IPAC2017 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
MOZB1	First Results with the Novel Peta-Watt Laser Acceleration Facility in Dresden	target, plasma, electron, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOZB1
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MOOCB2	Laser System Design and Operation for SNS H⁻ Beam Laser Stripping	experiment, operation, ion, neutron	57
	Y. Liu, A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, A.A. Menshov, A. Webster ORNL, Oak Ridge, Tennessee, USA A. Rakhman ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work has been partially supported by U.S. DOE grant DE-FG02-13ER41967. ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Recently, a high-efficiency laser assisted hydrogen ion (H⁻) beam stripping was successfully carried out in the Spallation Neutron Source (SNS) accelerator. The experiment was not only an important step toward foil-less H⁻ stripping for charge exchange injection, it also served as a first example of using megawatt ultraviolet (UV) laser in an operational high power proton accelerator facility. This talk reports the design, implementation, and commissioning results of the macropulse laser system, laser transport line, and laser operation for the laser stripping experiment. The macropulse laser consists of a mode-locked picosecond pulsed seed laser and a burst-mode Nd:YAG laser amplifier. The general design concept can be adapted to any temporal beam structures in most accelerators. We have achieved UV pulses with the pulse widths varying between 34 to 54 ps and a maximum peak power over 3.5 MW. A laser transport line is installed to deliver the UV beam to the laser stripping chamber at a transmission efficiency of 70%. Laser operation including remote control and monitor of laser parameters will be described.
	Slides MOOCB2 [11.306 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOOCB2
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MOPAB024	Proposal to Observe Half-Bare Electrons on a 40-MeV LINAC	electron, radiation, experiment, 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, electron, 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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MOPAB045	Reconstruction of the 3D Charge Distribution of an Electron Bunch Using a Novel Variable-Polarization Transverse Deflecting Structure (TDS)	simulation, electron, experiment, space-charge	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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MOPAB050	Reconstruction of Sub-Femtosecond Longitudinal Bunch Profile Measurement Data	electron, 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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MOPAB051	Progress in FLASH Optics Consolidation	optics, undulator, emittance, gun	211
	J. Zemella, M. Vogt DESY, Hamburg, Germany
	FLASH is the superconducting soft X-ray Free Electron Laser in Hamburg at DESY, Germany. A precise knowledge of the beam optics is a key aspect of the operation of a SASE FEL. A campaign of optics consolidation has started in 2013 when the second beam line FLASH2 was installed downstream of the FLASH linac. We give an update on progress of this effort and on recent results.
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MOPAB052	A Transverse Deflection Structure with Dielectric-Lined Waveguides in the Sub-THz Regime	electron, simulation, emittance, impedance	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	electron, simulation, 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	electron, wakefield, 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, electron, 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, electron, linac	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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MOPAB060	Thermal Issues for the Optical Transition Radiation Screen for the ELI-NP Compton Gamma Source	electron, target, radiation, simulation	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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MOPAB065	Breit-Wheeler Scattering Events Produced by Two Interacting Compton Sources	photon, scattering, electron, 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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MOPAB072	Measurement of Three-Dimensional Distribution of Electron Bunch Using RF Transverse Deflector	experiment, electron, 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	electron, FEL, detector, radiation	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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MOPAB075	Measurement of Electron Bunch Length via a Tunable-Gap Undulator	radiation, electron, undulator, 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	electron, 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, electron	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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MOPAB119	Beam Instrumentation Developments for the Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN	proton, electron, plasma, 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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MOPAB120	Beam Instrumentation for the CERN LINAC4 and PSB Half Sector Test	linac, instrumentation, emittance, proton	408
	F. Roncarolo, J.C. Allica Santamaria, M. Bozzolan, C. Bracco, S. Burger, G.J. Focker, G. Guidoboni, L.K. Jensen, B. Mikulec, A. Navarro Fernandez, U. Raich, J.B. Ruiz, L. Søby, J. Tan, W. Viganò, C. Vuitton, C. Zamantzas CERN, Geneva, Switzerland T. Hofmann Royal Holloway, University of London, Surrey, United Kingdom
	The construction, installation and initial commissioning of CERN's LINAC4 was completed in 2016 with H⁻ ions successfully accelerated to its top energy of 160 MeV. The accelerator is equipped with a large number of beam diagnostic systems that are essential to monitor, control and optimize the beam parameters. A general overview of the installed systems and their functional specifications will be followed by a summary of the most relevant results. This includes transverse profile monitors (wire scanners, wire grids and a laser profile monitor), beam position and phase monitors (whose ToF measurements were essential for adjusting RF cavity parameters), beam loss monitors, beam current transformers and longitudinal beam shape monitors. This contribution will also cover the beam instrumentation for the so-called PSB Half Sector Test, which has been temporarily installed in the LINAC4 transfer line to study H⁻ stripping efficiency. At this facility it was possible to test the new H⁰/H⁻ beam current monitor, designed to monitor the stripping efficiency and an essential element of the beam interlock system when the LINAC4 is connected to the PSB in 2019.
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MOPAB121	Installation and Test of Pre-series Wire Scanners for the LHC Injector Upgrade Project at CERN	vacuum, controls, electronics, detector	412
	R. Veness, P. Andersson, W. Andreazza, N. Chritin, B. Dehning, J. Emery, A. Goldblatt, D. Gudkov, F. Roncarolo, J.L. Sirvent, J. Tassan-Viol CERN, Geneva, Switzerland
	A new generation of fast wire scanners is being developed for the LHC Injectors Upgrade (LIU) project at CERN. These will be essential tools for transverse profile measurement with the higher brightness LIU beams, and are planned for installation in 2019 in all three synchrotrons making up the LHC injector chain. An active period of development and test has resulted in prototype installations in the SPS and PSB rings. This paper will summarise the design and report on the results to-date.
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MOPAB146	Electron Beam Diagnosis Using K-edge Absorption of Laser-Compton Photons	electron, 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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MOPIK003	Improvement of the Photoemission Efficiency of Magnesium Photocathodes	cathode, gun, SRF, cavity	500
	R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate HZDR, Dresden, Germany P. Patra IUAC, New Delhi, India
	Funding: The work is supported by the European Community under the FP7 programme (EuCARD-2) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1. To improve the quality of photocathodes is one of the critical issues in enhancing the stability and reliability of photo-injector systems. Presently the primary choice is to use metallic photocathodes for the ELBE SRF Gun-II to reduce the risk of contamination of the superconducting cavity. Magnesium has a low work function (3.6 eV) and shows high quantum efficiency (QE) up to 0.3 % after laser cleaning. The SRF Gun II with an Mg photocathode has successfully provided electron beam for ELBE users. However, the present cleaning process with a high intensi-ty laser (activation) is time consuming and generates unwanted surface roughness. This paper presents the investigation of alternative surface cleaning procedures, such as thermal treatment. The QE and topography of Mg samples after treatment are reported.
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MOPIK004	Demonstration of an All-Optically Driven Sub-keV THz Gun	electron, gun, acceleration, 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, electron, gun, 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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MOPIK007	THz Driven Electron Acceleration with a Multilayer Structure	electron, acceleration, 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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MOPIK011	Electron Beam Generation From InGaN/GaN Superlattice Photocathode	electron, 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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MOPIK018	Micro-Scale Electron Beam Generation Using Pyroelectric Crystals	electron, acceleration, 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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MOPIK021	Generation of Transversely Segmented Beam Using a Nano-Patterned Photocathode	cathode, simulation, gun, acceleration	545
	A. Lueangaramwong, P. Piot Northern Illinois University, DeKalb, Illinois, USA G. Andonian RadiaBeam, Santa Monica, California, USA P. Piot Fermilab, Batavia, Illinois, USA
	Funding: Work supported by US Department of Energy (DOE) contract DE-SC0009656 with Radiabeam Technologies and by NSF grant PHY-1535401 with Northern Illinois University. Plasmonic photocathodes – nano-patterned photocathodes with periodicity comparable to the excitation laser – have demonstrated enhanced quantum efficiency. In the present paper we present numerical simulations of the beam dynamics associated to the emission process from this type of cathodes and to the subsequent acceleration to relativistic energies by combining WARP and IMPACT-T programs. We especially consider the possibility to transversely image the cathode surface at high energy and enable the generation of transversely segment beams.
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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	electron, operation, 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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MOPIK052	Generation of Highly-Charged Carbon Ions from Thin Foil Target	target, ion, plasma, heavy-ion	635
	T. Kanesue, S. Ikeda, M. Okamura BNL, Upton, Long Island, New York, USA Y. Saito Sokendai, Ibaraki, Japan
	Funding: This work was supported by the U.S. Department of Energy and National Aeronautics and Space Administration. Generation of highly-charged heavy ions such as fully stripped C⁶⁺ of more than hundreds mA of beam current can be possible only with a laser ablation ion source (LIS). Heavy ions are produced from a solid target irradiated by a pulsed high power laser. Recent study showed that only sub-micron range of surface layer contributes for the generation of highly-charged heavy ions. In this paper, we experimentally investigated the difference of the performance of highly-charged carbon ion production from graphite targets of different thickness (25, 70, 254, and 3000 'm) to seek the possibility of a rolled target to overcome the limitation of a target lifetime.
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MOPIK053	Design Study of High Repetition Rate Laser Ion Source for High Power Beam Production	target, ion, plasma, heavy-ion	638
	T. Kanesue, S. Ikeda, M. Okamura BNL, Upton, Long Island, New York, USA Y. Saito Sokendai, Ibaraki, Japan
	Funding: This work was supported by the U.S. Department of Energy and National Aeronautics and Space Administration. We are studying a laser ion source (LIS) for a high average beam power heavy ion beam production. A LIS is the most intense source of pulsed highly-charged ions using a laser ablation scheme. By increasing the repetition rate, a LIS based heavy ion beam would approach the average beam power based on a low beam current and continuous beam regime. In addition, a high-repetition-rate LIS can be used as a heavy ion source for a medical accelerator with spot scanning technique. This paper will describe the requirements to realize the high repetition rate operation.
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MOPIK055	Beam by Design: Current Pulse Shaping Through Longitudinal Dispersion Control	electron, simulation, sextupole, synchrotron	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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MOPIK069	Approximate Matrices for Modeling the Focusing of the Undulator Periods and Undulator End Fields	undulator, focusing, betatron, dipole	686
	V. Balandin, N. Golubeva DESY, Hamburg, Germany
	We describe procedure for constructing approximate matrices for modeling the focusing of the undulator periods and undulator end fields and discuss applicability of these matrices to the European XFEL undulators.
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MOPIK072	Recent Upgrades of the Bunch Arrival Time Monitors at FLASH and European XFEL	software, controls, electronics, electron	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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MOPIK111	Initial Performance Measurements of Multi-GHz Electron Bunch Trains	electron, 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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MOPVA001	Coherent X-Ray Radiation From Electron Beam Processed by Channeling and Emittance Exchange	electron, photon, radiation, 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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MOPVA008	Commissioning Considerations for BERLinPro	diagnostics, gun, target, linac	862
	M. McAteer, M. Abo-Bakr, T. Kamps, G. Klemz, J. Kuszynski HZB, Berlin, Germany I. Will MBI, Berlin, Germany
	BERLinPro is an energy recovery linac project whose goal is to establish the accelerator physics knowledge and technology needed to produce 50 MeV beams with high current, low normalized emittance, and low losses. The machine will be commissioned in phases beginning in 2018, and extensive planning is underway for start-up of the machine and to prepare for measurements to verify the achievement of target beam parameters. This paper outlines the planned phases for the commissioning of the machine, details the operational modes, and gives an overview of the diagnostics available for beam-based measurements to verify the achievement of performance goals.
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MOPVA010	Setup and Status of an SRF Photoinjector for Energy-Recovery Linac Applications	gun, SRF, cathode, emittance	865
	T. Kamps, D. Böhlick, A.B. Büchel, M. Bürger, P. Echevarria, A. Frahm, F. Göbel, S. Heling, A. Jankowiak, S. Keckert, H. Kirschner, G. Klemz, J. Knobloch, G. Kourkafas, J. Kühn, O. Kugeler, A.N. Matveenko, A. Neumann, N. Ohm-Krafft, E. Panofski, F. Pfloksch, S. Rotterdam, M.A.H. Schmeißer, M. Schuster, H. Stein, J. Ullrich, A. Ushakov, J. Völker HZB, Berlin, Germany I. Will MBI, Berlin, Germany
	Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB. The Superconducting RF (SRF) photoinjector programme for the energy-recovery linac (ERL) test facility BERLinPro sets out to push the brightness and average current limits for ERL electron sources by tackling the main challenges related to beam dynamics of SRF photoinjectors, the incorporation of high quantum efficiency (QE) photocathodes, and suppression of unwanted beam generation. The paper details the experimental layout of the SRF photoinjector and the gun test facility GunLab at Helmholtz-Zentrum Berlin.
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MOPVA012	The Dedicated Accelerator R&D Facility Sinbad at DESY	linac, electron, 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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MOPVA016	ELI-NP GBS Status	linac, electron, 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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MOPVA019	60 pC Bunch Charge Operation of the Compact ERL at KEK	operation, emittance, cavity, linac	890
	T. Miyajima, K. Harada, Y. Honda, E. Kako, R. Kato, T. Miura, N. Nakamura, T. Obina, M. Shimada, R. Takai, K. Umemori, M. Yamamoto KEK, Ibaraki, Japan R. Hajima, R. Nagai QST, Tokai, Japan T. Hotei Sokendai, Ibaraki, Japan N. Nishimori Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	The compact ERL (cERL) at KEK was operated in March 2017 to demonstrate generation, acceleration and transportation of the target bunch charge of 60 pC without energy recovery. However, the maximum bunch charge was limited to 40 pC due to the limitation of the excitation laser power. For the bunch charge of 40 pC, the bunch length and the normalized emittance were measured in the injector diagnostic line. The results of the bunch length measurement gave good agreement with the values that had been obtained by model simulation. The measured normalized rms emittances for 40 pC were 0.9 to 2.4 mm mrad, and they were lager than the design value of 0.6 mm mrad. To achieve the design emittance, we have studied the source of the emittance growth for the bunch charge of 40 pC.
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MOPVA021	Optics Design of the Compact ERL Injector for 60 pC Bunch Charge Operation	optics, cathode, operation, gun	898
	T. Hotei Sokendai, Ibaraki, Japan R. Kato, T. Miyajima, N. Nakamura, M. Shimada KEK, Ibaraki, Japan
	EUV-FEL light source based on ERL has been designed at KEK for EUV lithography light source. The advantage of ERL is to accelerate high average current beam due to CW operation, and it is possible to drive high average power FEL. To generate the target EUV-FEL power, which is 10 kW, the bunch charge of 60 pC, the beam energy of 10.5 MeV and the bunch length of 1 ps are required at the end of the EUV-FEL injector. In order to demonstrate the target beam performance for the EUV-FEL accelerator, a high charge beam test was carried out at the cERL in KEK. We designed a new optics of the cERL injector prior to the high charge beam operation. To calculate beam dynamics more accurately, accelerator models corrected according to the condition of the actual cERL injector is used for the optics design. From results of the optics design that minimized the emittance and bunch length using the corrected accelerator models, the emittance and bunch length at the end of injector are 0.8 mm-mrad and 3.4 ps. Furthermore, based on the design optics, we carried out high bunch charge beam operation.
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MOPVA023	Luminosity Increase in Laser-Compton Scattering by Crab Crossing Method	electron, 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, electron, target, 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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MOPVA031	Low Energy Compact Storage Ring Design for Compton Gamma-Ray Light Source	electron, emittance, 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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MOPVA036	High Average Brilliance Compact Inverse Compton Light Source	electron, SRF, gun, brilliance	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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MOPVA066	Limits for the Operation of the European XFEL 3.9 GHz System in CW Mode	cavity, operation, cryomodule, linac	1023
	P. Pierini, A. Bosotti, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy J. Branlard, D. Kostin, C.G. Maiano, W.-D. Möller, P. Pierini, D. Reschke, J.K. Sekutowicz, E. Vogel DESY, Hamburg, Germany
	Future upgrades of the European XFEL (EXFEL) facility may require driving the linac at higher duty factor, possibly extending to CW mode at reduced gradients. A preliminary analysis for the accelerator modules has been presented in the EXFEL TDR, but no precise assessment has been performed so far for the present 3.9 GHz system design. By making use of data collected during the commissioning and operation phase of the EXFEL injector system, we discuss here an estimate for the limits of CW operation of the present system and a plan for its possible experimental verification with existing available cavities and the EXFEL spare module.
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MOPVA071	Press Forming Tests of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources	cavity, photon, niobium, resonance	1031
	M. Sawamura, R. Hajima QST, Tokai, Japan H. Hokonohara, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan T. Kubo, T. Saeki KEK, Ibaraki, Japan
	We are developing the superconducting spoke cavity for laser Compton scattered (LCS) photon sources. We adopt the superconducting spoke cavity for electron beam drivers to realize a wide use of LCS X-ray and '-ray sources in academic and industrial applications. The spoke cavity can make the accelerator more compact than an elliptical cavity because the cavity size is small at the same frequency and the packing factor is good by installing couplers on outer conductor. Though our proposal design for the photon source consists of the 325 MHz spoke cavities in 4K operation, we are fabricating the half scale model of 650 MHz spoke cavity in order to accumulate our cavity production experience by effective utilization of our limited resources. Since the spoke has more complicated structure than an elliptical cavity, we performed press forming tests for the half spoke and estimated the formed shapes with 3-dimensional measurement.
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TUOAA2	A Soft X-Ray Free-Electron Laser Beamline of SACLA	FEL, electron, undulator, photon	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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TUYB1	First Measurements of Trojan Horse Injection in a Plasma Wakefield Accelerator	plasma, electron, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUYB1
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TUOBB1	Experimental Demonstration of Energy-Chirp Reduction by a Plasma Dechirper	plasma, electron, 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, electron, 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, electron, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUOBB3
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TUPAB025	Experimental Results for Multiphoton Nonlinear Photoemission Processes on Phil Test Line	photon, electron, 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).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB025
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TUPAB029	UHV Photocathode Plug Transfer Chain for the BERLinPro SRF-Photoinjector	SRF, vacuum, cathode, cavity	1381
	J. Kühn, J. Borninkhof, M. Bürger, A. Frahm, A. Jankowiak, T. Kamps, M.A.H. Schmeißer, M. Schuster HZB, Berlin, Germany P. Murcek, J. Teichert, R. Xiang HZDR, Dresden, Germany
	A dedicated particle free UHV photocathode plug transfer chain from the preparation system to the SRF-Photoinjector was set up and commissioned at HZB for the BERLinPro project. The plug handling system was designed in collaboration with the ELBE team at HZDR, where the same transfer chain is in commissioning phase. In the future the exchange of photocathodes between the laboratories offers the possibility to test different types of photocathodes in different SRF-photoinjectors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB029
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TUPAB031	Status and Perspectives of the S-DALINAC Polarized-Electron Injector	electron, gun, cathode, experiment	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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TUPAB033	Design of a Stripline Kicker for the ELBE Accelerator	kicker, emittance, electron, neutron	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, electron, 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	electron, gun, acceleration, timing	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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TUPAB040	Status Update of the SINBAD-ARES Linac Under Construction at DESY	linac, electron, diagnostics, 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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TUPAB050	A Lifetime Study of CsK2Sb Multi-Alkali Cathode	cathode, vacuum, electron, 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, electron, 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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TUPAB056	New Achievements of the Laser System for RF-Gun at SuperKEKB Injector	operation, gun, electron, 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, electron, cavity	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	scattering, electron, 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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TUPAB074	Measurements of Thermal Emittance for Cesium Telluride Photocathodes in an L-Band RF Gun	emittance, gun, electron, 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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TUPAB076	Design of an X-Band Photocathode for Tsinghua Thomson Scattering X-Ray Source	gun, solenoid, cathode, emittance	1497
	L.Y. Zhou, H.B. Chen, Y.-C. Du, W. Gai, W.-H. Huang, J. Shi, C.-X. Tang, D. Wang, Z. Zhang, Z. Zhou TUB, Beijing, People's Republic of China
	Compared with S-band and C-band accelerating structures, X-band structures can run at a higher accelerating gradient and are more compact in size. In order to obtain higher electron energy in a limited space, a new X-band photo-injector operating at 11.424GHz has been designed at the Accelerator Laboratory of Tsinghua University. The structural design of the X-band photo-cathode RF gun and the accelerating structures as well as the beam dynamics simulation are presented in this paper, followed by the optimization of the structure based on the dispersed optimization experiment method(DOE). The results show that the design satisfies the working requirements with a small space occupied and a high beam quality.
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TUPAB077	A Combined THz/X-ray Source Based on Brake-applied Velocity Bunching and Magnetic Compression	electron, radiation, bunching, emittance	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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TUPAB094	Emittance Improvements in the MAX IV Photocathode Injector	emittance, linac, gun, quadrupole	1533
	J. Andersson, F. Curbis, M. Kotur, F. Lindau, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden
	The MAX IV injector design predicts a beam with 100 pC of charge and an emittance lower than 1 mm mrad. The photocathode pre-injector is based on the now close to standard 1.6-cell gun adapted to 2.9985 GHz, in combination with a Ti:Sapphire laser system. This system reaches the requirements of the injector operation for the SPF, but can be tuned beyond specifications to open up new operation modes. During 2016 and 2017 several aspects where investigated to improve the emittance from the current gun, the goal was to meet the SPF specifications. In this paper we report on the progress, discuss the steps taken leading to a final emittance of ~ 1 mm mrad and beyond.
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TUPAB095	The New MAX IV Gun Test Stand	gun, emittance, cathode, operation	1537
	J. Andersson, F. Curbis, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden
	The gun test stand from MAX-Lab has been upgraded and moved to a new facility at the MAX IV Laboratory. The new test stand will reuse parts of the equipment from the old test stand but a number of improvements to the setup are be made. In this paper we report on the design of the new gun test stand, research plans in the near future as well as planned and possible future research topics.
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TUPAB096	Pulse Shaping at the MAX IV Photoelectron Gun Laser	gun, electron, 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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TUPAB097	MAXIV Photocathode Gun Laser System Specification and Diagnostics	gun, linac, diagnostics, cathode	1544
	F. Lindau, J. Andersson, J. Björklund Svensson, M. Brandin, F. Curbis, L. Isaksson, M. Kotur, D. Kumbaro, E. Mansten, D. Olsson, R. Svärd, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden J. Björklund Svensson Lund University, Division of Atomic Physics, Lund, Sweden
	The MAXIV injector has two guns - a thermionic used for ring injections, and a photocathode used for short pulse facility operation. A commercial Ti:sapphire laser from KMLabs drives the copper based photocathode gun. It has been running without major issues for more than 3 years. The laser delivers up to §I{500}{\textmu J} on the cathode at the third harmonic, §I{263}{nm}, via a vacuum laser transport system. To achieve the desired pulse duration of 2–§I10{ps} the laser pulses, originally ~§I{100}{fs} long, are stretched with a prism pair and the resulting §I{1.5}{ps} pulses stacked by a series of birefringent \textalpha -BBO crystals. Diagnostics consist of photodiodes, spectrometers, and cameras. Longitudinal pulse characterization is done with a cross correlator and a UV FROG.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB097
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TUPAB102	Compact Electron RF Travelling Wave Gun Photo Injector	gun, cathode, solenoid, electron	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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TUPAB114	Design Study for a Plasma Undulator Experiment Using Capillary Based Discharge Plasma Source	plasma, electron, 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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TUPAB122	Engineering Optimization of The Support Structure and Drive System for the LCLS-II Soft X-Ray Undulator Segments	undulator, photon, simulation, experiment	1602
	A.J. DeMello, D. Arbelaez, D. Bianculli, A.P. Brown, J.N. Corlett, J.R. Dougherty, D.E. Humphries, J.-Y. Jung, M. Leitner, S. Marks, K.A. McCombs, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Linear Coherent Light Source II (LCLS-II) project, an upgrade to the free-electron laser facility at SLAC, is replacing the undulator system from a fixed gap to a variable gap system to enable tuning of the photon energy range. The LCLS-II project will include a soft x-ray (SXR) beam line and a hard x-ray (HXR) beam line. The SXR undulators are conventional vertical-gap horizontally-polarizing devices while the HXR undulators are novel horizontal-gap vertically-polarizing devices. This paper describes in detail the development of the SXR mechanical support structure and drive system. The effort has included extensive analysis of the various components to ensure that the undulators will perform within the design specifications. Engineering simulations undertaken and experiments performed to validate the computer modeling are presented together with measurement results from prototype and pre-production undulators.
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TUPAB124	Development of the Manufacturing and QA Processes for the Magnetic Modules of the LCLS-II Soft X-Ray Undulators	undulator, simulation, status, free-electron-laser	1609
	K.L. Ray, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, D.E. Humphries, J.-Y. Jung, D. Leitner, M. Leitner, S. Marks, K.A. McCombs, D.V. Munson, D.A. Sadlier, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund LBNL, Berkeley, California, USA D.E. Bruch, A.L. Callen, G. Janša, D.S. Martinez-Galarce, H.-D. Nuhn, E. Ortiz, 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. A new free electron laser being built at SLAC National Accelerator Laboratory, the Linear Coherent Light Source II (LCLS-II), will use 21 soft x-ray undulators (SXR) and 32 hard x-ray undulators (HGVPU). Lawrence Berkeley National Laboratory (LBNL) is responsible for the design and manufacturing of all variable-gap, hybrid permanent-magnet undulators. The physics requirements for the undulators specify a longitudinal pole misalignment maximum rms error of 25 μm and a vertical pole misalignment maximum error of 50 μm. In addition, magnet positioning critically influences the gap-dependent field properties due to saturation effects at the smallest operational gaps. This paper discusses the manufacturing and QA methods developed to carefully control the longitudinal and vertical pole and magnet positions during undulator production. Inspection results are discussed based on data gathered during construction of a prototype as well as pre-production soft x-ray undulator.
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TUPAB128	Single Photoemitter Tips in a DC Gun: Limiting Aberration-induced Emittance	emittance, electron, cathode, 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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TUPAB135	A 1.75 mm Period RF-Driven Undulator	undulator, electron, 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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TUPAB137	Evaluation of FEL Performance with a Longer Injector Drive Laser Pulse at the LCLS	emittance, FEL, electron, 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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TUPAB138	LCLS-II Injector Physics Design and Beam Tuning	emittance, gun, solenoid, cavity	1655
	F. Zhou, D. Dowell, P. Emma, J.F. Schmerge SLAC, Menlo Park, California, USA C.E. Mitchell, F. Sannibale LBNL, Berkeley, California, USA
	Funding: US DOE under grant No. DE-AC02-76SF00515. LCLS-II is a proposed high-repetition rate (up to 1 MHz) Free Electron Laser X-ray light source, based on a CW normal conducting (NC) RF gun injector and a CW 4-GeV superconducting (SC) linac, under construction at SLAC. LCLS-II CW injector consists of a 186 MHz NC RF gun, two solenoids, two BPMs, 1.3 GHz NC RF buncher, and 1.3 GHz SC standard 8-cavity cryomodule to boost the beam energy >95 MeV, and 5 pairs of steering correctors. In this paper, we describe the injector physics design including the beam optimization and low level RF requirement, and also present the studies of beam performance with any one SC cavity failure. The beam tuning procedure is developed with the correctors and two BPMs. The simulations of the phase/amplitude calibration for the gun and buncher and beam based alignment for cathode, two solenoids, and RF buncher with the limited diagnostics, will be presented.
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TUPAB142	Tracking of Electrons Created at Wrong RF Phases in the RHIC Low Energy Cooler	electron, cathode, space-charge, cavity	1666

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MOZB1

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

target, plasma, electron, 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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MOOCB2

Laser System Design and Operation for SNS H⁻ Beam Laser Stripping

experiment, operation, ion, neutron

57

Y. Liu, A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, A.A. Menshov, A. Webster
ORNL, Oak Ridge, Tennessee, USA
A. Rakhman
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work has been partially supported by U.S. DOE grant DE-FG02-13ER41967. ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Recently, a high-efficiency laser assisted hydrogen ion (H⁻) beam stripping was successfully carried out in the Spallation Neutron Source (SNS) accelerator. The experiment was not only an important step toward foil-less H⁻ stripping for charge exchange injection, it also served as a first example of using megawatt ultraviolet (UV) laser in an operational high power proton accelerator facility. This talk reports the design, implementation, and commissioning results of the macropulse laser system, laser transport line, and laser operation for the laser stripping experiment. The macropulse laser consists of a mode-locked picosecond pulsed seed laser and a burst-mode Nd:YAG laser amplifier. The general design concept can be adapted to any temporal beam structures in most accelerators. We have achieved UV pulses with the pulse widths varying between 34 to 54 ps and a maximum peak power over 3.5 MW. A laser transport line is installed to deliver the UV beam to the laser stripping chamber at a transmission efficiency of 70%. Laser operation including remote control and monitor of laser parameters will be described.

Slides MOOCB2 [11.306 MB]

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MOPAB024

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

electron, radiation, experiment, 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, electron, 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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MOPAB045

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

simulation, electron, experiment, space-charge

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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MOPAB050

Reconstruction of Sub-Femtosecond Longitudinal Bunch Profile Measurement Data

electron, 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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MOPAB051

Progress in FLASH Optics Consolidation

optics, undulator, emittance, gun

211

J. Zemella, M. Vogt
DESY, Hamburg, Germany

FLASH is the superconducting soft X-ray Free Electron Laser in Hamburg at DESY, Germany. A precise knowledge of the beam optics is a key aspect of the operation of a SASE FEL. A campaign of optics consolidation has started in 2013 when the second beam line FLASH2 was installed downstream of the FLASH linac. We give an update on progress of this effort and on recent results.

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MOPAB052

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

electron, simulation, emittance, impedance

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

electron, simulation, 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

electron, wakefield, 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, electron, 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, electron, linac

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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MOPAB060

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

electron, target, radiation, simulation

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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MOPAB065

Breit-Wheeler Scattering Events Produced by Two Interacting Compton Sources

photon, scattering, electron, 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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MOPAB072

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

experiment, electron, 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

electron, FEL, detector, radiation

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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MOPAB075

Measurement of Electron Bunch Length via a Tunable-Gap Undulator

radiation, electron, undulator, 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

electron, 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, electron

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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MOPAB119

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

proton, electron, plasma, 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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MOPAB120

Beam Instrumentation for the CERN LINAC4 and PSB Half Sector Test

linac, instrumentation, emittance, proton

408

F. Roncarolo, J.C. Allica Santamaria, M. Bozzolan, C. Bracco, S. Burger, G.J. Focker, G. Guidoboni, L.K. Jensen, B. Mikulec, A. Navarro Fernandez, U. Raich, J.B. Ruiz, L. Søby, J. Tan, W. Viganò, C. Vuitton, C. Zamantzas
CERN, Geneva, Switzerland
T. Hofmann
Royal Holloway, University of London, Surrey, United Kingdom

The construction, installation and initial commissioning of CERN's LINAC4 was completed in 2016 with H⁻ ions successfully accelerated to its top energy of 160 MeV. The accelerator is equipped with a large number of beam diagnostic systems that are essential to monitor, control and optimize the beam parameters. A general overview of the installed systems and their functional specifications will be followed by a summary of the most relevant results. This includes transverse profile monitors (wire scanners, wire grids and a laser profile monitor), beam position and phase monitors (whose ToF measurements were essential for adjusting RF cavity parameters), beam loss monitors, beam current transformers and longitudinal beam shape monitors. This contribution will also cover the beam instrumentation for the so-called PSB Half Sector Test, which has been temporarily installed in the LINAC4 transfer line to study H⁻ stripping efficiency. At this facility it was possible to test the new H⁰/H⁻ beam current monitor, designed to monitor the stripping efficiency and an essential element of the beam interlock system when the LINAC4 is connected to the PSB in 2019.

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MOPAB121

Installation and Test of Pre-series Wire Scanners for the LHC Injector Upgrade Project at CERN

vacuum, controls, electronics, detector

412

R. Veness, P. Andersson, W. Andreazza, N. Chritin, B. Dehning, J. Emery, A. Goldblatt, D. Gudkov, F. Roncarolo, J.L. Sirvent, J. Tassan-Viol
CERN, Geneva, Switzerland

A new generation of fast wire scanners is being developed for the LHC Injectors Upgrade (LIU) project at CERN. These will be essential tools for transverse profile measurement with the higher brightness LIU beams, and are planned for installation in 2019 in all three synchrotrons making up the LHC injector chain. An active period of development and test has resulted in prototype installations in the SPS and PSB rings. This paper will summarise the design and report on the results to-date.

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MOPAB146

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

electron, 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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MOPIK003

Improvement of the Photoemission Efficiency of Magnesium Photocathodes

cathode, gun, SRF, cavity

500

R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate
HZDR, Dresden, Germany
P. Patra
IUAC, New Delhi, India

Funding: The work is supported by the European Community under the FP7 programme (EuCARD-2) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
To improve the quality of photocathodes is one of the critical issues in enhancing the stability and reliability of photo-injector systems. Presently the primary choice is to use metallic photocathodes for the ELBE SRF Gun-II to reduce the risk of contamination of the superconducting cavity. Magnesium has a low work function (3.6 eV) and shows high quantum efficiency (QE) up to 0.3 % after laser cleaning. The SRF Gun II with an Mg photocathode has successfully provided electron beam for ELBE users. However, the present cleaning process with a high intensi-ty laser (activation) is time consuming and generates unwanted surface roughness. This paper presents the investigation of alternative surface cleaning procedures, such as thermal treatment. The QE and topography of Mg samples after treatment are reported.

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MOPIK004

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

electron, gun, acceleration, 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, electron, gun, 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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MOPIK007

THz Driven Electron Acceleration with a Multilayer Structure

electron, acceleration, 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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MOPIK011

Electron Beam Generation From InGaN/GaN Superlattice Photocathode

electron, 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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MOPIK018

Micro-Scale Electron Beam Generation Using Pyroelectric Crystals

electron, acceleration, 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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MOPIK021

Generation of Transversely Segmented Beam Using a Nano-Patterned Photocathode

cathode, simulation, gun, acceleration

545

A. Lueangaramwong, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
G. Andonian
RadiaBeam, Santa Monica, California, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Funding: Work supported by US Department of Energy (DOE) contract DE-SC0009656 with Radiabeam Technologies and by NSF grant PHY-1535401 with Northern Illinois University.
Plasmonic photocathodes – nano-patterned photocathodes with periodicity comparable to the excitation laser – have demonstrated enhanced quantum efficiency. In the present paper we present numerical simulations of the beam dynamics associated to the emission process from this type of cathodes and to the subsequent acceleration to relativistic energies by combining WARP and IMPACT-T programs. We especially consider the possibility to transversely image the cathode surface at high energy and enable the generation of transversely segment beams.

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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

electron, operation, 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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MOPIK052

Generation of Highly-Charged Carbon Ions from Thin Foil Target

target, ion, plasma, heavy-ion

635

T. Kanesue, S. Ikeda, M. Okamura
BNL, Upton, Long Island, New York, USA
Y. Saito
Sokendai, Ibaraki, Japan

Funding: This work was supported by the U.S. Department of Energy and National Aeronautics and Space Administration.
Generation of highly-charged heavy ions such as fully stripped C⁶⁺ of more than hundreds mA of beam current can be possible only with a laser ablation ion source (LIS). Heavy ions are produced from a solid target irradiated by a pulsed high power laser. Recent study showed that only sub-micron range of surface layer contributes for the generation of highly-charged heavy ions. In this paper, we experimentally investigated the difference of the performance of highly-charged carbon ion production from graphite targets of different thickness (25, 70, 254, and 3000 'm) to seek the possibility of a rolled target to overcome the limitation of a target lifetime.

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MOPIK053

Design Study of High Repetition Rate Laser Ion Source for High Power Beam Production

target, ion, plasma, heavy-ion

638

T. Kanesue, S. Ikeda, M. Okamura
BNL, Upton, Long Island, New York, USA
Y. Saito
Sokendai, Ibaraki, Japan

Funding: This work was supported by the U.S. Department of Energy and National Aeronautics and Space Administration.
We are studying a laser ion source (LIS) for a high average beam power heavy ion beam production. A LIS is the most intense source of pulsed highly-charged ions using a laser ablation scheme. By increasing the repetition rate, a LIS based heavy ion beam would approach the average beam power based on a low beam current and continuous beam regime. In addition, a high-repetition-rate LIS can be used as a heavy ion source for a medical accelerator with spot scanning technique. This paper will describe the requirements to realize the high repetition rate operation.

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MOPIK055

Beam by Design: Current Pulse Shaping Through Longitudinal Dispersion Control

electron, simulation, sextupole, synchrotron

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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MOPIK069

Approximate Matrices for Modeling the Focusing of the Undulator Periods and Undulator End Fields

undulator, focusing, betatron, dipole

686

V. Balandin, N. Golubeva
DESY, Hamburg, Germany

We describe procedure for constructing approximate matrices for modeling the focusing of the undulator periods and undulator end fields and discuss applicability of these matrices to the European XFEL undulators.

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MOPIK072

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

software, controls, electronics, electron

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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MOPIK111

Initial Performance Measurements of Multi-GHz Electron Bunch Trains

electron, 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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MOPVA001

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

electron, photon, radiation, 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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MOPVA008

Commissioning Considerations for BERLinPro

diagnostics, gun, target, linac

862

M. McAteer, M. Abo-Bakr, T. Kamps, G. Klemz, J. Kuszynski
HZB, Berlin, Germany
I. Will
MBI, Berlin, Germany

BERLinPro is an energy recovery linac project whose goal is to establish the accelerator physics knowledge and technology needed to produce 50 MeV beams with high current, low normalized emittance, and low losses. The machine will be commissioned in phases beginning in 2018, and extensive planning is underway for start-up of the machine and to prepare for measurements to verify the achievement of target beam parameters. This paper outlines the planned phases for the commissioning of the machine, details the operational modes, and gives an overview of the diagnostics available for beam-based measurements to verify the achievement of performance goals.

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MOPVA010

Setup and Status of an SRF Photoinjector for Energy-Recovery Linac Applications

gun, SRF, cathode, emittance

865

T. Kamps, D. Böhlick, A.B. Büchel, M. Bürger, P. Echevarria, A. Frahm, F. Göbel, S. Heling, A. Jankowiak, S. Keckert, H. Kirschner, G. Klemz, J. Knobloch, G. Kourkafas, J. Kühn, O. Kugeler, A.N. Matveenko, A. Neumann, N. Ohm-Krafft, E. Panofski, F. Pfloksch, S. Rotterdam, M.A.H. Schmeißer, M. Schuster, H. Stein, J. Ullrich, A. Ushakov, J. Völker
HZB, Berlin, Germany
I. Will
MBI, Berlin, Germany

Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB.
The Superconducting RF (SRF) photoinjector programme for the energy-recovery linac (ERL) test facility BERLinPro sets out to push the brightness and average current limits for ERL electron sources by tackling the main challenges related to beam dynamics of SRF photoinjectors, the incorporation of high quantum efficiency (QE) photocathodes, and suppression of unwanted beam generation. The paper details the experimental layout of the SRF photoinjector and the gun test facility GunLab at Helmholtz-Zentrum Berlin.

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MOPVA012

The Dedicated Accelerator R&D Facility Sinbad at DESY

linac, electron, 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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MOPVA016

ELI-NP GBS Status

linac, electron, 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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MOPVA019

60 pC Bunch Charge Operation of the Compact ERL at KEK

operation, emittance, cavity, linac

890

T. Miyajima, K. Harada, Y. Honda, E. Kako, R. Kato, T. Miura, N. Nakamura, T. Obina, M. Shimada, R. Takai, K. Umemori, M. Yamamoto
KEK, Ibaraki, Japan
R. Hajima, R. Nagai
QST, Tokai, Japan
T. Hotei
Sokendai, Ibaraki, Japan
N. Nishimori
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

The compact ERL (cERL) at KEK was operated in March 2017 to demonstrate generation, acceleration and transportation of the target bunch charge of 60 pC without energy recovery. However, the maximum bunch charge was limited to 40 pC due to the limitation of the excitation laser power. For the bunch charge of 40 pC, the bunch length and the normalized emittance were measured in the injector diagnostic line. The results of the bunch length measurement gave good agreement with the values that had been obtained by model simulation. The measured normalized rms emittances for 40 pC were 0.9 to 2.4 mm mrad, and they were lager than the design value of 0.6 mm mrad. To achieve the design emittance, we have studied the source of the emittance growth for the bunch charge of 40 pC.

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MOPVA021

Optics Design of the Compact ERL Injector for 60 pC Bunch Charge Operation

optics, cathode, operation, gun

898

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

EUV-FEL light source based on ERL has been designed at KEK for EUV lithography light source. The advantage of ERL is to accelerate high average current beam due to CW operation, and it is possible to drive high average power FEL. To generate the target EUV-FEL power, which is 10 kW, the bunch charge of 60 pC, the beam energy of 10.5 MeV and the bunch length of 1 ps are required at the end of the EUV-FEL injector. In order to demonstrate the target beam performance for the EUV-FEL accelerator, a high charge beam test was carried out at the cERL in KEK. We designed a new optics of the cERL injector prior to the high charge beam operation. To calculate beam dynamics more accurately, accelerator models corrected according to the condition of the actual cERL injector is used for the optics design. From results of the optics design that minimized the emittance and bunch length using the corrected accelerator models, the emittance and bunch length at the end of injector are 0.8 mm-mrad and 3.4 ps. Furthermore, based on the design optics, we carried out high bunch charge beam operation.

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MOPVA023

Luminosity Increase in Laser-Compton Scattering by Crab Crossing Method

electron, 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, electron, target, 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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MOPVA031

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

electron, emittance, 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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MOPVA036

High Average Brilliance Compact Inverse Compton Light Source

electron, SRF, gun, brilliance

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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MOPVA066

Limits for the Operation of the European XFEL 3.9 GHz System in CW Mode

cavity, operation, cryomodule, linac

1023

P. Pierini, A. Bosotti, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
J. Branlard, D. Kostin, C.G. Maiano, W.-D. Möller, P. Pierini, D. Reschke, J.K. Sekutowicz, E. Vogel
DESY, Hamburg, Germany

Future upgrades of the European XFEL (EXFEL) facility may require driving the linac at higher duty factor, possibly extending to CW mode at reduced gradients. A preliminary analysis for the accelerator modules has been presented in the EXFEL TDR, but no precise assessment has been performed so far for the present 3.9 GHz system design. By making use of data collected during the commissioning and operation phase of the EXFEL injector system, we discuss here an estimate for the limits of CW operation of the present system and a plan for its possible experimental verification with existing available cavities and the EXFEL spare module.

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MOPVA071

Press Forming Tests of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources

cavity, photon, niobium, resonance

1031

M. Sawamura, R. Hajima
QST, Tokai, Japan
H. Hokonohara, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
T. Kubo, T. Saeki
KEK, Ibaraki, Japan

We are developing the superconducting spoke cavity for laser Compton scattered (LCS) photon sources. We adopt the superconducting spoke cavity for electron beam drivers to realize a wide use of LCS X-ray and '-ray sources in academic and industrial applications. The spoke cavity can make the accelerator more compact than an elliptical cavity because the cavity size is small at the same frequency and the packing factor is good by installing couplers on outer conductor. Though our proposal design for the photon source consists of the 325 MHz spoke cavities in 4K operation, we are fabricating the half scale model of 650 MHz spoke cavity in order to accumulate our cavity production experience by effective utilization of our limited resources. Since the spoke has more complicated structure than an elliptical cavity, we performed press forming tests for the half spoke and estimated the formed shapes with 3-dimensional measurement.

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TUOAA2

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

FEL, electron, undulator, photon

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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TUYB1

First Measurements of Trojan Horse Injection in a Plasma Wakefield Accelerator

plasma, electron, 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, electron, 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, electron, 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, electron, 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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TUPAB025

Experimental Results for Multiphoton Nonlinear Photoemission Processes on Phil Test Line

photon, electron, 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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TUPAB029

UHV Photocathode Plug Transfer Chain for the BERLinPro SRF-Photoinjector

SRF, vacuum, cathode, cavity

1381

J. Kühn, J. Borninkhof, M. Bürger, A. Frahm, A. Jankowiak, T. Kamps, M.A.H. Schmeißer, M. Schuster
HZB, Berlin, Germany
P. Murcek, J. Teichert, R. Xiang
HZDR, Dresden, Germany

A dedicated particle free UHV photocathode plug transfer chain from the preparation system to the SRF-Photoinjector was set up and commissioned at HZB for the BERLinPro project. The plug handling system was designed in collaboration with the ELBE team at HZDR, where the same transfer chain is in commissioning phase. In the future the exchange of photocathodes between the laboratories offers the possibility to test different types of photocathodes in different SRF-photoinjectors.

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TUPAB031

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

electron, gun, cathode, experiment

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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TUPAB033

Design of a Stripline Kicker for the ELBE Accelerator

kicker, emittance, electron, neutron

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, electron, 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

electron, gun, acceleration, timing

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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TUPAB040

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

linac, electron, diagnostics, 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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TUPAB050

A Lifetime Study of CsK2Sb Multi-Alkali Cathode

cathode, vacuum, electron, 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, electron, 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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TUPAB056

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

operation, gun, electron, 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, electron, cavity

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

scattering, electron, 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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TUPAB074

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

emittance, gun, electron, 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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TUPAB076

Design of an X-Band Photocathode for Tsinghua Thomson Scattering X-Ray Source

gun, solenoid, cathode, emittance

1497

L.Y. Zhou, H.B. Chen, Y.-C. Du, W. Gai, W.-H. Huang, J. Shi, C.-X. Tang, D. Wang, Z. Zhang, Z. Zhou
TUB, Beijing, People's Republic of China

Compared with S-band and C-band accelerating structures, X-band structures can run at a higher accelerating gradient and are more compact in size. In order to obtain higher electron energy in a limited space, a new X-band photo-injector operating at 11.424GHz has been designed at the Accelerator Laboratory of Tsinghua University. The structural design of the X-band photo-cathode RF gun and the accelerating structures as well as the beam dynamics simulation are presented in this paper, followed by the optimization of the structure based on the dispersed optimization experiment method(DOE). The results show that the design satisfies the working requirements with a small space occupied and a high beam quality.

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TUPAB077

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

electron, radiation, bunching, emittance

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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TUPAB094

Emittance Improvements in the MAX IV Photocathode Injector

emittance, linac, gun, quadrupole

1533

J. Andersson, F. Curbis, M. Kotur, F. Lindau, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV injector design predicts a beam with 100 pC of charge and an emittance lower than 1 mm mrad. The photocathode pre-injector is based on the now close to standard 1.6-cell gun adapted to 2.9985 GHz, in combination with a Ti:Sapphire laser system. This system reaches the requirements of the injector operation for the SPF, but can be tuned beyond specifications to open up new operation modes. During 2016 and 2017 several aspects where investigated to improve the emittance from the current gun, the goal was to meet the SPF specifications. In this paper we report on the progress, discuss the steps taken leading to a final emittance of ~ 1 mm mrad and beyond.

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TUPAB095

The New MAX IV Gun Test Stand

gun, emittance, cathode, operation

1537

J. Andersson, F. Curbis, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

The gun test stand from MAX-Lab has been upgraded and moved to a new facility at the MAX IV Laboratory. The new test stand will reuse parts of the equipment from the old test stand but a number of improvements to the setup are be made. In this paper we report on the design of the new gun test stand, research plans in the near future as well as planned and possible future research topics.

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TUPAB096

Pulse Shaping at the MAX IV Photoelectron Gun Laser

gun, electron, 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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TUPAB097

MAXIV Photocathode Gun Laser System Specification and Diagnostics

gun, linac, diagnostics, cathode

1544

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

The MAXIV injector has two guns - a thermionic used for ring injections, and a photocathode used for short pulse facility operation. A commercial Ti:sapphire laser from KMLabs drives the copper based photocathode gun. It has been running without major issues for more than 3 years. The laser delivers up to §I{500}{\textmu J} on the cathode at the third harmonic, §I{263}{nm}, via a vacuum laser transport system. To achieve the desired pulse duration of 2–§I10{ps} the laser pulses, originally ~§I{100}{fs} long, are stretched with a prism pair and the resulting §I{1.5}{ps} pulses stacked by a series of birefringent \textalpha -BBO crystals. Diagnostics consist of photodiodes, spectrometers, and cameras. Longitudinal pulse characterization is done with a cross correlator and a UV FROG.

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TUPAB102

Compact Electron RF Travelling Wave Gun Photo Injector

gun, cathode, solenoid, electron

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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TUPAB114

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

plasma, electron, 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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TUPAB122

Engineering Optimization of The Support Structure and Drive System for the LCLS-II Soft X-Ray Undulator Segments

undulator, photon, simulation, experiment

1602

A.J. DeMello, D. Arbelaez, D. Bianculli, A.P. Brown, J.N. Corlett, J.R. Dougherty, D.E. Humphries, J.-Y. Jung, M. Leitner, S. Marks, K.A. McCombs, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Linear Coherent Light Source II (LCLS-II) project, an upgrade to the free-electron laser facility at SLAC, is replacing the undulator system from a fixed gap to a variable gap system to enable tuning of the photon energy range. The LCLS-II project will include a soft x-ray (SXR) beam line and a hard x-ray (HXR) beam line. The SXR undulators are conventional vertical-gap horizontally-polarizing devices while the HXR undulators are novel horizontal-gap vertically-polarizing devices. This paper describes in detail the development of the SXR mechanical support structure and drive system. The effort has included extensive analysis of the various components to ensure that the undulators will perform within the design specifications. Engineering simulations undertaken and experiments performed to validate the computer modeling are presented together with measurement results from prototype and pre-production undulators.

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TUPAB124

Development of the Manufacturing and QA Processes for the Magnetic Modules of the LCLS-II Soft X-Ray Undulators

undulator, simulation, status, free-electron-laser

1609

K.L. Ray, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, D.E. Humphries, J.-Y. Jung, D. Leitner, M. Leitner, S. Marks, K.A. McCombs, D.V. Munson, D.A. Sadlier, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund
LBNL, Berkeley, California, USA
D.E. Bruch, A.L. Callen, G. Janša, D.S. Martinez-Galarce, H.-D. Nuhn, E. Ortiz, 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.
A new free electron laser being built at SLAC National Accelerator Laboratory, the Linear Coherent Light Source II (LCLS-II), will use 21 soft x-ray undulators (SXR) and 32 hard x-ray undulators (HGVPU). Lawrence Berkeley National Laboratory (LBNL) is responsible for the design and manufacturing of all variable-gap, hybrid permanent-magnet undulators. The physics requirements for the undulators specify a longitudinal pole misalignment maximum rms error of 25 μm and a vertical pole misalignment maximum error of 50 μm. In addition, magnet positioning critically influences the gap-dependent field properties due to saturation effects at the smallest operational gaps. This paper discusses the manufacturing and QA methods developed to carefully control the longitudinal and vertical pole and magnet positions during undulator production. Inspection results are discussed based on data gathered during construction of a prototype as well as pre-production soft x-ray undulator.

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TUPAB128

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

emittance, electron, cathode, 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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TUPAB135

A 1.75 mm Period RF-Driven Undulator

undulator, electron, 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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TUPAB137

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

emittance, FEL, electron, 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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TUPAB138

LCLS-II Injector Physics Design and Beam Tuning

emittance, gun, solenoid, cavity

1655

F. Zhou, D. Dowell, P. Emma, J.F. Schmerge
SLAC, Menlo Park, California, USA
C.E. Mitchell, F. Sannibale
LBNL, Berkeley, California, USA

Funding: US DOE under grant No. DE-AC02-76SF00515.
LCLS-II is a proposed high-repetition rate (up to 1 MHz) Free Electron Laser X-ray light source, based on a CW normal conducting (NC) RF gun injector and a CW 4-GeV superconducting (SC) linac, under construction at SLAC. LCLS-II CW injector consists of a 186 MHz NC RF gun, two solenoids, two BPMs, 1.3 GHz NC RF buncher, and 1.3 GHz SC standard 8-cavity cryomodule to boost the beam energy >95 MeV, and 5 pairs of steering correctors. In this paper, we describe the injector physics design including the beam optimization and low level RF requirement, and also present the studies of beam performance with any one SC cavity failure. The beam tuning procedure is developed with the correctors and two BPMs. The simulations of the phase/amplitude calibration for the gun and buncher and beam based alignment for cathode, two solenoids, and RF buncher with the limited diagnostics, will be presented.

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TUPAB142

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

electron, cathode, space-charge, cavity

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

electron, 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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TUPIK003

Electron Transport on COXINEL Beam Line

electron, 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, electron, 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, electron, 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, electron, 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, electron, 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, experiment, electron, 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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TUPIK022

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

electron, 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, electron, 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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TUPIK026

Simulations of Positron Capture and Acceleration in the Linear Wakefield of Plasma

wakefield, positron, plasma, emittance

1737

M.M. Peng, W. Gai
TUB, Beijing, People's Republic of China

We present the study of positrons capturing dynamics in the wakefield of plasma generated either by a laser or electron beam. Only simplified linear wakefield models were used as first order approximation. By analysing the phase space and beam dynamics, we show that phase space for capturing is rather small, only high brightness beam with very short pulse length can be captured with reasonable rate for wakefields of 1 - 10 GeV/m and wave-length of 100 micron.

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TUPIK032

AWAKE Proton Beam Commissioning

proton, plasma, alignment, experiment

1747

J.S. Schmidt, D. Barrientos, M. Barros Marin, B. Biskup, A. Boccardi, T.B. Bogey, T. Bohl, C. Bracco, S. Cettour Cave, H. Damerau, V. Fedosseev, F. Friebel, S.J. Gessner, A. Goldblatt, E. Gschwendtner, L.K. Jensen, V. Kain, T. Lefèvre, S. Mazzoni, J.C. Molendijk, A. Pardons, C. Pasquino, S.F. Rey, H. Vincke, U. Wehrle
CERN, Geneva, Switzerland
J.T. Moody
MPI-P, München, Germany
K. Rieger
MPI, Muenchen, Germany

AWAKE will be the first proton driven plasma wakefield acceleration experiment worldwide. The facility is located in the former CNGS area at CERN and will include a proton, laser and electron beam line merging in a 10 m long plasma cell, which is followed by the experimental diagnostics. In the first phase of the AWAKE physics program, which started at the end of 2016, the effect of the plasma on a high energy proton beam will be studied. A proton bunch is expected to experience the so called self-modulation instability, which leads to the creation of micro-bunches within the long proton bunch. The plasma channel is created in a rubidium vapor via field ionization by a TW laser pulse. This laser beam has to overlap with the proton beam over the full length of the plasma cell, resulting in tight requirements for the stability of the proton beam at the plasma cell in the order of ~ 0.1 mm. In this paper the beam commissioning results of the ~810 m long transfer line for proton bunches with 3·10¹¹ protons/bunch and a momentum of 400 GeV/c will be presented with a focus on the challenges of the parallel operation of the laser and proton beam.

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TUPIK036

Use of Laser Wakefield Accelerators as Injectors for Compact Storage Rings

electron, 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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TUPIK058

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

vacuum, electron, 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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TUPIK069

PXIe Embedded Control Station Based the Electric Breakdown Data Acquisition and RF Conditioning System for C-Band Accelerating Structures Using for Shanghai Soft X-Ray Free Electron Laser (SXFEL)

controls, hardware, FPGA, vacuum

1855

Y. Li, W. Fang, J.Z. Gong, Q. Gu, J.J. Guo, L. Li, Z.B. Li, J.H. Tan, C.C. Xiao, J.Q. Zhang, M. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Funding: Shanghai Institute of Applied Physics, The Chinese Academy of Science., National Development and Reform Commission, the People's Republic of China., National Natural Science Foundation of China.
Shanghai Soft X-Ray Free Electron Laser (SXFEL) adopts C-band structure to accelerate the electron to 1.5-GeV. Due to high gradient operation, the electric breakdown and structure conditioning problems need to be perfectly resolved. For this purpose, we develop an automatic conditioning control and electric breakdown data acquisition system. The control based on a PXI Express (PXIe) embedded frame and the LabView-FPGA technique. The prototype system design, the software programming and hardware test will be introduced. The experiment setup and test results for a low-level signal will be shown.
' Corresponding author: liyingmin@sinap.ac.cn

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TUPIK121

Dark Sector Experiments at LCLS-II (DASEL) Accelerator Design

kicker, FEL, experiment, septum

2008

Y.M. Nosochkov, T.G. Beukers, A.R. Fry, C. Hast, T.W. Markiewicz, T.K. Nelson, N. Phinney, T.O. Raubenheimer, P.C. Schuster, N. Toro
SLAC, Menlo Park, California, USA

Funding: Work supported by the US DOE Contract DE-AC02-76SF00515.
DASEL (Dark Sector Experiments at LCLS-II) is a new accelerator and detector facility proposed to be built at SLAC. Its primary target is a direct observation of dark matter produced in electron-nuclear fixed-target collisions. DASEL takes advantage of the LCLS-II free electron laser (FEL) under construction at SLAC which will deliver a continuous electron beam from a 4-GeV superconducting linac. DASEL will operate parasitically to the LCLS-II FEL by extracting low intensity unused dark current bunches downstream of the FEL kickers. The DASEL key accelerator components include a 46-MHz gun laser system providing controlled intensity and timing of the dark current, a fast (MHz) kicker with 600-ns flat-top, a new transport line connecting the LCLS-II to the existing A-line and to End Station-A where the experiments will take place, and a spoiler and collimator system in the A-line for final shaping of the DASEL beam. An overview of the DASEL accelerator system is presented.

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WEYB1

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

electron, 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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WEPAB009

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

electron, 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

electron, 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, electron, 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, electron, 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

electron, FEL, operation, 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, electron, 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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WEPAB021

Experience with Multi-Beam and Multi-Beamline FEL-Operation

undulator, experiment, operation, FEL

2615

J. Rönsch-Schulenburg, B. Faatz, K. Honkavaara, M. Kuhlmann, S. Schreiber, R. Treusch, M. Vogt
DESY, Hamburg, Germany

DESY's free-electron laser FLASH provides soft X-ray pulses for scientific users at wavelengths down to 4 nm simultaneously in two undulator beamlines. They are driven by a common linear superconducting accelerator with a beam energy of up to 1.25 GeV. The superconducting technology allows the acceleration of electron bunch trains of several hundred bunches with a spacing of 1 microsecond or more and a repetition rate of 10 Hz. A fast kicker-septum system directs one part of the bunch train to FLASH1 and the other part to FLASH2 keeping the full 10 Hz repetition rate for both. The unique setup of FLASH allows independent FEL pulse parameters for both beamlines. In April 2016, simultaneous operation of FLASH1 and FLASH2 for external users started. This paper reports on our operating experience with this type of multi-beam, multi-beamline set-up.

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WEPAB024

Commissioning and First Heating with the European XFEL Laser Heater

undulator, electron, 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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WEPAB025

Status of the Soft X-Ray Free Electron Laser FLASH

FEL, photon, experiment, operation

2628

M. Vogt, B. Faatz, K. Honkavaara, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, R. Treusch
DESY, Hamburg, Germany

The superconducting free-electron laser user facility FLASH at DESY in Hamburg, routinely produces several thousand photon pulses per second. The operational parameters cover a wavelength range from 90 nm down to 4 nm with pulse energies from several uJ up to 1 mJ and with pulse durations of several hundred fs down to a few fs. The FLASH injector and linac drives two undulator beam lines (FLASH1, FLASH2) and therefore FLASH is capable of serving 2 independent experiments with photon pulse (sub-) trains of several 100 bunches at the full train repetition frequency of 10 Hz. We summarize here the highlights of the user operation at FLASH1/2 and the study program (machine development and FEL optimization) of the FLASH facility.

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WEPAB029

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

undulator, electron, FEL, radiation

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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WEPAB032

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

undulator, radiation, electron, 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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WEPAB034

Control of Seeded FEL Pulse Duration Using Laser Heater Pulse Shaping

electron, 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, FEL, electron

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, linac, electron, 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, electron, 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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WEPAB065

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

undulator, radiation, electron, 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

electron, 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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WEPAB070

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

electron, 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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WEPAB074

On the Coherence Properties of FEL

FEL, undulator, simulation, experiment

2753

M.A. Pop, F. Curbis, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

Free Electron Lasers (FEL) are one of the most brilliant light sources in the world and their unique properties are driving worldwide research in understanding and improving them. Numerous papers have already been published describing the output of the FEL in terms of coherence and bandwidth. In this contribution, however, we focus on how the coherence evolves along the FEL undulator and on what factors influence it the most. Using Genesis⁻¹.3* we have been able to follow and record the light field as it is being produced in the undulator. Our analysis method takes advantage of the extensively studied double pinhole experiment and uses the principles behind it to create a tool for extracting coherence information from the radiation field. We will present the scope, limitations and advantages of these virtual experiments as well as an application on an example FEL, to showcase what kind of information can be extracted using this method.
* Numerical simulation code used for particle and field distribution tracking along the undulator developed by Sven Reiche

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WEPAB077

The Soft X-Ray Laser Project at MAX IV

FEL, undulator, electron, 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

electron, undulator, FEL, 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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WEPAB087

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

electron, cavity, FEL, 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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WEPAB089

Design Study for the Generation of Few-Cycle FEL Pulses Using Mode-Locked Afterburner Scheme at Clara

FEL, bunching, simulation, radiation

2783

C.L. Shurvinton, D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Ultrashort pulse operation in FELs is a highly desirable capability for imaging matter on ultrafast timescales. This paper presents a design study for a proof-Âof-Âprinciple demonstration of the mode-locked afterburner (ML-AB) scheme on the FEL test facility CLARA. A start-to-end simulation has been constructed using the time-Âdependent three-Âdimensional FEL code GENESIS 1.3 to evaluate the performance of the scheme. The ability to produce pulses of several femtoseconds in duration with peak powers of the order of 100 MW at 100 nm wavelength is predicted.Â Such pulses have duration of 2 fs (6 optical cycles), a factor of ~5 shorter than the FEL cooperation length. Potential routes for further optimisation and alternative operating modes are explored.

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WEPAB090

Developments in the CLARA FEL Test Facility Accelerator Design and Simulations

FEL, undulator, simulation, optics

2787

P.H. Williams, D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

We present recent developments in the accelerator design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. The requirement to co-propagate the beam with laser seeds of very different wavelengths has led to a redesign of the section preceding the undulators, with a dogleg being replaced by a chicane. Additional refinements of the facility design include the inter-undulator sections. With this finalised design we show start to FEL simulations for all beam modes envisaged.

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WEPAB108

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

electron, FEL, radiation, 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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WEPAB116

LCLS Injector Laser Shaping and Applications

electron, 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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WEPAB123

A Phase Matching, Adiabatic Accelerator

electron, acceleration, 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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WEPIK107

Comparison Studies of Graphene Sey Results in NSRL and DL

electron, gun, factory, synchrotron

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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WEPVA001

Electron Injector for Multi-Stage Laser-Driven Plasma Accelerators

electron, 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

simulation, electron, 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

acceleration, electron, 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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WEPVA005

Simulation of a Many Period Dielectric Grating-based Electron Accelerator

electron, 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

electron, 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

experiment, electron, 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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WEPVA011

Development of a Laser Driven Dielectric Accelerator for Radiobiology Research

electron, 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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WEPVA012

Laser Proton Accelerator with Improved Repeatability at Peking University

target, proton, acceleration, plasma

3275

Y.R. Shou
Peking University, School of Physics, Beijing, People's Republic of China
Y.X. Geng, C. Li, L.R.F. Li, Q. Liao, C. Lin, H.Y. Lu, W.J. Ma, P. Wang, M. Wu, X. Xu, X.Q. Yan, Y.Y. Zhao, J.G. Zhu
PKU, Beijing, People's Republic of China

Funding: National Basic Research Program of China (Grant No. 2013CBA01502), National Natural Science Foundation of China (Grants No. 11575011) and National Grand Instrument Project (2012YQ030142).
The repeatability of laser proton accelerator is mainly limited by laser plasma interaction, laser target coupling and laser parameter variation. In our recent experiments performed on the Compact Laser Plasma Accelerator at Peking University, gain of proton beams with improved repeatability is demonstrated. In order to control the laser plasma interaction in pre-plasma, cross polarized-wave (XPW) generation technique is employed to provide a laser pulse with a good contrast of 10^-10. A semi-automatic laser and target alignment system with a sensitivity of few micrometers is employed. The repetition rate of the laser proton accelerator is improved to the level of 0.1 Hz which is beneficial to decrease laser parameter variation. The shot-to-shot variation of proton energies is about 9% for a level of confidence of 0.95.

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WEPVA013

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

neutron, target, plasma, electron

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

electron, 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, electron, ion, focusing

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, electron, 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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WEPVA020

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

electron, 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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WEPVA043

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

vacuum, radiation, electron

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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WEPVA052

The Infrastructure for the Elettra Sincrotrone Trieste

storage-ring, linac, FEL, operation

3375

D. Zangrando, D. Baron, A. Buonanno, A. Galimberti, A. Martinolli, M. Miculin, D. Morelli
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Elettra - Sincrotrone Trieste S.C.p.A. is a multidisciplinary international laboratory, specialized in generating high quality synchrotron and free-electron laser light and applying it in materials science. The main assets of the research centre are two advanced light sources, the electron storage ring Elettra and the free-electron laser (FEL) FERMI, continuously (H24) operated supplying light of the selected colour and quality to more than 30 experimental stations. In this paper, we are giving an overview on the status of the infrastructure plants devoted to ensuring the operation of Elettra and FERMI machines. We will also analyse the systems that mostly have impacted on the performance of both accelerators and their downtime.

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WEPVA070

Alignment and Calibration for Collimation System in CSNS/RCS

collimation, vacuum, alignment, shielding

3432

J.B. Yu, L. Dong, L. Kang, B. Li, X.J. Nie, A.X. Wang, G.Y. Wang, X.L. Wang, J.S. Zhang
IHEP, Beijing, People's Republic of China
J.X. Chen, T. Luo, C.J. Ning
CSNS, Guangdong Province, People's Republic of China

Funding: National Natural Science Foundation of China (Grant Nos.11375217)
In order to reduce the uncontrolled losses in the localized station, the beam collimation system has been performed for the 1.6GeV synchrotron of CSNS. The CSNS/RCS transverse collimation system is designed to be a two-stage system which consists of one primary collimator and four secondary collimators. All collimators had completed processing and now been installed in the tunnel. To meet the requirements of physical system, alignment for collimation system have to be done before circulating beams. This paper will show the alignment technique of collimation system. Then some problems during the alignment process will be mentioned. For the primary collimator will be replaced in second-stage of CSNS, and the alignment for the replaced collimator will be introduced finally.

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WEPVA113

Thermo-Physical and Mechanical Characterisation of Novel Materials under Development for HL-LHC Beam Intercepting Devices

luminosity, radiation, experiment, framework

3536

O. Sacristan De Frutos, A. Bertarelli, L. Bianchi, F. Carra, J. Guardia, M. Guinchard, S. Redaelli
CERN, Geneva, Switzerland

Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD-2, grant agreement no.312453
The collimation system for high energy particle accelerators as HL-LHC, must be designed to withstand the close interaction with intense and energetic particle beams, safely operating over an extended range of temperatures in extreme conditions (pressure, strain-rate, radiation), which are to become more demanding with the High Luminosity LHC. In order to withstand such conditions, the candidate materials must possess among other properties outstanding thermal shock resistance and high thermal and electrical conductivity, condition only met by advanced or novel materials. Therefore, an extensive R&D program has been launched to develop novel materials capable of replacing or complementing materials used for present collimators. So far, Molybdenum Carbide - Graphite and Copper-Diamond composites have been identified as the most promising materials. Literature data are scarce or non-existing for these materials. For this reason the successive characterisation campaigns constitute a linchpin of the R&D program. This paper reviews the experimental program followed for the thermo-physical and mechanical characterisation of the materials, and discusses the most relevant results.

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THYA1

New Scenarios of Microbunching Instability Control in Electron Linacs and Free Electron Lasers

FEL, electron, 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

electron, 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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THPAB009

Multi-Objective Optimization of an SRF Photoinjector for ERL and UED Applications

gun, electron, 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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THPAB013

A Fast Particle Tracking Tool for the Simulation of Dielectric Laser Accelerators

simulation, GPU, space-charge, plasma

3716

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

Funding: GBMF - Gordon and Betty Moore Foundation
In order to simulate the beam dynamics in grating based Dielectric Laser Accelerators (DLA) fully self-consistent PIC codes are usually employed. These codes model the evolution of both the electromagnetic fields inside a laser-driven DLA and the beam phase space very accurately. The main drawback of these codes is that they are computationally very expensive. While the simulation of a single DLA period is feasible with these codes, long multi-period structures cannot be studied without access to HPC clusters. We present a fast particle tracking tool for the simulation of long DLA structures. DLATracker is a parallelized code based on the analytical reconstruction of the in-channel electromagnetic fields and a Boris/Vay-type particle pusher. It computational kernel is written in OpenCL and can run on both CPUs and GPUs. The main code is following a modular approach and is written in Python 2.7. This way the code can be easiliy extended for different use cases. In order to benchmark the code, simulation results are compared to results obtained with the PIC code VSim 7.2.

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THPAB017

Investigation of High Repetition Rate Femtosecond Electron Diffraction at PITZ

electron, 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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THPAB053

Laser Heater Deisgn for the CLARA FEL Test Facility

undulator, electron, 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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THPAB072

Application of Voronoi Diagram to Mask-Based Intercepting Phase-Space Measurements

emittance, electron, linac, experiment

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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THPAB078

Beam Dynamics Studies of the Transverse Gradient Undulator and Its Application to Suppression of Microbunching Instability

FEL, electron, undulator, focusing

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, electron, coupling, dipole

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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THPAB092

Orbit and Dispersion Tool at European XFEL Injector

electron, 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

electron, 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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THPAB105

Design and Operation of the Integrated 1.3 GHz Optical Reference Module with Femtosecond Precision

detector, controls, operation, FEL

3963

T. Lamb, L. Butkowski, E.P. Felber, M. Felber, M. Fenner, S. Jabłoński, T. Kozak, J.M. Müller, P. Prędki, H. Schlarb, C. Sydlo, M. Titberidze, F. Zummack
DESY, Hamburg, Germany

In modern Free-Electron Lasers like FLASH or the European XFEL, the short and long-term stability of RF reference signals gains in importance. The requirements are driven by the demand for short FEL pulses and low-jitter FEL operation. In previous publications, a novel, integrated Mach-Zehnder Interferometer based scheme for a phase detector between the optical and the electrical domain was presented and evaluated. This Laser-to-RF phase detector is the key component of the integrated 1.3 GHz Optical Reference Module (REFM-OPT) for FLASH and the European XFEL. The REFM-OPT will phase-stabilize 1.3 GHz RF reference signals to the pulsed optical synchronization systems in these accelerators. Design choices in the final hardware configuration are presented together with measurement results and a performance evaluation from the first operation period in the European XFEL.

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THPAB108

Femtosecond Optical Synchronization System for the European XFEL

timing, FEL, free-electron-laser, electron

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

timing, detector, electron, 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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THPAB110

Custom Optomechanics for the Optical Synchronization System at the European XFEL

timing, alignment, FEL, coupling

3976

F. Zummack, M. Felber, C. Gerth, T. Lamb, J.M. Müller, M. Schäfer, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany

Free-electron-lasers like the upcoming European XFEL demand highly reliable optical synchronization in range of few femtoseconds. The well known optical synchronization system at FLASH had to be re-engineered to meet XFEL requirements comprising demands like ten times larger lengths and raised numbers of optically synchronized instruments. These requirements directly convert to optomechanical precision and have yielded in a specialized design accounting for economical manufacturing technologies. These efforts resulted in reduced spatial dimensions, improved optical repeatability, maintainability and even reduced production costs. To account for thermal influences the heart of the optical synchronization system is based on an optical table made out of SuperInvar. To fully exploit its excellent thermal expansion coefficient, mechanical details need to be taken into account. This work presents the design and its realization of the re-engineered optomechanical parts of the optical synchronization system, comprising mounting techniques, link stabilization units and optical delay lines for high drift suppression.

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THPAB119

Study on a Time-Domain Spectroscopy System for Coherent Terahertz Pulse Spectrum Measurement from 5 MeV Electron Beam

radiation, electron, 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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THPAB132

MCP Based Detectors Installation in European XFEL

detector, photon, ion, radiation

4031

E. Syresin, O.I. Brovko, A.Yu. Grebentsov
JINR, Dubna, Moscow Region, Russia
W. Freund
XFEL. EU, Hamburg, Germany
J. Grünert
European XFEL, Schenefeld, Germany
M.V. Yurkov
DESY, Hamburg, Germany

An important task of the photon beam diagnostics at the European XFEL is providing reliable tools for measurements aiming at the search for and fine tuning of the amplification process in the SASE FEL. Radiation detectors based onμchannel plates (MCP) were prepared for such measurements. These detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ to 25 mJ), and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2, and from 0.4 nm to 5.1 nm for SASE3. Photon pulse energies are measured at the MCP anode and with a photodiode. The transverse photon beam profile is measured by an MCP imager with phosphor screen anode. Three MCP devices are being installed, one in each of the three FEL beamlines (SASE1, SASE2, and SASE3). The units for SASE1 and SASE3 were already installed in the XFEL tunnel, and the technical commissioning of the MCP detectors and their electronics is progressing. Calibration and acceptance test experiments with beam are scheduled for early 2017.

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THPAB149

Characterization of the THz Radiation-Based Bunch Length Measurement System for the NSRRC Photoinjector

radiation, electron, 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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THPAB154

Mechanical Design of Compact Vertical and Horizontal Linear Nanopositioning Flexure Stages With Centimeter-Level Travel Range for X-Ray Beamline Instrumentation

controls, photon, instrumentation, synchrotron

4096

D. Shu, J.W.J. Anton, S.P. Kearney, B. Lai, W. Liu, J. Maser, C. Roehrig, J.Z. Tischler
ANL, Argonne, Illinois, USA
J.W.J. Anton
University of Illinois at Chicago, Chicago, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Nanopositioning techniques present an important capability to support the state-of-the-art x-ray instrumentation research for the APS operations and upgrade project. To overcome the performance limitations of precision ball-bearing-based or roller-bearing-based linear stage systems, compact vertical and horizontal linear nanopositioning flexure stages have been designed and developed at the APS with centimeter-level travel range and nanometer-level resolution for x-ray beamline instrumentation. Using improved deformation compensated linear guiding mechanisms [*,**], the APS T8-55 vertical linear flexure stage and T8-56 horizontal linear flexure stage are initially designed as a pair of sample scanning stages for a hard x-ray scanning microscope at the APS sector 2. Due to their unique repeatable nanopositioning performance over the centimeter-level travel range, these stages are also suitable for many photon beam lines optics with repeatable and stable nanopositioning requirements. The mechanical design and finite element analyses of the APS T8-55 and T8-56 flexural stages, as well as its initial mechanical test results with laser interferometer are described in this paper.
* D. Shu, W. Liu, S. Kearney, J. Anton, B. Lai, J. Maser, C. Roehrig, and J. Z. Tischler, Proceedings of MEDSI-2016, Sept. 11-16, 2016, Barcelona, Spain.
** U.S. Patent granted No. 8,957, 567, D. Shu, S. Kearney, and C. Preissner, 2015.

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THPAB155

Photoinjector Optimization Using a Derivative-Free, Model-Based Trust-Region Algorithm for the Argonne Wakefield Accelerator

gun, linac, emittance, simulation

4100

N.R. Neveu
IIT, Chicago, Illinois, USA
J.M. Larson, J.G. Power
ANL, Argonne, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: DE-SC0015479, DE-AC02-06CH11357, DE-AC02-06CH11357
Model-based, trust-region, derivative-free algorithms are increasingly popular for optimizing computationally expensive numerical simulations. A strength of such methods is their efficient use of function evaluations. In this paper, we use one such algorithm to optimize the beam dynamics in two cases of interest at the Argonne Wakefield Accelerator (AWA) facility. First, we minimize the emittance of the electron bunch produced by the AWA drive rf photocathode gun alone by adjusting three parameters: rf gun phase, solenoid strength, and laser radius. The algorithm used converges to a set of parameters with an emittance of 1.08 mm-mrad. Second, we expand the number of optimization parameters to model the complete AWA rf photoinjector linac (the gun and six accelerating cavities). These results are used in a Pareto study of the trade-off between beam emittance and bunch length for the AWA linac.

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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, electron, 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, electron, FEL, klystron

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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THPIK058

Development of a S-Band Pulse Compressor

cavity, klystron, coupling, linac

4227

P. Wang, H.B. Chen, C. Cheng, J. Shi, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

We designed and fabricated a pulse compressor for S-band high power test stand at Tsinghua University. This pulse compressor is made up of a sphere resonant cavity with quality factor of 100000 and a rf polarizer. It has the ability of compressing a pulse from 3.6 us to 300 ns with the power gain of 7. A short description of the pulse compressor is presented, together with the RF design and low level RF measurement.

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THPIK063

The RF System of Infrared Free Electron Laser Facility at NSRL

cavity, electron, simulation, LLRF

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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THPIK068

High Power Test of SINAP X-Band Deflector at KEK

cavity, electron, impedance, operation

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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THPVA044

Detector Structure Development Using Active And Passive Thermography

detector, target, cavity, experiment

4531

E. Rosenthal, D. Grunwald, G. Natour
Forschungszentrum Jülich GmbH, Central Institute of Engineering, Electronics and Analytics, Jülich, Germany

During the development and production of the mechanical support structures of the PANDA-Micro-Vertex-Detector(MVD)* experiments of passive and active thermography were applied and shown. The combination of mostly carbon-based materials enables the development of lightweight structures, which satisfy the mechanical stability and thermal requirements. The carrier structure of the MVD stripe detector is mainly composed of carbon foams, high fiber content CFC materials and PMI-based foams. This enables to selectively cool areas where heat is generated and to decouple them from the temperature-sensitive areas of the sensor system. Passive thermography is used during our development work mainly to validate the results of thermal simulations, for design optimization and for the functional control of the carrier structure. Additionally active thermography allows us to identify anomalies and thermal disturbances, which remain unnoticed in static processes. Also the investigation and characterization of adhesive layers are possible. For this purpose we developed special software algorithms which are sensitive to small-scale differences in temperature conductivity.
* PANDA Collaboration: W. Erni et al., arXiv: 1207.6581

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THPVA045

Telecommunication Concepts for Compact, Electro-Optical and Frequency Tunable Sensors for Accelerator Diagnostics

electron, 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

gun, cavity, electron, 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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THPVA055

The Preliminary Performance of the Timing and Synchronization System at Tsinghua University

LLRF, timing, monitoring, controls

4565

Z.Y. Lin, Y.-C. Du, W.-H. Huang, W.-H. Huang, C.-X. Tang, C.-X. Tang, J. Yang
TUB, Beijing, People's Republic of China
J.M. Byrd, L.R. Doolittle, G. Huang, Q. Qiang, R.B. Wilcox, Y.L. Xu
LBNL, Berkeley, California, USA

A precise timing and synchronization system is developed in Tsinghua University(THU). The whole system scheme includes fiber-based CW carrier phase reference distribution system (PRDS) for delivering stabilized RF phase reference to multiple receiver clients, Low Level RF (LLRF) control system to stabilized the accelerating mi-crowave field and laser-RF synchronization system for high precise synchronization of optical and RF signals. The system test and the demonstration experiment of each subsystem are carried on to evaluate the system and the phase error jitter resources are analysed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA055

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THPVA057

The Primary Control Network of HLS II

network, controls, synchrotron, linac

4573

W. Wang, L. Lin, F.F. Wu, Q. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

To meet the accuracy requirement of alignment and installation of HLS', the high accuracy control network is necessary. The high accuracy primary control network will provides reliable reference to the local control network. After optimization design that using Monte-Carlo method, according to the structure characteristic of HLS', the primary control network is measured by several different instruments, such as: Laser tracker, Total station and plummet. The accuracy of actual primary control network meets the design requirements, it provides strong foundation for subsequent project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA057

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THPVA072

Travelling Laser Focus System for the Particles Acceleration

acceleration, radiation, emittance, photon

4613

A.A. Mikhailichenko
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We describe the result of the wake-fields calculation in a device for acceleration of particles in the micro-structures illuminated by the swept laser bust. Calculations carried with help of FlexPDE code.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA072

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THPVA136

Non-Invasive Online Beam Monitor Using LHCb VELO

detector, proton, medical-accelerators, electronics

4780

R. Schnuerer
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch, S.L. Yap, H.D. Zhang
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 675265
Online beam monitoring is essential for ion beam therapy to assure effective delivery of the beam and maintain patient safety for cancer treatment. One candidate for such a monitoring device is the LHCb Vertex Locator (VELO) detector. It is a position sensitive silicon detector with an advantageous semi-circular design which enables approaching the core of the beam without interfering with it. In this contribution, tests using an infrared laser to calibrate the detector and obtain information about its dynamic range, spatial and time resolution will be discussed. Initial results from using the detector at the 60 MeV proton therapy beamline at the Clatterbridge Cancer Centre (CCC), UK are also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA136

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THPVA141

Non-Destructive Measurement of Electron Microbunch Separation

electron, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA141

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