, acceleration

1412

B. Marchetti, R.W. Aßmann, S. Baark, U. Dorda, C. Engling, K. Flöttmann, I. Hartl, J. Hauser, J. Herrmann, M. Hüning, M. Körfer, B. Krause, G. Kube, J. Kuhlmann, S. Lederer, F. Ludwig, D. Marx, F. Mayet, M. Pelzer, I. Peperkorn, A. Petrov, S. Pfeiffer, S. Pumpe, J. Rothenburg, H. Schlarb, M. Titberidze, S. Vilcins, M. Werner, Ch. Wiebers, L. Winkelmann, K. Wittenburg, J. Zhu
DESY, Hamburg, Germany

ARES (Accelerator Research Experiment at Sinbad) is a linear accelerator for the production of low charge (from few pC to sub-pC) electron bunches with 100 MeV energy, fs and sub-fs duration and excellent arrival time stability. This experiment is currently under construction at DESY Hamburg and it is foreseen to start operation by the beginning of 2018 with the commissioning of the RF-gun. After an initial beam characterization phase, ARES will provide high temporal resolution probes for testing novel acceleration techniques, such as Laser driven plasma Wake-Field Acceleration (LWFA), Dielectric Laser Acceleration (DLA) and THz driven acceleration. In this work we present an overview of the present design of the linac with a special focus on 3D integration and planned installation phases of the beamline.

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TUPAB042

Current Status of IPM Linac Control System

controls, EPICS, PLC, linac

1418

S. Haghtalab, F. Abbasi
Shahid Beheshti University, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran
F. Ghasemi, M. Lamehi
IPM, Tehran, Iran

This paper reports the progress of the control system for IPM 10 MeV accelerator. As an electron linac, it consists of beam injection acceleration tube, radio frequency production and transmission, target, diagnostics and control and safety. In support of this source, an EPICS-based integrated control system has been designed and being implemented from scratch to provide access to the critical control points and continues to grow to simplify operation of the system. In addition to a PLC-based machine protection component and IO interface, a CSS-based suite of control GUI monitors systems including Modulator and RF, Vacuum, Magnets, and electron gun. An overview of this system is presented in this article.

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TUPAB043

Design and Simulation of Voltage Multiplier Column of a 300keV, 10mAParallel Fed Cockcroft Walton Electron Accelerator for Industrial Applications

simulation, coupling, software, gun

1421

M. Nazari, F. Abbasi Davani, F. Ghasemi
Shahid Beheshti University, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran

In this article a 300keV, 10mA multiplier column has been designed for a parallel fed Cockcroft Walton electron accelerator for industrial applications. The parallel fed Cockcroft Walton multiplier is a capacitive coupling multiplier with diode rectification which can convert an input RF voltage to a low ripple output DC voltage. In this research tried to get a low ripple (300keV output) dc voltage. At first, the voltage multiplier column has been simulated with pspice simulation software. After doing the pspice simulations, optimum value of different parameters has been get. At the end we try to get the optimum values of pspice simulations with a mechanical design with CST STODIO. The mechanical design of voltage multiplier and its equivalent circuit hah a good accordance with each other.

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TUPAB044

SIMULATION, MEASUREMENT AND TUNING OF A PROTOTYPE DISK LOADED RF CAVITY

simulation, cavity, linac, operation

1424

S. Ahmadiannamin
ILSF, Tehran, Iran
F. Abbasi, F. Ghasemi
Shahid Beheshti University, Tehran, Iran
M. Lamehi, M. Shirshekan
IPM, Tehran, Iran

Constant impedance accelerator RF cavities are constructed from similar resonator cells that stacked to each other. Best operation condition is achieved when all of cells resonate in one resonance frequency with similar quality factors. So, measurement and tuning of RF cavities is the critical step for final best operation of linear accelerators. In this paper, the electromagnetic computer simulations, RF measurement and final tuning of a nine cell periodic accelerator structure was represented. All of cavities tuned in one resonant frequency and according to theoretical concepts we obtain nine resonant modes from RF measurements by vector network analyzer.

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TUPAB045

Design and Construction of a Pre-Buncher for Iranian Low Energy Linear Accelerator

cavity, linac, simulation, coupling

1428

S. Ahmadiannamin
ILSF, Tehran, Iran
M. Bahrami, M.R. Khalvati, M. Lamehi, H. Shaker, M. Shirshekan
IPM, Tehran, Iran

Iranian IPM low energy linear accelerator project (e-Linac) is in its final steps for commissioning. Beam dynamic simulations with and without Pre-buncher prior to buncher was done. The results represent improvement in capturing efficiency better than 25% by application of Pre-buncher cavity. In this paper, we present the simulation, construction, RF measurements and vacuum test results. After construction, we measured RF reflection coefficient better than -33 dB in the nominal frequency of 2997.9 MHz with quality factor of 4500.

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TUPAB048

Long Beam Pulses With SLED Compression in DAΦNE LINAC

linac, gun, klystron, flattop

1434

P. Valente
INFN-Roma, Roma, Italy
M. Belli, B. Buonomo, R. Ceccarelli, A. Cecchinelli, R. Clementi, D.G.C. Di Giulio, L.G. Foggetta, G. Piermarini, L.A. Rossi, S. Strabioli, R. Zarlenga
INFN/LNF, Frascati (Roma), Italy

The DAΦNE LINAC is a ~60 m long, S-band (2856 MHz) linear accelerator, made up by four 45 MW klystrons with SLED compression, and by 15 travelling-wave, 2/3p, SLAC-type, 3 m long accelerating sections. It serves as injector of the DAΦNE e⁺ e⁻ collider, with 510 MeV, 10 ns long, electron and positron pulses, and the Beam-Test Facility extraction line, with variable beam energy and intensity and with pulses from 1.5 to 40 ns. A new pulsing system for the gun allows longer beam pulses, but the shape of the accelerating field in the sections due to the SLED compression has to be taken into account. We describe the tuning of the RF power, phase and delays in the pre-buncher, buncher and following accelerating sections, and the results of the tests performed in order to reach >200 ns 500 MeV electron pulses and the characterization of the quality of the beam in terms of energy spread, time distribution, etc.

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TUPAB049

Development of the High Power Terahertz Light Sources at LEBRA Linac in Nihon University

target, radiation, FEL, linac

1437

T. Sakai, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Tanaka
LEBRA, Funabashi, Japan
H. Ogawa, N. Sei
AIST, Tsukuba, Ibaraki, Japan

Funding: This work was supported by JSPS KAKENHI (Grant-in-Aid for Young Scientists (B)) Grant Number JP16K17539.
Development of a THz light source has been underway at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University in collaboration with National Institute of Advanced Industrial Science and Technology (AIST) since 2011. Basic research on coherent transition radiation (CTR) in the THz region has been carried out using the Parametric X-ray Radiation (PXR)-beam line of LEBRA. Since fiscal year 2016, the THz transport line has been constructed on the same axis as the PXR beam line taking the construction cost and simultaneous use of the two beams into account. Basic measurement and intensity upgrading test have been carried out for the THz lights generated on the PXR-generating electron beam line. The average intensity of the THz lights obtained at the output port in the accelerator room has been 5 mW. Construction of the THz transport beam line and the property of the THz lights is discussed in the report.

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TUPAB050

A Lifetime Study of CsK2Sb Multi-Alkali Cathode

cathode, laser, vacuum, experiment

1440

M. Kuriki, L. Guo, M. Urano, A. Yokota
HU/AdSM, Higashi-Hiroshima, Japan
K. Negishi
Iwate University, Morioka, Iwate, Japan
Y. Seimiya
KEK, Ibaraki, Japan

Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science, and Technology, entitled High Brightness Photon Beam by Laser Compton Scattering and Cooperative supporting Program for Research Education in University by KEK(High Energy Accelerator Research Organization)
\rm CsK₂Sb is a high performance photo-cathode for accelerators requiring the high brightness electron beam. It can be driven by a green laser generated as SHG of a solid state laser. The quantum efficiency is as high as 10\%. In this article, the robustness of the cathode was studied experimentally. We found that 1/e lifetime of the cathode was inversely proportional to the vacuum pressure. The normalized temporal life was \rm (4.72± 0.08)× 10^-5~Pa.hour for 532 nm laser. The lifetime regarding to the extracted charge density was also inversely proportional to the vacuum pressure. The normalized charge life was \rm (1.19± 0.03± 0.04)× 10^-4 Pa.C/mm². The cathode is robust enough for a high brightness electron accelerator.

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TUPAB051

Substrate Dependence of CsK2Sb Cathode Performance

cathode, laser, experiment, lattice

1443

M. Kuriki, L. Guo, M. Urano, A. Yokota
HU/AdSM, Higashi-Hiroshima, Japan
K. Negishi
Iwate University, Morioka, Iwate, Japan
Y. Seimiya
KEK, Ibaraki, Japan

Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science, and Technology, entitled High Brightness Photon Beam by Laser Compton Scattering and Cooperative supporting Program for Research and education in University by KEK(High Energy Accelerator Research Organization).
\rm CsK₂Sb is a high performance cathode which can be driven with a green laser. The cathode is generated by evaporation on a substrate in a high vacuum environment. The cathode was evaporated on various material and surface condition to evaluate the dependence of the cathode performance. GaAs (100), Si(100), and Si(111) were examined as samples of the substrate. For each materials, the cathode on the cleaned and as-received substrates were examined and those on the cleaned showed better performance than the as-received for all materials. The detail of the experimental results are presented.

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TUPAB053

Proof-of-Principle Experiment of Phase-Combined Undulator

undulator, permanent-magnet, experiment, gun

1446

R. Kinjo, T. Tanaka
RIKEN SPring-8 Center, Hyogo, Japan
A. Kagamihata
JASRI/SPring-8, Hyogo, Japan

A huge attractive force is the largest concern in designing a mechanical structure of undulators, in which an accurate control and high uniformity of the gap between the upper and lower magnetic girders are required. This problem is especially serious for in-vacuum undulators, in which the girders are located inside the vacuum chamber. We have proposed a new concept called a phase-combined undulator, which has intrinsically no magnetic force*. In this undulator, the magnetic forces acting on the girders locally head to the longitudinal axis instead of the attractive direction, and are actually canceled out in total. Numerical calculations have shown that the attractive force will be reduced down to a negligible level. Recently, we performed a proof-of-principle experiment to examine the feasibility of this undulator concept in terms of the force between the girders and magnetic field distribution, which will be reported in the conference.
* R. Kinjo and T. Tanaka, Phys. Rev. ST Accel. Beams 17, 122401

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TUPAB056

New Achievements of the Laser System for RF-Gun at SuperKEKB Injector

laser, operation, gun, experiment

1452

R. Zhang, T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
KEK, Ibaraki, Japan

For realizing high charge and low emittance electron and positron beams in SuperKEKB, we have been making improvements in current laser system for RF-gun. In order to realize more excellent thermal management in current laser system at high repetition rate operation, novel soldering Yb:YAG thin disk and copper tungsten heat sink laser head is manufactured via gold tin solder. Comparing with old design, less residual stress is introduced and more efficient thermal removal can be obtained. These new soldering laser heads are placed into a compact vacuum chamber and cooled by Peltier plates directly. This design can realize higher gain and amplification factor in regenerative amplifier and multi-pass amplifier. In addition, the compact and simple cooling method can achieve excellent thermal management for the purpose of realize laser operation at high repetition rate for following phases of SuperKEKB project. A perspective towards the next step experiment is also presented in this paper.

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TUPAB059

Study on CsKSb Photocathode for the RF Electron Gun

cathode, gun, cavity, laser

1456

H. Ono, J. Miyamatsu, M. Washio
Waseda University, Tokyo, Japan
H. Iijima
Tokyo University of Science, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan

At Waseda University, we have been developing a Cs-Te photocathode S-band RF electron gun and application experiments of the electron beam. On the experiments, charge amount is important factor, which strongly depends on laser power and photocathode quality. At present, we are studying CsKSb photocathode to increase the charge amount of an electron beam generated from the RF-Gun. As a result of using CsKSb photocathode in the RF-cavity, we obtained as much charge as using Cs-Te photocathode but the lifetime was shorter than that of Cs-Te. In order to lengthen the photocathode lifetime, we tried to coat a protective film on CsKSb photocathode surface and investigated its robustness for poor vacuum condition that simulates cathode transportation and usage in the RF-Gun. In this conference, we report current status of fabricating coated photocathode and future prospects.
A. Buzulutskov et al. The protection of K-Cs-Sb photocathodes with CsBr films Nuclear Instruments and Methods in Physics Research A 400 (1997) 173-176

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TUPAB060

Development of the Laser System for the Proof-of-Principle Experiment of Crab Crossing Laser-Compton Scattering

laser, scattering, experiment, luminosity

1460

T. Takahashi, D. Igarashi, Y. Koshiba, S. Ota, M. Washio
RISE, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

An X-ray source via laser-Compton scattering has the advantage of small source, energy tunability and quasi-monochromaticity and is expected to be applied in a wide range of fields such as the industry and medical care. In laser-Compton scattering, the luminosity, which represents the collision frequency between the electrons and the photons, is very important. Increasing the luminosity is strongly required for increasing the scattered photon flux. One way to increase the luminosity is tilting electron bunches at the collision point, which is called crab crossing. It is the way to create the head-on collision artificially. The purpose of this study is the proof-of-principle of the crab crossing laser-Compton scattering. In this conference, we will report the design optimization and construction of the laser system for the collision and future prospects.
Variola Alessandro, et al. Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators. Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.

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TUPAB067

Studies of Beam Lifetime at HEPS

scattering, lattice, storage-ring, photon

1478

S.K. Tian, Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China

The electron storage ring's beam lifetime is determined by scattering of the electrons at the nucleus and the shell of the atoms of the residual gas (gas lifetime) and the scattering of electrons within a bunch (Touschek lifetime).Beam lifetime studies have been performed at the 6 GeV electron storage ring HEPS.

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TUPAB070

S-Band Accelerating Structure for High-Gradient Upgrade of TTX

impedance, simulation, accelerating-gradient, linac

1485

D.Z. Cao, H.B. Chen, Y.-C. Du, W. Gai, W.-H. Huang, X.C. Meng, J. Shi, C.-X. Tang, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

Thomson scattering x-ray source is an indispensable scientific X-ray imaging tool in various research fields. The 3-meter S-band linac in Tsinghua Thomson scatter-ing X-ray source (TTX) has been running at an accelerat-ing gradient of 15 MV/m so far. The gradient will be upgraded to 30MV/m by replacing the old structure with a shorter linac. Detailed optimization of the RF design of the new S-band linac structure is presented in this paper. Finally, further research on energy upgrade with X-band structures are also discussed.

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TUPAB071

Experimental Results on THz Superradiation From the Undulator in Tsinghua University Beamline

radiation, undulator, detector, experiment

1488

X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan
TUB, Beijing, People's Republic of China
Y.F. Liang
Tsinghua University, Beijing, People's Republic of China

In this paper, the first operation of a widely tunable 8-period undulator at terahertz (THz) frequency in Tsinghua University beamline was reported. Superradiate undulator radiation from sub-picosecond electron bunches compressed by chicane was observed. The measured radiation curve shows clearly that the radiation energy is proportional to the charge square, and the THz frequency can be changed from 0.4 THz to 10 THz with narrow-band spectrums. Our results demonstrate a high power and tunable coherent THz source, which could be useful for many applications in the future.

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TUPAB074

Measurements of Thermal Emittance for Cesium Telluride Photocathodes in an L-Band RF Gun

laser, emittance, gun, cathode

1491

L.M. Zheng, W. Gai, C.-X. Tang
TUB, Beijing, People's Republic of China
W. Gai, C.-J. Jing, W. Liu, N.R. Neveu, J.G. Power, J.H. Shao, E.E. Wisniewski
ANL, Argonne, Illinois, USA
W. Liu
Euclid TechLabs, LLC, Solon, Ohio, USA

The thermal emittance is a major contributor to the final emittance of an electron beam in a photocathode RF gun. In this paper we present measurement results of thermal emittance for the cesium telluride photocathode at the Argonne Wakefield Accelerator (AWA) facility using the quadrupole scan method. Measurements of the thermal emittance vs. the laser spot size are presented.

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TUPAB075

Compact High Energy Electron Radiography System Based on Permanent Magnet Quadrupole

quadrupole, target, experiment, permanent-magnet

1494

Z. Zhou, Y.-C. Du, W. Gai, W.-H. Huang, F. Li, T. Rui, C.-X. Tang
TUB, Beijing, People's Republic of China
W. Gai
ANL, Argonne, Illinois, USA

High energy electron radiography(HEER) is a promising diagnostic method for High Energy Density Physics (HEDP) or Inertial Confinement Fusion (ICF) owing to its capability of picosecond-nanometer spatio-temporal resolution, and is cost-effective in the meantime. A Compact HEER (CHEER) system based on Permanent Magnet Quadrupoles (PMQ) instead of conventional electromagnetic quadrupole is proposed. Its lattice design and beam optics optimization is finished, and experiment is to be carried out on Tsinghua Thomson X-ray source (TTX) beamline after PMQs fabrication and installation.

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TUPAB077

A Combined THz/X-ray Source Based on Brake-applied Velocity Bunching and Magnetic Compression

radiation, bunching, emittance, laser

1500

R. Huang, Z.G. He, Q.K. Jia, B. Li, W.W. Li, L. Wang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by Chinese Universities Scientific Fund under Contracts WK2310000063 and WK2310000047
Ultrashort electron beam can be realized by the process of velocity bunching and magnetic compression. Velocity bunching technique is able to compress the bunch at relatively low energy, which presents peculiar challenges when approaching a very high current and a low transverse emittance in photoinjectors. A brake-applied velocity bunching scheme was proposed, so that the transverse emittance of the beam could be almost compensated even if the compression factor was extremely high. By adding a magnetic compressor, one could obtain a shorter beam and achieve the coherent synchrotron radiation in THz range. Meanwhile, when making the final compressed beam collide with the laser, one could acquire high energy X-ray pulses. This opens the possibility for some interesting combinations of pump-and-probe experiments.

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TUPAB082

Research of L-Band Disk-Loaded Waveguides Travelling Wave Accelerating Structures for a High Power Linac

cavity, bunching, network, impedance

1506

Y.M. Zhang
USTC, SNST, Anhui, People's Republic of China
Y.J. Pei, L.S. Sheng, Y. Song
USTC/NSRL, Hefei, Anhui, People's Republic of China

L-band Electron Accelerator is widely used for industrial irradiation. This paper describes a constant-impedance, disk-loaded structure operating on the 2Pi/3 mode. The design details of L-band travelling wave accelerating structures are presented. All RF parameters in metal disk-loaded waveguides and fields were calculated. The SUPERFISH code was used to design the bunching and accelerating cavities. At the same time, we also calculated the beam dynamics. Some model cavities have been fabricated and experimental studies were carried on. In this study, some valuable results were obtained, which can provide a beneficial datum for the design and manufacture of L-band travelling-wave accelerating structures of 50MeV LINAC.

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TUPAB086

Design Study of a High-Intensity, Low-Energy Electron Gun

gun, simulation, emittance, FEL

1517

Q. Zhang, K. Fan, T. Hu, K.F. Liu, Z.Y. Mei
HUST, Wuhan, People's Republic of China

An independently-tunable-cells thermionic RF gun (ITC-RF gun) is adopted in a compact FEL-THz facility due to its compactness, low-cost and high intensity. An electron gun is required to generate maximum beam current of 3.2 A at low energy of 15keV for the ITC-RF gun, which creates difficulties for the design of electron gun because of the strong space charge effect. A double-anode gridded gun structure is adopted that controls the beam current easily while maintains the energy dispersion less than 0.5%, with high perveance and high compression ratio. CST code has been used extensively for design optimization, which includes electrode shape, influences of grid, installation errors. A measurement scheme is also proposed for key parameters verification. Beam current, emittance and energy dispersion can be measured.

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TUPAB087

Undulator Commissioning Experience at PAL-XFEL

undulator, background, radiation, site

1520

D.E. Kim, Y.G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, K.-H. Park, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
J. Pflüger
XFEL. EU, Hamburg, Germany

Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator while soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. In this report, the final measurement results of all the undulators, phase matching scheme, and the commissioning experiences will be summarized.

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TUPAB088

Wire Position System to Consistently Measure and Record the Location Change of Girders Following Ground Changes

alignment, undulator, power-supply, electronics

1523

H. J. Choi, S.Y. Baek, H.-S. Kang, S.H. Kim, H.-G. Lee, S.B. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

Several parts that comprise the large scientific device should be installed and operated at the accurate three-dimensional location coordinates where they should be subjected to survey and alignment. The location of the aligned parts should not be changed in order to ensure that the electron beam parameters of PAL-XFEL remain stable and can be operated without any problems. As time goes by, however, the ground goes through uplift and subsidence, which consequently deforms building floors. The deformation of the ground and buildings changes the location of several devices including magnets and RF accelerator tubes, which eventually leads to the alignment errors. Once alignment errors occur with regard to these parts, the electron beam deviates from its course and beam parameters change accordingly. PAL-XFEL has installed the Hydrostatic Leveling System to measure and record the vertical change of buildings and ground consistently and systematically and the Wire Position System to measure the two dimensional changes of girders. This paper is designed to introduce the operating principle and design concept of WPS and discuss the current situation regarding installation and operation.

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TUPAB093

Race-Track Microtron with Pulse-to-Pulse Beam Energy Switch

linac, microtron, extraction, focusing

1530

Yu.A. Kubyshin
UPC, Barcelona, Spain
V.I. Shvedunov, I.Yu. Vladimirov
LEA MSU, Moscow, Russia
V.I. Shvedunov
SINP MSU, Moscow, Russia

A race-track microtron with a few beam orbits can be an alternative to a standard electron linear accelerator in a number of applications in which high beam power is not needed, like radiation therapy, industrial radiography or cargo inspection. In these cases the advantages of race-track microtrons are low RF power consumption, and consequently low cost of the RF system, and a possibility of beam energy switch in a wide range by extracting the beam from different orbits. In the present work we describe the concept of a race-track microtron with pulse-to-pulse beam energy switch in the range from 3 MeV to 9 MeV. Special attention is given to the optimization of the end magnets of a new type which provide both the accelerating structure bypass and vertical beam focusing.

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TUPAB096

Pulse Shaping at the MAX IV Photoelectron Gun Laser

laser, gun, emittance, cathode

1541

M. Kotur, J. Andersson, M. Brandin, F. Curbis, L. Isaksson, D. Kumbaro, F. Lindau, E. Mansten, D. Olsson, R. Svärd, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden
J. Björklund Svensson
Lund University, Lund, Sweden

A motivation for the development of a versatile, programmable source of shaped picosecond pulses for use in photocathode electron gun preinjectors is presented. We present the experimental setup for arbitrary longitudinal pusle shaping of the MAX IV photocathode gun laser. The setup consists of a grating-based Fourier-domain shaper capable of stretching the pulses directly in the UV domain. Preliminary results are presented and discussed.

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TUPAB102

Compact Electron RF Travelling Wave Gun Photo Injector

gun, cathode, laser, solenoid

1550

R. Zennaro, P. Craievich, C.P. Hauri, L. Stingelin, A. Trisorio, C. Vicario
PSI, Villigen PSI, Switzerland

This paper reports on studies of a travelling wave photo gun as multipurpose device. The gun would be a cheap and compact alternative to thermionic guns with a bunching system or a standing wave photo injector gun. It allows one to reach much larger beam energies at the gun output. It can provide a beam with energy of up to 50 MeV and several hundred pC charge with low emittance and short bunch length. The laser system is a compact, industrial grade system with high MTBF and low maintenance cost. The gun design is based on the two-meter accelerating structures installed in SwissFEL, only the input coupler has been modified to accommodate the cathode. The gun is powered by a C-band (5.712 GHz) modulator-klystron system, identical to those of SwissFEL. The input coupler is a simple double feed coupler and it has been designed to increase the electric field enhancement at the cathode surface to improve the emittance. The first three accelerating cells have been readjusted in length in order to get the proper phase advance and synchronism with the beam. The remaining 110 accelerating cells and the output coupler follows the original design of the accelerating cavities for SwissFEL.

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TUPAB103

Orbit Correction With Path Length Compensation Based on Rf Frequency Adjusments in TPS

operation, feedback, site, photon

1553

P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.-C. Kuo, C.C. Liang, Y.-C. Liu, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

The 3 GeV Taiwan Photon Source has been routinely operated for public users since September 2016. Orbit reproducibility and stability are critical for the quality of user experiments. Ambient temperature variations and earth tides can cause a change in circumference, changing in turn the beam energy, and orbit drift. Therefore both, orbit correction and rf frequency adjustments are necessary to keep the ring circumference constant. A Fast Orbit Feedback (FOFB) system combined with rf frequency correction deduced from the fast corrector strengths is applied to the FOFB routine. The correlation between the measured frequency variation with ambient temperature and earth tides is also reported in this article.

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TUPAB110

Possible Limits of Plasma Linear Colliders

plasma, scattering, emittance, collider

1576

F. Zimmermann
CERN, Geneva, Switzerland

Plasma linear colliders have been proposed as next or next-next generation energy-frontier machines for high-energy physics. I investigate possible fundamental limits on energy and luminosity of such type of colliders, considering acceleration, multiple scattering off plasma ions, intrabeam scattering, bremsstrahlung, and betatron radiation. The question of energy efficiency will also be addressed.

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TUPAB111

Energy Distribution and Work Function Measurements for Metal Photocathodes with Measured Levels of Surface Roughness

emittance, FEL, detector, plasma

1580

L.B. Jones, T.S. Beaver, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S. Mistry
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
S. Mistry
Loughborough University, Leicestershre, United Kingdom

Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453.
The minimum achievable emittance in an electron accelerator depends strongly on the intrinsic emittance of the photocathode electron source which is measureable as the mean longitudinal and transverse energy spreads in the photoemitted electrons. Reducing emittance in an accelerator driving a Free Electron Laser (FEL) delivers significant reduction in the saturation length for an x-ray FEL, reducing machine cost and increasing x-ray beam brightness. There are many parameters which affect the intrinsic emittance of a photocathode. Surface roughness is a significant factor*, and consequently the development of techniques to manufacture low roughness photocathodes with optimum emission properties is a priority for the electron source community. In this work, we present transverse energy distribution and work function measurements made using our TESS facility** for electrons emitted from copper and molybdenum photocathodes with differing levels of measured surface roughness.
* Proc. FEL '06, THPPH013, 583-586
** Proc. FEL '13, TUPPS033, 290-293

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TUPAB114

Design Study for a Plasma Undulator Experiment Using Capillary Based Discharge Plasma Source

laser, plasma, undulator, experiment

1584

O. Mete Apsimon, R. Apsimon, Y. Ma, D. Seipt, M.J.V. Streeter, A.G.R. Thomas
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom

A plasma undulator is formed when a short laser pulse is injected into plasma off-axis or at an angle that causes the centroid of this laser pulse to oscillate. Ponderomotively driven plasma wake will follow this centroid given that the product of the plasma wave number and the characteristic Rayleigh length of the laser is much larger than one. This oscillating transverse wakefield may work as an undulator forcing particles to follow sinusoidal trajectories and emit synchrotron radiation. In this paper, plans for an experiment are introduced and resulting radiation and injected beam characteristics are discussed. The aforementioned laser centroid oscillations are demonstrated using, EPOCH, a PIC code for laser-plasma interactions.

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TUPAB115

Impact of Electron Beam Heating on Insertion Devices at Diamond Light Source

wiggler, cryogenics, insertion-device, insertion

1588

E.C.M. Rial, Z. Patel
DLS, Oxfordshire, United Kingdom

Electron beam heating is a widely observed phenomenon at synchrotron facilities around the world, and has a large impact particularly on cryogenic insertion devices, but also on room temperature devices. This paper seeks to outline electron beam heating measurements taken at Diamond Light Source (DLS) and produces an empirical heat load relationship that matches the form of heating through the anomalous skin effect, although gives an order of magnitude higher than that predicted by theory. Resistive wall heating should vary inversely with the gap of installed cryogenic and permanent magnet insertion devices. This is also examined in this paper and the results presented.

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TUPAB123

Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project

undulator, linac, photon, FEL

1605

M. Leitner, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, M. Hoyt, D.E. Humphries, D. Jacobs, C. Joiner, J.-Y. Jung, D. Leitner, S. Marks, K.A. McCombs, D.V. Munson, K.L. Ray, D.A. Sadlier, J.J. Savino, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund
LBNL, Berkeley, California, USA
C.J. Andrews, D.E. Bruch, A.L. Callen, G. Janša, S. Jansson, K.R. Lauer, Yu.I. Levashov, D.S. Martinez-Galarce, B.D. McKee, H.-D. Nuhn, Â. Oven, M. Rowen, Z.R. Wolf
SLAC, Menlo Park, California, USA

Funding: Work supported by the Director Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a free-electron laser (FEL) which will deliver x-rays at an energy range between 0.2 keV and 5 keV at high repetition rate of up to ~1 MHz using a new 4 GeV superconducting RF linac, and at and an energy range between 1 keV and 25 keV when driven by an existing copper linac at up to 120 Hz repetition rate. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. Lawrence Berkeley National Laboratory is responsible for fabricating the 53 undulator segments. This paper summarizes the main parameters and design attributes for both LCLS-II undulator segment types.

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TUPAB126

Multi-objective Genetic Optimization of Single Shot Ultrafast Electron Diffraction Beamlines

gun, emittance, cathode, cavity

1615

C.M. Gulliford, A.C. Bartnik, I.V. Bazarov
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.M. Maxson
UCLA, Los Angeles, California, USA

We present the results of multi-objective genetic algorithm optimizations of two single-shot ultrafast electron diffraction (UED) beam lines. The first is based on a 225 kV dc gun featuring a novel cryocooled photocathode system and buncher cavity. The second uses a 100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2 Pi/3 bunching cavity placed between two solenoids. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed. These results demonstrate the viability of the approaches taken for both beamlines studied as well as the use of using genetic algorithms in the design and operation of UED beamlines.

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TUPAB127

A Cryogenically Cooled High Voltage DC Photogun

gun, cryogenics, vacuum, cathode

1618

H. Lee, I.V. Bazarov, L. Cultrera
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A DC high voltage photogun with cryogenically cooling of the electrode has been newly built at Cornell University. This gun is designed to provide a DC high voltage and a photocathode in this gun can be cooled down to a cryogenic temperature. A photocathode puck design from INFN/DESY/LBNL is used, so we will be able to run a photocathode from other institutions as well. This paper describes the mechanical, thermal, and high voltage design of this gun. We also present data of high voltage conditioning and the thermal profile along the electrode structure.

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TUPAB128

Single Photoemitter Tips in a DC Gun: Limiting Aberration-induced Emittance

emittance, cathode, laser, cryogenics

1622

I.V. Bazarov, L. Cultrera, C.M. Gulliford, H. Lee
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
H.K. Fung
Cornell University, Ithaca, New York, USA
J.M. Maxson
UCLA, Los Angeles, California, USA

Ultrafast electron diffraction (UED) offers unique advantages over x-ray diffraction, like stronger scattering cross-section, versatility in sample types and ability to offer smaller apparatus foot print. There is a growing need to increase brightness of electron beams especially for single-shot UED applications. We explore the utilization of field enhancement from a micron-scale single tip inside a DC gun to obtain brighter sub-pC electron beams using a nominal cathode electric field of several MV/m. The additional field enhancement can place moderate voltage sources on par with the highest gradient devices and allow improved performance presently not possible in the existing photoemission guns.

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TUPAB129

Optimization of Beam Dynamics for an S-Band Ultra-High Gradient Photoinjector

brightness, gun, emittance, cathode

1626

A.D. Cahill, A. Fukasawa, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
C. Limborg, W. Qin
SLAC, Menlo Park, California, USA

Funding: Work Supported by DOE/SU Contract DE-AC02-76-SF00515, US NSF Award PHY-1549132, the Center for Bright Beams, and DOE SCGSR Fellowship. Travel to IPAC'17 supported by the Div. of Phys. of the US NSF (Accel. Sci. Prog.) and the Div. of Beam Phys. of the APS
New electron sources with improved brightness are desired to enhance the capabilities of FELs, making them more compact and fully coherent. Improvements in electron source brightness can be achieved by increasing electric fields on the cathode of photo-emitted electron guns. Recent developments in pulsed RF accelerator structures show that very high gradient fields can be sustained with low breakdown rates by operating at cryo-temperatures, which when applied to photoguns will lead to a large increase in the electron beam brightness. In particular, our simulations show that when operating with a peak gradient field of 240 MV/m on the cathode of an S-band, electron beam brightness of 80~nC/(mm· mrad)²/mm can be achieved with 100~pC bunches. In this paper, we present the design and optimization of an 1.x cell S-Band RF photoinjector, where the x varies from 4-6. The optimization in brightness has been obtained by using a multi-objective genetic algorithm on the solutions calculated with the ASTRA code. We calculate the optimum length of the rf gun, position of accelerating structure, and laser pulse dimensions for a variety of charges.

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TUPAB134

Life Expectancy Studies for LCLS-II Permanent Magnet Undulators

undulator, radiation, permanent-magnet, optics

1640

M. Santana-Leitner, D.E. Bruch, R.C. Field, D.S. Martinez-Galarce, B.D. McKee, H.-D. Nuhn, M. Rowen, S.W. Score
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
LCLSII at SLAC National Accelerator Laboratory will add a 4 GeV superconducting Linac to the existing 20 GeV Cu structure. Electron beams from the two sources going through two new variable gap undulators [*] will produce FEL ranging 200-5000 keV at up to 929 kHz, also reaching 20 keV at low frequency. Such performance will be achieved by hybrid design undulators with NdFeB magnet blocks until radiation-induced demagnetization exceeds 0.01%. This is a sizable challenge, as LCLS-II will carry 120 kW beams in both its soft (SXR) and hard (HXR) beam-lines. Even small fractional losses could result excessive if too frequent or not detected and aborted fast enough. A model of SXR undulator was set for FLUKA [**] radiation transport, including segments, phase-shifters, quadrupoles, RFBPM, stands/pillars and interconnecting parts. Components were installed according to MAD files, which were also used to code the optics. Beam-loss/shower propagation was simulated for beam mis-steering, interception at wire scanners and gas-bremsstrahlung interactions. Results help set limits on shut-off times, uniform loss levels and wire scanner use, and to define placement for beam loss monitors.
* M. Leitner et al, Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project, these proceedings
** A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)

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TUPAB135

A 1.75 mm Period RF-Driven Undulator

undulator, laser, FEL, cavity

1643

F. Toufexis, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
To reduce the linac energy, and hence the size required for a Free Electron Laser radiating at a given wavelength, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling* the electromagnetic fields while maintaining over-moded features for power handling capability and electron beam wakefield mitigation. In this work, we present a novel end section of an RF undulator at 91.392 GHz. To confine the fields inside the undulator, a corrugated waveguide is connected through a matching section to a linear taper and a mirror. After the mirror, a Bragg reflector and a matching section are used to reflect back all the fields leaking out of the mirror opening.
* F. Toufexis, J. Neilson, and S.G. Tantawi, Coupling and Polarization Control in a mm-wave Undulator, these proceedings.

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TUPAB136

Coupling and Polarization Control in a mm-wave Undulator

undulator, polarization, coupling, controls

1647

F. Toufexis, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling the electromagnetic fields while maintaining overmoded features for power handling capability and electron beam wakefield mitigation. We have designed a mm-wave undulator cavity at 91.392 GHz*. This undulator requires approximately 1.4 MW for sub-microsecond pulses to generate an equivalent K value of 0.1. Transferring such amounts of power in mm-wave frequencies requires overmoded corrugated waveguides, and coupling through irises creates excessive pulsed heating. We have designed a novel mode launcher that allows coupling power from a highly overmoded corrugated waveguide to the undulator through the beam pipe. Additionally, this mode launcher can be used along with grating polarizers to control the polarization of the produced light.
* F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.

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TUPAB137

Evaluation of FEL Performance with a Longer Injector Drive Laser Pulse at the LCLS

laser, emittance, FEL, simulation

1651

F. Zhou, Y. Ding, J.P. Duris, S. Gilevich, P. Hering, S. Vetter
SLAC, Menlo Park, California, USA

Funding: US DOE under grant No. DE-AC02-76SF00515.
It is known that the X-ray Free Electron Laser (FEL) performance strongly depends on the beam emittance and peak current. Lengthening injector laser pulse can improve the injector emittance but the injector peak current is notably compromised, in comparison to nominal laser pulse. With this longer laser pulse, a stronger bunch compression through downstream bunch compressors is thus required to keep same final peak current as the nominal laser pulse mode. This process may cause stronger micro-bunching effect. At the LCLS, we perform preliminary experiments with doubling injector laser pulse. In this paper, we present the experimental results of the injector emittance, microbunching effects and FEL performance with the longer drive laser pulse.

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TUPAB140

Analysis and Correction of in-Vacuum Undulator Misalignment Effects in a Storage Ring Synchrotron Radiation Source

undulator, alignment, radiation, storage-ring

1663

O.V. Chubar, T.A. Caswell, Y. Chen-Wiegart, A. Fluerasu, Y. Hidaka, D.A. Hidas, C.A. Kitegi, M.S. Rakitin, T. Tanabe, J. Thieme, L. Wiegart, G. Williams
BNL, Upton, Long Island, New York, USA

Funding: Work was partially supported by US DOE SBIR grants DE-SC0006284 and DE-SC0011237.
In-vacuum undulators (IVU) are currently very extensively used at different light source facilities, and in particular in medium-energy storage rings, for the production of high-brightness and high-flux hard X-rays. The relatively small (~5 mm or less) vertical magnetic gaps used in these planar undulators make them, however, rather sensitive to the accuracy of alignment of magnet arrays with respect to electron orbit in the vertical plane. Based on results of commissioning of a number of IVUs at hard X-ray beamlines of NSLS-II, their eventual misalignment with respect to the electron orbit was found to be among frequent reasons of spectral underperformance of the beamlines. We will present results of simulations of different IVU misalignment effects on magnetic fields seen by electron beam and on the emitted undulator radiation spectra. The simulations show e.g. that an impact of angular misalignment of an IVU on the radiation spectrum can be minimized if the IVU elevation is selected to make the electron orbit to pass through the IVU magnetic center. Experimental results of spectrum-based alignment of IVUs at hard X-ray beamlines will be presented.

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TUPAB142

Tracking of Electrons Created at Wrong RF Phases in the RHIC Low Energy Cooler

cathode, space-charge, cavity, laser

1666

J. Kewisch, A.V. Fedotov, D. Kayran, S. Seletskiy
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US Department of Energy under contract No. DE-SC0012704.
The RHIC Low Energy Cooler will be based on a 400 keV DC electron gun with a photo-cathode and a 2.2 MeV SRF booster cavity. Electron that leave the cathode at the wrong time may be decelerated and turned around in the booster and return to the cathode with energies up to 1 MeV. On the way back these electron will encounter the defocussing EM fields up to nine following electron bunches. Such electrons may be created for various reasons: Cosmic rays, stray laser light including a catastrophic failure of the laser timing system or as secondaries of returning electrons. We present tracking results from the GPT program* and discuss the consequences for the machine protection system.
* www.pulsar.nl

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TUPAB143

Dependence of LEReC Beam Energy Spread on Photocathode Laser Modulation

laser, space-charge, impedance, flattop

1669

S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, M.G. Minty, B. Sheehy, Z. Zhao
BNL, Upton, Long Island, New York, USA
B. Sheehy
Sheehy Scientific Consulting, Wading River, New York, USA

Present requirements to the photocathode DC gun of the low energy RHIC electron cooling (LEReC) project is to produce 100 ps long bunch of electrons with 130 pC charge. The laser pulse of required length will be produced with the stacking of multiple few picosecond long sub-pulses. Depending on the choice of the laser sub-pulse length and on the relative delay between these sub-pulses one can obtain laser pulse with various longitudinal intensity modulations. The longitudinal modulation of laser intensity creates longitudinal modulation of electron bunch charge. Such modulation is known to cause the growth of e-beam uncorrelated energy spread in photoinjectors - the effect we would like to avoid. In this paper we estimate growth of e-beam energy spread due to its initial density modulation and set requirements to the maximum allowable depth of longitudinal modulation of photocathode laser intensity.

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TUPAB145

Alignment of Electron and Ion Beam Trajectories in Non-Magnetized Electron Cooler

solenoid, alignment, ion, ISOL

1672

S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, R.J. Michnoff, I. Pinayev
BNL, Upton, Long Island, New York, USA

The cooling section (CS) of the low energy RHIC electron cooler (LEReC) consists of two 20 m long parts each containing six solenoids with trajectory correctors placed inside the solenoids and the BPMs located downstream of each solenoid. The solenoids are used to minimize the scalloping of the electron beam envelope. To obtain the cooling it is required to keep the overall RMS electron angles in the cooling section below 100 urad. Possible mechanical misalignment, such as shift and inclination of the CS solenoids can cause an unacceptable misalignment of the e-beam trajectory with respect to the ideal trajectory set by ions. Therefore, it is critical to perform a beam based alignment of the CS solenoids. In this paper we suggest a procedure for such an alignment.

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TUPIK001

Upgrade of the Two-Screen Measurement Setup in the AWAKE Experiment

proton, plasma, wakefield, experiment

1682

M. Turner
TUG/ITP, Graz, Austria
V. Clerc, I. Gorgisyan, E. Gschwendtner, S. Mazzoni, A.V. Petrenko
CERN, Geneva, Switzerland

The AWAKE project at CERN uses a self-modulated §I{400}{GeV/c} proton bunch to drive GV/m wakefields in a §I10{m} long plasma with an electron density of n_pe = 7 × 10¹⁴ \rm{electrons/cm}³. We present the upgrade of a proton beam diagnostic to indirectly prove that the bunch self-modulated by imaging defocused protons with two screens downstream the end of the plasma. The two-screen diagnostic has been installed, commissioned and tested in autumn 2016 and limitations were identified. We plan to install an upgraded diagnostics to overcome these limitations.

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TUPIK002

H-, D-, C2-: A Comparison of RF andFilament Powered Volume-Cusp Ion Sources

ion, ion-source, plasma, extraction

1685

S.V. Melanson, M.P. Dehnel, D.E. Potkins
D-Pace, Nelson, British Columbia, Canada
H.C. McDonald, C. Philpott
BSL, Auckland, New Zealand

Today's industrial ion source applications often require high beam currents with long source lifetime and low maintenance. Filament powered ion sources produce high beam currents but are limited by the short lifetime (~5000 mA*h) of the filament, while RF ion sources with external antennas do not require such maintenance. By changing the filament back plate of our TRIUMF licensed ion source to the ceramic window, planar coil antenna and 13.56 MHz RF amplifier of our University of Jyväskylä licensed ion source, we are able to directly compare the effect of the two technologies for powering sources on negative ion production in volume-cusp ion sources for the case of H-, D- and C2- using our ion source test facility.

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TUPIK003

Electron Transport on COXINEL Beam Line

laser, undulator, free-electron-laser, FEL

1688

T. André, I.A. Andriyash, F. Blache, F. Bouvet, F. Briquez, M.-E. Couprie, Y. Dietrich, J.P. Duval, M. El Ajjouri, A.M. Ghaith, C. Herbeaux, N. Hubert, M. Khojoyan, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, P. N'gotta, P. Rommeluère, K.T. Tavakoli, M. Valléau
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, C. Evain, C. Szwaj
PhLAM/CERLA, Villeneuve d'Ascq, France
S. Corde, J. Gautier, J.-P. Goddet, G. Lambert, B. Mahieu, V. Malka, S. Smartzev, C. Thaury
LOA, Palaiseau, France
E. Roussel
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

COXINEL experiment aims at demonstrating free electron laser (FEL) amplification with a laser plasma accelerator (LPA). For COXINEL, a dedicated 8 m transport line has been designed and prepared at SOLEIL. We present here LPA beam transport results around 180 MeV through this line. Different electron beam optics were applied.

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TUPIK006

FLASHForward - A Future-Oriented Wakefield-Accelerator Research and Development Facility at FLASH

plasma, laser, diagnostics, injection

1692

R.T.P. D'Arcy, A. Aschikhin, C. Behrens, S. Bohlen, J. Dale, L. Di Lucchio, M. Felber, B. Foster, L. Goldberg, J.-N. Gruse, Z. Hu, G. Indorg, S. Karstensen, O. S. Kononenko, V. Libov, K. Ludwig, A. Martinez de la Ossa, F. Marutzky, T.J. Mehrling, P. Niknejadi, J. Osterhoff, P. Pourmoussavi, M. Quast, J.-H. Röckemann, L. Schaper, H. Schlarb, B. Schmidt, S. Schröder, J.-P. Schwinkendorf, B. Sheeran, G.E. Tauscher, J. Thesinga, V. Wacker, S. Weichert, S. Wesch, S. Wunderlich, J. Zemella
DESY, Hamburg, Germany
B. Foster, T.J. Mehrling
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
A. Knetsch
University of Hamburg, Hamburg, Germany
C.A.J. Palmer, M.J.V. Streeter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Funding: Helmholtz ARD program and the VH-VI-503
FLASHForward is a beam-driven plasma wakefield acceleration facility, currently under construction at DESY (Hamburg, Germany), aiming at the stable generation of electron beams of several GeV with small energy spread and emittance. High-quality 1 GeV-class electron beams from the free-electron laser FLASH will act as the wake driver. The setup will allow studies of external injection as well as density-downramp injection. With a triangular-shaped driver beam electron energies of up to 5 GeV from a few centimeters of plasma can be anticipated. Particle-In-Cell simulations are used to assess the feasibility of each technique and to predict properties of the accelerated electron bunches. In this contribution the current status of FLASHForward, along with recent experimental developments and upcoming scientific plans, will be reviewed.

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TUPIK009

External Injection Into a Laser-Driven Plasma Accelerator With Sub-Femtosecond Timing Jitter

plasma, laser, injection, acceleration

1699

A. Ferran Pousa, R.W. Aßmann, R. Brinkmann, A. Martinez de la Ossa
DESY, Hamburg, Germany
A. Martinez de la Ossa
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

The use of external injection in plasma acceleration is attractive due to the high control over the electron beam parameters, which can be tailored to meet the plasma requirements and therefore preserve its quality during acceleration. However, using this technique requires an extremely fine synchronization between the driver and witness beams. In this paper, we present a new scheme for external injection in a laser-driven plasma accelerator that would allow, for the first time, sub-femtosecond timing jitter between laser pulse and electron beam.

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TUPIK010

Investigating the Key Parameters of a Staged Laser- and Particle Driven Plasma Wakefield Accelerator Experiment

plasma, laser, wakefield, acceleration

1703

T. Heinemann, R.W. Aßmann, O. S. Kononenko, A. Martinez de la Ossa
DESY, Hamburg, Germany
J.P. Couperus, A. Irman, A. Köhler, O. Zarini
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
T. Heinemann, B. Hidding
USTRAT/SUPA, Glasgow, United Kingdom
T. Heinemann
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
A. Knetsch
University of Hamburg, Hamburg, Germany
T. Kurz
HZDR, Dresden, Germany
U. Schramm
TU Dresden, Dresden, Germany

Plasma wakefield accelerators can be driven by either a powerful laser pulse (LWFA) or a high-current charged particle beam (PWFA). A plasma accelerator combining both schemes consists of a LWFA providing an electron beam which subsequently drives a PWFA in the highly nonlinear regime. This scenario explicitly makes use of the advantages unique to each method, particularly exploiting the capabilities of PWFA schemes to provide high-brightness beams, while the LWFA stage inherently fulfils the demand for compact high-current electron bunches required as PWFA drivers. Effectively, the sub-sequent PWFA stage operates as beam brightness and energy booster of the initial LWFA output, aiming to match the demanding beam quality requirements of accelerator based light sources. We report on numerical studies towards the implementation of a proof-of-principle experiment at the DRACO laser facility at Helmholtz-Zentrum Dresden-Rossendorf (HZDR).

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TUPIK013

Improved Electron Beam Quality from External Injection in Laser-Driven Plasma Acceleration at SINBAD

plasma, laser, emittance, acceleration

1707

M.K. Weikum, R.W. Aßmann, U. Dorda, A. Ferran Pousa, T. Heinemann, B. Marchetti, E.N. Svystun, P.A. Walker
DESY, Hamburg, Germany
T. Heinemann, F.Y. Li, Z.M. Sheng, M.K. Weikum
USTRAT/SUPA, Glasgow, United Kingdom
T. Heinemann
University of Hamburg, Hamburg, Germany
Z.M. Sheng
Shanghai Jiao Tong University, Shanghai, People's Republic of China

External injection into laser wakefield accelerators is one of the possible routes towards high energy, high quality electron beams through plasma acceleration. Among other reasons this is due to the increased control over the electron beam parameters and overall experimental setup when compared to other plasma schemes, such as controlled self-injection. At the future SINBAD (Short INnovative Bunches and Accelerators at DESY) facility at DESY this technique is planned to be tested experimentally through injection and acceleration of a sub-femtosecond electron beam, produced from a conventional RF-injector, with a charge of around 0.7 pC and initial mean energy of 100 MeV at the plasma entrance. A summary of optimisation steps for the potential experimental setup is presented in this paper, including considerations regarding effects of electron beam self-fields and matching of the beam into the plasma stage. The discussion is complemented by first start-to-end simulations of the plasma accelerator setup based on these findings.

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TUPIK017

Next Generation Plasma Cell for PWFA Experiments at PITZ

plasma, laser, experiment, Windows

1715

O. Lishilin, J. Engel, M. Groß, G. Koss, G. Loisch, S. Philipp, R. Schütze, F. Stephan
DESY Zeuthen, Zeuthen, Germany
R. Brinkmann
DESY, Hamburg, Germany
F.J. Grüner
Center for Free-Electron Laser Science, Universität Hamburg, Hamburg, Germany
D. Richter
HZB, Berlin, Germany
C.B. Schroeder
LBNL, Berkeley, California, USA

A proof-of-principle experiment for the AWAKE experiment is ongoing at the Photo-Injector Test Facility at DESY, Zeuthen site (PITZ). The goal of the experiment is to observe and measure the energy and density self-modulation of a long electron beam passing through a laser-generated Lithium plasma*. Key devices of the experiment are a heat pipe based plasma cell, a photocathode laser system which enables production of long electron beams with sharp rising edges and well-developed diagnostics at PITZ, including a transverse deflecting cavity and a high-resolution electron spectrometer. In this report we present the current status of the experiment, including the latest updates of the experimental setup. The plasma cell is a lithium heat pipe oven with inert gas buffers at all input/output ports. An ArF ionization laser is coupled through side ports. Main improvements of the second generation plasma cell are an altered geometry of side arms and a new heat pipe design. Among other updates are an improved ArF laser beamline and new electron windows. We present here measurements of plasma density and homogeneity as well as results of beam transport studies for the experiment.
*O. Lishilin, M. Gross, et al., Â«First results of the plasma wakefield acceleration experiment at PITZÂ», NIM A, Volume 829, 1 September 2016, Pages 37-42, http://dx.doi.org/10.1016/j.nima.2016.01.005

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TUPIK020

Application of Optical Emission Spectroscopy to High Current Proton Sources

plasma, proton, ion, diagnostics

1721

G. Castro, L. Celona, S. Gammino, O. Leonardi, D. Mascali, M. Mazzaglia, E. Naselli, L. Neri, D. Nicolosi, R. Reitano, G. Torrisi
INFN/LNS, Catania, Italy
F. Leone
INAF-OACT, Catania, Italy
M. Mazzaglia, R. Reitano
Universita Degli Studi Di Catania, Catania, Italy
E. Naselli
Catania University, Catania, Italy
B. Zaniol
Consorzio RFX, Padova, Italy

Optical Emission Spectroscopy (OES) represents a very reliable technique to carry out non-invasive measurements of plasma density and plasma temperature in the range of tens of eV. Instead of other diagnostics, it also allows to characterize the different populations of neutrals and ionized particles constituting the plasma. At INFN-LNS, OES techniques have been developed and applied to characterize the plasma generated by the Flexible Plasma Trap, an ion source used as testbench of the proton source built for European Spallation Source. This work presents the characterization of the parameters of a hydrogen plasma in different conditions of neutral pressure, microwave power and magnetic field profile along with the perspectives for further upgrades of the OES diagnostics system.

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TUPIK022

Innovative Single-Shot Diagnostics for Electrons From Laser Wakefield Acceleration at FLAME

laser, target, acceleration, emittance

1727

F.G. Bisesto, M.P. Anania, E. Chiadroni, A. Curcio, M. Ferrario, R. Pompili
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
A. Zigler
The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel

Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV/m), enabling acceleration of electrons to GeV energy in few centimeters. Here we present all the plasma related activities currently underway at SPARC_LAB exploiting the high power laser FLAME. In particular, we will give an overview of the single shot diagnostics employed: Electro Optic Sampling (EOS) for temporal measurement and optical transition radiation (OTR) for an innovative one shot emittance measurements. In detail, the EOS technique has been employed to measure for the first time the longitudinal profile of electric field of fast electrons escaping from a solid target, driving the ions and protons acceleration, and to study the impact of using different target shapes. Moreover, a novel scheme for one shot emittance measurements based on OTR, developed and tested at SPARC_LAB LINAC, used in an experiment on electrons from laser wakefield acceleration still undergoing, will be shown.

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TUPIK023

Gas-filled Capillaries for Plasma-Based Accelerators

plasma, acceleration, laser, background

1731

F. Filippi
INFN-Roma, Roma, Italy
M.P. Anania, A. Biagioni, E. Brentegani, E. Chiadroni, M. Ferrario, R. Pompili, S. Romeo
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
INFN-Roma II, Roma, Italy
A. Zigler
The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel

Plasma Wakefield Accelerators are based on the excitation of large amplitude plasma waves excited by either a laser or a particle driver beam. The amplitude of the waves, as well as their spatial dimensions and the consequent accelerating gradient depend strongly on the background electron density along the path of the accelerated particles. The process needs stable and reliable plasma sources, whose density profile must be controlled and properly engineered to ensure the appropriate accelerating mechanism. Plasma confinement inside gas filled capillaries have been studied in the past since this technique allows to control the evolution of the plasma, ensuring a stable and repeatable plasma density distribution during the interaction with the drivers. Moreover, in a gas filled capillary plasma can be pre-ionized by a current discharge to avoid ionization losses. Different capillary geometries have been studied to allow the proper temporal and spatial evolution of the plasma along the acceleration length. Results of this analysis obtained by varying the length and the number of gas inlets will be presented.

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TUPIK030

Characterization of the AMIT Internal Ion Source With a Devoted DC Extraction Test Bench

ion, ion-source, cathode, cyclotron

1740

D. Obradors-Campos, M.B. Ahedo, J.M. Barcala, J. Calero, P. Calvo, M.A. Domínguez, E.F. Estévez, J.M. Figarola, L. García-Tabarés, D. Gavela, P. Gómez, A. Guirao, J.L. Gutiérrez, J.I. Lagares, D. López, L.M. Martínez, J. Munilla, C. Oliver, J.M. Pérez Morales, I. Podadera, E. RodrÃguez GarcÃa, F. Toral, R. Varela, C. Vázquez
CIEMAT, Madrid, Spain
R. Iturbe, B. López
ANTEC Magnets SLU, Vizcaya, Spain

Funding: Work partially funded under the Resolution of the Spanish Ministery of Economy, Industry and Competitiveness dated May 24 th, 2016 and project FIS2013-40860-R
With the main aim of a compact machine for 18F and 11C radioisotope production, AMIT cyclotron relies on a superconducting 4T magnet with an internal cold cathode PIG ion source for H⁻ production. Given the limited access to the ion source in the cyclotron as well the reduced number of beam diagnostics, an experimental facility was proposed for the commissioning of such ion source. The versatility of this test bench, which includes a movable puller, gives us the opportunity to validate and characterize the ion source behavior as well as to optimize the H⁻ production. In a first stage, the discharge characteristics of the ion source has been studied in the CIEMAT IST facilities.

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TUPIK031

Driver-Witness-Bunches for Plasma-Wakefield Acceleration at the MAX IV Linear Accelerator

plasma, linac, wakefield, simulation

1743

J. Björklund Svensson, H.E. Ekerfelt, O. Lundh
Lund University, Lund, Sweden
J. Andersson, F. Curbis, M. Kotur, F. Lindau, E. Mansten, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

Beam-driven plasma-wakefield acceleration is an acceleration scheme promising accelerating fields of at least two to three orders of magnitude higher than in conventional radiofrequency accelerating structures. The scheme relies on using a charged particle bunch (driver) to drive a non-linear plasma wake, into which a second bunch (witness) can be injected at an appropriate distance behind the first, yielding a substantial energy gain of the witness bunch particles. This puts very special demands on the machine providing the particle beam. In this article, we use simulations to show that, if driver-witness-bunches can be generated in the photo-cathode electron gun, the MAX IV Linear Accelerator could be used for plasma-wakefield acceleration.

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TUPIK033

Test and Commissioning Results of NSC KIPT 100 MeV/ 100 kW Electron Linear Accelerator, Subcritical Neutron Source Driver

neutron, gun, vacuum, klystron

1751

A.Y. Zelinsky, O.E. Andreev, V.P. Androsov, S.V. Bazarov, O. Bezditko, O.V. Bykhun, Y.L. Chi, A.N. Gordienko, V.A. Grevtsev, A. Gvozd, D.Y. He, X. He, V.E. Ivashchenko, A.A. Kalamayko, I.I. Karnaukhov, I.M. Karnaukhov, X.C. Kong, V.P. Lyashchenko, H.Z. Ma, M. Moisieienko, S. Pei, X.H. Peng, A.V. Reuzayev, I.M. Subotenko, D.V. Tarasov, V.I. Trotsenko, X. Wang
NSC/KIPT, Kharkov, Ukraine
Y.L. Chi, D.Y. He, X. He, X.C. Kong, H.Z. Ma, S. Pei, X.H. Peng, X. Wang
IHEP, Beijing, People's Republic of China
S. Shu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

Neutron Source on the base of subcritical assembly has been constructed and is under commissioning in NSC KIPT, Kharkov, Ukraine. The source uses 100 MeV/ 100 kW electron linear accelerator as a driver. The accelerator was designed and manufactured in IHEP, Beijing, China. The accelerator has been assembled at NSC KIPT, all accelerator systems and components were and accelerator is under commissioning. Reports describes the status of the NSC KIPT 100 MeV/ 100 kW electron linear accelerator. The results of the first tests are presented.

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TUPIK034

NSC KIPT Neutron Source on the Base of Subcritical Assembly With Electron Linear Accelerator Driver

neutron, target, shielding, operation

1754

A.Y. Zelinsky, I.M. Karnaukhov, A. Mytsykov, I. Ushakov
NSC/KIPT, Kharkov, Ukraine
Y.L. Chi
IHEP, Beijing, People's Republic of China
Y. Gohar
ANL, Argonne, Illinois, USA

National Science Center Kharkov Institute of Physics & Technology (NSC KIPT) together with ANL, Chicago, USA developed up to date scientific facility that is Neutron Source on the base of subcritical assembly driven with 100 MeV/100 kW electron accelerator. During bombarding of the Tungsten or Uranium targets the electron beam generates the original neutrons that are multiplied in the facility core of low enriched uranium trough the fission process. The maximal value of the neutron multiplication factor is 0.98. So the total neutron flux output is increased as much as 50 times and is 2·10 13 n·cm^-2·c-1. The subcriticality of the system eliminates the possibility of self-sustained chain reaction existence that increases the nuclear safety of the facility drastically. The neutron source mentioned above is the first facility of such type in the world. The results that will be obtained at studies of neutron characteristics of the neutron source with low enriched uranium core and during optimization of the operation modes of the facility systems will became the scientific background for the further development of the safe, ecological nuclear energetics of the future.

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TUPIK036

Use of Laser Wakefield Accelerators as Injectors for Compact Storage Rings

laser, storage-ring, injection, emittance

1760

K.A. Dewhurst, H.L. Owen
UMAN, Manchester, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
B.D. Muratori
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work is funded by the STFC (Science and Technology Facilities Council).
Compact storage rings require a compact acceleration solution. We propose the use of a laser wakefield accelerator (LWFA) as an injector for compact electron storage rings to produce synchrotron radiation. In particular, we study the injection of 0.7 GeV and 3 GeV electrons into the DIAMOND storage ring and consider implications for future storage ring design. Whilst laser-based acceleration is well-known as a driver for future electron-positron colliders and future free-electron lasers, here we propose it is also advantageous to provide electrons for 3rd-generation storage rings. The electron beams produced by LWFAs have a naturally very small emittance around 1 nm and moderate energy spread of a few percent. Combining these beam parameters with the compact size of a LWFA makes them highly favourable compared to traditional linac or booster synchrotron injector chains.chains.

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TUPIK041

Cleaning of Parasitic Bunches for Time Structured Filling of the ESRF Storage Ring During Top Up Operation

extraction, booster, kicker, storage-ring

1774

E. Plouviez, L. Farvacque, J.M. Koch, T.P. Perron, B. Roche, K.B. Scheidt, R. Versteegen, S.M. White
ESRF, Grenoble, France

In order to generate time structured synchrotron radiation the 6GeV ESRF storage ring can be operated with 16 buckets filled with 15nC separated by 16 gaps of 61 nearly perfectly empty buckets. The contrast required by some users between the population of the main and empty buckets is 10¹¹. In order to obtain these empty buckets some RF knock out (cleaning) of the parasitic bunches is needed. Until now this cleaning was performed on the beam stored in the storage ring. Recently we have started to deliver this 16 bunches filling in a so called top up mode, drastically increasing the rate of the storage ring refills. In this top up mode it is very penalizing to perform the cleaning in the storage ring so we are now performing it in the booster synchrotron which accelerates the 200MeV beam coming from the linac up to 6GeV. We describe the set up used to perform the cleaning in the booster and all the measurement and experiments performed in order to correctly understand the origin of the unwanted electrons populating buckets of the gaps separating the 16 main bunches.

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TUPIK042

Solenoid Alignment for the SRF Photoinjector of BERLinPro at HZB

solenoid, alignment, SRF, software

1778

G. Kourkafas, A. Jankowiak, T. Kamps, J. Li, J. Völker
HZB, Berlin, Germany
M. Schebek
Humboldt University Berlin, Berlin, Germany

The Berlin Energy Recovery Linac Prototype (BERLinPro) at Helmholtz Zentrum Berlin (HZB) aims to deliver a continuous-wave (cw) electron beam of high average current (100 mA) and brilliance (normalized emittance below 1 mm mrad). The achievement of these demanding goals depends significantly on the performance of the electron source, a superconducting RF (SRF) photoinjector. A critical component for the quality of the generated beam is the superconducting solenoid magnet. In order to optimize its operation and minimize parasitic contributions, special attention has been given to the precise alignment of this element using a hexapod mover. Due to the strict limitations inside a cryostat, a complex coupling between the solenoid in vacuum and the hexapod in air has been realized, requiring sophisticated software and hardware mechanisms to prevent collisions. Along with this setup, the developed beam-based alignment procedure and its performance are demonstrated in this article.

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TUPIK043

Upgrade of the Neutron Dose Measurement System at BESSY

neutron, radiation, injection, synchrotron

1781

K. Ott, Y. Bergmann, M. Martin, L. Pichl
HZB, Berlin, Germany

Funding: Funded by the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie and by the Land Berlin
Neutron radiation fields at synchrotron light sources are caused by bremsstrahlung from electron losses in accelerator components. Inside the enclosure and in transversal direction neutron and gamma radiation is of the same order of magnitude but high energy neutrons are much more penetrating. This causes outside the shielding neutron spectra with two broad maxima at about 1 MeV and 100 MeV. Standard Anderson-Braun or Leake neutron monitors measure thermalized neutrons in a proportional counter tube by nuclear reactions which limits the measurement range to neutron energies < 10 MeV. This implies two considerable systematic errors: Pulsed neutron beams causes dead-time losses due to the time structure of injections and the moderators are not sufficient to moderate high energy neutrons down to thermal energies. We determined and fixed these measurement errors by faster preamplifiers and by a more effective moderator developed by us, which expands the measurement range up to several GeV. Examples of the application at BESSY are presented.

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TUPIK054

The MAMI-C Accelerator: 25 Years of Operation and Strategies for the Next Decade

klystron, operation, experiment, microtron

1816

M. Dehn, K. Aulenbacher, F. Fichtner, R.G. Heine, P. Jennewein, W. Klag, H.-J. Kreidel, J.R. Röthgen, V. Tioukine
IKP, Mainz, Germany

Funding: Work supported by DFG (CRC 1044) and the German federal state of Rheinland-Pfalz
The Mainz Microtron Accelerator (MAMI-C) is a staged Race Tack Microtron (RTM) accelerator for 100μA polarised electrons up to 1.6 GeV energy. This report addresses the problems and our strategies to reliably operate the MAMI-C Accelerator for at least another ten years and what lessons have been learned for the new Mainz Energy recovering Superconducting Accelerator (MESA).

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TUPIK055

Target Investigation Driven by a 10 MeV Electron Linac for Bremsstrahlung Production

target, linac, radiation, photon

1819

M. Yarmohammadi Satri, M. Lamehi, H. Shaker
IPM, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran

IPM E-Linac is a 10 MeV electron linear accelerator presently under construction at Institute for Research in Fundamental Sciences (IPM). It will accelerate electron from 45 keV to 10 MeV along the 160 cm accelerating tube. One of the beam energy measurement devices is designed based on the production of bremsstrahlung radiation. Target of the electron linac presents a key role in the production of bremsstrahlung. In this paper, we present the simulation results for an investigation on the bremsstrahlung radiation production based on target thickness, radius and atomic number, Z. We have applied Fluka Monte Carlo code for collecting the dose equiva-lent of generated bremsstrahlung along the target central axis at 30cm located downstream the target.

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TUPIK058

The Machine Protection System for the ELI-NP Gamma Beam System

vacuum, laser, gun, operation

1824

S. Pioli, D. Alesini, D. Di Giovenale, G. Di Pirro, A. Gallo, L. Piersanti, A. Vannozzi, A. Variola
INFN/LNF, Frascati (Roma), Italy
F. Cardelli, L. Palumbo
University of Rome La Sapienza, Rome, Italy

The new Gamma Beam System (GBS), within the ELI-NP project, under installation in Magurele (RO) by INFN, as part of EuroGammas consortium, can provide gamma rays that open new possibilities for nuclear photonics and nuclear physics. ELI-GBS gamma rays are produced by Compton back-scattering to get monochromaticity (0,1% bandwidth), high flux (10¹³ photon/s the highest in the world), tunable directions and energies up to 19 MeV. Such gamma beam is obtained when a high-intensity laser collides a high-brightness electron beam with energies up to 720 MeV with a repetition rate of 100 Hz in multi-bunch mode with trains of 32 bunches. An advanced Machine Protection System was developed in order to ensure proper operation for this challenging facility. Such system operate on different layers of the control system to be interfaced with all sub-systems of the control system. It's equipped with different beam loss monitors based on Cherenkov optical fiber, hall probes, fast current transformer together with BPM and an embedded system based on FPGA with distributed I/O over EtherCAT to monitor vacuum and RF systems which requires fast response to be interlocked within the next RF pulse.

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TUPIK066

Beam Loss Simulation and Radiation Shielding for Top-Off Operation of Hefei Light Source

storage-ring, shielding, injection, simulation

1845

X. Zhou, J.Y. Li, J.G. Wang, S.W. Wang, W.B. Wu, W. Xu, K. Xuan, Q.B. Zeng
USTC/NSRL, Hefei, Anhui, People's Republic of China

The Hefei Light Source (HLS) is undergoing a series of upgrades to prepare for the top-off operation. To ensure radiation safety in the experimental hall under abnormal beam loss, simulations under various system errors in the HLS storage ring are performed to get in-depth understanding of the induced radiation nature. To make the radiation shielding more effective, a beam scraper is used to decrease the aperture opening of the vacuum chamber, and additional shielding is installed around the scraper. Simulation and beam test results are reported in this paper.

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TUPIK102

Introduction of Operating Procedures at TPS

controls, operation, injection, vacuum

1951

C.S. Huang, B.Y. Chen, C.H. Chen, J.Y. Chen, M.-S. Chiu, S. Fann, C.H. Kuo, T.Y. Lee, C.C. Liang, W.Y. Lin, Y.-C. Liu
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is the latest generation of 3 GeV synchrotron light source which subsystem includes magnet, power supply, vacuum, RF system, insertion device, control system, etc. The operating procedures and checking items are complex. To speed up the machine start-up and shut-down procedures, check the system's status, and prevent misoperation, we summarize the procedures for routine operation and develop the integrated control interface, which concentrates most machine information and control functions into a single window. This interface clearly indicates the machine status and improves operational efficiency.

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TUPIK104

Effects of Non-axisymmetric Solenoid Field on Beam Quality in Velocity Bunching

solenoid, linac, emittance, alignment

1958

Y.H. Wen
NTHU, Hsinchu, Taiwan
C.H. Chen, N.Y. Huang, W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan

Space-charge effect is not negligible during the early stage of beam acceleration in a photoinjector rf linac that is operated for generation of short electron pulses by velocity bunching. A solenoid with iron shield can be used to provide the required axis-symmetric magnetic field to balance the radial space-charge force of the beam. However, the iron shield cannot be perfectly symmetric because openings are reserved for feeding water pipes and electrical cables to the coils. In addition, alignment errors of the solenoid may also spoil the symmetry of the focusing field. In this study, simulation is carried out to investigate how does the non-axisymmetric solenoid field of different origins influence beam properties, such as beam size, transverse emittance during the rf bunch compression.

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TUPIK106

Analysis of the Synchrotron Radiation from Segmented Undulator in Double-Mini Beta Function

undulator, radiation, brilliance, photon

1964

H.W. Luo, C.H. Lee
NTHU, Hsinchu, Taiwan
T.Y. Chung, C.-S. Hwang
NSRRC, Hsinchu, Taiwan
C.-S. Hwang
NCTU, Hsinchu, Taiwan

Three long straight sections with double-mini beta-y lattice were created in the Taiwan Photon Source (TPS) for which the effects of focusing elements and phase shifters between the collinear undulators result in incorrect calculations of the brilliance while assuming a Gaussian-approximation. Therefore, an on-axis Wigner distribution function (WDF), which includes effects of wave phenomena, is a natural way to measure the intensity of synchrotron radiation and is used in this article as the definition of brilliance.

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TUPIK110

Optimisation of a High-Resolution, Low-Latency Stripline Beam Position Monitor System for Use in Intra-Train Feedback

feedback, extraction, cavity, collider

1979

N. Blaskovic Kraljevic, R.M. Bodenstein, T. Bromwich, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
JAI, Oxford, United Kingdom
D.R. Bett
CERN, Geneva, Switzerland

A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in feedback systems at particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. The fast analogue front-end signal processor is based on a single-stage RF down-mixer, with a measured latency of 15.6 ± 0.1 ns. The processor has been optimised, doubling the maximum operating beam intensity up to 1.6 nC, and the signal processing in the custom digital acquisition board has been upgraded in order to improve the resolution beyond the 300 nm level measured previously. The latest results, demonstrating a position resolution of order 150 nm with single-pass beam, will be presented.

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TUPIK130

A Permanent Magnet Quadrupole Magnet for CBETA

permanent-magnet, quadrupole, dipole, lattice

2016

H. Witte, J.S. Berg, J. Cintorino, G.J. Mahler, N. Tsoupas, P. Wanderer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Recently a collaboration between Brookhaven National Laboratory and Cornell University was established, aiming to build the CBETA accelerator. CBETA is a 150 MeV electron test accelerator, which prototypes essential technologies of eRHIC, which is a proposed upgrade to the existing Relativistic Heavy Ion Collider (RHIC) hadron facility at Brookhaven National Laboratory. Similar to eRHIC, CBETA employs an FFAG lattice for the arcs. The arcs require short, large aperture quadrupole magnets, which are located close together. BNL has been working on a design employing permanent magnets; we show the concept and the engineering design of these magnets. Prototype magnets have been constructed recently; we report on magnetic field quality measurements and their agreement with computer simulations.

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TUPVA018

Macroparticle Simulation Studies of the LHC Beam Dynamics in the Presence of Electron Cloud

simulation, dipole, quadrupole, octupole

2081

A. Romano, G. Iadarola, K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland

Beam quality degradation caused by the Electron Cloud (EC) effects has been identified as one of the main performance limitations for the high intensity 25 ns beams in the Large Hadron Collider (LHC). When a proton bunch passes through an EC, electrons are attracted towards the transverse center of the beam resulting into an increasing electron density within the bunch. The effects driven by the interaction of the electrons with the bunch have been studied with macroparticle simulations in order to evaluate, in different operational scenarios, the threshold for the coherent instabilities as well as the incoherent tune spread. This contribution will summarize the main findings of the simulation study and compare them with the available experimental observations.

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TUPVA019

Impact and Mitigation of Electron Cloud Effects in the Operation of the Large Hadron Collider

cryogenics, operation, injection, impedance

2085

G. Iadarola, B. Bradu, P. Dijkstal, L. Mether, G. Rumolo
CERN, Geneva, Switzerland

In 2015 and in 2016 the Large Hadron Collider has been routinely operated with 25 ns bunch spacing. With this beam configuration electron clouds develop in a large fraction of the beam chambers, in spite of a very large electron dose accumulated on the surfaces. This posed several challenges to different aspects of the beam operation. In particular, the machine settings had to be optimized in order to mitigate coherent and incoherent effects of the electron cloud on the beam dynamics while a specifically designed feed-forward control had to be implemented and optimized in order to dynamically adapt the regulations of the cryogenic system to the strong heat load deposited by the electron cloud on the beam screens of the cryogenic magnets. At the same time, the data collected from the different accelerator subsystems (heat loads, vacuum pressures, evolution of the bunch by bunch beam parameters) allowed to significantly improve our models and understanding on these phenomena.

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TUPVA045

Compensation of Head-on Beam-Beam Induced Resonance Driving Terms and Tune Spread in the Relativistic Heavy Ion Collider

lattice, proton, optics, resonance

2171

W. Fischer, X. Gu, C. Liu, Y. Luo, A. Marusic, R.J. Michnoff, T.A. Miller, M.G. Minty, C. Montag, A.I. Pikin, G. Robert-Demolaize, V. Schoefer, P. Thieberger
BNL, Upton, Long Island, New York, USA
S.M. White
ESRF, Grenoble, France

Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
A head-on beam-beam compensation scheme was implemented for operation in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The compensation consists of a lattice for the minimization of beam-beam driven resonance driving terms, and electron lenses for the reduction of the beam-beam induced tune spread. We describe the implementations of the lattice and electron lenses, and report on measurements of lattice properties and the effect of the electron lenses on the hadron beam.

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TUPVA059

Overcoming the Space Charge Limit: Development of an Electron Lens for SIS18

ion, gun, space-charge, injection

2211

D. Ondreka, P.J. Spiller
GSI, Darmstadt, Germany
P. Apse-Apsitis
Riga Technical University, Riga, Latvia
K. Schulte
IAP, Frankfurt am Main, Germany

The 'Facility for Anti-Proton and Ion Research' (FAIR) presently under construction will deliver intense ion beams to its experimental users. The requested intensities require filling the existing synchrotron SIS18, which serves as injector to FAIR, up to the space charge (SC) limit. Operation under these conditions is challenging due to the large tune footprint of the beam, demanding delicate control of adverse effects caused by machine imperfections to avoid emittance growth and beam loss. To facilitate the high intensity operation, the installation of an electron lens for SC compensation into SIS18 is foreseen. This requires an electron beam of a current of several amperes with longitudinal and transverse distributions matched to those of the ion beam during the cycle. The electron beam needs to be RF modulated at a bandwidth of a few MHz with time varying amplitude ranging from DC to fully modulated, while the transverse size needs to be continuously adapted to the adiabatically shrinking ion beam. This contribution reports on the requirements on an electron lens for SC compensation in SIS18.

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TUPVA080

Stochastic Cooling Hardware for Low Energy Deuterons at COSY

pick-up, kicker, impedance, experiment

2261

B. Breitkreutz, R. Greven, N. Shurkhno, R. Stassen, H. Stockhorst
FZJ, Jülich, Germany

One of the central utilizations of the COSY facility nowadays is to host experiments for the JEDI (Jülich Electric Dipole moment Investigations) collaboration. These experiments use polarized deuteron beams at momenta below 1 GeV/c, that are stored for several minutes. In order to increase the spin coherence time, beam cooling is necessary. Electron cooling is applied to pre-cool the beam, but the solenoids of the electron cooler may not be perfectly compensated. Thus, stochastic cooling would be desirable instead. Unfortunately, the existing stochastic cooling system is not sensitive at low beam velocities. This paper presents newly developed stochastic cooling pickups and kickers for a system dedicated to low beam velocities of approximately 0.5c. The design is based on the slot-ring type pickups that have been developed for the High Energy Storage Ring (HESR), but optimized for low particle velocities and a low frequency band of 350-700 MHz. Since the structures get much bigger in comparison to the HESR version, mechanical properties must be reconsidered and a trade-off between electrical properties, cooling performance and constructability must be found.

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TUPVA115

Progress with Long-Range Beam-Beam Compensation Studies for High Luminosity LHC

simulation, cathode, proton, optics

2358

A. Rossi, O. Aberle, J. Albertone, A. Bertarelli, C.B. Boccard, F. Carra, G. Cattenoz, Y. Delaup, S.D. Fartoukh, G. Gobbi, J. Lendaro, Y. Papaphilippou, D. Perini, S. Redaelli, H. Schmickler, C. Zanoni
CERN, Geneva, Switzerland
A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
M. Fitterer, A.S. Patapenka, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA

Long-range beam-beam (LRBB) interactions can be a source of emittance growth and beam losses in the LHC during physics and will become even more relevant with the smaller '* and higher bunch intensities foreseen for the High Luminosity LHC upgrade (HL-LHC), in particular if operated without crab cavities. Both beam losses and emittance growth could be mitigated by compensat-ing the non-linear LRBB kick with a correctly placed current carrying wire. Such a compensation scheme is currently being studied in the LHC through a demonstration test using current-bearing wires embedded into col-limator jaws, installed either side of the high luminosity interaction regions. For HL-LHC two options are considered, a current-bearing wire as for the demonstrator, or electron lenses, as the ideal distance between the particle beam and compensating current may be too small to allow the use of solid materials. This paper reports on the ongoing activities for both options, covering the progress of the wire-in-jaw collimators, the foreseen LRBB experiments at the LHC, and first considerations for the design of the electron lenses to ultimately replace material wires for HL-LHC.

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TUPVA134

Accelerators Validating Antimatter Physics (AVA)

antiproton, experiment, storage-ring, diagnostics

2414

C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk'odowska-Curie grant agreement No 721559.
Antimatter experiments are at the cutting edge of science. They are, however, very difficult to realize and have been limited by the performance of the only existing facility in the world, the Antiproton Decelerator (AD) at CERN. The Extra Low Energy Antiproton ring (ELENA) will be a critical upgrade to this unique facility and commissioned from autumn 2016. This will significantly enhance the beam quality and enable new experiments. To fully exploit the discovery potential of this facility, advances are urgently required in numerical tools that can adequately model beam transport, life time and interaction, beam diagnostics tools and detectors to characterize the beam's properties, as well as in novel experiments that exploit the enhanced beam quality that ELENA will provide. AVA is a new European research and training initiative between universities, research centers and industry that will carry out R&D into ELENA and related facilities. This contribution gives an overview of the AVA research programme across its three scientific work packages.

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TUPVA153

Accelerator-Based Education Activities at JINR

vacuum, controls, linac, radiation

2455

M.A. Nozdrin, D. Belozerov, K. Gikal, V. Kobets, S. Pakuliak, V. Shabratov, G. Shirkov, D. Shvidkiy, K. Verlamov, A. Zhemchugov, D. Zlydenny
JINR, Dubna, Moscow Region, Russia

Professional practice is essential to train an engineer. However, many activities are impossible to run at high school, especially if they require sophisticated equipment such as accelerators. A series of practical engineering courses is being set up at the Joint Institute for Nuclear Research to overcome these difficulties while educating students from the JINR Member States. A dedicated 'training' beamline of the Linac-200 electron accelerator is being constructed to practice the beam management and diagnostics, including the operation of standard beamline elements such as a bending dipole, quadrupoles, a sextupole and steerers. Various types of particle detectors can be used in the beam area as well in order to study the passage of electrons and photons through matter and to learn about the detector operation and properties. The practice at the beam will be accompanied by a series of hands-on trainings on radiation protection, vacuum and RF technology, electronics and metrology.

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WEYA1

Crab Cavity Systems for Future Colliders

cavity, collider, luminosity, proton

2474

S. Verdú-Andrés, I. Ben-Zvi, Q. Wu
BNL, Upton, Long Island, New York, USA
I. Ben-Zvi
Stony Brook University, Stony Brook, USA
R. Calaga
CERN, Geneva, Switzerland

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy, by the US LARP program and by the HL-LHC project.
KEKB was the first facility to implement the crab crossing technique in 2007, for the interaction of electron and positron beams. The High Luminosity Large Hadron Collider (HL-LHC) project envisages the use of crab cavities for increasing and levelling the luminosity of proton-proton collisions in LHC. Crab cavities have also been proposed and studied for future colliders like CLIC, ILC and eRHIC. This contribution will focus on the near and far future of crab cavities for particle colliders.

Slides WEYA1 [6.571 MB]

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WEOBA2

Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

emittance, simulation, experiment, operation

2482

M. Fitterer, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA
R. Bruce, G. Papotti, S. Redaelli, D. Valuch, C. Xu
CERN, Geneva, Switzerland
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy.
Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

Slides WEOBA2 [2.074 MB]

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WEOCA1

Performance of SOLARIS Storage Ring

storage-ring, injection, closed-orbit, photon

2490

A.I. Wawrzyniak, P.B. Borowiec, M.B. Jaglarz, A. Kisiel, P.M. Klimczyk, M.A. Knafel, M.P. Kopeć, A.M. Marendziak, S. Piela, P. Sagało, M.J. Stankiewicz, K. Wawrzyniak, M. Zając
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland

After one year of the Solaris storage ring commission-ing excellent performance has been achieved. The optics was corrected close to the design values. However, some minor adjustments are still needed. The commissioning of the Solaris 1.5 GeV storage ring required a big effort in machine parameters optimization. Performance of posi-tion monitoring devices has proven essential for the suc-cessful optimization of beam parameters such as: closed orbit, tune, chromaticity, and dispersion. Now, the effort is focused on fine-tuning the machine by implementing the linear optics from orbit correction (LOCO) and reduc-ing the disparity between model and measured results revealed by the phase advance analysis and dispersion measurement. Moreover, during daily operation the main task is to maintain long-term stability of the circulating electron beam allowing for beamlines commissioning. Within this presentation the current status of the Solaris facility and the commissioning results will be reported.

Slides WEOCA1 [13.180 MB]

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WEOAB1

Hénon-Heiles Single Particle Dynamics at IOTA

sextupole, lattice, experiment, synchrotron

2508

S. A. Antipov
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev
Fermilab, Batavia, Illinois, USA

A Hénon-Heiles system is a simple, classical nonlinear Hamiltonian system offering a wide range of particle dynamics from regular orbits to resonant behavior to chaotic trajectories. Initially proposed to describe the motion of stars around a galactic center, it remains a vivid topic in Dynamics and Mathematical Physics since its discovery in 1964. Although the system and its modifications have been extensively studied numerically, its dynamics has never been observed in a controlled experiment. In this report we show that it is possible to create the Hénon-Heiles Hamiltonian using sextupoles in a realistic accelerator lattice. We propose a special sextupole channel to create the desired potential at the IOTA ring and study the 3D single particle dynamics by frequency map analysis and Poincare cross-sections. The proposed experiment would allow real world testing of regular and chaotic motion with a controlled strength of the nonlinearity.

Slides WEOAB1 [4.685 MB]

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WEYB1

Towards a Fully Integrated Accelerator on a Chip: Dielectric Laser Acceleration (DLA) From the Source to Relativistic Electrons

laser, acceleration, emittance, simulation

2520

K.P. Wootton, R.J. England, S.G. Tantawi
SLAC, Menlo Park, California, USA
R.W. Aßmann, I. Hartl, W. Kuropka, F. Mayet, A. Rühl
DESY, Hamburg, Germany
D.S. Black, R.L. Byer, H. Deng, S. Fan, J.S. Harris, T.W. Hughes, N. Sapra, O. Solgaard, J. Vuckovic
Stanford University, Stanford, California, USA
B.M. Cowan
Tech-X, Boulder, Colorado, USA
T. Egenolf, U. Niedermayer
TEMF, TU Darmstadt, Darmstadt, Germany
P. Hommelhoff, A. Li, N. Schönenberger
University of Erlangen-Nuremberg, Erlangen, Germany
J. Illmer, J.C. McNeur, A.K. Mittelbach, A.D. Tafel
Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany
R. Ischebeck, L. Rivkin
PSI, Villigen PSI, Switzerland
F.X. Kärtner
MIT, Cambridge, Massachusetts, USA
F.X. Kärtner
CFEL, Hamburg, Germany
W. Kuropka, F. Mayet
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
Y.J. Lee, M. Qi
Purdue University, West Lafayette, Indiana, USA
P. Musumeci
UCLA, Los Angeles, California, USA
L. Rivkin
EPFL, Lausanne, Switzerland

Funding: This work was supported by the U.S. Department of Energy, Office of Science, under Contract no. DE-AC02-76SF00515, and by the Gordon and Betty Moore Foundation under grant GBMF4744 (Accelerator on a Chip).
Dielectric laser acceleration of electrons has recently been demonstrated with significantly higher accelerating gradients than other structure-based linear accelerators. Towards the development of an integrated 1 MeV electron accelerator based on dielectric laser accelerator technologies, development in several relevant technologies is needed. In this work, recent developments on electron sources, bunching, accelerating, focussing, deflecting and laser coupling structures are reported. With an eye to the near future, components required for a 1 MeV kinetic energy tabletop accelerator producing sub-femtosecond electron bunches are outlined.

Slides WEYB1 [12.774 MB]

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WEOBB1

Recirculated Electron Beam Photo-Converter for Rare Isotope Production

target, photon, TRIUMF, isotope-production

2526

A. Laxdal, R.A. Baartman, I.V. Bylinskii, S. Ganesh, A. Gottberg, F.W. Jones, P. Kunz, L.A. Lopera, T. Planche, A. Sen
TRIUMF, Vancouver, Canada

The TRIUMF 50 MeV electron linac has the potential to drive cw beams of up to 0.5 MW to the ARIEL photo-fission facility for rare isotope science. Due to the cooling requirements, the use of a thick Bremsstrahlung target for electron to photon conversion is a difficult technical challenge in this intensity regime. Here we present a different concept in which electrons are injected into a small storage ring to make multiple passes through a thin internal photo-conversion target, eventually depositing their remaining energy in a cooled central core absorber. We discuss the design requirements and propose a set of design parameters for the Fixed Field Alternating Gradient (FFAG) ring. Using particle simulation models, we estimate various beam properties, as well as the MPS for the electron loss.

Slides WEOBB1 [4.650 MB]

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WEPAB009

Pilot Experiments and New Developments at the DELTA Short-Pulse Facility

laser, radiation, undulator, experiment

2578

S. Khan, B. Büsing, F. Götz, M.A. Jebramcik, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, R. Niemczyk, B. Riemann, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann
DELTA, Dortmund, Germany
U. Bovensiepen, S. Döring, A. Eschenlohr, M. Ligges, L. Plucinski, M. Plötzing, C.M. Schneider, S. Xiao
Universität Duisburg-Essen, Duisburg, Germany
S. Cramm
Forschungszentrum Jülich, Peter-Gruenberg-Institut-6, Jülich, Germany
M. Gehlmann
Forschungszentrum Jülich, Peter Gruenberg Institut, Jülich, Germany

Funding: BMBF 05K16PEA, BMBF 05K16PEB, Mercur Pr-2014-0047
At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort radiation pulses in the vacuum ultraviolet (VUV) and terahertz (THz) regime are routinely generated by the interaction of electron bunches with femtosecond laser pulses. A laser-induced energy modulation is converted into a density modulation (microbunching) by a magnetic chicane, leading to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). Path length differences of the energy-modulated electrons along the magnetic lattice lead to a dip in the longitudinal charge distribution, which gives rise to the coherent emission of THz radiation. In first pump-probe photoemission experiments, the spatial and temporal overlap of laser pump and CHG probe pulse on the sample was demonstrated. Furthermore, the effect of two temporally separated seed pulses was studied in the VUV and (sub-)THz regime.

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WEPAB010

Progress Towards an EEHG-Based Short-Pulse Source at DELTA

laser, radiation, undulator, synchrotron

2582

A. Meyer auf der Heide, F.H. Bahnsen, B. Büsing, F. Götz, S. Hilbrich, M.A. Jebramcik, S. Khan, N.M. Lockmann, C. Mai, R. Niemczyk, B. Riemann, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann
DELTA, Dortmund, Germany

Funding: Work supported by the accelerator initiative (ARD) of the Helmholtz society, BMBF 05K13PE3, BMBF 05K16PEA.
The short-pulse source at the 1.5-GeV synchrotron light source DELTA, operated by the TU Dortmund University, enables the generation of sub-ps radiation pulses in the VUV regime based on coherent harmonic generation (CHG). As an upgrade, the employment of echo-enabled harmonic generation (EEHG) is planned which allows to produce shorter wavelengths. Recent developments and measurements regarding the twofold energy modulation required for EEHG are presented.

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WEPAB015

Parameter Optimization for Operation of sFLASH With Echo-Enabled Harmonic Generation

FEL, laser, operation, bunching

2592

J. Bödewadt, R.W. Aßmann, C. Lechner
DESY, Hamburg, Germany
W. Hillert, T. Plath, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Khan, N.M. Lockmann
DELTA, Dortmund, Germany

The free-electron laser facility FLASH has a dedicated experimental setup for external FEL seeding applications for the XUV and soft x-ray spectral range. Recently the setup is operated as high-gain harmonic generation FEL. Furthermore, it also allows the operation of echo-enabled harmonic generation (EEHG). A versatile laser injection system allows operation with seed wavelength in the infra-red, visible, and ultra-violet. Here, we present the parameter optimization for operating the seeding setup with EEHG. First experimental tests are planned in the first half of 2017.

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WEPAB016

Experience in Operating sFLASH With High-Gain Harmonic Generation

FEL, laser, radiation, photon

2596

J. Bödewadt, R.W. Aßmann, N. Ekanayake, B. Faatz, I. Hartl, T. Laarmann, C. Lechner, M.M. Mohammad Kazemi, A. Przystawik
DESY, Hamburg, Germany
Ph. Amstutz, A. Azima, M. Drescher, W. Hillert, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
K.E. Hacker, S. Khan, N.M. Lockmann, R. Molo
DELTA, Dortmund, Germany

sFLASH, the experimental setup for external seeding of free-electron lasers (FEL) at FLASH, has been operated in the high-gain harmonic generation (HGHG) mode. A detailed characterization of the laser-induced energy modulation, as well as the temporal characterization of the seeded FEL pulses is possible by using a transverse deflecting structure and an electron spectrometer. FEL saturation was reached for the 7th harmonic of the 266 nm seed laser. In this contribution, we present the latest experimental results.

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WEPAB017

Generation of Ultra-Short Electron Bunches and FEL Pulses and Characterization of Their Longitudinal Properties at FLASH2

FEL, operation, laser, undulator

2600

F. Christie, J. Rönsch-Schulenburg, S. Schreiber, M. Vogt
DESY, Hamburg, Germany

The free-electron laser in Hamburg (FLASH) is a user facility, delivering soft X-ray radiation, consisting of two beam lines, FLASH1 and FLASH2. The injector and the main linac are shared between both beam lines. Starting in 2014, FLASH2 has been commissioned for user operation. Currently, there is no hardware installed for the direct measurement of the electron bunch length nor the photon pulse duration at FLASH2. Exact knowledge of the pulse duration is essential for time-resolved user experiments performed at FLASH. Therefore, we are designing a modified beam line, containing a new type of X-band deflecting cavity* and a dipole, downstream of the FLASH2 undulator, to map the longitudinal phase space onto a beam screen. Anticipating the feasibility of measuring the longitudinal phase space with high resolution, a study on optimizing the free-electron laser (FEL) performance for shortest bunches is ongoing.
*B. Marchetti et al., X-Band TDS project, contribution to these conference proceedings

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WEPAB019

Concept for a Seeded FEL at FLASH2

FEL, laser, undulator, free-electron-laser

2607

C. Lechner, R.W. Aßmann, J. Bödewadt, M. Dohlus, N. Ekanayake, B. Faatz, G. Feng, I. Hartl, T. Laarmann, T. Lang, L. Winkelmann, I. Zagorodnov
DESY, Hamburg, Germany
A. Azima, M. Drescher, Th. Maltezopoulos, T. Plath, J. Roßbach, W. Wurth
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Khan
DELTA, Dortmund, Germany

The free-electron laser (FEL) FLASH is a user facility delivering photon pulses down to 4 nm wavelength. Recently, the second FEL undulator beamline 'FLASH2' was added to the facility. Operating in self-amplified spontaneous emission (SASE) mode, the exponential amplification process is initiated by shot noise of the electron bunch, resulting in photon pulses of limited temporal coherence. In seeded FELs, the FEL process is initiated by coherent seed radiation, improving the longitudinal coherence of the generated photon pulses. The conceptual design of a possible seeding option for the FLASH2 beamline foresees the installation of the hardware needed for high-gain harmonic generation (HGHG) seeding upstream of the already existing undulator system. In this contribution, we present the beamline design and numerical simulations of the seeded FEL.

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WEPAB020

Beam Loss Simulations for the Implementation of the Hard X-Ray Self-Seeding System at European XFEL

undulator, simulation, collimation, neutron

2611

S. Liu, W. Decking, L. Fröhlich
DESY, Hamburg, Germany

The European XFEL is designed to be operated with a nominal beam energy of 17.5 GeV at a maximum repetition rate of 27000 bunches/second. The high repetition rate together with the high loss sensitivity of the undulators raises serious radiation damage concern, especially for the implementation of the Hard X-ray Self-Seeding (HXRSS) system, where a 100 um thick diamond crystal will be inserted close to the beam in the undulator section. Since the seeding power level highly depends on the delay of the electron beam with respect to the photon beam, it is crucial to define the minimum electron beam offset to the edge of the crystal in the HXRSS chicane. At European XFEL a ~200 m long post-linac collimation section has been designed to protect the undulators. In the HXRSS scheme, however, beam halo hitting the crystal can generate additional radiation. Particle tracking simulations have been performed using GEANT4 and BDSIM for the undulator and the collimation section, respectively. The critical number of electrons allowed to hit the crystal is estimated for a certain operation mode and the efficiency of beam halo collimation is investigated to predict the minimum HXRSS chicane delay.

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WEPAB022

Background-free Harmonic Production in XFELs via a Reverse Undulator Taper

undulator, FEL, background, radiation

2618

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Nonlinear harmonics in X-ray FELs can be parasitically produced as soon as FEL reaches saturation, or can be radiated in dedicated afterburners. In both cases there is a strong background at the fundamental, since it is much stronger than harmonics. One can get around this problem by application of the recently proposed reverse undulator tapering. In this contribution we present numerical simulations of harmonic production in such a configuration as well as recent results from FLASH where the second and the third harmonics were efficiently generated with a low background at the fundamental. We also present the results for a high-contrast operation when the afterburner is tuned to the fundamental.

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WEPAB023

First Operation of a Harmonic Lasing Self-Seeded FEL

FEL, undulator, operation, brightness

2621

E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov
DESY, Hamburg, Germany

Harmonic lasing is a perspective mode of operation of X-ray FEL user facilities that allows to provide brilliant beams of higher energy photons for user experiments. Another useful application of harmonic lasing is so called Harmonic Lasing Self-Seeded Free Electron Laser (HLSS FEL) that allows to improve spectral brightness of these facilities. In the past, harmonic lasing has been demonstrated in the FEL oscillators in infrared and visible wavelength ranges, but not in high-gain FELs and not at short wavelengths. In this paper we report on the first evidence of the harmonic lasing and the first operation of the HLSS FEL at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. Spectral brightness was improved in comparison with Self-Amplified Spontaneous emission (SASE) FEL by a factor of six in the exponential gain regime. A better performance of HLSS FEL with respect to SASE FEL in the post-saturation regime with a tapered undulator was observed as well. The first demonstration of harmonic lasing in a high-gain FEL and at a short wavelength paves the way for a variety of applications of this new operation mode in X-ray FELs.

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WEPAB024

Commissioning and First Heating with the European XFEL Laser Heater

laser, undulator, cathode, FEL

2625

M. Hamberg
Uppsala University, Uppsala, Sweden
F. Brinker, M. Scholz
DESY, Hamburg, Germany

Funding: We thank DESY and Swedish research council under Project number DNR-828-2008-1093 for financial support.
The Laser Heater of the European XFEL has been installed and commissioning is in progress. We discuss the setup and the results of the first electron beam heating in the injector section.

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WEPAB027

Frequency Doubler and Two-color Mode of Operation at Free Electron Laser FLASH2

undulator, radiation, operation, FEL

2635

M. Kuhlmann, E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

We report on the results of the first operation of a frequency doubler at free electron laser FLASH2. The scheme uses the feature of the variable gap undulator. Undulator is divided in two parts. The second part of the undulator is tuned to the double frequency of the first part. Amplification process in the first undulator part is stopped at the onset of the nonlinear regime, such that nonlinear higher harmonic bunching in the electron beam density becomes pronouncing, but the radiation level is still small to disturb the electron beam significantly. Modulated electron beam enters the second part of the undulator and generates radiation at the 2nd harmonic. Frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. Tuning of the electron beam trajectory, phase shifters and compression allows to tune intensities of the first and the second harmonic. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved with frequency doubler scheme, which is significantly below the design value for the standard SASE option.

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WEPAB029

Optimum Undulator Tapering of SASE FEL: From the Theory to Experiment

undulator, FEL, radiation, laser

2639

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Optimization of the amplification process in FEL amplifier with diffraction effects taken into account results in a specific law of the undulator tapering [*]. It is a smooth function with quadratic behavior in the beginning of the tapering section which transforms to a linear behavior for a long undulator. In practice, undulator consists of a sequence of modules of fixed length separated with intersections. Two modes of undulator tapering can be implemented: step tapering, and smooth tapering. Procedure of the step tapering applies step change of the undulator gap from module to module, and smooth tapering assumes additional linear change of the gap along each module. In this report we simulate the performance of the both experimental options and compare with theoretical limit.
[*] E.A. Schneidmiller and M.V. Yurkov, Optimization of a high efficiency free electron laser amplifier, Phys. Rev. ST Accel. Beams 18 (2015) 030705.

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WEPAB031

OCELOT as a Framework for Beam Dynamics Simulations of X-Ray Sources

simulation, wakefield, FEL, space-charge

2642

S.I. Tomin
XFEL. EU, Hamburg, Germany
I.V. Agapov, M. Dohlus, I. Zagorodnov
DESY, Hamburg, Germany

We describe the OCELOT open source project focusing on new beam dynamics simulation capabilities of the whole machine in modern electron-based x-ray sources. Numerical approaches for particle tracking and field calculations are discussed. In developing of the full-dimensional numerical modeling we pursue two important competitive aspects: the simulation has to be fast and has to include accurate estimations of collective effects. The simulation results for the European XFEL [1] are presented. The results have been benchmarked agains other codes and some of such benchmarks are shown.

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WEPAB032

A Novel Optical Beam Concept for Producing Coherent Synchrotron Radiation with Large Energy Spread Beams

undulator, radiation, laser, photon

2646

R. Rossmanith, A. Bernhard, V. Saile, P. Wesolowski
KIT, Karlsruhe, Germany
R.W. Aßmann, U. Dorda, B. Marchetti
DESY, Hamburg, Germany

Up to now two FEL concepts are known in conventional accelerators: 1.) In THz lasers an off-crest cavity adds a chirp to the bunch followed by a bunch compressor. Particles with different energies travel on different trajectories to the radiator. 2.) For EUV and X-ray FELs the beam enters an undulator which produces microbunches which then radiate. In this paper it is proposed to copy the THz laser scheme for EUV lasers. The incoming beam is chirped and a dogleg forces afterwards the particles with different energies to move on different parallel trajectories. Considering a detector plane perpendicular to the trajectories the particles with different energies arrive in general at different times. When in this plane for instance a TGU (Transverse Gradient Undulator) is positioned the emitted radiation in the TGU is monochromatic. If in addition chirp and dogleg are selected in such a way that the particles with different energies arrive at the same time at the entrance of the TGU the radiation is monochromatic and coherent similar to the THz laser concept.

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WEPAB033

Experimental Optimization and Characterization of Electron Beams for Generating IR/THz SASE FEL Radiation with PITZ

emittance, FEL, simulation, radiation

2650

P. Boonpornprasert, Y. Chen, J.D. Good, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, H.J. Qian, Y. Renier, T. Rublack, F. Stephan
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
C. Saisa-ard
Chiang Mai University, Chiang Mai, Thailand
Q.T. Zhao
IMP/CAS, Lanzhou, People's Republic of China

The Photo Injector Test facility at DESY, Zeuthen site (PITZ), develops high brightness electron sources for modern linac-based Free Electron Lasers (FELs). The PITZ accelerator can also be considered as a suitable machine for the development of an IR/THz source prototype for pump-probe experiments at the European XFEL. One of the interesting options for the IR/THz generation with PITZ is to generate the radiation by means of a SASE FEL using an uncompressed electron beam with bunch length of a few 10 ps and a peak current of ~200 A. In this paper, results of experimental optimizations and characterizations, including transverse phase space, slice transverse emittance and longitudinal phase space, of electron beams with bunch charges of 4 nC are presented and discussed. The measurements were done with beam momenta of 15 MeV/c and 22 MeV/c. Results of IR/THz SASE FEL calculations by using the GENESIS1.3 code based on the measured beam parameters are also presented and discussed.

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WEPAB034

Control of Seeded FEL Pulse Duration Using Laser Heater Pulse Shaping

laser, FEL, simulation, experiment

2654

V. Grattoni
Università degli Studi di Trieste, Trieste, Italy
E. Allaria, L. Badano, M.B. Danailov, A.A. Demidovich, S. Di Mitri, L. Giannessi, G. Penco, E. Roussel, P. Sigalotti, S. Spampinati, M. Trovò, M. Veronese
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
E. Ferrari
PSI, Villigen PSI, Switzerland

New Free-Electron Laser facilities deliver VUV and X-ray radiation with pulse length in the range of hundreds and tens of fs. A further reduction of the FEL pulse length is desired by those experiments aiming at probing ultrafast phenomena. Unlike SASE FEL, where the pulse duration is mainly driven by the electron bunch duration, in a seeded FEL the pulse duration can be determined by the seed laser properties. The use of techniques able to locally deteriorate the electron beam properties such as emittance or energy spread have been used in SASE FELs to reduce the region of the electron beam that is able to produce FEL radiation and hence reduce the FEL pulse length. The temporal shaping of the laser heater can be used to create an electron beam characterized by a very large energy spread all along the bunch except for a small region. We report measurements of the effect of the laser heater shaping on the electron beam phase-space performed at FERMI. Impact on the final FEL pulse properties are predicted with a series of numerical simulations.

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WEPAB037

Two-Bunch Operation at the FERMI FEL Facility

linac, wakefield, laser, FEL

2663

G. Penco, E. Allaria, S. Bassanese, P. Cinquegrana, S. Cleva, M.B. Danailov, A.A. Demidovich, S. Di Mitri, M. Ferianis, G. Gaio, D. Gauthier, L. Giannessi, M. Predonzani, F. Rossi, E. Roussel, S. Spampinati, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
E. Roussel
PhLAM/CERLA, Villeneuve d'Ascq, France

FERMI is a linac-driven free electron laser (FEL) based upon the High Gain Harmonic Generation (HGHG) scheme. In standard conditions a bunch of 700 pC of charge with sub mm-mrad emittances is accelerated to 1.2-1.5GeV in a normal conducting S-band linac and drives FEL-1 or FEL-2 undula-tor line, which lase respectively in the range 100-20nm or 20-4nm. A number of two-color schemes have been implemented at FERMI for pump/probe experiments, all consisting in making two portions of the same electron bunch lase at two different wavelengths, with a time-separation from 0 to few hundreds of fs. In order to increase the time separation to ns and tens of ns we have explored the acceleration of two inde-pendent electron bunches separated by multiple of the linac main radio-frequency period, i.e. 333ps. Measure-ments and characterization of this two-bunch mode oper-ation are presented, including trajectory control, impact of longitudinal and transverse wakefields on the trailing bunch and manipulation of the longitudinal phase space.

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WEPAB039

Development Perspectives at FERMI

FEL, laser, linac, experiment

2666

M. Svandrlik, E. Allaria, L. Badano, F. Bencivenga, C. Callegari, F. Capotondi, F. Cilento, P. Cinquegrana, M. Coreno, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, M. Di Fraia, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, L. Giannessi, F. Iazzourene, S. Krecic, M. Lonza, N. Mahne, M. Malvestuto, C. Masciovecchio, M. Milloch, F. Parmigiani, G. Penco, A. Perucchi, L. Pivetta, O. Plekan, M. Predonzani, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, E. Roussel, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste, operating in the ultraviolet to soft X-rays spectral range; the radiation produced by the seeded FEL is characterized by a number of desirable properties, such as wavelength stability, low temporal jitter and longitudinal coherence. In this paper, after an overview of the FEL performances, we will present the development plans under consideration for the next 3 to 5 years. These include an upgrade of the linac and of the existing FEL lines, the possibility to perform multipulse experiments in different configurations and an Echo Enabled Harmonic Generation (EEHG) experiment on FEL-2, the FEL line extending to 4 nm (310 eV).

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WEPAB058

Commissioning Status of the Dalian Cohernet Light Source

FEL, laser, undulator, linac

2709

G.L. Wang
DICP, Dalian, People's Republic of China

The Dalian Coherent Light Source (DCLS) is a seeded FEL user facility working at 50-150 nm, now under commissioning in Dalian, China. The facility consists of a 300 MeV normal-conducting S-band linear accelerator (LINAC) and two undulator beamlines. The first beam-line (FEL-1) will provide picosecond FEL radiation with the pulse energy up to several hundreds micro-joule, the second beam-line (FEL-2) will be a femtosecond and polarization FEL. The LINAC and FEL-1 beam-line construction was complete by the summer of 2016, the installation of FEL-2 is in preparation. High power RF conditioning of the LINAC started in August 2016 and the beam commissioning initiated 3 months later. This article describes the commissioning status of DCLS, reports on the goals achieved so far.

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WEPAB063

Considerations on Developing a Dedicated Terahertz Light Source Based on the HLS-II Storage Ring

radiation, storage-ring, synchrotron, synchrotron-radiation

2716

S.W. Wang, J.Y. Li, W.B. Wu, W. Xu, K. Xuan, X. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

There is an increasing interest in generating terahertz radiation for different kinds of researches. A high-power terahertz light source can be realized through coherent synchrotron radiation from a storage ring. The radiation power of coherent synchrotron radiation is proportional to square of the number of electrons in a bunch. To generate coherent synchrotron radiation, the electron bunch length should be shorter than its radiation wavelength. This paper presents our preliminary study on developing a terahertz light source based on Hefei Light Source. We will introduce the status of Hefei Light Source (HLS) and discusses the approach to change it to a dedicated Terahertz light source using coherent synchrotron radiation. Several schemes are proposed to shorten the electron bunch length in the storage ring, including using a low alpha lattice, adopting a magnetic chicane and upgrading the RF system with much higher frequency. The related beam instabilities are also analyzed to predict the beam current threshold.

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WEPAB065

Proposal for the Generation of Terawatt, Attosecond X-Ray Pulses in Free Electron Lasers

undulator, radiation, laser, FEL

2723

Z. Wang, C. Feng, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A feasible novel method is proposed to generate attosecond terawatt X-ray radiation pulse in free electron lasers, which could find its application on multiple science fields. In our scheme, a chirped laser is employed to generate a chirped periodic current enhancement and a series of spatiotemporal shifters are applied between the undulator sections to generate ultra-short radiation pulse. Three-dimensional start-to-end simulations are carried out and the calculation results show that a 0.15nm X-ray pulse with the peak power of about 1TW and the pulse length of 0.1fs could be achieved in our scheme.

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WEPAB066

POP Experiment for the HB-HGHG Scheme at SXFEL

laser, radiation, FEL, free-electron-laser

2727

K.S. Zhou, H.X. Deng, C. Feng, D. Wang
SINAP, Shanghai, People's Republic of China

Abstract High brightness, fully coherent and ultra-short free electron lasers (FEL) operating in the soft x-ray region are opening up new frontiers in many scientific fields. In this paper, we perform the design studies for the proof-of-principle experiment of the recently proposed HB-HGHG scheme at SXFEL test facility with a two-stage setup. The first stage of SXFEL is used for the generation of the coherent signal at 30th harmonic of the seed through the coherent harmonic generation process. Then this coherent signal is shifted ahead by the 'fresh bunch' chicane of SXFEL and initiates the strong coherent radiation in the radiator of the second stage of SXFEL. The output properties have been compared with the conventional EEHG and the two-stage cascaded HGHG with the same harmonic up-conversion number.

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WEPAB067

Electron Beam Lifetime in SOLARIS Storage Ring

storage-ring, scattering, vacuum, damping

2731

M.B. Jaglarz, P.B. Borowiec, A. Kisiel, A.I. Wawrzyniak
Solaris, Kraków, Poland
A.M. Marendziak
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland

Solaris storage ring is a recently constructed and commissioned machine. At the beginning of storage ring operation the lifetime was very short mostly dominated by the ion trapping and residual gas scattering. After a 390 A·h of beam cleaning the measured total lifetime has reached 20 h for 100mA of a stored current. Since the main contribution to the total lifetime in the storage ring comes from single Coulomb and Touschek scattering the dependence of the residual gas pressure and the vertical aperture of storage ring is investigated. Moreover to improve the Touschek lifetime the 3^rd harmonic cavities were installed. Recently the cavities were tuned close to the resonance and the total lifetime increased significantly. This presentation will report on the lifetime measurements and calculations carried out for Solaris 1.5 GeV storage ring at different vacuum and RF conditions.

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WEPAB068

Residual Gas in the Vacuum System of the Solaris 1.5GeV Electron Storage Ring

vacuum, storage-ring, ion, injection

2734

A.M. Marendziak, S. Piela, M.J. Stankiewicz, A.I. Wawrzyniak, M. Zając
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
E. Al-Dmour
MAX IV Laboratory, Lund University, Lund, Sweden

Solaris is a third generation light source constructed at the Jagiellonian University in Kraków, Poland. The machine was designed by the MAX IV Laboratory team. The replica of the 1.5 GeV storage ring with 96 m circumference of a vacuum system was successfully built and now the synchrotron facility is after the 3rd phase of commissioning. Recent installation of the Residual Gas Analyzer (RGA) in the storage ring allows now for evaluation of the residual gas composition. Within this paper the result of residual gas analysis in the vacuum system of storage ring during different states of the machine will be presented. Result of vacuum performance regarding beam cleaning and beam lifetime will be presented. Moreover, the NEG strips performance will be evaluated and reported.

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WEPAB070

Study of ESASE Scheme with Microbunching Instability for Generating Attosecond-Terawatt X-Ray Pulse in XFELs

laser, simulation, FEL, free-electron-laser

2741

C.H. Shim, D.E. Kim, I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
Y.W. Parc
PAL, Pohang, Kyungbuk, Republic of Korea

Recent studies show that the attosecond-terawatt X-ray pulse in XFELs can be generated by using ESASE (enhanced self-amplified spontaneous emission) scheme to obtain a sub-femtosecond spike in the electron peak current. However, ESASE scheme is not working properly when the microbunching instability is taken into account. The instability can be suppressed when the laser heater system which increases the uncorrelated energy spread of the electron beam is used in the injector. The effect of the microbunching instability on the performance of ESASE scheme will be discussed. In addition, the optimized results with the laser heater system for generating attosecond-terawatt X-ray pulse in XFELs is also presented.

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WEPAB071

Single Bunch Bucket Selection Injection Modes in the ALBA Storage Ring

injection, linac, operation, storage-ring

2744

R. Muñoz Horta, G. Benedetti, D. Lanaia, J. Moldes, F. Pérez, M. Pont, L. Torino
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The ALBA Synchrotron has been operating routinely in top-up mode since 2014, performing reinjections of multi-bunches every 20 minutes. Recently, the control of the timing has been upgraded to allow single bunches to be injected into any storage ring bucket and therefore to top up the stored current also in single bunch injector mode. In addition, by means of a specific algorithm, a new injection mode called Single Bunch Bucket Selection (SBBS) has been developed to provide any kind of filling pattern in the ALBA storage ring. This mode controls independently the amount of current injected into each bucket, and injects first into those buckets with lowest charge. When used in top-up mode, SBBS keeps the charge distribution of the filling pattern with a uniformity below 10%. The improved flexibility and stability of the filling pattern increases the scope of research for the ALBA experiments and for machine studies development. The implementation of the new injection modes and their performance are presented.

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WEPAB077

The Soft X-Ray Laser Project at MAX IV

laser, FEL, undulator, linac

2760

S. Werin, J. Andersen, F. Curbis, L. Isaksson, M. Kotur, F. Lindau, E. Mansten, D. Olsson, H. Tarawneh, P.F. Tavares, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden
S. Bonetti, A. Nilsson
Stockholm University, Stockholm, Sweden
V.A. Goryashko
Uppsala University, Uppsala, Sweden
P. Johnsson
Lund University, Lund, Sweden
M. Larsson, P. Salén
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
O. Tjernberg
KTH Physics, Stockholm, Sweden

A soft x-ray laser beamline utilising FEL technology is being designed for the Short Pulse Facility (SPF) at the MAX IV Laboratory. A conceptual design study has been started following on the scientific case already prepared in collaboration between several Swedish Universities and driven by a strong (Swedish) user demand [*]. The baseline goal of the SXL beamline is to generate intense and short pulses in the range 1-5 nm (1-0.2 keV). The system is building on the MAX IV linac system, already today providing 3 GeV and pulses compressed to 100 fs for other applications within the SPF. As a special feature we foresee a variety of pump-probe capabilities. We here describe design issues and solutions for the accelerator and FEL system.
* http://frielektronlaser.se/onewebmedia/SXL_science_case₁61102.pdf

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WEPAB083

Development of Linac-Based MIR/THz FEL Facility and Photocathode RF-gun in Thailand

undulator, FEL, laser, gun

2763

K. Buakor, N. Chaisueb, K. Damminsek, S. Rimjaem, J. Saisut, C. Thongbai, W. Thongpakdi
Chiang Mai University, Chiang Mai, Thailand

A linac-based MIR/THz free-electron laser facility is under the development at the Plasma and Beam Physics Research Facility, Chiang Mai University. The ultimate goal of the project is to generate the infrared radiation covering the wavelengths from 13 to 125 μm. The main applications of the radiation involved MIR/THz imaging and spectroscopy. The future FEL facility will consists of an injector system, an experimental station for coherent transition radiation, two magnetic bunch compressors and two undulator magnets equipped with optical cavities for MIR and THz beamlines. An expected electron beam energy is between 10 to 20 MeV with an energy spread of about or less than 1 %. Two undulator magnets with maximum undulator parameters of 1 and 0.95 will be used for generation of the THz-FEL and MIR-FEL, respectively. In this paper, we present the status of the design and construction of this future FEL facility.

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WEPAB084

Development of Injector System for MIR/THz Free-Electron Laser Facility in Thailand

gun, undulator, simulation, FEL

2767

W. Thongpakdi, S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand

Development of a linac-based MIR/THz FEL light source is ongoing at the Plasma and Beam Physics Research Facility, Chiang Mai University. The future facility will consist of an S-band thermionic cathode RF electron gun, a pre-magnetic bunch compressor in a form of alpha magnet, an S-band travelling-wave linac structure, a 180-degree achromat system and two undulator magnets equipped with optical cavities. This research focuses on start-to-end beam dynamics simulations of the injector system. The aim of the study is to produce high quality electron beam at the entrance of the THz undulator magnet. The simulation was conducted by using programs PARMELA and ELEGANT. The program PARMELA was utilized to study the electron beam dynamics inside the RF-gun. Then, the program ELEGANT was used to optimize the injector system parameters. Optimization of physical specifications for the achromat system was performed to obtain short electron bunches with small energy spread at the undulator entrance. In this paper, results of beam dynamics simulations with suitable condition for the THz-FEL beamline are presented and discussed.

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WEPAB085

Siam Photon Source: Present Machine Status and Future Upgrades

storage-ring, injection, photon, operation

2770

P. Klysubun, S. Boonsuya, N. Juntong, K. Kittimanapun, S. Kongtawong, S. Krainara, A. Kwankasem, T. Pulampong, P. Sudmuang, N. Suradet
SLRI, Nakhon Ratchasima, Thailand

Siam Photon Source, the Thailand synchrotron light source, has received several upgrades in recent years. Most important of which are the improvement of the positional stability of the stored electron beam, and the installation of 2 IDs, i.e. a 2.2 T hybrid multipole wiggler and a 6.5 T superconducting wavelength shifter, to extend the available SR spectrum into hard x-ray region. The beam stability improvement was achieved through several activities, including improving the BPM system, upgrading the existing corrector power supplies, and implementing global orbit feedback. The two new IDs provide higher-intensity and higher-energy (up to 25 keV) synchrotron light, which will be utilized for MX, high-energy SAXS, WAXS, XAS, and microtomography. Ongoing machine upgrades include increasing the energy of the booster and transport line to 1.2 GeV for full-energy injection and eventual top-up operation. Utilization of the electron beam is also being explored. A beam test facility, which extracts electron beam in the booster for characterizing high-energy particle sensors, as well as calibrating other beam diagnostic instruments, has been constructed and is now in operation.

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WEPAB087

TARLA: The First Facility of Turkish Accelerator Center (TAC)

cavity, FEL, laser, linac

2776

A.A. Aksoy, A.A. Aydin, C. Kaya
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
B. Ketenoğlu, O. Yavaş
Ankara University, Faculty of Engineering, Tandogan, Ankara, Turkey

Funding: Work supported by Ministry of Development of Turkey
Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is proposed as first accelerator based infrastructure in Turkey as a first step Turkish Accelerator Center (TAC). The facility under construction at Institute of Accelerator Technologies of Ankara University since 2012. Based superconducting technology, TARLA accelerator will offer a multi-experiment facility providing various accelerator-based radiation sources for the users coming from different fields like physics, chemistry, biology, material sciences, medicine and nanotechnology. Two of the planed free-electron laser (FEL) beamlines of TARLA will provide Continuous Wave (CW) tunable radiation of high brightness in the mid- and far-infrared regime. In addition a Bremmstrahlung radiation station is proposed within current scope of TARLA. In this paper current status of facility is presented.

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WEPAB088

Dark Current Studies in the CLARA Front-End Injector

gun, solenoid, linac, simulation

2779

F. Jackson, I.R. Gessey, J.W. McKenzie, B.L. Militsyn, P.J. Tipping
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

At STFC Daresbury a new facility CLARA (Compact Linear Accelerator for Research and Applications) is being designed and constructed. The principal aim of CLARA is advanced Free Electron Laser research. Halo and dark current in CLARA is a concern for damage to the undulator, and other applications of the machine. Recently the front end (gun, diagnostics, first linac) of CLARA has been installed including some collimation to mitigate halo effects. Beam halo may arise from gun field emission or due to beam dynamics in the early stages of acceleration, which may achieve the same energy as the core beam and thus may be transported to the undulator. The code CST is used to study the gun field emission. The code ASTRA is used to study the transport of field emission through the front end, including the effectiveness of collimators. Machine measurements of dark current are compared against these simulations.

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WEPAB093

Mechanical Engineering of the Diamond DDBA Upgrade

insertion-device, storage-ring, insertion, vacuum

2794

N.P. Hammond, A.G. Day, R.K. Grant, R. Holdsworth, J. Kay
DLS, Oxfordshire, United Kingdom

The Diamond storage ring has been upgraded to replace one cell of Double Bend Achromat (DBA) with a Double Double Bend Achromat (DDBA). This upgrade has enabled the construction of a new straight to install a much brighter insertion device X-ray source for a new beamline rather than use a weaker bending magnet source. The engineering challenges and experience from this project are described, especially those aspects relevant to building a future low emittance storage ring at Diamond.

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WEPAB097

Modelling Two-Colour FEL with Wide Wavelength Separation and Individual Polarisation Tuning

polarization, FEL, undulator, simulation

2808

D. Bultrini, N. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R.J. Allan
The Hartree Centre, Science and Technology Facilities Council (STFC/DL), Warrington, United Kingdom
L.T. Campbell, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.D.A. Smith
TXUK, Warrington, United Kingdom

Free electron lasers (FELs) are currently enabling cutting edge research in chemistry, biology and physics. We use simulations to assess a new FEL capability that would add to the impressive repertoire of experiments made possible by the technology: a two-colour independent polarization mode, which allows for light pulses with variable temporal separation, individually tuneable polarisation, and widely separated wavelength. Simulations are carried out using the broad bandwidth FEL code Puffin, the results of which are used to discuss the radiation properties of the output. This scheme is applicable to existing and proposed facilities which feature undulators with variable ellipticity and gap.

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WEPAB099

Development of the Manufacturing and QA Processes for the LCLS-II Injector Source VHF Electron Gun

gun, operation, site, cavity

2815

J.A. Doyle, J.N. Corlett, M.J. Johnson, R. Kraft, T.D. Kramasz, D. Leitner, S.P. Virostek
LBNL, Berkeley, California, USA

Funding: * This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
The Linear Coherent Light Source-II (LCLS-II), a new free electron laser currently under construction at SLAC, requires a high repetition rate, high brightness, continuous wave electron source. Lawrence Berkeley National Laboratory (LBNL) has developed a design for a normal conducting VHF gun in response to that need and is responsible for its production and that of the associated beamline, with much of the fabrication done in-house. The 186 MHz copper cavity dissipates approximately 90 kW of RF power while maintaining a vacuum pressure on the order of 10^-10 Torr. The gun is a critical component that requires a very high level of operational reliability to ensure uninterrupted availability for future system users. A quality assurance system to instruct manufacturing and change control is vital to ensure production of a gun that reliably meets physics requirements over an extended period of usage. This paper describes the QA processes developed for fabrication and assembly of the Injector Source electron gun along with results and lessons learned from their current implementation.

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WEPAB108

Angular Trajectory Kicks in a High-Gain Free-Electron Laser

FEL, radiation, laser, free-electron-laser

2830

P. Baxevanis, Z. Huang, G. Stupakov
SLAC, Menlo Park, California, USA

In a free-electron laser (FEL), transverse momentum offsets (or kicks) are introduced either inadvertently (through wakefields or mis-steering of the electron beam) or as part of dedicated schemes that require off-axis radiation propagation. Studying the influence of this effect on the performance of machines such as LCLS-I/II is critical both from a tolerance point of view and for its practical applications. A theoretical analysis of a high-gain FEL driven by such a kicked beam will be presented, with a critical evaluation of previous studies.

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WEPAB109

Multipole Field Effects in a Transverse Gradient Undulator

undulator, multipole, FEL, simulation

2833

P. Baxevanis, Z. Huang
SLAC, Menlo Park, California, USA

Using a transverse gradient undulator (TGU) is one of the methods proposed in order to enable the utilization of electron beams with large energy spread (such as those from plasma-based accelerators) in a free-electron laser (FEL). Most of the analytical treatments of this scheme assume a linear variation of the undulator field with one of the transverse coordinates. While this assumption leads to a simplified and more tractable model, including higher-order multipoles allows us to offer a more complete and rigorous description of the system. In this paper, we investigate the magnetic field components of a TGU using both theory and simulation and explore the impact of higher-order multipoles on the FEL performance.

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WEPAB116

LCLS Injector Laser Shaping and Applications

laser, FEL, cathode, emittance

2844

S. Li, S.C. Alverson, D.K. Bohler, A.B. Egger, A.R. Fry, S. Gilevich, Z. Huang, A. Miahnahri, D.F. Ratner, J. Robinson, F. Zhou
SLAC, Menlo Park, California, USA

In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The beam emittance and FEL performance are highly related to the transverse shape of the injector laser. When the injector laser has hot spots and non-uniformities that can carry over to the electron beam and degrade electron emittance and FEL performance, it requires long hours of manual adjustment by laser engineers and strenuous machine tuneup. The injector laser shaping project at LCLS aims to have precise control of the driver laser transverse profile in order to produce arbitrary electron beam profiles, which will enable us to study effects of laser shape on beam emittance and FEL performances. We use a digital micromirror device (DMD) to manipulate the drive laser profile. In this paper, we briefly discuss the implementations of laser shaping at LCLS. We demonstrate two applications of laser shaping. We present results of using laser shaping to control the X-ray laser output via an online optimizer. We also show the photocathode quantum efficiency measurements across cathode surface using the DMD.

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WEPAB118

High Power Sub-Femtosecond X-Ray Pulse Study for the LCLS

undulator, simulation, space-charge, photon

2848

J.P. MacArthur
Stanford University, Stanford, California, USA
J.P. Duris, Z. Huang, A. Marinelli
SLAC, Menlo Park, California, USA

The desire to resolve sub-femtosecond electron dynamics has pushed FEL facilities to shorter pulse lengths. However, current short-pulse schemes provide low pulse energy and a gain-length limited lower bound on the pulse duration. The X-ray Laser-Enhanced Attosecond Pulses (XLEAP) project at SLAC is designed implement an Enhanced Self Amplified Spontaneous Emission (ESASE) scheme, which produces sub-fs current spikes by modulating and compressing the electron beam. We show through a series of Genesis simulations that the current spike is capable of producing sub-fs pulses with a peak power well above 100 GW. Space-charge induced beam chirp can decrease pulse lengths below 400 as, and multi-stage schemes can increase peak x-ray powers to around 1 TW.

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WEPAB122

Experimental Demonstration of Ballistic Bunching with Dielectric-Lined Waveguides at Pitz

experiment, linac, bunching, wakefield

2857

F. Lemery
University of Hamburg, Hamburg, Germany
G.A. Amatuni, B. Grigoryan
CANDLE, Yerevan, Armenia
P. Boonpornprasert, Y. Chen, J.D. Good, M. Krasilnikov, O. Lishilin, G. Loisch, S. Philipp, H.J. Qian, Y. Renier, F. Stephan
DESY Zeuthen, Zeuthen, Germany
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

We report on the experimental demonstration of ballistic bunching of photoinjected, nC-scale electron bunches at the PITZ facility. In the experiment, electron bunches emanating from the photocathode were directly focused into a mm-scale dielectric-lined waveguide. The wakefield excited by the bunch acts back onto itself, leading to an energy modulation, which at a relatively low energy of 6~MeV, is converted into a density modulation before entering the linac ∼ 1~m downstream. We discuss the basic theory, experimental layout and results.

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WEPAB123

A Phase Matching, Adiabatic Accelerator

acceleration, laser, plasma, wakefield

2861

F. Lemery
University of Hamburg, Hamburg, Germany
K. Flöttmann
DESY, Hamburg, Germany
F.X. Kärtner
MIT, Cambridge, Massachusetts, USA
F.X. Kärtner
CFEL, Hamburg, Germany
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Tabletop accelerators are a thing of the future. Reducing their size will require scaling down electromagnetic wavelengths; however, without correspondingly high field gradients, particles will be more susceptible to phase-slippage – especially at low energy. We investigate how an adiabatically-tapered dielectric-lined waveguide could maintain phase-matching between the accelerating mode and electron bunch. We benchmark our simple model with CST and implement it into ASTRA; finally we provide a first glimpse into the beam dynamics in a phase-matching accelerator.

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WEPAB132

Research Program and Recent Results at the Argonne Wakefield Accelerator Facility (AWA)

wakefield, experiment, emittance, acceleration

2885

M.E. Conde, S.P. Antipov, D.S. Doran, W. Gai, Q. Gao, G. Ha, C.-J. Jing, W. Liu, N.R. Neveu, J.G. Power, J.Q. Qiu, J.H. Shao, Y.R. Wang, C. Whiteford, E.E. Wisniewski, L.M. Zheng
ANL, Argonne, Illinois, USA
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
Q. Gao, L.M. Zheng
TUB, Beijing, People's Republic of China
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
N.R. Neveu
IIT, Chicago, Illinois, USA
Y.R. Wang
IMP/CAS, Lanzhou, People's Republic of China

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357
We give an overview of the research program at the Argonne Wakefield Accelerator Facility (AWA), including some highlights of recent experiments. The AWA facility is dedicated to the study of beam physics and the development of technology for future particle accelerators. Two independent electron linacs are used to study wakefield acceleration: 70 MeV high charge electron bunches of up to 100 nC are used to drive wakefields, which can be probed by bunches originating from the same linac or from the 15 MeV linac. Recent Two-Beam-Acceleration (TBA) experiments operating at 11.7 GHz reached accelerating gradients of up to 150 MV/m. No indication of witness beam quality degradation was observed, and bunch charge was preserved during the acceleration process. Two identical TBA setups were used in series in order to demonstrate staging capabilities. Dielectric loaded structures operating at 26 GHz are also used in TBA experiments. Another main thrust of the research program consists of exploring and developing techniques to manipulate the phase space of electron bunches. These efforts include bunch shaping and the exchange of emittances in the transverse and the longitudinal phase spaces

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WEPAB134

Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices

plasma, simulation, emittance, scattering

2891

J.S. Ellison
IIT, Chicago, Illinois, USA
P. Snopok
Fermilab, Batavia, Illinois, USA
P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by the U.S. Department of Energy.
New computational tools are essential for accurate modeling and simulation of the next generation of muon-based accelerators. One of the crucial physics processes specific to muon accelerators that has not yet been simulated in detail is beam-induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the progress of developing the required simulation tools and applying them to study the properties of plasma and its effects on the beam in muon ionization cooling channels.

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WEPAB137

Cold Muonium Negative Ion Production

ion, target, collider, plasma

2898

V.G. Dudnikov, M.A. Cummings, R.P. Johnson
Muons, Inc, Illinois, USA
A.V. Dudnikov
BINP SB RAS, Novosibirsk, Russia

Charged muons as Muonium negative ions (consisting of positive Mu-meson and 2 electrons) have affinity S=0.75 eV. Muonium have ionization energy I=13.6 eV. Muonium negative ions were observed in 1987 [10, 11] by interaction of muons with a foil. In these work an efficiency of transformation of mu mesons to negative musonium ions were very low 10^-4. However, with using Tungsten or palladium single crystal with deposition cesium it can be improved up to 40-50%.

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WEPIK001

Advanced Beam Dump for FCC-ee

collider, simulation, distributed, positron

2906

A. Apyan
ANSL, Yerevan, Armenia
B. Goddard, F. Zimmermann
CERN, Geneva, Switzerland
K. Oide
KEK, Ibaraki, Japan

A modified beam dump for the future electron positron circular collider FCC-ee is discussed. The extraction line with a dilution kicker system distributes bunches at different transverse locations on the face of the beam dump. For a standard absorber the maximum energy deposition of all bunches occurs at the same longitudinal position inside the beam dump. This region experiences an enormous temperature rise compared with the surrounding parts of the beam dump. We propose a novel type of beam dump which spreads out the deposited energy over its whole volume quasi-uniformly, thereby reducing the maximum temperature rise. Results of Monte-Carlo simulations for a multi-material mosaic beam dump and for absorbers with distorted shapes are shown.

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WEPIK002

Experimental Activities on High Intensity Positron Sources Using Channeling

positron, target, photon, experiment

2910

I. Chaikovska, R. Chehab, H. Guler, V. Kubytskyi
LAL, Orsay, France
X. Artru
IN2P3 IPNL, Villeurbanne, France
K. Furukawa, T. Kamitani, F. Miyahara, M. Satoh, Y. Seimiya, T. Suwada
KEK, Ibaraki, Japan
V. Rodin
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
P. Sievers
CERN, Geneva, Switzerland

The positron source under investigation is using channeling radiation of multi-GeV electrons in a tungsten crystal. The radiated photons are impinging on the amorphous targets creating e⁺e⁻ pairs. A dipole magnet between the crystal-radiator and the amorphous-converter allows the charged particles to be swept off and only emitted photons to generate e⁺e⁻ pairs in the converter. Granular targets of different thicknesses, made of small tungsten spheres, have been recently investigated as a target-converter. This paper is describing the experimental studies conducted at the KEKB linac with such device. After the description of the experimental set-up and beam parameters, the measurement methods and preliminary results are presented.

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WEPIK008

Problems in SuperKEKB Vacuum System During the Phase-1 Commissioning and Their Mitigation Measures

wiggler, vacuum, photon, positron

2925

Y. Suetsugu, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, S. Terui
KEK, Ibaraki, Japan

The first (Phase-1) commissioning of the SuperKEKB, an energy-asymmetric electron-positron collider in KEK, Japan, started in February and ended in June, 2016. The vacuum system of the main ring worked well through the commissioning period as a whole, but experienced several problems, such as the electron cloud effect (ECE) in the positron ring, the pressure bursts accompanying beam losses due to dust particles in the beam pipe, an air leak at a connection flange due to the direct hitting of synchrotron radiation (SR), and so on. Towards the next (Phase-2) commissioning, countermeasures to these problems are taken during the shutdown period. For example, permanent magnets generating axial magnetic fields are attached to beam pipes at drift spaces for the suppression of the ECE. Knockers, which can artificially drop dust particles attached to the top surface in beam pipes by continuous impacts, are prepared to the beam pipes at which the pressure bursts had been frequently observed. Bellows chambers with masks are installed to protect the leaked flange from SR. The problems and their mitigation measures will be summarized in the presentation.

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WEPIK013

Electron Beam Injection Septum

injection, septum, emittance, synchrotron

2943

T. Mori, N. Iida, M. Kikuchi, T. Mimashi, Y. Sakamoto, S. Takasaki, M. Tawada
KEK, Ibaraki, Japan

The SuperKEKB project is in progress toward the initial physics run in autumn 2018. It assumes the nano-beam scheme, in which the emittance of the colliding beams is 4.6 nm. To achieve such a low emittance, it is vitally important to preserve the emittance during the transport of the beam from the linac to the main ring. One of the most difficult sections is the injection system. Since the dynamic aperture is small for the low emittance, the allowed distances between the stored beam and the injected beam at the injection point are 7.8 mm for the betatron injection and 7.2 mm for the synchrotron injection. The new septum magnets has been constructed and installed in the beam line after the measurement of magnetic flux density and aging test. It has been also checked the septum magnets are capable of design orbit. The initial beam injection succeeded on schedule and they had been operated without any big troubles in the first beam run of Phase-1.

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WEPIK015

Optimized Monochromatization for Direct Higgs Production in Future Circular e⁺e⁻ Colliders

collider, luminosity, emittance, radiation

2950

F. Zimmermann
CERN, Geneva, Switzerland
M.A. Valdivia García
DCI-UG, León, Mexico

Funding: This work was supported in part by the European Commission under the HORIZON2020 Integrating Activity project ARIES, grant agreement 730871, and by the Mexican CONACyT ‘‘BEAM'' Programme.
Direct s-channel Higgs production in e⁺e⁻ collisions is of interest if the centre-of-mass energy spread can be reduced to be comparable to the width of the standard model Higgs boson. A monochromatization scheme could be employed in order to achieve the desired reduction, by introducing a non-zero horizontal dispersion of opposite sign for the two colliding beams at the interaction point. In high-energy high-luminosity circular colliders, beamstrahlung may increase the energy spread and bunch length. The horizontal emittance blow up due to beamstrahlung, a new effect not present in past monochromatization proposals, may degrade the performance, especially the luminosity. We study, for the FCC-ee at 62.5 GeV beam energy, how we can optimize the IP optics parameters (betax*, Dx*) along with the number of particles per bunch so as to obtain maximum luminosity at a desired target value of the collision energy spread.

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WEPIK025

Spectral Diagnostics of Argon Plasma in a 10mm Aperture Plasma Window

plasma, cathode, vacuum, ion

2978

P.P. Gan, S. Huang, Y.R. Lu, S.Z. Wang, Z.X. Yuan, K. Zhu
PKU, Beijing, People's Republic of China

A 10 mm diameter 60 mm long plasma window has been designed and managed to generate arc discharge with argon gas experimentally in Peking University. Based on the previous experiments and simulations, we have measured the electron temperature and density of the plasma via argon spectral diagnostics, and analyzed the conditions to satisfy the criterion of local thermal equilibrium (L.T.E). The electron temperature is in the range of 12000 K to 16000 K. The electron density is in the range of 2.2×10¹⁶ cm^-3 to 3.2×10¹⁶ cm^-3, increasing with discharge current and gas flow rate. The results indicate that our argon plasma is in the L.T.E status. The sealing pressure characteristics of the plasma window is mentioned as well.

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WEPIK028

Status of the Electron-Positron Collider VEPP-4

collider, storage-ring, positron, experiment

2985

P.A. Piminov
BINP SB RAS, Novosibirsk, Russia

The next phase of the e⁺e⁻ collider VEPP-4 (Budker INP, Novosibirsk) is focused on experiments in the energy range from 4 to 10 GeV (c.m.). To recover the lack of positrons at high energy a new positron source was connected to the collider. The paper discusses the facility performance with new injection and other aspects of experimental study at high energy including laser polarimeter for precise energy calibration.

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WEPIK035

Adapting the JLEIC Electron Ring for Ion Acceleration

ion, booster, lattice, dipole

3007

B. Mustapha, Z.A. Conway, J.L. Martinez Marin, P.N. Ostroumov
ANL, Argonne, USA
Y.S. Derbenev, F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A key component of the recently proposed alternative design approach for the JLab-EIC (JLEIC) ion complex is to consolidate the electron storage ring (e-ring) as a large booster for the ions*. A preliminary parameter study showed that it is possible to do so for different design options of the e-ring. In this paper we will report on the adaptation of the e-ring lattice to accelerate ions. After studying the beam dynamics at the injection and extraction energies, we will determine the RF requirements for ion acceleration, in particular the number of required accelerating sections and their locations. The effect of this potential lattice change on the electron beam will be investigated. In a second stage, we will focus on the spin manipulation and determine if the spin rotators and flippers available for the electron could be used for the ions.
* An Alternative Approach for the JLEIC Ion Accelerator Complex, B. Mustapha et al, Proceedings of NAPAC-2016, October 9-14, Chicago, IL.

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WEPIK041

Update on the JLEIC Electron Collider Ring Design

sextupole, emittance, lattice, ion

3018

Y.M. Nosochkov, Y. Cai, M.K. Sullivan
SLAC, Menlo Park, California, USA
Y.S. Derbenev, F. Lin, V.S. Morozov, F.C. Pilat, G.H. Wei, Y. Zhang
JLab, Newport News, Virginia, USA
M.-H. Wang
Self Employment, Private address, USA

Funding: Authored by Jefferson Science Associates, LLC under US DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
We present an update on the lattice design of the electron ring of the Jefferson Lab Electron-Ion Collider (JLEIC). The electron and ion collider rings feature a unique figure-8 layout providing optimal conditions for preservation of beam polarization. The rings include two arcs and two intersecting long straight sections containing a low-beta interaction region (IR) with special optics for detector polarimetry, electron beam spin rotator sections, ion beam cooling sections, and RF-cavity sections. Recent development of the electron ring lattice has been focused on minimizing the beam emittance while providing an efficient non-linear chromaticity correction and large dynamic aperture. We describe and compare three lattice designs, from which we determine the best option.

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WEPIK047

Frequency Choice Studies of eRHIC Crab Cavity

luminosity, cavity, ion, simulation

3028

Y. Hao, Y. Luo, V. Ptitsyn
BNL, Upton, Long Island, New York, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Crab crossing scheme is essential collision scheme to achieve high luminosity for the future electron-ion collider (EIC). Since the ion beam is long when cooling is not present, the nonlinear dependence of the crabbing kick may present a challenge to the beam dynamics of the ion beam, hence a impact to the luminosity lifetime. In this paper, we present the initial result of the weak-strong and strong-strong beam-beam tracking with the crab crossing scheme. The result provides beam dynamics guidance in choosing the proper frequency the crab cavity for the future EIC.

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WEPIK048

Evaluation and Mitigation of Synchrotron Radiation Background in the eRHIC Ring-Ring Interaction Region

detector, radiation, photon, quadrupole

3032

C. Montag
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Synchrotron radiation is a potential source of background in the detector of any future electron-ion collider. In the case of the eRHIC ring-ring design, a 22mrad crossing angle eliminates the need for a separator dipole, which would otherwise be a major source of synchrotron radiation. However, electrons in the transverse tails experience strong magnetic fields in the low-beta quadrupoles near the interaction point. Despite the low electron density in the tails the resulting hard radiation generated in these strong fields is a major concern, and a set of masks needs to be in place to shield the detector from these photons. We present simulation studies and a first design of a synchrotron radiation masking scheme.

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WEPIK049

Overview of the eRHIC Ring-Ring Design

luminosity, proton, storage-ring, polarization

3035

C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, J.M. Brennan, A.V. Fedotov, W. Fischer, W. Guo, Y. Hao, A. Hershcovitch, Y. Luo, F. Méot, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, S. Seletskiy, T.V. Shaftan, V.V. Smaluk, S. Tepikian, D. Trbojevic, E. Wang, F.J. Willeke, H. Witte, Q. Wu
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The ring-ring electron-ion collider eRHIC aims at an electron-ion luminosity in the range from 10³² to 10³³cm^-2sec^-1 over a center-of-mass energy range from 20 to 140GeV. To minimize the technical risk the design is based on existing technologies and beam parameters that have already been achieved routinely in hadron-hadron collisions at RHIC, and in electron-positron collisions elsewhere. This design has evolved considerably over the last two years, and a high level of maturity has been achieved. We will present the latest design status and give an overview of studies towards evaluating the feasibility.

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WEPIK050

Parameters for eRHIC

luminosity, proton, emittance, synchrotron

3038

R.B. Palmer, C. Montag
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Requirements for the proposed BNL eRHIC Ring-Ring Electron Ion Collider (EIC) are discussed, together with the dependence of luminosity with the beam divergence and forward proton acceptance. Parameters are given for four cases. The first two use no cooling and could represent a first phase of operation. The next two use strong cooling and increased beam currents. In each case parameters are given that 1) meets the requirement for forward proton acceptance, and 2) has somewhat higher divergences giving somewhat higher luminosity.

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WEPIK073

Three Dimensional Wake Field for an Electron Moving in Undulator

undulator, radiation, electromagnetic-fields, wakefield

3098

K. Ohmi
KEK, Ibaraki, Japan

Electro-magnetic field for given trajectory of an electron is calculated by Lienard-Wiechert potential. The field near the electron moving in an undulator is presented. The field is regarded as a wake field in the undulator. Motion of a bunch is studied in the wake field.

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WEPIK075

Electron Cloud Instability in SuperKEKB Phase I Commissioning

target, simulation, permanent-magnet, solenoid

3104

K. Ohmi, J.W. Flanagan, H. Fukuma, H. Ikeda, E. Mulyani, K. Shibata, Y. Suetsugu, M. Tobiyama
KEK, Ibaraki, Japan

Beam size blow-up due to electron cloud has been observed in Phase I commissioning of SuperKEKB. Vacuum chambers in LER (low energy positron ring) were cured by antechamber and TiN coating for electron cloud. Some parts, bellows, were not cured by the coating. In the early stage of Phase I commissioning, beam size blow up has been observed above a threshold current. The blow up was suppressed by weak permanent magnets generating longitudinal field, which cover the bellows. Electron cloud current have been monitored during the commissioning. The thresholds for the electron cloud induced fast head-tail instability have been simulated in the operating beam conditions. Coupled bunch instability caused by electron cloud has been measured in the operating beam conditions and installation of the permanent magnets. The measurement and simulation results are presented.

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WEPIK080

Preliminary Study of Beam Dynamics Compensation for the Elliptically Polarized Undulator at the HLS-II

simulation, software, undulator, dynamic-aperture

3114

Z.H. Yang, Z.H. Bai, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

An elliptically polarized undulator (EPU) was installed at the upgraded Hefei Light Source, HLS-II, for special users. Due to that the area of good field of the EPU is not large enough, the resulting beam dynamics is serious. At present, the lattice is changed to lower beta functions at the EPU to solve this problem. However, the compensation for the EPU is necessary for better operation of the machine in the future. In this paper, we used the surface fitting method to extract the Hamiltonian of the EPU from the real surface magnetic field data. Thus, we can obtain the effective Hamiltonian of the ring, which can be analyzed using normal form or other techniques. Then the beam dynamics effects resulting from the EPU can be compensated by optimizing the nonlinear quantities with striplines.

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WEPIK081

The Logitudinal Broadband Impedance and Energy Spread Measurements at the VEPP-4M Electron-Positron Collider

impedance, synchrotron, collider, scattering

3117

V.M. Borin, V.A. Kiselev, G.Y. Kurkin, S.A. Nikitin, P.A. Piminov, S.V. Sinyatkin
BINP SB RAS, Novosibirsk, Russia
V.L. Dorokhov, O.I. Meshkov
BINP, Novosibirsk, Russia

The paper presents measurements of the longitudinal broadband impedance and beam energy spread of the beam at the VEPP-4M electron-positron collider in an energy range of 1.0 - 3.5 GeV. In order to measure the longitudinal bunch size at various beam currents we used PS-1/S1 streak camera with picosecond temporal resolution. The dependence of bunch length from the bunch current at different energies demonstrates a microwave instability threshold. The bunch lengthening was caused by potential well distortion as well. Potential well distortion lengthening was used to estimate a value of the reactive part of the longitudinal impedance of the vacuum chamber of the collider Observed microwave instability thresholds was used to measure the value of the broadband impedance. The impact of the Touschek effect in the beam energy spread is discussed.

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WEPIK085

Beam Shaping with 4N-order Multipole Magnets

octupole, focusing, multipole, quadrupole

3124

B.T. Folsom, E. Laface
ESS, Lund, Sweden

A uniformly irradiating beam is beneficial in spallation for preventing irregular wear on the target. For octupoles (n = 4) and higher-order (n = 4N) magnets, passing charged-particle bunches undergo symmetric shaping effects along the x and y axes. Using a Lie-mapping formalism, we illustrate how well Gaussian distributions can be flattened symmetrically in 2D with single, dual-pulse, and RF magnets of 4N order. Incidental shaping effects are also discussed.

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WEPIK094

LEIR Impedance Model and Coherent Beam Instability Observations

impedance, ion, injection, space-charge

3159

N. Biancacci, H. Bartosik, A. Huschauer, E. Métral, T.L. Rijoff, B. Salvant, R. Scrivens
CERN, Geneva, Switzerland
M. Migliorati
University of Rome La Sapienza, Rome, Italy

The LEIR machine is the first synchrotron in the ion acceleration chain at CERN and it is responsible to deliver high intensity ion beams to the LHC. Following the recent progress in the understanding of the intensity limitations, detailed studies of the machine impedance started. In this work we describe the present LEIR impedance model, detailing the contribution to the total longitudinal and transverse impedance of several machine element. We then compare the machine tune shift versus intensity predictions against measurements at injection energy and summarize the coherent instability observations in absence of transverse damper feedback.

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WEPIK098

Resonant Kicker System With Sub-part-per-million Amplitude Stability

kicker, resonance, operation, dipole

3174

M. Paraliev, C.H. Gough
PSI, Villigen PSI, Switzerland

High stability resonant kicker magnet systems have been developed as part of the fast electron beam switching system of Swiss Free Electron Laser (SwissFEL). They are designed to separate two closely spaced electron bunches (28 ns apart) accelerated in one RF macro-pulse and to send them to two separate undulator lines. High shot-to-shot amplitude stability is required to minimize the disturbance of the electron beam trajectories and to ensure stable X-ray lasing. The stability and speed was unlikely to be achieved by standard pulsed systems and a novel 18 MHz, lumped-element resonator deflector with high Q was developed. It is driven into resonance by a specialized pulsed RF driver. At resonance, the circulating currents can approach 300 A and the resulting magnetic field gives the required deflection to the electron bunches. The advanced DC offset measurement system is also described in this paper. The measured stability reached less than 1 ppm (10e-6) rms, well within the project requirements.

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WEPIK107

Comparison Studies of Graphene Sey Results in NSRL and DL

gun, factory, synchrotron, laser

3196

J. Wang, Y. Wang, B. Zhang, Y.X. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China
B.S. Sian, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P.V. Tyagi
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
R. Valizadeh, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G.X. Xia
UMAN, Manchester, United Kingdom
G.L. Yu
University of Manchester, Manchester, United Kingdom

Graphene has many excellent properties, such as high electron carrier mobility, good thermal conductivity and transparency etc. The secondary electron yield (SEY) of graphene with copper substrate had been studied in National Synchrotron Radiation Laboratory (NSRL) of China. The results show that the maximum SEY ('max) of 6~8 layers graphene film with copper substrates is about 1.25. Further studies indicate that many factors can affect the SEY test results. The recent SEY tests of graphene films with copper substrates in Daresbury Laboratory (DL) of UK gave the maximum SEY of as-received copper, graphene samples with copper substrates are 1.89, 1.83, and 1.68, respectively, under the incident charge per unit surface (Q) of 7.6×10^-8 C 'mm-2. Meanwhile, the SEY test parameters and measurement results of graphene in both laboratories are compared and analysed. The effect of defects on the SEY results of graphene films with copper substrate is also discussed.

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WEPIK109

Experimental Study of Vertical-Longitudinal Coupling Induced by Wakefields at CesrTA

wakefield, lattice, coupling, simulation

3200

S. Wang, J.D. Perrin, S. Poprocki, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by NSF PHY-1416318, PHYS-1068662
Transverse vertical wakefields can cause vertical beam size growth in accelerators. Here we report recent measurements and simulations of wakefields from movable scrapers at the CesrTA. The charge dependent vertical beam size growth was observed while a single scraper was inserted through the top of the chamber. No change in the beam size was observed with top and bottom scrapers inserted symmetrically. The apparent growth in the vertical beam size was due in large part to the y-z coupling (vertical crabbing) induced by the monopole wake of the asymmetric scraper configuration. We explored this y-z coupling by varying vertical betatron phase advance between the vertical beam size monitor and the scrapers. In addition, we found that existing residual, current independent y-z coupling could be compensated by the scraper wake. Predictions of a tracking simulation are in good agreement with the measurements.

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WEPIK114

Study of Electron Polarization Dynamics in the JLEIC at JLab

polarization, collider, simulation, synchrotron

3218

F. Lin, Y.S. Derbenev, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA
D.P. Barber
DESY, Hamburg, Germany

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The design of an electron polarization scheme in the Jefferson Lab Electron-Ion Collider (JLEIC) aims to attain a high longitudinal electron polarization (over 70%) at collision points as required by the nuclear physics program. Comprehensive strategies for achieving this goal have been considered and developed including injection of highly polarized electrons from CEBAF, mechanisms for manipulation and preservation of the polarization in the JLEIC collider ring and measurement of the electron polarization. In particular, maintaining a sufficiently long polarization lifetime is crucial for accumulation of adequate experimental statistics. The chosen electron polarization configuration, based on the unique figure-8 geometry of the ring, removes the electron spin-tune energy dependence. This significantly simplifies the control of the electron polarization and suppresses the synchrotron sideband resonances. This paper reports recent studies and simulations of the electron polarization dynamics in the JLEIC electron collider ring.

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WEPIK117

A Comprehensive Study of the Microwave Instability

lattice, simulation, storage-ring, vacuum

3224

A. Blednykh, B. Bacha, G. Bassi, O.V. Chubar, M.S. Rakitin, V.V. Smaluk, M. Zhernenkov
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract DE-SC0012704
Several instability thresholds and special waveform beam pattern have been observed during measurements of the horizontal beam size change vs single bunch current by the synchrotron light monitor (SLM) camera installed in a low dispersion area of the NSLS-II storage ring. The electron beam energy spread from In-Vacuum Undulator (IVU) of the Soft Matter Interfaces (SMI) beam line confirmed the microwave beam pattern behavior as a current dependent effect. The numerically obtained total longitudinal wakepotential by the GdfidL code allowed us to compare the measured results with particle tracking simulations using the SPACE code. The instability thresholds behavior at different RF voltages are in some sort of overarching agreement.

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WEPVA001

Electron Injector for Multi-Stage Laser-Driven Plasma Accelerators

laser, plasma, simulation, acceleration

3244

B. Cros, T. Audet, P. Lee, G. Maynard
CNRS LPGP Univ Paris Sud, Orsay, France
A. Chancé, O. Delferrière, A. Mosnier
CEA/DSM/IRFU, France
N. Delerue
LAL, Orsay, France
S. Dobosz-Dufrénoy, A. Maitrallain, P. Monot
CEA, Gif-sur-Yvette, France
J. Schwindling
CEA/IRFU, Gif-sur-Yvette, France
A. Specka
LLR, Palaiseau, France

Funding: LAbex PALM, Labex P2IO, Triangle de la Physique, ANR grant Equipex CILEX APOLLON, EU H2020 research and innovation programme under grant agreement No. 653782 EUPRAXIA.
An electron injector in the 50-200 MeV range, based on laser wakefield acceleration, is studied in the context of multi-stage laser plasma acceleration. Test experiments carried out at the UHI100 laser facility show that electron bunches in the 100 MeV range, generated by ionization-induced injection mechanism, and accelerated by laser driven wakefield in a mm-scale length plasma can be transported using a magnetic line and precisely analysed. A comparison with simulation results provides insights on electron dynamics and indicates ways to optimize the injector.

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WEPVA002

Simulations of DLA Grating Structures in the Frequency Domain

laser, simulation, cavity, acceleration

3247

T. Egenolf, O. Boine-Frankenheim, U. Niedermayer
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim
GSI, Darmstadt, Germany

Dielectric laser accelerators (DLA) driven by ultrashort laser pulses can reach orders of magnitude larger gradients than contemporary RF electron accelerators. A new implemented field solver based on the finite element method in the frequency domain allows the calculation of the structure constant, i.e. the ratio of energy gain to laser peak amplitude. We present the maximization of this ratio as a parameter study looking at a single grating period only. Based on this optimized shape the entire design of a beta-matched grating is completed in an iterative process. The period length of a beta-matched grating increases due to the increasing velocity of the electron when a subrelativistic beam is accelerated. The determination of the optimal length of each grating period thus requires the knowledge of the energy gain within all so far crossed periods. Furthermore, we outline to reverse the excitation in the presented solver for beam coupling impedance calculations and an estimation of the beam loading intensity limit.

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WEPVA003

Designing a Dielectric Laser Accelerator on a Chip

laser, acceleration, bunching, synchrotron

3250

U. Niedermayer, O. Boine-Frankenheim, T. Egenolf
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This work is funded by the Gordon and Betty Moore Foundation (Grant GBMF4744 to Stanford) and the German Federal Ministry of Science and Education (Grant FKZ:05K16RDB).
Dielectric Laser Acceleration (DLA) achieves gradients of more than 1GeV/m, which are among the highest in non-plasma accelerators. The long-term goal of the ACHIP collaboration* is to provide relativistic (>1 MeV) electrons by means of a laser driven microchip accelerator. Examples of slightly resonant dielectric structures showing gradients in the range of 70% of the incident laser field (1 GV/m) for electrons with β=0.32 and 200% for β=0.91 are presented. We demonstrate the bunching and acceleration of low energy electrons in dedicated ballistic buncher and velocity matched grating structures. However, the design gradient of 500 MeV/m leads to rapid defocusing. Therefore we present a scheme to bunch the beam in stages, which does not only reduce the energy spread, but also the transverse defocusing. The designs are made with a dedicated homemade 6D particle tracking code.
* https://achip.stanford.edu

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WEPVA004

Simulation of an Electromagnetic Field Excitation by a THz-pulse and Acceleration of an Electron Bunch in a Dielectric-loaded AXSIS Linac

linac, acceleration, injection, simulation

3253

K. Galaydych, R.W. Aßmann, U. Dorda, B. Marchetti, G. Vashchenko, I. Zagorodnov
DESY, Hamburg, Germany

Funding: The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 609920
The Attosecond X-ray Science: Imaging and Spectroscopy (AXSIS) experiment at DESY will use a dielectric loaded waveguide to accelerate electron bunches up to 15 MeV. Such a linac will be powered by a narrowband multicycle THz-pulse with a central frequency of 300 GHz. In this paper we focus on the reflection of the excited field at a pinhole, on the optimization of the bunch injection time and on the bunch dynamics in the acceleration process. The linac excitation by the THz-pulse and the bunch acceleration in the excited field are investigated using CST and ECHO simulations.

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WEPVA005

Simulation of a Many Period Dielectric Grating-based Electron Accelerator

laser, simulation, emittance, acceleration

3256

W. Kuropka, R.W. Aßmann, U. Dorda, F. Mayet
DESY, Hamburg, Germany
W. Kuropka, F. Mayet
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Funding: GBMF - Gordon and Betty Moore Foundation
Dielectric laser driven particle accelerators have become a research area of major interest due to the high acceleration gradients achievable. Those are mainly attributed to the high damage thresholds of dielectrics at optical frequencies. Simulations of these structures are usually computed with Particle-In-Cell (PIC) codes. Their accuracy and self consistency comes with a major drawback of high computation costs. Computation of structures consistent of hundreds to thousands of periods are only viable with High Performance Computing clusters. In this proceeding a compromise of CST* PIC simulations combined with a transfer function model is presented to simulate relativistic electron accelerators for particle energies up to the GeV regime or higher. In addition a simplified example accelerator design is investigated and the required electron bunch parameters from a sub-relativistic source are computed.
*CST - Computer Simulation Technology, available from www.
cst.com.

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WEPVA006

A Concept for Phase-Synchronous Acceleration of Microbunch Trains in DLA Structures at SINBAD

laser, acceleration, simulation, linac

3260

F. Mayet, R.W. Aßmann, J. Bödewadt, R. Brinkmann, U. Dorda, W. Kuropka, C. Lechner, B. Marchetti, J. Zhu
DESY, Hamburg, Germany
W. Kuropka, F. Mayet
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
J. Zhu
University of Hamburg, Hamburg, Germany

Funding: GBMF - Gordon and Betty Moore Foundation
The concept of dielectric laser accelerators (DLA) has gained increasing attention in accelerator research, because of the high achievable acceleration gradients (~GeV/m). This is due to the high damage threshold of dielectrics at optical frequencies. In the context of the Accelerator on a Chip International Program (ACHIP) we plan to inject electron bunches into a laser-illuminated dielectric grating structure. At a laser wavelength of 2 micro-meter the accelerating bucket is <1.5 fs. This requires both ultra-short bunches and highly stable laser to electron phase. We propose a scheme with intrinsic laser to electron synchronization and describe a possible implementation at the SINBAD facility (DESY). Prior to injection, the electron bunch is conditioned by interaction with an external laser field in an undulator. This generates a sinusoidal energy modulation that is transformed into periodic microbunches in a subsequent chicane. The phase synchronization is achieved by driving both the modulation process and the DLA with the same laser pulse. This allows scanning the electron bunch to laser phase and will show the dependence of the acceleration process on this delay.

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WEPVA007

Simulations and Plans for a Dielectric Laser Acceleration Experiment at SINBAD

laser, experiment, linac, simulation

3264

F. Mayet, R.W. Aßmann, U. Dorda, W. Kuropka, B. Marchetti, J. Zhu
DESY, Hamburg, Germany
W. Kuropka, F. Mayet
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
J. Zhu
University of Hamburg, Hamburg, Germany

Funding: GBMF - Gordon and Betty Moore Foundation
In this work we present the outline of an experimental setup for dielectric laser acceleration of relativistic electron bunches produced by the ARES linac under construction at the SINBAD facility (DESY Hamburg). The experiment will be performed as part of the Accelerator on a Chip International Program (ACHIP), funded by the Gordon and Betty Moore Foundation. At SINBAD we plan to test the acceleration of already pre-accelerated relativistic electron bunches in a laser-illuminated dielectric grating structure. In addition to the conceptual layout of the experiment we present first start-to-end simulation results for different ARES working points. The simulations are performed using a combination of the well known particle tracking code ASTRA and the self-consistent particle in cell code VSim.

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WEPVA008

Beam Dynamics in THz Dielectric Loaded Waveguides for the AXSIS Project

linac, gun, injection, emittance

3268

T. Vinatier, R.W. Aßmann, U. Dorda, B. Marchetti
DESY, Hamburg, Germany
F. Lemery
CFEL, Hamburg, Germany

In this paper, we investigate with ASTRA simulations the beam dynamics in dielectric-loaded waveguides driven by THz pulses, used as linac structure for the AXSIS project. We show that the bunch properties at the linac exit are very sensitive to the phase velocity of the THz pulse and are limited by the strong phase slippage of the bunch respective to it. We also show that some margins for instabilities of the injection phase into the linac structure are allowed. We finally demonstrate that the bunch properties are optimized when low frequencies (< 300 GHz) are used inside the linac, and that the longitudinal focal point can be put several tens of cm away from the linac exit thanks to ballistic bunching. However, a strong asymmetry in the bunch transverse sizes remains for which a solution is still to be found.

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WEPVA011

Development of a Laser Driven Dielectric Accelerator for Radiobiology Research

laser, acceleration, experiment, simulation

3272

K. Koyama, M. Yoshida
KEK, Ibaraki, Japan
Z. Chen, H. Okamoto
The University of Tokyo, Tokyo, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was supported by KAKENHI, (Grant-in-Aid for Scientific Research) Grant Number 15H03595 and partly supported by NIMS Nanofabrication Platform in Nanotechnology Platform Project sponsored by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
A laser-driven dielectric accelerator below 1 MeV is under development for applying a sub-micron size electron-beam to radiobiological research. Simulations of the electric field and electron trajectories in the proximity of the dielectric structure (transmission grating) were performed in order to fix parameters of the demonstration experiment. Serious deflection of electron beam towards the grating limited the injection phase as well as the height from the structure. The energy gain of 50-keV electron was estimated to be 1 keV in 30-micron length at the optimum condition. Transmission gratings for the experiment were fabricated by using facilities of the NIMS Nanofabrication Platform. In addition to the acceleration experiment using the simple grating, a resonator type accelerator structure was designed for exciting the acceleration field by a moderately small laser.

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WEPVA013

Small Size Neutron Generators with Laser Induced Plasma and Electron Conductivity Suppressed by Magnetic Field

laser, neutron, target, plasma

3278

V.I. Rashchikov, S.M. Polozov, A.E. Shikanov
MEPhI, Moscow, Russia

Coaxial neutron tubes generators with transverse dimension less than 0.1 m are discussed. Laser plasma containing deuterons is created at the anode by a focused laser beam. Deuterons from plasma are accelerated by pulse voltage and produces neutrons on cylindrical cathode symmetrically surrounding the anode. Magnetic field was used to suppress knock on parasitic electron current in the accelerating gap. Computer simulation with code SUMA* was fulfilled to investigate output neutron flow dependence on laser produced plasma density, magnetic fields and pulse voltage shapes and amplitudes, cathode and anode materials. The results obtained are in a good agreement with conducted experiments on diode with electron conductivity suppressed by magnetic field produced by permanent magnets**.
*V.I.Rashchikov, Problems of Atomic Science and Technology. Series: Nuclear Physics Investigations, 10(18), 50 (1990).
**A.E.Shikanov et al., Atomic energy, 119, No.4, 258 (2016).

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WEPVA016

Dielectric Laser Accelerator Investigation, Setup Substrate Manufacturing and Investigation of Effects of Laser Induced Electromigration RF Cavity Breakdown Influences

laser, acceleration, vacuum, controls

3286

M. Hamberg, M. Jacewicz, J. Ögren
Uppsala University, Uppsala, Sweden
M. Karlsson, E. Vargas Catalan
Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
M. Kuittinen, I. Vartiainen
UEF, Joensuu, Finland

Funding: I thank Stockholm Uppsala centre for FEL research for funding.
Dielectric laser acceleration (DLA) where the high electric fields in lasers are used to accelerate electrons next to nanofabricated dielectric structures has recently been proven in proof of concept studies. In this paper I describe investigations setup and substrate manufacturing. Additionally we describe using the setup for evaluating RF structure breakdown due to laser induced electromigration occurences.

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WEPVA017

Efficiency Enhancement Induced by a Precursor Electron Bunch in Quasi-Phase Matched Direct Laser Acceleration

plasma, ion, focusing, laser

3289

C.-Y. Hsieh, S.-H. Chen
NCU, Chung Li, Taiwan
I. Jovanovic
NERS-UM, Ann Arbor, Michigan, USA
M.W. Lin
National Tsing-Hua University (NTHU), Hsinchu, Taiwan

Funding: This work is supported by the Ministry of Science and Technology in Taiwan by Grant MOST 104-2112-M-008-013-MY3 and the United States Defense Threat Reduction Agency through contract HDTRA1-11-1-0009
Direct laser acceleration (DLA) of an electron bunch can be achieved by utilizing the axial field of a well-guided, radially polarized laser pulse in a density-modulated plasma waveguide*. However, the ponderomotive force of a TW-class laser pulse excites a plasma wave that can generate a defocusing electrostatic field, which significantly deteriorates the transverse properties of the injected electron witness bunch**. To improve the quality of the accelerated witness bunch, an additional leading electron bunch, termed as a precursor, is introduced to generate ion-focusing force to effectively confine the trailing witness bunch. We conducted three-dimensional particle-in-cell simulations to investigate the effect of bunch charge, transverse size of the precursor, and the axial separation between the precursor and the witness bunch on the efficacy of DLA. Results indicate that the transverse properties of the witness bunch can be maintained and the overall DLA efficiency can be improved, when a favorable ion-focusing force is provided by the precursor.
* A. G. York, et al., Phys. Rev. Lett. 100, 195001 (2008).
** M. -W. Lin et al., Phys. Plasmas 21, 093109 (2014).

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WEPVA018

Drive-Witness Acceleration Scheme Based on Corrugated Dielectric mm-Scale Capillary

acceleration, wakefield, laser, experiment

3292

K. Lekomtsev, S.T. Boogert, P. Karataev, A. Lyapin
JAI, Egham, Surrey, United Kingdom
A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
A.A. Tishchenko
MEPhI, Moscow, Russia

Funding: This project has received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179.
In this paper, we investigate a corrugated mm-scale capillary as a compact accelerating structure in a drive-witness acceleration scheme, and suggest a methodology to measure acceleration of a witness bunch. Two typical measurements and the energy gain in a witness bunch as a function of the distance between bunches are discussed. A corrugated capillary is considered as an accelerator/decelerator with an adjustable wakefield pattern depending on a transverse beam position.

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WEPVA019

Group Velocity Matching in Dielectric-Lined Waveguides and its Role in Electron-THz Interaction

acceleration, simulation, accelerating-gradient, interface

3296

A.L. Healy, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Terahertz(THz)-driven dielectric-lined waveguides have applications in electron manipulation, particularly acceleration, as the use of dielectric allows for phase velocities below the speed of light. However matching a single frequency to the correct velocity does not maximise electron-THz interaction; waveguide dispersion typically results in an unmatched group velocity and so the pulse envelope of a short THz pulse changes along the length of the structure. This reduces field amplitude and therefore accelerating gradient as the envelope propagates at a different velocity to the electron. Presented here is an analysis of the effect of waveguide dispersion on THz-electron interaction and its influence on structure dimensions and choice of THz pulse generation. This effect on net acceleration is demonstrated via an example of a structure excited by a single-cycle THz pulse, with a comparison of multi-cycle, lower intensity THz pulses on net acceleration.

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WEPVA020

Dual-Grating Dielectric Accelerators Driven by A Pulse-Front-Tilted Laser

laser, simulation, accelerating-gradient, vacuum

3299

Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
M.M. Dehler, E. Ferrari, N. Hiller, R. Ischebeck
PSI, Villigen PSI, Switzerland
J.D.A. Smith
TXUK, Warrington, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G.X. Xia
UMAN, Manchester, United Kingdom

Dual-grating Dielectric Laser-driven Accelerators (DLAs) are considered to be one of the most promising technologies to miniaturize future particle accelerators. Accelerating gradients in the GV/m range seem accessible and 690 MV/m has been demonstrated in fused silica structures. However, the increase in beam energy is limited by the short interaction length between the laser pulses and the electron bunch. In this contribution, a pulse-front-tilt operation for a laser beam is studied to extend the interaction length, resulting in a greater energy gain for a dual-grating DLA. The VSIM code is used to compare this new scheme with the commonly used approach of a normally incident laser beam and advantages are summarized.
[1]T. Plettner, et al., Phys. Rev. ST Accel. Beams 9, 111301 (2006)
[2]K. P. Wootton, et al., Opt. Lett., 41, 2696 (2016).
[3]E. A. Peralta, et al., Nature 503, 91 (2013)

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WEPVA021

Phase Space Manipulation of Sub-Picosecond Electron Bunches Using Dielectric Wakefield Structures

emittance, wakefield, FEL, simulation

3302

T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom
D.J. Dunning, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Dielectric lined waveguides have drawn interest due to their application as high gradient accelerating structures, in both externally driven and wakefield schemes. We present simulation studies of sub-picosecond electron bunches interacting with dielectric structures in the self-wake regime. The parameter space for a tunable, sub-millimeter aperture, terahertz frequency structure is investigated. The potential application as a longitudinal phase space dechirper is demonstrated, with specific application to CLARA at Daresbury Laboratory. The impact of transverse effects is considered and minimised. The resulting FEL output is simulated.

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WEPVA043

Study of the Suitability of 3D Printing for Ultra-High Vacuum Applications

vacuum, laser, radiation

3356

S. Jenzer, M. Alves, N. Delerue, A. Gonnin, D. Grasset, F. Letellier-Cohen, B. Mercier, E. Mistretta, C. Prevost
LAL, Orsay, France
A. Vion
BV Proto, Sévenans, France
J-P. Wilmes
AGS Fusion, Izernore, France

Funding: IN2P3/CNRS
In the recent year additive fabrication (3D printing) has revolutionized mechanical engineering by allowing the quick production of mechanical components with complex shapes. So far most of these components are made in plastic and therefore can not be used in accelerator beam pipes. We have investigated samples printed using a metal 3D printer to study their behavior under vacuum. We report on our first tests showing that such samples are vacuum compatible and comparing pumping time.

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WEPVA058

Development of HOM Absorber for SuperKEKB

HOM, vacuum, photon, plasma

3394

S. Terui, T. Ishibashi, Y. Suetsugu, Y. Takeuchi, K. Watanabe
KEK, Ibaraki, Japan
H. Ishizaki, A. Kimura, T. Sawhata
Metal Technology Co. Ltd., Ibaraki, Japan

Higher-order modes (HOM) absorbers are necessary components for recent high-power accelerators in order to prevent beam instabilities (e.g. HOM- Beam Break Up instabilities) or the overheating of vacuum components. Several kinds of absorber materials, such as SiC, ferrite and Kanthal, have been investigated and applied in accelerators. Among these materials, ferrite has been found to be superior to others because of its higher HOM absorbing efficiency. However, because of its low tensile strength and small thermal expansion rate, it cannot be easily bonded to other metals thus limiting its use as a HOM absorber. We reported the success of the fabrication of ferrite-copper-blocks using the spark plasma sintering (SPS)-technique last year. This year we report testing with a high-power RF source and measuring gas desorption rate after baking and secondary electron yield.

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WEPVA061

High-Precision Pattern Power Supply of Kicker Magnet for Multi-Beamline Operation at SACLA

operation, power-supply, kicker, optics

3404

C. Kondo, T. Fukui, T. Hara, T. Inagaki, Y. Otake, H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
K. Fukami
JASRI/SPring-8, Hyogo-ken, Japan
H. Kawaguchi, Y. Kawaguchi
Nichicon (Kusatsu) Corporation, Shiga, Japan
S. Nakazawa
SES, Hyogo-pref., Japan

At the Japanese XFEL facility SACLA, two XFEL beamlines (BL2 and BL3) and an injection line to the SPring-8 storage ring are switched by a kicker magnet. This multi-beamline operation has been tested since February 2015, however, CSR effects at a dogleg beam transport to BL2 with a deflecting angle of 3 degree currently limit the peak current of the electron beam. In order to suppress and cancel out the CSR effects, new beam optics is introduced for the dogleg in January 2017. In the new optics, a deflecting angle of the first kicker magnet is increased to 1.5 degree, which is three times larger than that of the old optics. To drive the kicker magnet, a high-power pattern power supply has been developed. To achieve the maximum output of 300 A and 1 kV, SiC MOSFETs are used as switching modules. The newly developed power supply can generate bipolar trapezoidal current waveforms at 60 Hz, and the amplitude and polarity of each waveform are controlled from pulse to pulse according to the beam energy and destination. The target stability is 10 ppm (peak to peak). In this presentation, we report the design and operation results of the newly developed pattern power supply.

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WEPVA067

Preliminary Results on the Resonant Excitation of THz Wakefield in a Multi-Mode Dielectric Loaded Waveguide by Bunch Train

wakefield, radiation, experiment, space-charge

3426

D. Wang, Y.-C. Du, W. Gai, W.-H. Huang, L. Niu, X.L. Su, C.-X. Tang, Q.L. Tian, L.X. Yan
TUB, Beijing, People's Republic of China
S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
Y.F. Liang
Tsinghua University, Beijing, People's Republic of China

Funding: Work supported by the National Nature Science Foundation of China (NSFC Grants No.11475097) and the National Key Scientific Instrument and Equipment Development Project of China (Grants No. 2013YQ12034504)
We report the preliminary experimental results on the resonant excitation of THz wakefield in a multi-mode dielectric loaded waveguide (DLW) by electron bunch train at the Tsinghua University accelerator beamline. The bunch train with certain longitudinal periodicity was generated based on nonlinear longitudinal space charge oscillation [1]. By passing such bunch train through a multi-mode DLW, we observed selective excitation of the fifth longitudinal mode (TM05 mode) was resonantly excited. Future experiment plan is to tune the bunch train interval with a chicane in the beamline in order to selectively excite arbitrary mode for tunable THz radiation source with multi-mode DLWs.
*wangdan16@mail.tsinghua.edu.cn
*yanlx@mail.tsinghua.edu.cn

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WEPVA071

Preliminary Conceptual Study of Next Generation Tau-Charm Factory at China

luminosity, factory, collider, positron

3436

Q. Luo
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China 11375178 and the Fundamental Research Funds for the Central Universities, Grant No WK2310000046
As BEPC II would accomplish its mission in the next decade, research on high energy science demands a successor. The luminosity of this successor should be one or two orders higher than BEPC II, while the electron beam should be longitudinal polarized at the IP. This paper discusses the feasibility and key technologies of the next tau-charm collider: a greenfield new facility or an upgrade of BEPC II.

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WEPVA075

Labview-Based Software for Electron Gun Controller

controls, software, LabView, gun

3439

Z.X. Shao, H. Gao, W. Liu, C.Y. Pan
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by the National Science Foundation of China (No: 21327901)
Instrument control can improve measurement level of automation. In the actual control of the accelerator electron gun, we need to obtain a voltage with different amplitudes for the filament. Boost and voltage regulator modules should be used in the 220V AC input conditions. In order to adjust the filament voltage and stabilize the filament current more convenient, we developed a control software based on LabVIEW.

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WEPVA097

Upgrading the SPS Fast Extraction Kicker Systems for HL-LHC

kicker, impedance, extraction, resonance

3483

M.J. Barnes, M.S. Beck, H.A. Day, L. Ducimetière, E. Garcia-Tabares Valdivieso, B. Goddard, H. Neupert, A. Romano, L. Vega Cid, W.J.M. Weterings
CERN, Geneva, Switzerland
C. Zannini
ADAM SA, Geneva, Switzerland

The CERN SPS has two fast extraction systems, each consisting of travelling wave kicker magnets (MKEs). The beam induced heating in the ferrite yoke of these magnets was historically kept to an acceptable level by implementing water cooling of the kicker magnets: in addition serigraphy was applied on the surfaces of the ferrite yoke facing the beam. Nevertheless, high intensity beams needed in the future for HL-LHC will significantly increase the beam induced heating, potentially raising the MKE ferrite yoke temperature to its Curie point. Hence detailed studies of longitudinal beam coupling impedance were carried out to identify simple but effective methods of further reducing beam induced power deposition. Based on the results of these studies, and in the framework of the LHC Injectors Upgrade (LIU) project, an upgraded MKE kicker magnet was installed during the 2015-2016 shutdown. This paper reports and compares results of predictions, laboratory measurements, temperature measurements during SPS operation, and machine development studies. Measurements of both dynamic pressure rise in the upgraded magnet and Secondary Electron Yield, on samples, are also reported.

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WEPVA100

Operational Experience of the Upgraded LHC Injection Kicker Magnets During Run 2 and Future Plans

injection, kicker, impedance, vacuum

3495

M.J. Barnes, A. Adraktas, G. Bregliozzi, L. Ducimetière, B. Goddard, B. Salvant, J. Sestak, L. Vega Cid, W.J.M. Weterings, C. Yin Vallgren
CERN, Geneva, Switzerland

During Run 1 of the LHC, one of the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, there were also sporadic issues with vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during Long Shutdown 1 (LS 1). These upgrades included a new design of beam screen to reduce both beam coupling impedance of the kicker magnet and the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. This paper presents operational experience of the injection kicker magnets during the first years of Run 2 of the LHC, including a discussion of faults and kicker magnet issues that limited LHC operation. In addition, in light of these issues, plans for further upgrades are briefly discussed.

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WEPVA105

Upgrading of Ageing CERN Underground Infrastructure to Fulfil the Space Requirements of New Facilities at CERN

monitoring, experiment, gun, interface

3510

A. Martínez Sellés, E. Carlier, V. Di Murro, B. Goddard, E. Gschwendtner, F.J. Magnin, R.F. Morton, J.A. Osborne
CERN, Geneva, Switzerland
V. Di Murro
University of Cambridge, Cambridge, United Kingdom

Particle accelerator technology is constantly being developed, and new equipment and machines replace the former ones to keep pushing the energy and intensity frontiers. Therefore, in order to meet the space requirements of new equipment, the infrastructure often needs to be modified, and given its rigid nature, this presents a challenge for the civil engineers to provide the needed space without compromising the safety and serviceability of the structures. In this paper two underground works are presented: a new cross-passage tunnel for the AWAKE experiment completed in 2014 and the future SPS Beam Dump. The challenges that must be faced are: (a) to make sure that the movements of the adjacent structures remain within admissible limits, (b) to design and execute the works such that the life span of the structure is not reduced, (c) To ensure the effectiveness of existing and new drainage systems during and after the works. For these purposes, in the frame of future tunnel asset management, the use of novel and conventional monitoring techniques plays a crucial role as it can predict in real time potential tunnel deformations which can lead, in the worst scenario, to tunnel failure

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WEPVA117

Preliminary Mechanical Design Study of the Hollow Electron Lens for HL-LHC

solenoid, cathode, proton, gun

3547

C. Zanoni, G. Gobbi, D. Perini
CERN, Geneva, Switzerland
G. Stancari
Fermilab, Batavia, Illinois, USA

A Hollow Electron Lens has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field generated by a set of solenoids. Mechanical design and integration require a preliminary knowledge of the optimal configuration of the solenoids that drive the electron trajectories. The estimation of such trajectories by means of a dedicated Matlab tool is presented. The influence of the main geometrical and electrical parameters is analysed and discussed. The main mechanical design choices are also outlined along with the concept of the electron collector. The aim of this paper is to provide an overview of the feasibility study of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar devices.

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WEPVA120

Beam Dynamics Simulation for EPU200 in TPS

emittance, storage-ring, undulator, simulation

3551

M.-S. Chiu, C.H. Chen, J.Y. Chen, P.J. Chou, T.Y. Chung, Y.-C. Liu, F.H. Tseng
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at Natioal Synchrotron Radiation Research Center (NSRRC). Five in-vacuum undulator beamlines were delivered to users on Sep. 22, 2016. To generate 10 ~ 500 eV photon with variuos polarizations, users proposed a new EPU : EPU200. In this paper, we present the preliminary results of beam dynamics simulation for EPU200.

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WEPVA136

Vacuum System for the Diamond Light Source DDBA Upgrade

vacuum, dipole, simulation, photon

3587

M.P. Cox, M.J. Duignan, R. Howard, S.C. Lay, A.G. Miller, H.S. Shiers, A. Wolfenden
DLS, Oxfordshire, United Kingdom

One cell of the Diamond Light Source (Diamond) storage ring was upgraded in late 2016 to a Double Double Bend Achromat (DDBA) configuration to provide an additional mid-achromat insertion device straight. For practical reasons it was decided to use discrete non-evaporable getter (NEG) pumps rather than NEG coatings. This paper outlines the vacuum design of the up-grade, the reasons for the choices made and the vacuum simulation tools used as well as describing the vacuum system engineering, assembly, installation and commissioning. The measured vacuum performance is found to be in close agreement with the simulations and a simple expression is derived for the beam gas lifetime.

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WEPVA145

Analysis of Mean Free Path and Field Dependent Surface Resistance

cavity, niobium, SRF, radio-frequency

3609

J.T. Maniscalco, F. Furuta, D.L. Hall, P.N. Koufalis, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF-PHY 1416318
Work from Cornell in 2016 built on recent theoretical research in the field of SRF to link the electron mean free path to the field-dependent BCS surface resistance. This research relates the magnitude of the ‘‘anti-Q-slope'', the puzzling reduction of surface resistance with increasing RF field intensity observed in certain cavities, to the doping level of nitrogen-doped niobium, quantified by the mean free path: shorter mean free paths correspond directly with stronger anti-Q-slopes. The theoretical connection comes through the overheating of the quasiparticles, which more effectively transfer their energy to the lattice at short mean free paths. In this report, we present an update of this analysis, investigating recent test results of low-temperature-doped single-cell and nine-cell cavities. We also study the theoretical implications for cavities at frequencies higher and lower than the often-studied 1.3~GHz.

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WEPVA146

Vacuum System Design and Simulation for CHESS-U

vacuum, dipole, operation, distributed

3612

Y. Li, S.T. Barrett, D.C. Burke, J.V. Conway, X. Liu, A. Lyndaker
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by National Science Foundation Reward #DMR-1332208
A major upgrade project (dubbed CHESS-U) is planned to elevate performance of Cornell High Energy Synchrotron Source (CHESS) to the state-of-art 3rd generation light sources. In the project, about 80-m of Cornell Electron Storage Ring (CESR) will be replaced with double-bend achromat (DBA) lattice to reduce electron beam emittance. In this presentation, we will describe designs of the CHESS-U vacuum system, including new beam pipe extrusions and chambers, sliding joints, and crotch absorbers. Vacuum pumping system consists of distributed pumps (in the form of NEG strips) in the dipole chambers, and compact discrete NEG/Ion pumps in the quad straight and undulator beampipes. MolFlow+ is used to evaluate pumping performances of the CHESS-U vacuum system. First, we demonstrate that the planned vacuum pumping system can achieve and sustain required ultra-high vacuum level in CHESS-U operations, after an initial beam conditioning. Second, we will explore beam commissioning processes of the new vacuum chambers, and simulate the saturation of the NEG strips during the commissioning. These simulations will aid continuing design optimization for the CHESS-U vacuum pumping system.

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WEPVA148

Dynamics of Target Motion Under Exposure of Hard Gamma Undulator Radiation

target, positron, undulator, photon

3618

A.A. Mikhailichenko
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We describe time dependent dynamics of the target motion under exposure by undulator radiation in a system for positron production. We took into account inertia of material of target. Calculations carried with help of FlexPDE code.

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WEPVA151

The eRHIC Interaction Region Magnets

quadrupole, hadron, dipole, shielding

3624

B. Parker, R.B. Palmer, H. Witte
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Designing eRHIC Interaction Region (IR) magnets faces special Machine Detector Interface challenges. Based upon HERA-II experience, a fundamental consideration is to avoid excessive background due to synchrotron radiation striking masks and septa in the vicinity of the experiment. Circumventing such radiation is problematic because the colliding beams have quite different rigidities; we must shield the e-beam from hadron IR magnet multi-tesla coil fields. On the outgoing-hadron, i.e. forward IR side, this difficulty is compounded by needing large hadron beam apertures to enable downstream separation and experimental detection of a mix of scattered and produced forward going charged particles and (in the electron-ion case) a wide-spread cone of neutrons. Here we present superconducting magnet designs with combinations of active and passive shielding and Sweet Spot coils to meet these requirements along with the design of a superferric spectrometer dipole, with an integrated cancel coil, that extends the forward experimental acceptance.

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THYA1

New Scenarios of Microbunching Instability Control in Electron Linacs and Free Electron Lasers

FEL, laser, linac, controls

3642

E. Roussel, E. Allaria, M.B. Danailov, S. Di Mitri, E. Ferrari, D. Gauthier, L. Giannessi, G. Penco, M. Veronese
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Laser-heater systems are essential tools to control and optimize high-gain free-electron lasers (FELs) working in the x-ray wavelength range. Indeed, these systems induce a controllable increase of the energy spread of the electron bunch. The heating suppresses longitudinal microbunching instability which otherwise would limit the FEL performance. We demonstrate that, through the action of the microbunching instability, a long-wavelength modulation of the electron beam induced by the laser heater at low energy can persist until the beam entrance into the undulators. This coherent longitudinal modulation is exploited to control the FEL spectral properties, in particular, multicolor extreme-ultraviolet FEL pulses can be generated through a frequency mixing of the modulations produced by the laser heater and the seed laser in the electron beam. We present an experimental demonstration of this novel configuration carried out at the FERMI FEL.
*E. Roussel et al., Phys. Rev. Lett. 115, 214801 (2015)

Slides THYA1 [14.837 MB]

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THOAB1

Study of Medical Applications of Compact Laser-Compton Light Source

laser, synchrotron, radiation, scattering

3656

Y. Hwang, T. Tajima
UCI, Irvine, California, USA
G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Compton scattering of laser photons by a relativistic electron beam produces monoenergetic, tunable and small source size X-rays similar to synchrotron light sources in a very compact setting, due to the shorter undulator period of lasers. These X-ray sources can bring to every hospitals advanced radiology and radiotherapy that are currently only being conducted at synchrotron facilities. Few examples include phase contrast imaging utilizing the micron-scale source size, K-edge subtraction imaging from two monoenergetic X-rays at different energies and radiation therapy using radiosensitization of high-Z nanoparticles. At LLNL, 30 keV X-rays have been generated from the 30 MeV X-band linac, and the X-rays have been characterized and agree with the modeling very well. This source is being used to study the feasibility of aforementioned medical applications. Experimental setup of K-edge subtraction of contrast agents are presented, demonstrating the low-dose, high-contrast imaging potential of the light source. Plans to study enhanced radiotherapy using Gold nanoparticles with the upgrade of the machine to higher energies are discussed.

Slides THOAB1 [2.818 MB]

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THPAB001

Microbunching Instability as a Caustic Phenomenon

radiation, linac, bunching, synchrotron

3676

T.K. Charles, D.M. Paganin
Monash University, Faculty of Science, Clayton, Victoria, Australia
M.J. Boland
The University of Melbourne, Melbourne, Victoria, Australia
M.J. Boland, R.T. Dowd
SLSA, Clayton, Australia

Microbunching instability if left alone, threatens to degrade the beam quality of high brightness electron beams in Free Electron Lasers. Recently, caustic formation in electron trajectories was identified as a mechanism describing current modulations in accelerated particle beams. Here we consider CSR-induced microbunching as a caustic phenomenon. This analysis reports on the influence of longitudinal dispersion, R56, on the microbunching process, as well as elucidating the influence of the second and third order longitudinal dispersion values, T566 and U5666.

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THPAB006

Nuage, Ion Cloud Tracker

ion, simulation, storage-ring, injection

3692

A. Gamelin, C. Bruni, D. Radevych
LAL, Orsay, France

Funding: Work is supported by ANR-10-EQPX-51, by grants from Région Ile-de- France, IN2P3 and Pheniics Doctoral School.
NUAGE is a data parallel Matlab code which simulates the ion cloud effect in electron storage rings. The ion cloud is tracked in the ring taking into account the transverse and longitudinal effect of the beam-ion interaction, tracking in magnetic elements, usage of electrodes and gaps as clearing means. This program has been used to compute ionised ion equilibrium state and its neutralisation factor. In this article the NUAGE code is presented. The model, analysis method and performances are discussed.

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THPAB009

Multi-Objective Optimization of an SRF Photoinjector for ERL and UED Applications

gun, laser, SRF, emittance

3704

E. Panofski, A. Jankowiak, T. Kamps, G. Kourkafas
HZB, Berlin, Germany
S. Eisebitt
MBI, Berlin, Germany

Superconducting RF photoinjectors, running in continuous-wave (cw) mode, are able to generate electron beams of high average brightness and ultra-short bunches. Therefore, they satisfy the requirements of future accelerator facilities, such as energy recovery linacs (ERL). Further, SRF guns are able to provide relativistic probe beams for ultrafast electron diffraction (UED). Choosing suitable values for the drive laser, cavity and solenoid settings poses a great challenge for the injector commissioning and operation. Using multi-objective optimization based on an evolutionary algorithm, optimum gun parameter settings are extracted from Pareto-optimum solutions. The development of a universal multi-objective optimization algorithm for SRF photoinjectors as well as first Pareto optimum results for an ERL and UED application of GunLab, the compact SRF gun test facility at Helmholtz-Zentrum Berlin, will be presented.

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THPAB012

Beam Transport Optimization for Applying an SRF Gun at the ELBE Center

gun, SRF, linac, radiation

3712

P.N. Lu, A. Arnold, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
HZDR, Dresden, Germany

An SRF gun at the ELBE center has been operated with a magnesium cathode. Electron beams were produced with a maximum bunch charge of 200 pC and an emit-tance of 7.7 μm. Simulations have been conducted with ASTRA and Elegant for applying the SRF gun to ELBE user experiments, including neutron beam generation, positron beam generation, THz radiation and Compton backscattering experiment. Beam transport has been optimized to solve the best beam performance for these user stations at the bunch charge of 200 pC. Simulation results indicate that the SRF gun is potential to benefit the high bunch charge applications at ELBE.

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THPAB014

An Adaptive Mesh-Based Method for the Efficient Simulation of LSC-Driven Microbunching Gain in FEL Applications

FEL, bunching, acceleration, simulation

3720

Ph. Amstutz
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
M. Vogt
DESY, Hamburg, Germany

Electron beams with high peak current as they are required for the operation of free-electron lasers (FELs) are often generated by means of a series of magnetic bunch compressors. In conjunction with a collective coherent force, e.g. longitudinal space-charge (LSC), bunch compressors can possibly cause a wavelength dependent amplification of initial density inhomogeneities, potentially to an extent detrimental to the operation of the FEL. A common model, consisting of LSC, acceleration (kicks), and magnetic chicanes (drift-type maps), is governed by a time-discrete Vlasov-Poisson system. Such systems have been successfully simulated using mesh based representations of the phase space density (PSD) and the method of characteristics for the update step. However, for the irregular and exotic PSDs, prevalent in FEL applications, a homogeneous high resolution discretization on a naive rectangular mesh can be prohibitively wasteful. Here we present an approach based on adaptive tree refinement that addresses the complexity of the PSDs and allows for the efficient simulation of LSC-driven micro-bunching in FELs.

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THPAB016

Investigation on the Ion Motion Towards Clearing Electrodes in an Accelerator

ion, simulation, linac, software

3723

G. Pöplau
COMPAEC e.G., Rostock, Germany
A. Meseck
HZB, Berlin, Germany

High brightness beams provided by linac-based accelerators require several measures to preserve their high quality and to avoid instabilities, where the mitigation of the impact of residual ions is one of these measures, in particular if high repetition rates are aimed for. Over the last decade three ion-clearing strategies: clearing electrodes, bunch gaps and beam shaking have been applied to counteract the degrading impact of the ions on the electron beam. Currently, their merit as clearing strategies for next generation high brightness accelerators such as energy recovery linacs (ERLs) are under intensive investigations with both simulations and measurements. In this paper, we present numerical studies for the behavior of ions generated by electron bunch passages within the field of electrodes. The objective is to investigate the ion motion towards the electrodes and to study under which circumstances and up to which ratio, equilibrium between ion generation and ion-clearing is established. Hereby several ion species and shapes of electrodes are considered with typical parameters of future high current linacs.

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THPAB017

Investigation of High Repetition Rate Femtosecond Electron Diffraction at PITZ

laser, gun, emittance, experiment

3727

H.J. Qian, M. Groß, M. Krasilnikov, A. Oppelt, F. Stephan
DESY Zeuthen, Zeuthen, Germany

PITZ is a photoinjector test facility for FLASH and European XFEL, and it has been proposed to be a prototype machine to develop an accelerator based THz/IR source for European XFEL pump-probe experiment. In addition, the machine can also support femtosecond electron diffraction at the same beam repetition rate as European XFEL, which brings XFEL users more flexibility for different experiments. In this paper, a femtosecond electron diffraction scheme based on the PITZ accelerator setup is investigated.

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THPAB021

Wake Field and Head-Tail Instability in Beam-Beam Collision with a Large Crossing Angle

wakefield, positron, simulation, dipole

3738

K. Ohmi, D. Zhou
KEK, Ibaraki, Japan
N. Kuroo
UTTAC, Tsukuba, Ibaraki, Japan
K. Oide, F. Zimmermann
CERN, Geneva, Switzerland

Head-tail type of coherent beam-beam instability has been seen in a strong-strong beam-beam simulation for collision with a large Piwinski angle σ_zθ/σ_x>>1, where θ is a half crossing angle. Beta x* is key parameter for the instability. The instability is not serious for SuperKEKB, but can be seen in phase II commissioning stage. It has a large impact for design of FCC-ee. We introduce wake field due to the beam-beam collision. The wake field gives turn-by-turn correlation of head-tail mode. Head-tail instability caused by the wake field explains that seen in the strong-strong beam-beam simulation.

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THPAB023

The Influence of Initial Current Density Distribution on the Emittance Reduction

emittance, cathode, gun, flattop

3744

H. Yamashita, T. Kii, K. Masuda, K. Nagasaki, T. Nogi, H. Ohgaki, K. Torgasin, H. Zen
Kyoto University, Kyoto, Japan

In this study, the influence of current density distribu-tion on the cathode surface on the beam emittance evolution was investigated. The emittance evolution with different beam profiles (flat-top, peak and hollow distribution) have been compared. The modification of the current profile was shown to affect the axial distance of the point of minimal emittance over wide range. The hollow profile allows extending the axial distance of the point of emittance minimum keeping its value extremely low. Further the parameters of a peak profile, which give the smallest emittance were determined. This work demonstrates the significance of initial current density distribution for the emittance evolution.

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THPAB031

Study of Beam Break Up in Irradiation Linacs

wakefield, linac, experiment, simulation

3767

X.C. Meng, H.B. Chen, W. Gai, J. Shi, S.X. Zheng
TUB, Beijing, People's Republic of China
G.H. Li, J.S. Liu, Y.H. Liu
NUCTECH, Beijing, People's Republic of China
F.H. de Sá
LNLS, Campinas, Brazil

Many recent experiments of the irradiation linacs produced at Tsinghua University indicate that beam power is limited by beam break up (BBU). Limits exist while the beam current or the pulse width is increased. In this paper, we illustrate the bream break up (BBU) phenomenon in the cases of both the 10MeV travelling-wave linac and 10MeV backward travelling-wave linac. The higher order modes in the linacs are analysed and the wake fields are calculated both with theoretical analysis and numerical simulation. Also, the beam dynamics is studied on the basis of the wakefield results to find a BBU threshold in these structures.

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THPAB036

An Experimental Study of Beam Dynamics in the ERL-Based Novosibirsk Free Electron Laser

radiation, FEL, diagnostics, synchrotron

3781

V.M. Borin, L.M. Schegolev, O.A. Shevchenko, N.A. Vinokurov
BINP SB RAS, Novosibirsk, Russia
V.L. Dorokhov, O.I. Meshkov
BINP, Novosibirsk, Russia

Transverse and longitudinal dynamics of the electron beam of the Novosibirsk infrared Free Electron Laser is studied. The Novosibirsk FEL is based on the multi-turn energy recovery linac (ERL). The ERL operate in CW mode with an average current about 10 mA. Therefore non-destructive beam diagnostics is preferable. The beam energy at the last track of the ERL is 42 MeV. As a result, significant part of synchrotron radiation from bending magnets is in the visible range. The transverse beam dimensions were measured with the optical diagnostics before and after the undulator applied for generation of middle-infrared coherent radiation. The obtained data is used to calculate the beam energy spread and emittance. The longitudinal beam dynamics was studied with electro-optical dissector.

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THPAB041

Implementation of Hollow Electron Lenses in SixTrack and First Simulation Results for the HL-LHC

simulation, collimation, octupole, proton

3795

M. Fitterer, R. De Maria, S. Redaelli, K.N. Sjobak, J.F. Wagner
CERN, Geneva, Switzerland
G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy.
Electron lenses have found a wide range of applications for hadron colliders, where the main applications are machine protection and beam-beam compensation. This paper summarizes the status of the current electron lens implementation in SixTrack with the focus on hollow electron beams for beam collimation and shows some first simulation results of the High-Luminosity upgrade of the LHC (HL-LHC).

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THPAB043

Evolution of Python Tools for the Simulation of Electron Cloud Effects

simulation, interface, hadron, toolkit

3803

G. Iadarola, E. Belli, K.S.B. Li, L. Mether, A. Romano, G. Rumolo
CERN, Geneva, Switzerland

PyECLOUD was originally developed as a tool for the simulation of electron cloud build-up in particle accelerators. Over the last five years the code has become part of a wider set of modular and scriptable python tools that can be combined to study different effects of the e-cloud in increasingly complex scenarios. The Particle In Cell solver originally included in PyECLOUD later developed into a stand-alone general purpose library (PyPIC) that now includes advanced features like a refined modeling of curved boundaries and optimized resolution based on the usage of nested grids. The effects of the e-cloud on the beam dynamics can be simulated interfacing PyECLOUD with the PyHEADTAIL code. These simulations can be computationally very demanding due to the multi-scale nature of this kind of problems. Hence, a dedicated parallelization layer (PyPARIS) has been recently developed to profit of parallel computing resources in order to significantly speed-up the computation.

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THPAB047

New Features of the 2017 SixTrack Release

simulation, collimation, HOM, coupling

3815

K.N. Sjobak, J. Barranco García, R. De Maria, E. McIntosh, A. Mereghetti
CERN, Geneva, Switzerland
M. Fitterer
Fermilab, Batavia, Illinois, USA
V. Gupta
IIT, Guwahati, Assam, India
J. Molson
LAL, Orsay, France

The SixTrack particle tracking code is routinely used to simulate particle trajectories in high energy circular machines like the LHC and FCC, and is deployed for massive simulation campaigns on CERN clusters and on the BOINC platform within the LHC@Home volunteering computing project. The 2017 release brings many upgrades that improve flexibility, performance, and accuracy. This paper describes the new modules for wire- and electron lenses (WIRE and ELEN), the expert interface for beam-beam element (BEAM/EXPERT), the extension of the number of simultaneously tracked particles, the new Frequency Map Analysis (FMA) postprocessing option, the generation of a single zip of selected output files (ZIPF) in order to extend the coverage of the studies in LHC@HOME (e.g. FMA and on-line aperture checks), coupling to external codes (DYNK-PIPE and BDEX), a new CMAKE based build- and test mechanism, and internal restructuring.

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THPAB050

Simulations of Beam-Beam Interactions With RF-Track for the AWAKE Primary Beam Lines

proton, simulation, plasma, space-charge

3823

J.S. Schmidt, A. Latina
CERN, Geneva, Switzerland

The AWAKE project at CERN will use a high-energy proton beam at 400 GeV/c to drive wake'elds in a plasma. The amplitude of these wake'elds will be probed by injecting into the plasma a low-energy electron beam (10-20 MeV/c), which will be accelerated to several GeV. Upstream of the plasma cell the two beams will either be transported coaxially or with an o'set of few millimetres for about 6 m. The interaction between the two beams in this beam line has been investigated in the past, with a dedicated simulation code tracking particles under the in'uence of direct space-charge e'ects. These simulations have recently been crosschecked with a new simulation code called RF-Track, developed at CERN to simulate low energy accelerators. RF-Track can track multiple-specie beams at arbitrary energies, taking into account the full electromagnetic particle-to-particle inter-action. For its characteristics RF-Track seems an ideal tool to study the AWAKE two-beam interaction. The results of these studies are presented in this paper and compared to the previous results. The implications for the facility performance are discussed.

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THPAB053

Laser Heater Deisgn for the CLARA FEL Test Facility

laser, undulator, FEL, dipole

3833

A.D. Brynes, S.P. Jamison, B.D. Muratori, N. Thompson, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.P. Jamison, B.D. Muratori, N. Thompson, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom

We present considerations of microbunching studies in the CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility under construction at Daresbury Laboratory. CLARA, a high-brightness electron linac, presents an opportunity to study the microbunching instability. A number of theoretical models have been proposed concerning the causes of this instability, and it has also been observed at various FEL facilities. We have applied these models to the CLARA FEL, and propose a suitable laser heater design which will provide flexibility in terms of the range of modes of operation for CLARA. We also propose a method for inducing and controlling the microbunching instability via pulse stacking of the photoinjector laser.

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THPAB058

PyZgoubi Simulations of the CBETA Lattice

lattice, closed-orbit, dipole, framework

3847

S.C. Tygier
UMAN, Manchester, United Kingdom
C.E. Mayes
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
F. Méot, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by New York State Energy Research and Development Authority (NYSERDA)
The Cornell-BNL Electron Test Accelerator CBETA is a 4 pass up, 4 pass down energy recovery linac using Fixed-Field Alternating-Gradient (FFAG) recirculation arcs with a top energy of 150 MeV. We present lattice implemented in the tracking code pyZgoubi, with both hard edge and field map magnet versions. We also describe the recent developments in pyZgoubi such as importing lattice tables from other tracking codes.

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THPAB059

CSR and Space Charge Studies for the CLARA Phase 1 Beamline

dipole, simulation, linac, space-charge

3851

B.S. Kyle, R.B. Appleby
UMAN, Manchester, United Kingdom
J.K. Jones, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.J. de Loos, S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

The installation of Phase 1 of CLARA, the UK's new FEL test facility, is currently underway at Daresbury Laboratory. When completed, it will be able to deliver 45 MeV electron beams to the pre-existing VELA beamline, which runs parallel. Phase 1 consists of a 10 Hz photocathode gun, a 2 m long S-band travelling wave linac, a spectrometer line, and associated optics and diagnostics. A detailed study into the beam dynamics of the lattice is presented, with a focus towards the effects of space charge and coherent synchrotron radiation on the electron bunch. Simulations disagreed with predictions from a one-dimensional model of coherent radiation, and this disagreement is believed to be due to a violation of the Derbenev criterion.

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THPAB066

Modeling Cathode Roughness, Work Function, and Field Enhancement Effects on Electron Emission

emittance, simulation, scattering, photon

3869

D.A. Dimitrov, G.I. Bell, D.N. Smithe, S.A. Veitzer
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, J. Smedley
BNL, Upton, Long Island, New York, USA
J. Feng, S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences under grant DE-SC0013190.
Recent developments in material design and growth have resulted in photocathodes that can deliver high quantum efficiency and are sufficiently robust to use in high electric field gradient photoinjectors and free electron lasers. The growth process usually produces photoemissive material layers with rough surface profiles that lead to transverse accelerating fields and possible work function variation resulting in emittance growth. To better understand the effects of surface roughness on emitted electron beams, we have developed realistic three-dimensional models for photocathode materials with grated surface structures. They include general modeling of electron excitation due to photon absorption, charge transport and emission from rough surfaces taking into account image charge and field enhancement effects. We implemented these models in the VSim particle-in-cell code. We report results from simulations using different photocathode materials with grated and flat surfaces to investigate how controlled roughness, work function variation, and field enhancement affect emission properties.

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THPAB072

Application of Voronoi Diagram to Mask-Based Intercepting Phase-Space Measurements

emittance, linac, experiment, laser

3872

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
Q. Gao, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
Q. Gao
TUB, Beijing, People's Republic of China
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
P. Piot
Fermilab, Batavia, Illinois, USA

Intercepting multi-aperture masks (e.g. pepper pot or multislit mask) combined with a downstream transverse-density diagnostics (e.g. based on optical transition radiation or employing scintillating media) are commonly used for characterizing the phase space of charged particle beams and the associated emittances. The required data analysis relies on precise calculation of the RMS sizes and positions of the beamlets originated from the mask which drifted up to the analyzing diagnostics. Voronoi diagram is an efficient method for splitting a plane into subsets according to the distances between given vortices. The application of the method to analyze data from pepper pot and multislit mask based measurement is validated via numerical simulation and applied to experimental data acquired at the Argonne Wakefield Accelerator facility. We also discuss the application of the Voronoi diagrams to quantify transversely-modulated beams distortion.

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THPAB073

Magnetized and Flat Beam Experiment at FAST

emittance, quadrupole, radiation, cathode

3876

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Hyun
Sokendai, Ibaraki, Japan
D. Mihalcea, P. Piot, T. Sen, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA

A photocathode, immersed in solenoidal magnetic field, can produce canonical-angular-momentum (CAM) dominated electron beams. Such beams have an application in electron cooling of hadron beams and can also be uncoupled to yield asymmetric-emittance (flat) beams. In the present paper we explore the possibilities of the flat beam generation at Fermilab's Accelerator Science and Technology (FAST) facility linear accelerator. We present optimization of the beam flatness and four-dimensional transverse emittance and investigate the mapping and its limitations of the produced eigen-emittances to conventional emittances using a skew-quadrupole channel. Possible application of flat beams at the FAST facility are also discussed.

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THPAB074

MuSim, a Graphical User Interface for Multiple Simulation Programs

simulation, interface, proton, storage-ring

3880

T.J. Roberts, R.J. Abrams, M.A. Cummings
Muons, Inc, Illinois, USA
Y. Bao
UCR, Riverside, California, USA

MuSim is a user-friendly program designed to interface to many different particle simulation codes, regardless of their data formats or geometry descriptions. It presents the user with a compelling graphical user interface that includes a flexible 3-D view of the simulated world plus powerful editing and drag-and-drop capabilities. All aspects of the design can be parameterized so that parameter scans and optimizations are easy. It is simple to create plots and display events in the 3-D viewer, allowing for an effortless comparison of different simulation codes. Simulation codes: G4beamline 3.02, MCNP 6.1, and MAD-X; more are coming. Many accelerator design tools and beam optics codes were written long ago, with primitive user interfaces by today's standards. MuSim is specifically designed to make it easy to interface to such codes, providing a common user experience for all, and permitting the construction and exploration of models with very little overhead. For today's technology-driven students, graphical interfaces meet their expectations far better than text-based tools, and education in accelerator physics is one of our primary goals.

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THPAB078

Beam Dynamics Studies of the Transverse Gradient Undulator and Its Application to Suppression of Microbunching Instability

FEL, undulator, focusing, laser

3895

T. Liu, Y. Ding, Z. Huang, W. Qin
SLAC, Menlo Park, California, USA
T. Liu
University of Chinese Academy of Sciences, Beijing, People's Republic of China
T. Liu, D. Wang
SINAP, Shanghai, People's Republic of China

A transverse gradient undulator (TGU) which was initially proposed for high gain free electron lasers (FELs) driven by electron beams with relatively large energy spread, can be extended to the application of beam dynamics, such as phase-merging enhanced harmonic generation FEL and suppression of microbunching instability. In this contribution we present beam dynamics studies of the TGU, analyze the resulting focusing and dispersion, and discuss the effects of an additional corrector on the TGU. As an application to beam dynamics, we show a feasible transport system based on the TGU as a reversible electron beam heater to suppress the microbunching instability of the electron beam.

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THPAB079

Terahertz Chirper for the Bunch Compression of Ultra-Low Emittance Beams

emittance, coupling, dipole, laser

3899

A.R. Vrielink, A. Marinelli, E.A. Nanni
SLAC, Menlo Park, California, USA

Recent efforts have demonstrated the possibility of achieving ultralow transverse emittance beams for high brightness light sources and free electron lasers*. While these lower emittances should translate to improved lasing efficiency and higher peak brightness in FELs, these beams are commensurately more vulnerable to coherent synchrotron radiation (CSR) for the selfsame reasons. Conserving these ultralow emittances through the bunch compressors in an FEL given their increased propensity to emit CSR is particularly challenging. We investigate the possibility of imposing a large energy chirp at terahertz wavelengths to reduce the required magnetic fields in the compressor, counteracting the ultralow emittance in the generation of CSR. A second, higher frequency THz chirper would then be used to dechirp the beam after the chicane. Operation at THz as opposed to conventional radiofrequencies offers significantly larger chirp at similar input powers, yet still with wavelengths greater than typical FEL bunch lengths (several femtoseconds). Potential experimental schemes will be suggested in the context of LCLS and their feasibility evaluated.
* S. Bettoni, M. Pedrozzi and S. Reiche, Phys. Rev. ST Accel. Beams. 18, 123403 (December, 2015).

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THPAB080

Estimations of Coherent Instabilities for JLEIC

impedance, ion, proton, collider

3903

R. Li
JLab, Newport News, Virginia, USA

Funding: Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177
JLEIC is the medium energy electron-ion collider currently under active design at Jefferson Lab*. The design goals of JLEIC are both high luminosity (1033-1034 cm^-2ses⁻¹) and high polarization (>70%) for the electron and light ion beams, for a wide range of electron and ion beam energies and for a wide spectrum of ion species. The unprecedented luminosity goal for this electron-ion collider sets strong requirements for the understanding and management of potential collective effects in JLEIC. In this paper, we present preliminary estimations of single and coupled bunch coherent instabilities for the electron and proton beams at collision energies for the JLEIC design. Further improvement of the estimations and mitigation methods are discussed.
* MEIC design summary, http://arxiv.org/ftp/arxiv/papers/1504/1504.07961.pdf, (2015).

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THPAB082

The Beam-Beam Effect and Its Consequences for the Modeling of the Jefferson Lab EIC

proton, beam-beam-effects, emittance, collider

3909

E.W. Nissen
JLab, Newport News, Virginia, USA

Funding: Notice: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy
In this work we address the effect of beam jitter on emittance growth as caused by the beam-beam effect on the Jefferson Lab Electron Ion Collider (JLEIC). This proposed collider would collide up to 100 GeV proton beams with up to 10 GeV electron beams. Due to the asymmetric rigidities of the beams and their non-linear lensing action on each other during a collision, collective effects can limit beam storage times. Using simulations we determined that one of JLEIC's synchronization concepts would require a new set of software tools to accurately understand phase space evolution.

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THPAB086

Long-Term Simulations of Beam-Beam Dynamics on GPUs

GPU, simulation, collider, beam-beam-effects

3918

B. Terzić, C.M. Cotnoir, A.L. Godunov, T. Satogata, M. Stefani
ODU, Norfolk, Virginia, USA
A. Arumugam, R.T. Majeti, D. Ranjan, M. Zubair
ODU CS, Norfolk, Virginia, USA
F. Lin, V.S. Morozov, E.W. Nissen, Y. Roblin, T. Satogata, H. Zhang
JLab, Newport News, Virginia, USA

Funding: Jefferson Lab
Future machines such as the electron-ion colliders (JLEIC), linac-ring machines (eRHIC) or LHeC are particularly sensitive to beam-beam effects. This is the limiting factor for long-term stability and high luminosity reach. The complexity of the non-linear dynamics makes it challenging to perform such simulations which require millions of turns. Until recently, most of the methods used linear approximations and/or tracking for a limited number of turns. We have developed a framework which exploits a massively parallel Graphical Processing Units (GPU) architecture to allow for tracking millions of turns in a sympletic way up to an arbitrary order and colliding them at each turn. The code is called GHOST for GPU-accelerated High-Order Symplectic Tracking. As of now, there is no other code in existence that can accurately model the single-particle non-linear dynamics and the beam-beam effect at the same time for a large enough number of turns required to verify the long-term stability of a collider. Our approach relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for the beam-beam interaction.

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THPAB087

Emittance Measurements and Simulations in 112 MHz Super-Conducting RF Electron Gun With CsK2Sb Photo-Cathode

emittance, gun, solenoid, SRF

3921

K. Mihara
Stony Brook University, Stony Brook, USA
D. Kayran, V. Litvinenko, T.A. Miller, I. Pinayev
BNL, Upton, Long Island, New York, USA

The commissioning of the coherent electron cooling (CeC) proof of principle experiment is under way at Relativistic Heavy Ion Collider (RHIC).. A 112 MHz superconducting radio frequency photo-emission gun is used to generate the electron beam for this experiment. In this paper we report selected results of experimental emittance measurements and compare them with our simulations.

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THPAB088

Comparison of Theory, Simulation, and Experiment for Dynamical Extinction of Relativistic Electron Beams Diffracted Through a Si Crystal Membrane

simulation, scattering, experiment, emittance

3924

L.E. Malin, W.S. Graves, J. Spence, C. Zhang
Arizona State University, Tempe, USA
R.K. Li, C. Limborg, E.A. Nanni, X. Shen, S.P. Weathersby
SLAC, Menlo Park, California, USA

Diffraction in the transmission geometry through a single-crystal silicon slab is exploited to control the intensity of a relativistic electron beam. The choice of crystal thickness and incidence angle can extinguish or maximize the transmitted beam intensity via coherent multiple Bragg scattering; thus, the crystal acts as a dynamical beam stop through the Pendel'sung effect, a well-known phenomenon in X-ray and electron diffraction. In an initial experiment, we have measured the ability of this method to transmit or extinguish the primary beam and diffract into a single Bragg peak. Using lithographic etching of patterns in the crystal we intend to use this method to nanopattern an electron beam for production of coherent x-rays. We compare the experimental results with simulations using the multislice method to model the diffraction pattern from a perfect silicon crystal of uniform thickness, considering multiple scattering, crystallographic orientation, temperature effects, and partial coherence from the momentum spread of the beam. The simulations are compared to data collected at the ASTA UED facility at SLAC for a 340 nm thick Si(100) wafer with a beam energy of 2.35 MeV.

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THPAB092

Orbit and Dispersion Tool at European XFEL Injector

laser, dipole, quadrupole, GUI

3932

N. Ghazaryan
CANDLE SRI, Yerevan, Armenia
M.E. Castro Carballo, W. Decking
DESY, Hamburg, Germany

Trajectory and electron beam size play an essential role in Free Electron Laser (FEL) obtainment. Since transverse dispersion changes off-energy particle trajectories and increases the effective beam size, dispersion and orbit must constantly be controlled and corrected along the whole lattice. In this paper the principles underlying the orbit and dispersion correction tool, developed at DESY, are described. The results of its testing on European XFEL injector are presented.

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THPAB093

Synchronization of a Photo-Injector and a High Power Laser With Independent Clocks

laser, plasma, gun, feedback

3935

N. Delerue, C. Bruni, K. Cassou, V. Chaumat, R. Chiche, D. Douillet, N. ElKamchi, S. Jenzer, V. Kubytskyi, P. Lepercq, H. Purwar, H. Roesch
LAL, Orsay, France
E. Baynard, M. Pittman
CLUPS, Orsay, France
J. Demailly, O. Guilbaud, S. Kazamias, G. Maynard, O. Neveu, D. Ros
CNRS LPGP Univ Paris Sud, Orsay, France
D. Garzella
CEA, Gif-sur-Yvette, France
R. Prazeres
LCP/CLIO, Orsay, Cedex, France

Funding: LAL/IN2P3/CNRS and Université Paris-Sud
The plasma acceleration project ESCULAP (ElectronS CoUrts pour L'Acc\'el\'eration Plasma) aims at studying electrons injection into a laser plasma accelerator. This requires the injection of short electron bunches generated by the photo injector PHIL (Photo injector at LAL) into a plasma wave by the high power femtosecond Laser LASERIX. As a first step we have studied how to synchronize PHIL and LASERIX. As these two machines had not been initially designed to work together, simple synchronization solutions were not available. We detail here the synchronisation scheme that we have tested and the experimental results obtained.

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THPAB108

Femtosecond Optical Synchronization System for the European XFEL

laser, timing, FEL, free-electron-laser

3969

C. Sydlo, M. Felber, C. Gerth, T. Kozak, T. Lamb, J.M. Müller, H. Schlarb, F. Zummack
DESY, Hamburg, Germany

Accurate timing synchronization on the femtosecond timescale is an essential installation for time-resolved experiments at free-electron lasers (FELs) such as FLASH and the upcoming European XFEL. Conventional RF timing systems suffer from RF attenuation for such long distances and have reached to date a limit for synchronization precision of around 100 femtoseconds. An optical synchronization system is used at FLASH and is based on the distribution of femtosecond laser pulses over actively stabilized optical fibers. The upcoming European XFEL has raised the demands due to its large number of stabilized optical fibers and a length of 3400 m. The increased lengths for the stabilized optical fibers necessitated major advancement in precision to achieve the requirement of less than 10 femtosecond precision. This paper reports on the status of the laser-based synchronization system at the European XFEL.

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THPAB109

Fs Level Laser-to-RF Synchronization at REGAE

laser, timing, detector, electronics

3972

M. Titberidze, M. Felber, T. Lamb, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
R.A. Loch
MPSD, Hamburg, Germany

The Relativistic Electron Gun for Atomic Exploration (REGAE) is a unique linear accelerator capable of producing ultrashort (~ 10 fs) electron bunches for studying fast processes in matter by means of ultrafast electron diffraction (UED) experiments. Additionally, REGAE is suitable for upcoming external injection experiments for laser wakefield acceleration (LWFA). In order to carry out both mentioned experiments, it is crucial to achieve fs level stability in terms of Laser-to-RF synchronization. In this paper we present an advanced laser-to-RF synchronization scheme based on integrated Mach-Zehnder modulator. The setup demonstrated the Titanium Sapphire photo-injector laser synchronization with 11 fs (rms) precision in the bandwidth up to 100 kHz. Long term timing drift measurements showed unprecedented peak-to-peak stability of 31 fs (7 fs rms) over 43 hours of measurement time. In addition, AM-PM coefficient of the MZM based laser-to-RF synchronization setup has been evaluated and showed a factor of 10 improved performance compared to conventional direct conversion based laser synchronization setup.

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THPAB111

Sub-Femtosecond Jitter Ultra High Performance Oscillators for Accelerator Timing

controls, coupling, cavity, impedance

3979

A. Gronefeld
Ingenieurbüro Gronefeld, Herten, Germany

Extremely stable RF-Sources are at the heart of Electron Beam Accelerators and impact beam quality and beam energy. Jitter requirements on those sources are very tight and linked to the quest of ever decreasing (XFEL) laser pulse length, currently in the tens of femtoseconds. For the Pohang Accelerator Laboratory in Pohang/Korea, a 2.856GHz phase-lockable oscillator with a jitter performance of 0.8fS (10kHz..10MHz) was developed and deployed, together with a master oscillator that supplies rubidium-stabilized 476MHz for synchronization. In terms of phase noise, these 2.856GHz oscillators exhibit -125dBc/Hz@1kHz, -145dBc/Hz@10kHz and -165dBc/Hz@100kHz offset, while reaching a noise floor of -180dBc/Hz. Using the same technology of a dielectric resonator oscillator, a 3.9GHz source was developed for the European XFEL at DESY/Hamburg, achieving 0.3fS (10kHz/10MHz). Phase noise is down to -125dBc/Hz@1kHz, -155dBc/Hz@10kHz and -175dBc/Hz@100kHz offset, with a noise floor of -180dBc/Hz. The strategy of designing ultra low phase-noise sources with dielectric resonators is outlined, and challenges and limitations within the oscillator design, but also measurement technology are presented.

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THPAB119

Study on a Time-Domain Spectroscopy System for Coherent Terahertz Pulse Spectrum Measurement from 5 MeV Electron Beam

laser, radiation, polarization, detector

4003

R. Yanagisawa, T. Toida
Waseda University, Tokyo, Japan
K. Kan
ISIR, Osaka, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan

Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083.
Terahertz wave, expected to apply spectral analysis and imaging, has recently developed both source and detector components. For the terahertz source, the coherent radiation from electron linac is expected to be the high power terahertz source. At Waseda University, we have been studying high quality electron beam generation using Cs-Te photocathode RF-Gun and its application. We tried to generate terahertz wave by the coherent radiation and to measure its spectrum by a time-domain spectroscopy (TDS) technique. Adopting this technique, ultra-short laser pulse is needed as probe light. A terahertz waveform appears by delaying the timing of probe pulse. A spectrum of terahertz wave is also led by the waveform, by using the Fourier transform. We succeeded in constructing the probe laser system operating at 119 MHz repetition rate. The pulse duration was compressed down to 190 fs (FWHM) by using pulse compressor. We also succeeded in measuring a terahertz radiation from a photoconductive antenna. In this conference, we will report the outline of our terahertz TDS system, recent progress of our laser system, and terahertz wave generation and detection, with the future prospects.

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THPAB123

Low Level RF Control System Architecture OF IR-FEL

controls, LLRF, klystron, FEL

4014

B. Du, G. Huang, L. Lin, W. Liu, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Infrared free electron laser (IR-FEL) is one type of laser driven by accelerator and generated by undulator. It is built by National Synchrotron Radiation Laboratory (NSRL). Compared to synchrotron radiation light source, it have much higher demand of beam quality. Low level RF control system (LLRF) need to reach higher controlled accuracy corresponded to the demand. Accelerating structure which contains one pre-buncher, one buncher and two accelerating tube can accelerate beam to 60MeV. Frequency distribution system use direct digital synthesizer technology to generate 5 signal of different frequency. LLRF system detect 8 channels signal, one for control loop, and the others for monitor and interlock. The hardware contain MTCA.4 architecture which is advanced in global; RF board for downconverter and IQ modulation output; DSP board for sampling, controller and transmission.

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THPAB149

Characterization of the THz Radiation-Based Bunch Length Measurement System for the NSRRC Photoinjector

radiation, laser, detector, software

4080

C.C. Liang, B.Y. Chen, C.H. Chen, M.C. Chou, S. Fann, C.S. Huang, N.Y. Huang, J.-Y. Hwang, W.K. Lau, A.P. Lee, T.Y. Lee, W.Y. Lin, T.-C. Yu
NSRRC, Hsinchu, Taiwan

A part of high brightness photo-injection (HBI) project at NSRRC is intending to adopt Coherent Transition Radiation (CTR) and Coherent Undulator Radiation (CUR) to generate THz radiation with an ultrashort electron bunch. Such high intensity THz sources allow the THz spectrum to be conducted easily with a THz interferometer and a Golay cell detector. Furthermore, the radiation spectrum carries information of the electron distribution which allows ultrashort electron bunch length measurements. For verifying correct measuring procedure during the CTR and CUR experiments, a conventional THz radiation generated by optical rectification from a ZnTe crystal has been performed. The produced THz pulse was sent into a Michelson interferometer which is designed for the autocorrelation of the intense, sub-mm and mm-wavelength, spatially-coherent radiation pulses. The THz spectrum can be further obtained from the interferogram by the Fourier transform process. In such way, the THz spectrum can be investigated if the result is satisfactory and can be applied on the THz CTR and CUR experiments for the next step.

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THPIK008

Beam Dynamics for the ThomX Linac

emittance, gun, solenoid, focusing

4121

L. Garolfi, C. Bruni, M. El Khaldi, C. Vallerand
LAL, Orsay, France

We report the results of a recent beam dynamics study that has led to promising working points for the split ThomX photoinjector. ThomX is a back-scattering Thomson light source that will use S-band electron Linac with an energy of 50 MeV to produce 45 keV high X-rays flux (10¹¹ - 10¹³ ph/s), by means of collision between electron bunches and laser pulses, in the energy range from 45 keV to 90 keV. Since Thomx has been conceived to maximise the average X-rays flux in a fixed bandwidth, the high rate electron-photon collisions impose a linear accelerator combined with a storage ring. The high performances of the accelerator are largely affected by the high quality of the electron beam at the interaction point in the ring. Beam specifications should be achieved at the interaction point to the extent that 1 nC, 50 nA average current per bunch with normalised rms transverse emittance less than 5 mm and around 0.3% energy spread, at the end of the linac. The beam dynamics along the linac has been studied to demonstrate the capability of the accelerator to meet the requirements for the high brightness electron beam using an RF photoinjector configuration.

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THPIK014

Travelling Wave Accelerating Structure for Areal 50 MeV Energy Upgrade

cavity, impedance, simulation, gun

4130

A. Vardanyan, V. Danielyan, S.G. Dekhtiarov, B. Grigoryan, L. Hakobyan, T. Markosyan, A.S. Simonyan
CANDLE SRI, Yerevan, Armenia
W. Ackermann
TEMF, TU Darmstadt, Darmstadt, Germany
A.V. Tsakanian
HZB, Berlin, Germany

AREAL facility development implies energy upgrade to 50 MeV in order to drive a THz free electron laser. To reach this goal, the installation of two 1.6 m long S-Band travelling wave accelerating sections, with nominal accel-erating gradient of 15 MV/m, are foreseen. In this paper the design study of accelerating sections along with the matching performance of RF couplers are presented. The simulations are performed using the CST Microwave Studio. The first results of the accelerating structure proto-type fabrication are discussed.

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THPIK022

Measurements of High-Order Magnetic Field Components of Permanent Quadrupole Magnets for a Laser-Plasma-Driven Undulator X-Ray Source

quadrupole, laser, plasma, permanent-magnet

4145

P. Winkler
University of Hamburg, Hamburg, Germany
D. Kocon, A.Y. Molodozhentsev
ELI-BEAMS, Prague, Czech Republic
A.R. Maier
CFEL, Hamburg, Germany
L. Pribyl
Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
M. Trunk
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Laser wakefield acceleration as a novel source of high-energy electron beam is a prominent candidate to drive a next generation of compact light sources. For applications, the electron beam needs to be captured using quadrupole magnets with extremely high field gradient. It allows to preserve properties of the laser-plasma driven electron beam. We designed and manufactured compact permanent quadrupole magnets providing magnetic field gradient up to 510 T/m at an aperture radius of only of a few mm. The Halbach-type quadrupole magents use 12 NdFeB wedges with a remanent magnetic field of 1.2 Tesla. We measured the magnetic field of the permanent magnet quadrupoles using the pulsed-wire and rotating-coil methods. Here, we present an analysis of the magnetic field quality and, in particular, the integrated field gradient and high-order field components. We further discuss the influence of the field imperfections on the electron beam quality and its consequences for application in the transport line of a laser-plasma-driven undulator X-ray source.

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THPIK038

Design of a 100 kW Solid-State RF Pulse Amplifier with a TE011 Mode RF Combiner at 476 MHz

cavity, FEL, klystron, laser

4180

Y. Otake, T. Asaka, T. Inagaki
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

Solid-state RF amplifiers, which have long lifetimes and small failures, are the recent current of high-power RF sources for particle accelerators. Hence, we designed a 100 kW solid-state amplifier with a TE011 mode cavity (Q0=100, 000) power combiner with extreme low-loss operated at 476 MHz and a 6 us pulse width. Developing this amplifier is for replacement of a high-power amplifier using an induction output tube, IOT, in the X-ray free-electron laser, SACLA. In SACLA, highly RF phase and amplitude stabilities of less than 0.01 deg. and 10^-4 in rms are necessary to stable lasing within a 10 % intensity fluctuation. The amplifier comprises a drive amplifier, a reentrant cavity RF power divider, 100 final amplifier modules with a 1 kW output each and a TE011 mode cavity combiner. Water-cooling within 10 mK and a DC power supply with a noise of less than -100 dBV at 10 Hz for the amplifier is necessary to realize the previously mentioned stabilities. Based on the experimental results of a test amplifier module and test combiner cavities, possibility to realize the above-mentioned specifications is large. We report the detail and a part of the performance of the 100 kW amplifier.

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THPIK042

The Magnetic Measurement of Conventional Magnets for Electron Beam Accelerator of Northwest Institute of Nuclear Technology

dipole, quadrupole, collimation, solenoid

4190

Z. Zhang, L. Yang
IHEP, Beijing, People's Republic of China

The project of electron beam accelerator is worked together completed by NINT (Northwest Institute of Nuclear Technology) and IHEP (Institute of High Energy Physics, China). Conventional magnet of the project includes a total of three dipole magnets, four quadrupole magnets, six solenoid magnets, and four correction magnets. All of magnets to complete the measurement by IHEP hall measuring equipment. The integrated magnetic field measurement of the arc-shaped dipole magnet requires simultaneous movement by the X-axis and the Z-axis, using Labview software written a new measurement procedure, the new measurement procedure has been completed by setting the measuring angle and the measuring radius. All measurement results of conventional magnets have reached the physical design requirements, and each magnet were carried out more than twice the measurement, the reproducibility of the measurement results are better than one-thousandth, fully meet the design claim of NINT.

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THPIK056

Design of a C-Band High-Efficiency Multi-Beam Klystron

klystron, bunching, cavity, simulation

4221

Z.N. Liu, H.B. Chen, M.M. Peng, J. Shi
TUB, Beijing, People's Republic of China

A multi-beam klystron at 5.712GHz has been designed with efficiency of more than 80%. It can generate a pulse with output power of about 3MW and a pulse length of 5 us. Space charge effect and large signal theory, which both increase the accuracy theoretically, are considered in the simulation. A series of parameters of cavities are given after optimizing, including the frequency, R/Q, Q0 and Qe. This paper describes the beam dynamics design of the klystron as well as a preliminary machenical design.

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THPIK060

Tuning of an S-Band 10 MeV Traveling-Wave Accelerating Structure with a Non-uniform Section

impedance, network, cavity, collider

4233

J.H. Shao, H.B. Chen, C. Gong, J. Shi, X.W. Wu, S.X. Zheng
TUB, Beijing, People's Republic of China

A tuning method of nonuniform travelling wave structures has been developed based on non-resonant perturbation measurement at Tsinghua University. The filed distribution is normalized with the shunt impedance and attenuation of each cell. Then their internal reflection can be deduced and corrected by cavity deforming. This method has been applied to an S-band 10 MeV travelling wave structure successfully. In this paper, the detailed tuning method and cold test results will be presented.

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THPIK063

The RF System of Infrared Free Electron Laser Facility at NSRL

cavity, simulation, LLRF, laser

4239

L. Lin, B. Du, G. Huang, K. Jin, F.F. Wu
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: The Natural Science Foundation of China
An infrared free electron laser light source (IRFEL) is being constructed at National Synchrotron Radiation Laboratory, which could be used in the study of far infrared detection, light dissociation and light excitation. The accelerator of IRFEL deliver a average current 300 A electron beam at 15~60 MeV, the energy spread is less than 240 keV, and the emittance is less than 30 mm*mrad. IRFEL is consisted of two optical resonator system, which could create 2.5~50 um, 40~200um infrared laser respectively. The design of IRFEL RF system is introduced, the recent progress of prebuncher, buncher, frequency distribution, accelerator and DLLRF system are also present in this paper.

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THPIK067

A C-Band Compact Spherical RF Pulse Compressor for the SXFEL Linac Energy Upgrade

cavity, coupling, simulation, linac

4248

Z.B. Li, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A new compact C-band (5712 MHz) spherical RF pulse compressor has been designed for Shanghai Soft X-ray Free Electron Laser (SXFEL) facility energy upgrading at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences (CAS). This pulse compressor contains one high Q0 spherical RF resonant cavity which works on two TE113 modes and a novel coupler. As there is only one storage cavity, this pulse compressor can be much smaller than the traditional SLED. With the coupling coefficient 4.9, the average power gain can be as high as 3.8. In this paper, the scheme of the C-band spherical pulse compressor and RF design are presented.

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THPIK068

High Power Test of SINAP X-Band Deflector at KEK

cavity, impedance, operation, laser

4251

J.H. Tan, W. Fang, Q. Gu, X.X. Huang, Z.B. Li, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
T. Higo
KEK, Ibaraki, Japan
D.C. Tong
TUB, Beijing, People's Republic of China

A crucial RF structure used for bunch length measurement for Shanghai X-ray Free Electron Lasers (SXFEL) at the Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Science [1]. The design, fabrication, measurement and tuning have been completed at SINAP [2], and the high power test was carried out at Nextef of KEK with international collaboration. This paper presents the RF conditioning process and test results.

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THPIK070

Localization of RF Breakdown Point in a Coaxially Loaded LINAC Cavity

linac, cavity, operation, accelerating-gradient

4254

Q.S. Chen, T. Hu, B. Qin
HUST, Wuhan, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

Here we report how the RF breakdown point (RFBP) can be localized in a coaxially loaded linac cavity with just the forward and the reflected power signal. The cavity uses 4 load cells instead of output coupler to absorb remanent power, so no transmitted power signal could be recorded. We propose two methods to analyze the measured signals and localize the RFBP. One method focuses on the time delay of the two signals while the other one focuses on the amplitude. Quantitative analysis showed the two methods were well consistent with each other and indicated the RFBP located at the end of the linac cavity.

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THPIK084

Results from the 704 MHz Klystron and Multi-beam IOT Prototypes for the European Spallation Source

klystron, factory, linac, operation

4282

M. Jensen, C. Marrelli
ESS, Lund, Sweden

The European Spallation Source, currently under construction in Lund, Sweden, will contain 155 RF sources for proton beam acceleration. Of these, 120 are at 704 MHz. Each cavity will be powered by individual RF sources. The nominal beam pulse width is 2.86 ms and the RF systems are being specified for a pulse width up to 3.5 ms to allow for ramping and time for regulation. The repetition frequency is 14 Hz which results in 5% duty. The 704 MHz linac is divided into two sections, the medium beta and the high beta cavities. For schedule reasons, the medium beta linac, 36 RF sources, will be based on 1.5 MW pulsed power klystrons and the high beta section, 84 RF sources, is planned to be operated with 1.2 MW multi-beam IOTs. ESS ordered three klystron prototypes designed for the ESS parameters from different supplies and two multi-beam IOT technology demonstrators under two different contracts. We present the specifications for the amplifiers and the results of the klystron prototypes and report the result of the first 1.2 MW multi-beam IOT prototypes.

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THPIK093

Blow-Up Due to Intra Beam Scattering during Deceleration in ELENA

emittance, simulation, scattering, antiproton

4303

C. Carli, M. Martini
CERN, Geneva, Switzerland

Intra Beam Scattering (IBS) is expected to be the main performance limitation of the Extra Low Energy Antiproton ring (ELENA), a small synchrotron equipped with electron cooling under construction at CERN to decelerate antiprotons from 5.3 MeV to 100 keV. Thus, the duration of the ramps must not be too long to avoid excessive blow up due to IBS. On the other hand, the bending magnets are C-shaped and the vacuum chambers are without insulated junctions, which are difficult for fully baked machines; thus, the ramps must not be too short. The evolution of transverse and longitudinal emittances along the ramps have been estimated assuming that IBS is the main phenomenon leading to blow-up. The blow-up due to IBS found along the ramps have been found to be acceptable.

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THPIK097

High Power Tests of a Prototype X-Band Accelerating Structure for CLIC

vacuum, klystron, linac, collider

4318

R. Zennaro, H. Blumer, M. Bopp, T. Garvey, L. Rivkin
PSI, Villigen PSI, Switzerland
T. Argyropoulos, D. Esperante Pereira
IFIC, Valencia, Spain
N. Catalán Lasheras, A. Grudiev, G. McMonagle, A. Solodko, I. Syratchev, R. Wegner, B.J. Woolley, W. Wuensch
CERN, Geneva, Switzerland
T.G. Lucas, M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia

Funding: Partially funded by SNF FLARE grant 20FL20₁47463
We present the design, construction and high-power test of an X-band radio-frequency accelerating structure, built as a prototype for the CERN LInear Collider (CLIC) study. X-band structures have been attracting increasing attention in recent years with applications foreseen in the domains of compact free electron lasers, medical accelerators and as diagnostics for ultra-short (femtosecond) electron bunches (when used in deflecting mode). To date, the main motivation for developments in this field has been as accelerating structures for linear colliders such as CLIC. In the context of a CERN/PSI collaboration we have built a prototype structure based on an existing CERN design, but with some modification, and following, as closely as possible, the realization and vacuum brazing techniques employed in the production of the C-band structures for the Swiss Free Electron Laser, SwissFEL. We will present the basic design of the structure and describe the fabrication process. The results of high power conditioning of the structure at CERN on an X-box test stand, to assess conditioning times, accelerating field and measure breakdown rates, will also be presented.

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THPIK098

Bz Calculation of TPS Linac Focusing Coils and a Toolkit for Bz Optimization

toolkit, linac, focusing, operation

4321

H.H. Chen, H.-P. Chang, C.L. Chen, C.-S. Fann, K.-K. Lin, Y.K. Lin, K.L. Tsai
NSRRC, Hsinchu, Taiwan

A set of focusing coils is installed along TPS linac beam centerline at low energy region (< 10 MeV) in order to confine the beam radius within 5 mm. The longitudinal magnetic field calculation along the beam centerline has been carried out in this study. The estimated Bz is obtained based on Biot-Savart law calculation. Then, it is verified by field measurement using Gauss meter at specific centerline locations. Calibration process is performed by comparing the calculated and measured Bz fields at selected operation settings. The comparison result is presented in this report. The linac operation experience indicates that tuning of the coil settings is critical concerning beam property optimization. Consequently, a Bz calculation toolkit is developed to cope with the multi-knobs optimization process while tuning of numerous focusing coils installed in the system at various locations. The applications of the Bz calculation toolkit is briefly described.

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THPIK102

Commissioning of the SLRI Storage Ring Second RF System

cavity, LLRF, storage-ring, rf-amplifier

4328

N. Juntong, S. Boonsuya, S. Cheedket, Ch. Dhammatong, S. Krainara, W. Phacheerak, R.R. Rujanakraikarn, N. Suradet
SLRI, Nakhon Ratchasima, Thailand

The old RF cavity in the storage ring of SIAM Photon Source (SPS), the 1.2 GeV second generation synchrotron light source in Thailand, has been pushed to its maximum capability to compensate electron energy lost in the storage ring. This energy lost is the effect from two additional insertion devices, which have been installed in SPS storage ring during June to August 2013. The new RF system has been planned since 2012, but with some technical and procurement difficulty the new system was successfully commissioning and running in August 2016. The installation, acceptance testing, conditioning and commissioning results of the new RF cavity, RF high power transmitter, and the low level RF system will be presented

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THPIK120

The RF and Mechanical Design of a Compact, 2.5 kW, 1.3 GHz Resonant Loop Coupler for the APEX Buncher Cavity

cavity, vacuum, operation, resonance

4380

S.P. Virostek, F. Sannibale, J.W. Staples
LBNL, Berkeley, California, USA
H.J. Qian
DESY Zeuthen, Zeuthen, Germany

Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is an injector system designed to demonstrate the capability of a normal conducting 186 MHz RF gun operating in CW mode to deliver the brightness required by X-ray FEL applications operating at MHz repetition rate, such as LCLS-II. A 240 kV, 1.3 GHz CW buncher cavity design was developed as part of the APEX experiment. The two-cell cavity profile has been optimized to minimize the RF power requirements and to remove multipacting resonances over the full range of operation. In order to excite the cavity stably at pi-mode and remove the dipole-like coupler kick, the two cells are to be independently driven by four, 2.5 kW, coaxial resonant loop couplers with integrated ceramic windows and a matching section in the body of the coupler. The coupler's inner conductor has a single diameter change at a specified distance from the ceramic insulator in order to cancel the wave reflected from the ceramic window, thus comprising the matching section. The details of the RF analysis, mechanical design, fabrication and testing of the coupler are presented here.

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THPIK124

Using Conductive Nanoparticles to Reduce the Surface Charging of Ceramics

cryogenics, experiment, vacuum, cavity

4392

M.L. Neubauer, A. Dudas
Muons, Inc, Illinois, USA
F. Marhauser
JLab, Newport News, Virginia, USA

Beam pipe ceramics used for various purposes suffer from the problem of surface charging in the presence of an electron beam. A novel technique has been proposed for a method for reducing the charging effects by filling nano sized pores in the ceramic with a conductive medium. Pores in ceramics can be formed in a chain with varying depths depending on sintering temperatures and methods for creating the pores. In the pre-formed condition of these novel ceramics, a nanoparticle slurry is infused by capillary action into the ceramic and fired at temperatures and atmospheres to stabilize the conductive medium inside the ceramic. The microwave characteristics of these ceramics will be investigated in a Phase I program with the design of a complete beam pipe lossy ceramic in a Phase II.

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THPIK125

Ultra High Gradient Breakdown Rates in X-Band Cryogenic Normal Conducting Rf Accelerating Cavities

accelerating-gradient, cryogenics, cavity, experiment

4395

A.D. Cahill, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V.A. Dolgashev, S.G. Tantawi, S.P. Weathersby
SLAC, Menlo Park, California, USA

Funding: Work Supported by DOE/SU Contract DE-AC02-76-SF00515, US NSF Award PHY-1549132, the Center for Bright Beams, and DOE SCGSR Fellowship.
RF breakdown is one of the major factors limiting the operating accelerating gradient in rf particle accelerators. We conjecture that the breakdown rate is linked to the movements of crystal defects induced by periodic mechanical stress. Pulsed surface heating possibly creates a major part of this stress. By decreasing crystal mobility and increasing yield strength we hope to reduce the breakdown rate for the same accelerating gradient. We can achieve these properties by cooling a copper accelerating cavity to cryogenic temperatures. We tested an 11.4 GHz cryogenic copper accelerating cavity at high power and observed that the rf and dark current signals are consistent with Q₀ changing during rf pulses. To take this change in Q₀ into account, we created a non-linear circuit model in which the Q₀ is allowed to vary inside the pulse. We used this model to process the data obtained from the high power test of the cryogenic accelerating structure. We present the results of measurements with low rf breakdown rates for surface electric fields near 500 MV/m for a shaped rf pulse with 150 ns of flat gradient.

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THPIK126

Design of a Field-Emission X-Band Gun Driven by Solid-State RF Source

gun, cavity, experiment, linac

4399

E.A. Nanni, V.A. Dolgashev, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA
B.E. Carlsten, J.W. Lewellen, D.C. Nguyen
LANL, Los Alamos, New Mexico, USA
M. Othman
UCI, Irvine, California, USA

We present the design of a field-emission X-band gun designed to be powered using a solid-state RF source. The source of the electron beam is a field emission nano-tip array. The RF gun is intended to be a beam source for 1 MeV solid-state driven linac for deployment on a satellite to map magnetic fields in the magnetosphere. The gun has to satisfy strict requirements on both average and peak power consumption, as well as rapid turn on time. In order to achieve low power consumption, the RF gun operates at relatively low accelerating gradient of 2 MeV/m. The beam exit energy is ~20 keV for an RF power 1.5 kW. Each cell of the RF gun is separately powered by commercially available, GaN high electron mobility transistors. In proof of principle experiments we successfully powered a 9.3 GHz accelerating cavity with a 100 W transistor and a 1% duty cycle.

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THPIK129

Non-Linear Inserts for the IOTA Ring

vacuum, alignment, operation, quadrupole

4407

F.H. O'Shea, R.B. Agustsson, P.S. Chang, Y.C. Chen
RadiaBeam, Santa Monica, California, USA
D.W. Martin, J.D. McNevin
RadiaBeam Systems, Santa Monica, California, USA

Funding: Work supported by DOE under contract DE-SC0009531.
We present here the complete non-linear insert for the IOTA ring at Fermilab. In particular, we will show the results for the magnetic measurements and a discussion of leak correction in the unusually shaped vacuum chamber. A test assembly of the insert has been successfully completed and the insert functions mechanically as designed.

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THPVA004

Pushing the Space Charge Limit: Electron Lenses in High-Intensity Synchrotrons?

space-charge, synchrotron, ion, resonance

4417

W.D. Stem, O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim
GSI, Darmstadt, Germany

Funding: Work is supported by BMBF contract FKZ:05P15RDRBA
Several accelerator projects require an increase in the number of particles per bunch, which is constrained by the space charge limit. Above this limit the transverse space charge force in combination with the lattice structure causes beam quality degradation and beam loss. Proposed devices to mitigate this beam loss in ion beams are electron lenses. An electron lens imparts a nonlinear, localized focusing kick to counteract the (global) space-charge forces in the primary beam. This effort is met with many challenges, including a reduced dynamic aperture (DA), resonance crossing, and beam-beam alignment. This contribution provides a detailed study of idealized electron lens use in high-intensity particle accelerators, including a comparison between analytical calculations and pyORBIT particle-in-cell (PIC) simulations.

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THPVA005

Investigation of Electron Beam Assisted Density Boosting in Plasma Traps Using the Example of a Gabor Plasma Lens

plasma, simulation, experiment, space-charge

4421

C. Beberweil, M. Droba, S. Klaproth, O. Meusel, D. Noll, H. Podlech, K. Schulte, K.I. Thoma
IAP, Frankfurt am Main, Germany
S. Gammino, D. Mascali
INFN/LNS, Catania, Italy
L. Malferrari, A. Montanari, F. Odorici
INFN-Bologna, Bologna, Italy

Gabor lenses are plasma traps that can be used for focusing an ion beam linearly without aberrations* by the electric field of a confined electron cloud. They combine strong electrostatic focusing with the possibility of space charge compensation and provide an attractive alternative to conventional ion beam optics in a LEBT section. The focusing performance strongly depends on the density and distribution of the enclosed electron plasma*. As the Gabor lens is usually operated close to the ion source, residual gas ionization is supposed to be the central electron generation mechanism. An electron source is introduced in order to investigate the possibility of boosting the electron density in plasma traps using the example of a Gabor lens. This way, a Gabor lens could be operated under XUHV conditions, where residual gas ionization is suppressed. The particle in cell code bender** was used to simulate the injection into the confining fields of the space charge lens in different geometrical configurations and a prototype experiment was constructed consisting of a Gabor lens and an electron source system. In this contribution, simulations and measurements will be presented.
* Schulte, K., et al. Electron cloud dynamics in a Gabor space charge lens. 2012
** Noll, D., et al. The particle-in-cell code bender and its application to non-relativistic beam transport. 2015

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THPVA006

Space-Charge Compensation in the Transition Area Between LEBT and RFQ

rfq, injection, ion, simulation

4425

P.P. Schneider, D. Born, V.A. Britten, M. Droba, O. Meusel, H. Podlech, A. Schempp
IAP, Frankfurt am Main, Germany
D. Noll
CERN, Geneva, Switzerland

Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) #05P15RFRBA and by HORIZON 2020 for the MYRRHA project #662186
The transition from a space charge compensated beam in the LEBT to an uncompensated beam in the RFQ will influence the beam parameters. To investigate the impact of the electric fields on the space charge compensation, an insulated cone is used as a repeller electrode in front of the RFQ. Depending on the time dependent potential of the RFQ rods respectively to the beam potential, the compensation electrons may be prevented from moving into the RF field which oozes out of the RFQ entrance. The simulation studies are performed with the particle-in-cell code bender*. The simulations may substantiate measurements at the CW-operated RFQ in Frankfurt University** as well as at the foreseen MYRRHA LEBT-RFQ interface.*** In this contribution, a study on a LEBT-RFQ interface is shown. Results of numerical and experimental investigations will be compared.
*Noll, D. et al.The Particle-in-Cell Code Bender and Its Application to Non-Relativistic Beam Transport, WEO4LR02, HB'14
**Meusel, O. et al.FRANZ Accelerator Test Bench and Neutron Source.,MO3A03, LINAC'12
***R. Salemme et al.Design Progress of the MYRRHA Low Energy Beam Line, MOPP137, LINAC'14

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THPVA007

Matching Space-charge Dominated Electron Bunches into the Plasma Accelerator at SINBAD

emittance, plasma, simulation, focusing

4429

J. Zhu, R.W. Aßmann, U. Dorda, B. Marchetti
DESY, Hamburg, Germany

The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to provide sub-fs to tens of fs electron bunches for Laser Wake-Field Acceleration (LWFA) experiments. In order to avoid emittance growth in plasma cells with ultra-high accelerating gradients the injection and transport of electron bunches with beta functions of mm-size or even smaller are required. This kind of bunch is usually space-charged dominated since the energy is low (< 200 MeV) while the peak current is high for allowing the electron bunches to be used for Free Electron-Laser (FEL) generation. We present the beamline design and explore the possible beam parameters at the SINBAD linac by start-to-end simulations.

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THPVA009

Transverse Beam Dynamics of an 8 MeV Electron Linac

emittance, solenoid, focusing, linac

4432

S. Sanaye Hajari, M. Dayyani Kelisani, H. Shaker
IPM, Tehran, Iran
S. Haghtalab
Shahid Beheshti University, Tehran, Iran

The IPM Electron Linac is an 8 MeV (upgradable to 11 MeV) electron linear accelerator under development at the Institute for Research in Fundamental Science (IPM), Tehran, Iran. The linac is mainly regarded as a research project providing hands-on experience in the accelerator science and technology. However, it could serve as an x-ray source or play the injector role for a larger facility. The linac consists of a thermionic gun followed by a travelling wave buncher joined to two accelerating tubes. The transverse focusing is provided by the solenoid mag-nets over the buncher and the accelerating structures. Using the code ASTRA, the transverse beam dynamics is studied and optimized in order to limit the RF emittance. Particularly, the effect of coupler asymmetry is investigated, a beam dynamics design of the solenoid channel is presented, and the effect of the solenoid misalignment on the beam quality is examined.

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THPVA010

Electron Cloud Simulations for the Main Ring of J-PARC

simulation, proton, detector, vacuum

4436

B. Yee-Rendón, R. Muto, K. Ohmi, K. Satou, M. Tomizawa, T. Toyama
KEK, Ibaraki, Japan

The simulation of beam instabilities is a helpful tool to evaluate potential threats against the machine protection of the high intensity beams. At Main Ring (MR) of J-PARC, signals related to the electron cloud have been observed during the slow beam extraction mode. Hence, several studies were conducted to investigate the mechanism that produces it, the results confirmed a strong dependence on the beam intensity and the bunch structure in the formation of the electron cloud, however, the precise explanation of its trigger conditions remains incomplete. To shed light on the problem, electron cloud simulations were done using an updated version of the computational model developed from previous works at KEK. The code employed the signals of the measurements to reproduce the events seen during the surveys.

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THPVA027

Commissioning and First Results of the IBEX Paul Trap

ion, gun, experiment, focusing

4481

S.L. Sheehy, E. Carr, L. Martin
JAI, Oxford, United Kingdom
K. Budzik
Warsaw University, Warsaw, Poland
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
C.R. Prior
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The Intense Beam Experiment (IBEX) is a linear Paul trap designed to replicate the dynamics of intense particle beams in accelerators. Similar to the S-POD apparatus at Hiroshima University, IBEX is a small scale experiment which has been constructed and recently commissioned at the Rutherford Appleton Laboratory in the UK. Its aim is to support theoretical studies of next-generation high intensity proton and ion accelerators, complementing existing computer simulation approaches. Here we report on the status of commissioning and first results obtained.

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THPVA031

Beam Tests of Diamond-Like Carbon Coating for Mitigation of Electron Cloud

proton, operation, extraction, emittance

4497

J.S. Eldred, M. Backfish, C.-Y. Tan, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
S. Kato
KEK, Ibaraki, Japan

Electron cloud beam instabilities are an important consideration in virtually all high-energy particle accelerators and could pose a formidable challenge to forthcoming high-intensity accelerator upgrades. Our results evaluate the efficacy of a diamond-like carbon (DLC) coating for the mitigation of electron in the Fermilab Main Injector. The interior surface of the beampipe conditions in response to electron bombardment from the electron cloud and we track the change in electron cloud flux over time in the DLC coated beampipe and uncoated stainless steel beampipe. The electron flux is measured by retarding field analyzers placed in a field-free region of the Main Injector. We find the DLC coating reduces the electron cloud signal to roughly 2\% of that measured in the uncoated stainless steel beampipe.

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THPVA034

Comparison of the Coupling of Dipole Motion From Bunch to Bunch in an Electron Beam Caused by Electron Clouds at CesrTA Due to Variations in Bunch Length and Chromaticity

damping, positron, dipole, coupling

4509

M.G. Billing, L.Y. Bartnik, J.A. Crittenden, M.J. Forster, N.T. Rider, J.P. Shanks, M.B. Spiegel, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
R. Holtzapple
CalPoly, San Luis Obispo, California, USA
E.C. Runburg
University of Notre Dame, Indiana, USA

Earlier experiments at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) have probed the interaction of the electron cloud (EC) with a 2.1 GeV stored positron beam. Since a very low EC density is expected with the electron bunches, these results characterize the dependence of beam-vacuum chamber impedance interactions, which are common to both positron and electron beams. The experiments were performed on a 30-bunch electron train with a 14 ns spacing, at a fixed current of 0.75mA/bunch, at two different vertical chromaticity settings and for four different bunch lengths (or synchrotron tunes.) The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 20 turn-by-turn beam position monitors in CESR to measure the correlated bunch-by-bunch dipole motion and an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the analysis of the observations from these experiments and compare them with effects of the EC on the positron beam's dipole motion and coupling of the motion from each bunch to its succeeding bunches.

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THPVA035

Dependence of the Coupling of Dipole Motion From Bunch to Bunch Caused by Electron Clouds at CesrTA Due to Variations in Bunch Length and Chromaticity

damping, positron, dipole, synchrotron

4512

M.G. Billing, L.Y. Bartnik, J.A. Crittenden, M.J. Forster, N.T. Rider, J.P. Shanks, M.B. Spiegel, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
R. Holtzapple
CalPoly, San Luis Obispo, California, USA
E.C. Runburg
University of Notre Dame, Indiana, USA

The Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) has conducted experiments to probe the interaction of the electron cloud (EC) with a 2.1 GeV stored positron beam. These experiments investigate the dependence of beam'electron cloud interactions vs. bunch length (or synchrotron tune) at two values of the vertical chromaticity. The experiments utilized a 30-bunch positron train with a 14 ns spacing, at a fixed current of 0.75mA/bunch. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 20 turn-by-turn beam position monitors in CESR to measure the correlated bunch-by-bunch dipole motion and an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and a more detailed analysis for the coupling of dipole motion via the EC from each bunch to succeeding bunches in the train.

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THPVA039

Nanopositioning and Actuation in Extreme Environment Using Piezoelectric Multilayer Actuators and Motors

vacuum, radiation, diagnostics, operation

4519

C. Mangeot
Noliac A/S, Kvistgaard, Denmark

Piezoelectric devices find numerous applications in Science projects, when precise and fast positioning is needed, particularly in harsh environment. This paper reviews some of the latest environmental tests performed on piezoelectric devices, illustrating how they enable higher performance or even new technical solutions. In the field of particle accelerators and instrumentation, two applications can be mentioned: the precise goniometer to be installed in the Large Hadron Collider (LHC) and active Lorentz force detuning compensation systems*. Multilayer actuators have been demonstrated over a wide range of temperatures, from cryogenic (4K) to 220°C, in UHV and under radiation. Other examples can be mentioned within the ITER project: the In-Vessel Viewing System (IVVS) and the Electron Cyclotron Emission (ECE) diagnostic**. For these applications, a piezo motor is needed. The Piezo Actuator Drive (PAD) was demonstrated at high temperature, UHV and submitted to high magnetic fields.
* P. Bosland et al.; 'Mechanical study of the Saclay Piezo Tuner PTS (Piezo Tunning System)', CARE-Note-2005-004-SRF
** G. Taylor et al.; 'Status of the design of the ITER ECE diagnostic', EC18, 2015

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THPVA045

Telecommunication Concepts for Compact, Electro-Optical and Frequency Tunable Sensors for Accelerator Diagnostics

laser, diagnostics, photon, synchrotron

4534

E. Bründermann, A.-S. Müller
KIT, Karlsruhe, Germany
I. Hosako, I. Morohashi, S. Nakajima, S. Saito, N. Sekine
NICT, Tokyo, Japan

Funding: Supported by Invitation Fellowship for Research ID No. S16704 of Japan Society for the Promotion of Science (JSPS) awarded to E.B. hosted by I.H.
Terahertz diagnostics* for investigating the properties of electron and photon beams**, especially the investigation of electron bunch instabilities, accompanied by terahertz photon bursts is increasingly employed to monitor and investigate electron bunch dynamics***. Recent advances in information and communications technology promise compact sensors based on telecom and thus industry standards. We present potential applications of such technology concepts for accelerators, including a miniature probe for electro-optical sampling, which could be employed for electron bunch electrical near-field studies, and laser sources with widely tunable pulse repetition rates adaptable for pulsed diagnostics***.
* E. Bründermann, H.-W. Hübers, M.F. Kimmitt, Terahertz Techniques, Springer-Verlag (2012).
** J.L. Steinmann et al., Phys. Rev. Lett. 117, 174802, 2016.
*** M. Brosi et al., Phys. Rev. Accel. Beams 19, 110701, 2016.
**** I. Morohashi et al., Nano Commun Netw 10, 79, 2016.

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THPVA047

Developing an Yb/Nd Doped Hybrid Solid Laser of RF Gun for SuperKEKB Phase II Commissioning

laser, gun, cavity, emittance

4540

X. Zhou, T. Natsui, Y. Ogawa, M. Yoshida, R. Zhang
KEK, Ibaraki, Japan

The electron beams with a charge of several nC and a normalized emittance of less than 10 'm are expected to be generated in the photocathode RF gun for injector linac of SuperKEKB accelerator project. By development of the Yb-doped laser system, more than 1.0 nC electron has been obtained in 25 Hz. The laser system is already for commissioning phase I. But, the 30 ps pulse width stretch limit the pulse energy of the amplifier laser system. As well-established laser material, Nd:YAG rods with high optical homogeneity and high damage threshold, simplify the design of high-pulse-energy amplifier. Therefore, a new Nd/Yb hybrid laser system is development to increase the pulse energy of the laser source. For phase II commissioning, more than 3 nC electron beam is expected. Also, a chirped pulse amplification (CPA) laser system is prepared for the phase III commissioning, both pulse energy and pulse shaping controller are expected.

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THPVA067

Observation of Beam Disturbance Caused by ID Gap Variation at TLS Storage Ring

undulator, injection, synchrotron, insertion-device

4598

H.C. Chen, C.L. Chen, H.H. Chen, C.H. Kuo, Y.K. Lin
NSRRC, Hsinchu, Taiwan

Insertion device is controlled by user for specific experimental condition on user beam time. It operates with user defined gap and phase. Three different undulators are installed in TLS (Taiwan Light Source), including one elliptically polarized undulator. Interactions between these undulators were studied to demonstrate the impact on beam performance. How to get more stable beam under undulators' interaction is discussed in this study.

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THPVA069

NSC KIPT Experience in Use of Laser Tracker Leica at 401 in Equipment Alignment of 100 MeV/100 KW Electron Linear Accelerator of Neutron Source Driver

target, survey, quadrupole, neutron

4604

M. Moisieienko, O. Bezditko, I.M. Karnaukhov, A. Mytsykov, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine

For successful operation of electron linear accelerator that is driver of NSC KIPT Neutron source it is necessary that all the acceleration sections and all the electromagnetic elements should be installed in design position according to the designed lattice. Accuracies of all electromagnetic elements installation are 150 mkm in transverse positions and 200 mrad for all three rotation directions. The whole process, fiducialization and developing of coordinate net, is controlled by Laser tracker Leica AT 401. Well-planned methods allow to realize uniform irradiation of neutron-generation target.

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THPVA070

Cooling and Thermo Stabilization System of 100MeV/100kW Electron Linear Accelerator of Neutron Source Driver

operation, neutron, controls, klystron

4607

M. Moisieienko, I.M. Karnaukhov, A. Mytsykov, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine

Cooling system and temperature control technology elements of the linear electron accelerator of 100 MeV/100kW is a complex technological system composed of three subsystems: the cooling klystron gallery equipment (30 C ± 1), cooling of the accelerator tunnel equipment (30 C ± 1) and the cooling and temperature control accelerating sections and waveguide (40 ° C ± 0,2). The block diagram of cooling and temperature control of the linear electron accelerator of 100 MeV/100 kW, describes the basic principles to formulate requirements to the cooling systems. It describes the status of the installation, commissioning and testing of the cooling and temperature control of the accelerator - driver subcritical neutron source KIPT.

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THPVA079

First Optics Design and Beam Performance Simulation of PRAE: Platform for Research and Applications With Electrons at Orsay

instrumentation, optics, gun, detector

4637

A. Faus-Golfe, S. Barsuk, B. Borgo, D. Douillet, M. El Khaldi, L. Garolfi, A. Gonnin, M. Langlet, P. Lepercq, M. Omeich, V. Puill, C. Vallerand
LAL, Orsay, France
P. Ausset, M. Ben Abdillah, S. Blivet, P. Duchesne, B. Genolini, M. Hoballah, G. Hull, R. Kunne, C. Le Galliard, J. Lesrel, D. Marchand, E. J-M. Voutier
IPN, Orsay, France
A. Hrybok, A. Pastushenko
National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev, Ukraine
A. Vnuchenko
IFIC, Valencia, Spain

The PRAE project aims at creating a multidisciplinary R&D facility in the Orsay campus gathering various scientific communities involved in radiobiology, subatomic physics, instrumentation and particle accelerators around an electron accelerator delivering a high-performance beam with energy up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and future challenging R&D. In addition PRAE will provide a major education and training asset for students and engineers yielding a regional instrument of advanced technology at the heart of the scientific, technological and academic complex of the Paris-Saclay University. In this paper we report the first optics design and performance evaluations of such a multidisciplinary machine, including a first description of future experiments and the required beam instrumentation.

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THPVA081

Radiation Tests of Aerospace Components at ELBE

radiation, experiment, gun, detector

4641

Ch. Schneider, D. Bemmerer, P. Michel, D. Stach
HZDR, Dresden, Germany

The cw electron accelerator ELBE operates mainly in the beam energy range 6 to 32 MeV and beam current range 1μA to 1mA. For most experiments a thermionic gun is used as electron source. The cw electron pulse structure so as the pulse charge is realized by applying electrical pulses with specific amplitudes and frequencies on the grid of the gun. The standard cw operation frequency is 13 MHz but can be divided sequentially by the factor 2 down to 101 kHz. For very special pulse structures a so called single pulser module exist performing different patterns also with dark current suppression via a macro pulser gate. For evaluating the performance and hardness under irradiation of e.g. aerospace components much lower doses respectively currents lower than the μA range are required. Furthermore reproducible and stable doses in a specific area for consecutively radiation of samples are necessary. In the presentation the investigations and concepts used at ELBE for the irradiation of different aerospace components are described.

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THPVA086

Beam Dynamics Studies of an Accelerating Tube for 6 MeV Electron LINAC

emittance, simulation, space-charge, linac

4657

S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
F. Abbasi
Shahid Beheshti University, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
M. Lamehi
IPM, Tehran, Iran

Side coupled standing wave accelerating tubes are widely used in a low energy linear accelerator because of relatively high accelerating gradient and low sensitivity to construction tolerances. The effective interaction of particles and electromagnetic fields is important for accelerate electrons to intended energy with the greatest efficiency and beam quality output. In this paper, we present the beam dynamics of a 6 MeV Side coupled standing wave accelerating tube using a space charge tracking algorithm (ASTRA). The designed accelerating tube that feeds by a maximum power of 2.6 MW resonant at frequency of 2998.5 MHz in pi/2 mode. 37.5 percent capture efficiency, 6.82 pi-mm-mrad horizontal emittance, 6.78 pi-mm-mrad vertical emittance, 2.24 mm horizontal and vertical beam size and 1079 keV energy spread of the output beam have been determined from the results of beam dynamics studies in ASTRA

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THPVA087

Thermal and Mechanical Analysis of 3 GHz Side Coupled RF Cavity for Medical Linacs

cavity, simulation, linac, operation

4660

M. Mohseni Kejani, F. Abbasi
Shahid Beheshti University, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran

Medical linear accelerators have wide applications for cancer treatment in the world. Side coupled RF cavities was used in this accelerators for production of X-ray in range of energies between 4 to 25 MeV. Usually, the RF source is magnetron with lower cost in comparison to klystron in this type of applications. Side coupled cavity is a biperiodic structure with sensitive performance to operational thermal and mechanical conditions. In this paper, thermal and mechanical simulations for a period of the structure are presented.

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THPVA088

DESIGN AND CONSTRUCTION OF BRAZED SIDE COUPLED CAVITY OF MEDICAL ACCELERATOR

coupling, simulation, cavity, vacuum

4664

S. Ahmadiannamin, Kh.S. Sarhadi
ILSF, Tehran, Iran
F. Abbasi, M. Mohseni Kejani
Shahid Beheshti University, Tehran, Iran
M. Bahrami, M. Lamehi
IPM, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran

Two types of standing wave RF cavities are used routinely in construction of medical linear accelerators. These two types are Side coupled and on-axis coupled standing wave cavities. This selection is based on higher shunt impedance and compactness in comparison to travelling wave RF cavities. In this paper, we present the simulation, construction and measurement results of brazed section of 3 GHz side coupled RF cavity. It is the first successful experience of its kind in Iran. The obtained experiences can be used effectively for construction of side coupled thermionic RF guns and RF cavities of medical or industrial linacs.

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THPVA089

Optimization Study on Production of Mo-99 Using High Power Electron Accelerator Linac

target, linac, photon, neutron

4667

A. Taghibi Khotbeh-Sara, F. Rahmani
KNTU, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran

Molybdenum-99 is used for preparing 99mTc, which is the most widely used isotope in nuclear medicine. As a recent and now shortages in reactor-based supplies of 99Mo/99mTc and also some problems due to the time limitation in a direct production approach such as 100Mo(p, 2n)99mTc reaction by cyclotrons, many of developed countries have started the plan to produce this type of radioisotopes based on the production of non-reactor methods, especially by linac. In this study, the investigation on 99Mo production based on high power electron linac as an alternative approach has been performed, in which the use of 100Mo(gamma, n)99Mo (photoneutron production) has been proposed.

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THPVA105

A Novel Side Coupling Standing-Wave Accelerating Structure for a Medical Linac

cavity, coupling, impedance, linac

4710

Zh. X. Tang, Z.H. Bai, Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

A novel side coupling standing-wave (SW) accelerat-ing tube for low energy medical linac has been designed that operating frequency is 2998 MHz, operating mode is ', final energy is 6 MeV and beam current is 130 mA. A novel bridge hole between an accelerating cavity and coupling cavity has been utilized to reduce the mutual effect between two cavities and improve the anti-jamming capability and the long term stability. The inner end plate of the inlet of the first accelerating cavity in-cludes the nose cone to realize self-focusing in transverse to improve the beam quality. The simulation of the elec-tromagnetic field of structure and beam dynamic has been carried out with the SUPERFISH, CST Microwave studio and Parmela, respectively.

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THPVA114

Status of High-Efficiency Klystron Development for the PLS-II and PAL-XFEL

klystron, cavity, gun, cathode

4726

S.J. Park, H.S. Han, W.H. Hwang, S.D. Jang, Y.D. Joo, K.R. Kim, C.D. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
J.H. Hwang, S.S. Jang
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.Y. Hyun, H.S. Seo, D.H. Yu
Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea

Funding: This work was supported by the National R&D program (grant number: 2016R1A6B2A01016828) through the National Research Foundation of Korea (NRF).
We are developing a high-efficiency klystron for use in the PLS-II(Pohang Light Source II) and the PAL-XFEL in the Pohang Accelerator Laboratory. Since the PLS-II and the PAL-XFEL are already running with ~70 klystron modulator systems, newly developed klystrons should be designed to fit into existing installation spaces and power supplies, and their overall lengths(< 2 m) and beam perveances(2 upervs) should not be changed. In order to achieve the high efficiency with aforementioned boundary conditions, we are going to adopt a multi-cell output cavity in which, unlike those of the the SLAC X-band and KEK C-band klystrons, the cell frequencies are independently tuned to provide maximum beam-to-rf power conversion. In this article we report on our physics and engineering design efforts to achieve the high efficiency with minimum instabilities.

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THPVA126

Monte Carlo Simulation of Electron Beam Irradiation System for Natural Rubber Vulcanization

simulation, vacuum, linac, target

4747

K. Kosaentor
IST, Chiang Mai, Thailand
E. Kongmon, S. Rimjaem, J. Saisut, C. Thongbai
Chiang Mai University, Chiang Mai, Thailand

This paper presents the results of Monte Carlo simulation of electron beam irradiation system for natural rubber vulcanization, which is underway at Chiang Mai University in Thailand. The accelerator system can produce electron beams with adjustable energy and current in the ranges of 0.5-4 MeV and 10-100 mA, respectively. The electron beam exits from vacuum environment in the accelerator to the atmospheric air through a titanium (Ti) window. The electron dose absorption in Ti window and air was calculated by using the program GEANT4. The simulation results show that 50 μm Ti foil causes the energy loss of 1 and 18% for the beam of 4.0 and 0.5 MeV, respectively. The air gap between vacuum window and rubber surface is adjustable from 180 mm to 540 mm. The total beam energy loss of around 8-17% and 1-3% from the initial energies of 0.5 and 4 MeV, respectively. The proper depth of the natural rubber for the vulcanization process is 0.13 to 1.68 cm with the surface dose of 5.32 kGy for 0.5 MeV electron beam and 3.34 kGy for 4.0 MeV electron beam at the pulse repetition rate of 200 Hz. Accordingly, the treatment time of around 10-15 second per irradiated point is required.

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THPVA137

A Monte Carlo Approach to Imaging and Dose Simulations in Realistic Phantoms Using Compact X-Ray Source

simulation, photon, detector, radiation

4783

E. Skordis, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
E. Skordis, V. Vlachoudis
CERN, Geneva, Switzerland
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

X-ray emitters are amongst the most widely used tools in medicine. Based on compact electron beams, they are utilised for a range of applications, including medical imaging and cancer treatment. The optimisation of a specific X-ray source relies on detailed simulation studies into the achievable resolution and intensity distribution. Monte Carlo (MC) codes are widely used in the medical community for dose estimation to patients and the environment. They are also ideally suited for simulating 3D intensity distributions in realistic environments. This demands accurate and reliable physical models capable of handling all components of the expected radiation field. In this paper the capabilities of the FLUKA MC code to simulate complex X-ray sources are presented. Advanced phantoms, based on imported DICOM format, are used to evaluate the dose to relevant areas, including the patient, individual organs and the treatment room. It is also shown how they can provide a good basis to reproduce radiography images by scoring photon fluencies.

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THPVA139

Relative Insensitivity to Inhomogeneities on Very High Energy Electron Dose Distributions

simulation, experiment, radiation, photon

4791

A. Lagzda, R.M. Jones
UMAN, Manchester, United Kingdom
D. Angal-Kalinin, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
K. Kirkby
The Christie NHS Foundation Trust, Manchester, United Kingdom

Funding: Science and Technology Facilities Council, United Kingdom Cockroft Institute, United Kingdom Christie Hospital, Manchester, United Kingdom
We investigated the effects of heterogeneous regions on dose deposition of very high-energy electrons (VHEE) using both Geant4 simulations and experiments performed at the CALIFES facility at CERN. Small air and acetal plastic (bone equivalent) cavities were embedded in a water phantom and irradiated with a 197 MeV electron beam. Experimentally determined transverse dose profiles were acquired using radiation sensitive EBT3 Gafchromic films embedded in the water phantom at various depths. EBT3 Gafchromic films were found to be a suitable dosimeter for relative dose dosimetry of VHEE beams. Simulated and measured results were found to be consistent with each other and the largest discrepancy was found to be no more than 5%. Dose profiles of VHEE beams were found to be relatively insensitive to embedded high and low density geometries.

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THPVA141

Non-Destructive Measurement of Electron Microbunch Separation

laser, radiation, experiment, gun

4798

H. Zhang, G. Doucas, H. Harrison, I.V. Konoplev, A.J. Lancaster
JAI, Oxford, United Kingdom
A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

With the development of femtosecond lasers, the generation of micro-bunched beams directly from a photocathode becomes routine; however, the monitoring of the separation is still a challenge. We present the results of proof-of-principle experiments measuring the distance between two bunches via the amplitude modulation analysis of a monochromatic radiation signal. Good agreement with theoretical prediction is shown.

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THPVA147

KlyLac Conceptual Design for Borehole Logging

linac, klystron, cavity, vacuum

4808

A.V. Smirnov, S. Boucher, M.A. Harrison, A.Y. Murokh
RadiaBeam Systems, Santa Monica, California, USA
R.B. Agustsson, D. Chao, J.J. Hartzell, K.J. Hoyt, A.Yu. Smirnov
RadiaBeam, Santa Monica, California, USA
E.A. Savin
MEPhI, Moscow, Russia

Funding: This work was supported by the U.S. Department of Energy (award No. DE-SC0015721).
Linac-based system for borehole logging exploits KlyLac approach combing klystron and linac sharing the same electron beam, vacuum volume, and RF net-work. The conceptual design tailors delivering 3.5-4 MeV electrons within 3.5 inch borehole at ambient temperatures 150 degrees C to replace 137Cs, >1 Ci source used in borehole logging. The linac part is based on a very robust, high group velocity, cm-wave, standing wave accelerating structure. The design concept features i) self-oscillation analog feedback that automatically provides modal stability; ii) ferrite-free isolation of the klystron; and iii) long accelerating section with large (0.3%) frequency separation between adjacent modes; and iv) low-voltage klystron.

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THPVA148

Inexpensive Brazeless RF Accelerator

gun, vacuum, operation, cathode

4812

S.P. Antipov, C.-J. Jing, R.A. Kostin, S.V. Kuzikov, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Funding: DOE SBIR
A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun - type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells.

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THPVA151

Halbach Magnets for CBETA and eRHIC

permanent-magnet, simulation, proton, quadrupole

4814

H. Witte, J.S. Berg, B. Parker
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
At Brookhaven National Laboratory two design efforts are underway: eRHIC and CBETA. eRHIC is a proposed upgrade to the existing Relativistic Heavy Ion Collider (RHIC), which would allow collisions of up to 21 GeV polarized electrons with protons or heavy ions. CBETA is a 150 MeV electron accelerator, aiming to demonstrate essential technology necessary for eRHIC. Both machines employ FFAG arcs and are designated to use permanent magnet material for the required quadrupole magnets. One proposed design is a Halbach magnet; this paper investigates the feasibility of this approach.

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FRXBA1

Compact and Efficient Accelerators for Radioisotope Production

cyclotron, target, isotope-production, linac

4824

C. Oliver
CIEMAT, Madrid, Spain

The production in an efficient way of radioisotopes for medical use is crucial. With the closing in the next ten years of nuclear reactors the problem of the production of some of them is being critical. New approaches of producing these radioisotopes via accelerators are being developed. In the other hand a big effort is being made for making the accelerators for the production of radioisotopes more compact, efficient and with an optimized cost. This paper describes the recent advances in this kind of accelerator techniques.

Slides FRXBA1 [2.797 MB]

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FRXBB1

Novosibirsk Four-Orbit ERL With Three FELs

FEL, radiation, undulator, gun

4836

N.A. Vinokurov, V.S. Arbuzov, K.N. Chernov, I.V. Davidyuk, O.I. Deichuli, E.N. Dementyev, B.A. Dovzhenko, Ya.V. Getmanov, Ya.I. Gorbachev, B.A. Knyazev, E.I. Kolobanov, A.A. Kondakov, V.R. Kozak, E.V. Kozyrev, S.A. Krutikhin, V.V. Kubarev, G.N. Kulipanov, E.A. Kuper, I.V. Kuptsov, G.Y. Kurkin, L.E. Medvedev, S.V. Motygin, V.N. Osipov, V.K. Ovchar, V.M. Petrov, A.M. Pilan, V.M. Popik, V.V. Repkov, T.V. Salikova, M.A. Scheglov, I.K. Sedlyarov, S.S. Serednyakov, O.A. Shevchenko, A.N. Skrinsky, S.V. Tararyshkin, V.G. Tcheskidov, A.G. Tribendis, P. Vobly, V. Volkov
BINP SB RAS, Novosibirsk, Russia
I.V. Davidyuk, Ya.V. Getmanov, B.A. Knyazev, E.V. Kozyrev, S.S. Serednyakov, N.A. Vinokurov
NSU, Novosibirsk, Russia
A.G. Tribendis
NSTU, Novosibirsk, Russia

The Novosibirsk FEL facility has three FELs, installed on the first, second and fourth orbits of the ERL. The first FEL covers the wavelength range of 90 - 240 mkm at an average radiation power of up to 0.5 kW with a pulse repetition rate of 5.6 or 11.2 MHz and a peak power of up to 1 MW. The second FEL operates in the range of 40 - 80 mkm at an average radiation power of up to 0.5 kW with a pulse repetition rate of 7.5 MHz and a peak power of about 1 MW. These two FELs are the world's most powerful (in terms of average power) sources of coherent narrow-band (less than 1%) radiation in their wavelength ranges. The third FEL was commissioned in 2015 to cover the wavelength range of 5 - 20 mkm. The Novosibirsk ERL is the first and the only multiturn ERL in the world. Its peculiar features include the normal-conductive 180 MHz accelerating system, the DC electron gun with the grid thermionic cathode, three operation modes of the magnetic system, and a rather compact (6×40 m2) design. The facility has been operating for users of terahertz radiation since 2004.

Slides FRXBB1 [51.485 MB]

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FRYBA1

From Niels Bohr to Quantum Computing

operation, coupling, controls, factory

4852

K. Mølmer
AU, Aarhus, Denmark

The development and use of accelerators for research has been closely linked to an era of modern physics which of course includes quantum mechanics. Niels Bohr was one of the foreground figures in the development of quantum mechanics and the IPAC community would like to recognise his contributions to this field in 2017, when IPAC takes place in Copenhagen, where he was active. Quantum computing is a subject of enormous potential and interest, and we would like to hear about the historical links to Niels Bohr and the so called Copenhagen School of Quantum Mechanics, and what we realistically can expect from this development.

Slides FRYBA1 [2.490 MB]

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FRYCA1

The Future of High-energy Accelerators

collider, proton, hadron, positron

4856

J. Mnich
DESY, Hamburg, Germany

The physics results from high energy colliders, neutrino experiments and from experiments in space are changing the particle physics landscape. In the last decade several accelerator designs and studies have taken shape and reached a high level of maturity both at the high energy and high intensity frontiers. The talk should review the physics questions facing the HEP community and the strategy to address them in view of the next update of the European Strategy for Particle Physics.

Slides FRYCA1 [9.087 MB]

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