IPAC2014 - List of Keywords (undulator)

Paper	Title	Other Keywords	Page
MOYAA01	Innovative Ideas for Single-pass FELs	electron, FEL, operation, photon	12
	T. Hara RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	SASE FELs are a powerful light source in short wavelengths from VUV to X-ray regions to investigate matters and phenomena. SASE was first experimentally obtained in 2000 at DESY TTF with an output wavelength of 10⁹ nm. Subsequently, FLASH, LCLS and SACLA have achieved lasing in VUV, soft X-rays and hard X-rays. Although SASE has already been widely used for many application experiments in broad scientific fields, its spiky spectrum and time structures due to the lack of longitudinal coherence sometimes become problematic. To improve its longitudinal coherence, various ideas have been proposed and some of them are already demonstrated experimentally, such as a self-seeded scheme, high-gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG). There is also another direction of developments to enhance the capability and potentiality of SASE, for example short pulse generation and two-color lasing. This talk will review recent innovative ideas of short wavelength FELs together with their experimental results.
	Slides MOYAA01 [10.701 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOYAA01
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MOPRO057	Undulator Photon Beams with Orbital Angular Momentum	emittance, photon, experiment, storage-ring	213
	J. Bahrdt, K. Holldack, P. Kuske, R. Müller, M. Scheer, P.O. Schmid HZB, Berlin, Germany
	Photons carrying orbital angular momentum (OAM) are present in the off-axis radiation of higher harmonics of helical undulators. Usually, the purity and visibility of OAM photons is blurred by electron beam emittance. However, high brightness OAM beams are expected in ultimate storage rings and FELs, and they may trigger a new class of experiments utilizing the variability of the topological charge, a 3rd degree of freedom besides wavelength and polarization. We report on the first detection of OAM photons in helical undulator radiation in the 3rd generation storage ring BESSY II. Measurements and simulations are compared and the impact of emittance and energy spread is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO057
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MOPRO084	Recent Development and Operational Status of PF-Ring and PF-AR	vacuum, injection, photon, operation	286
	T. Honda, M. Adachi, S. Asaoka, K. Haga, K. Harada, Y. Honda, M. Izawa, T. Kageyama, Y. Kamiya, Y. Kobayashi, K. Marutsuka, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, M. Ono, T. Ozaki, H. Sagehashi, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, M. Shimada, K. Shinoe, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Ma. Yoshida, S.I. Yoshimoto KEK, Ibaraki, Japan
	Update of the first-generation undulators installed in 1980s is pushed forward at PF-Ring, a 2.5-GeV SR source of KEK, taking advantage of the expanded straight sections reconstructed in 2005. New undulators have been designed as elliptically polarizing undulators each has 6 magnetic arrays to obtain various polarization states, not only circular polarization but also linear (horizontal and vertical) polarization. Three undulators will be installed in FY2013 and FY2014 for BL02, BL13 and BL28. For BL02, the longest straight section of about 9 m, the new undulator will be installed in tandem with the existing planar undulator, in order to cover the wide photon energy range from 15 eV to 2 keV. At PF-AR, a 6.5-GeV SR source, a new direct beam transport (BT) line from the injector LINAC is under construction. Super KEKB which shares the injector LINAC with PF-Ring and PF-AR will be commissioned at the end of FY2014. The full-energy continuous injection of PF-AR will be available as a simultaneous injection with the 7-GeV HER, the 4-GeV LER and PF-Ring not so later than the commissioning of Super KEKB.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO084
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MOPME021	Vicky: Computer Code Update	quadrupole, optics, multipole, sextupole	421
	F. Iazzourene Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	Vicky is a computer code for designing and simulating charged particle accelerators. We recall mainly that Vicky is a very user friendly code, the particle motion is described by 10 parameters: four beta-functions, four alpha-functions and two phase advances, and a large variety of insertion devices, wigglers and undulators, linearly and elliptically polarized, are treated. The features include Twiss functions matching, orbit correction, tune and chromaticity adjustment, dynamic aperture and phase space tracking. The paper describes new aspects and the present status. F. IAZZOURENE, “Vicky: A Computer Code for Use in the Design and Simulation of Particle Accelerators”, proceedings IPAC 2011.
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MOPRI006	Possible Uses of Gamma-rays at Future Intense Positron Sources	positron, synchrotron, software, electron	586
	A.O. Alrashdi, I.R. Bailey Lancaster University, Lancaster, United Kingdom A.O. Alrashdi, I.R. Bailey, D. Newton Cockcroft Institute, Warrington, Cheshire, United Kingdom A.O. Alrashdi KACST, Riyadh, Kingdom of Saudi Arabia D. Newton The University of Liverpool, Liverpool, United Kingdom
	Funding: This research is funded in part by STFC grant ST/G008248/1 The baseline design of the ILC (International Linear Collider) positron source requires the production of an intense flux of gamma rays. In this paper we present an investigation of using the gamma ray beam of the ILC for additional applications, including nuclear physics. As a result of changing the collimator shape, as well as the parameters of the undulator magnets, we obtained spectra from numerical simulations using the HUSR/GSR software package. We present results from simulations and a discussion of possible future investigations in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI006
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TUOCA01	The Linac Coherent Light Source-II Project	linac, electron, cryomodule, laser	935
	J.N. Galayda SLAC, Menlo Park, California, USA
	Funding: Work supported by US DOE Contract DE-AC02-766SF00515 The “Linac Coherent Light Source–II” Project, initiated in September 2010, has gone through a radical transformation beginning in August 2013. In its new form, LCLS-II will construct a 4 GeV CW superconducting linac in the first kilometre of the existing linac tunnel. A new undulator, optimized as a soft x-ray (200-1,300 eV) source, will receive electrons from the new SC linac. The existing undulator system will be replaced with a new variable gap device, which will receive electrons from either the new SC linac (providing 1-5 keV photons) or the copper linac presently used by LCLS (providing 1-25 keV x-rays). First light from the new facility is expected in September 2019. galayda@slac.stanford.edu
	Slides TUOCA01 [9.380 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUOCA01
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TUOCA03	Production of Quasi-monochromatic GeV Photons by Compton Scattering using Undulator X-ray Radiation at SPring-8	photon, electron, laser, experiment	941
	H. Ohkuma, A. Mochihashi, M. Oishi, S. Suzuki, K. Tamura JASRI/SPring-8, Hyogo-ken, Japan N. Muramatsu, H. Shimizu Tohoku University, Research Center for Electron Photon Science, Sendai, Japan T. Nakano RCNP, Osaka, Japan
	Funding: This work is supported by JSPS KAKENHI (Grant-in-Aid for Scientific Research) Grant Number 24241035. Backward Compton scattering (BCS) of X-ray photons emitted by undulator and reflected back by a single crystal from the electron beam can produce a quasi-monochromatic gamma-ray beam up to an energy very close to the electron beam energy. The SPring-8 beam diagnostics beamline (BL05SS) is used to inject a reflected undulator X-ray radiation against 8 GeV stored electron beam and to extract a quasi-monochromatic 8 GeV gamma-ray produced by BCS. BL05SS has conditions to do a pilot experiment to obtain the gamma-ray beam using BCS of X-ray photons from existing undulator. Experimental setup including a Bragg mirror system is now under construction. Preliminary reflectivity measurement of a silicon Bragg mirror using around 10keV photons has been done. Status of the experimental preparation and the future outlook is presented.
	Slides TUOCA03 [1.889 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUOCA03
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TUZB01	Prospects for the use of Permanent Magnets in Future Accelerator Facilities	permanent-magnet, radiation, lattice, dipole	968
	J. Chavanne, G. Le Bec ESRF, Grenoble, France
	Permanent magnet based accelerator magnets may offer a viable alternative to their conventional electromagnetic pairs for many applications, especially where strong gradients and low power consumption is needed. As an example, the development of future light sources based on ultimate storage ring needs to be done in an important energy saving context aiming at a significant reduction of operational costs. After more than two decades of continuous developments in the field of permanent insertion devices, a knowledge capital on different issues such as aging effects has been gained. This technology seems ready to jump into the design and construction of advanced accelerator magnets. This talk reviews the status of the permanent magnet technology and the perspectives for its implementations in standard lattice magnets, highlighting both the advantages and the challenges as compared to electromagnetic magnets.
	Slides TUZB01 [9.341 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUZB01
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TUOCB03	Performance of Elliptical Polarization Undulators at TPS	polarization, multipole, photon, FEL	987
	T.Y. Chung, C.-H. Chang, C.H. Chang, J.C. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin, C.Y. Wu NSRRC, Hsinchu, Taiwan
	Design, assembly, field shimming, and performance of APPLE-II type undulators in NSRRC are described in this article. Essentially, the mechanical error has been well controlled based on the optimize design and mechanical arts. Effectively initial sorting of permanent magnets is developed to minimize several adverse effects, such as magnetic inhomogeneities, no perfection geometry of blocks, and mechanical frame issue, those challenge the sorting expectation, especially for an adjusted polarization undulator. The sorting algorithm shows a quantitative prediction of magnetic field and is verified by measurement results. 2D virtual shimming algorithm has been developed to optimize field quality, including multipole, phase error, and particle trajectory. We describe the considering of each procedure and demonstrate the optimization together with measurement results.
	Slides TUOCB03 [1.503 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUOCB03
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TUPRO036	Start-to-end Optic of the FSF Multi-turn ERL Project	emittance, linac, injection, simulation	1099
	T. Atkinson, A.V. Bondarenko, A.N. Matveenko, Y. Petenev HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association VH NG 636 and HRJRG-214 Advanced magnetic optic designs are required to meet the heavy demands of future light sources: diffraction limited emittance, femto-second pulses and low energy spread. This paper highlights the magnetic optic that is presently being investigated in the ERL-simulation group at HZB. The injector optic is based on subtle emittance compensation techniques of space charge dominated beams. The high energy arcs are designed to suppress emittance growth due to CSR through horizontal phase advance manipulation, ISR effects by keeping the radiation integrals small and reduce the degradation due to chromatic aberrations. Optimised Start-to-End beam dynamic simulations are presented.
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TUPRO044	Bunch Compression of the Low-energy ELBE Electron Beam for Super-radiant THz Sources	radiation, electron, linac, emittance	1123
	U. Lehnert, P. Michel, R. Schurig HZDR, Dresden, Germany A.A. Aksoy Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey P.E. Evtushenko JLab, Newport News, Virginia, USA J.M. Krämer Danfysik A/S, Taastrup, Denmark
	At the ELBE radiation source two super-radiant THz sources, a broad-band trasnsition/diffraction radiation source and a planar undulator narrow-band sourc are under commissioning. At present the facility is driven from the ELBE linac with a CW electron beam of 100kHz repetition rate and up to 100pC of bunch charge. With the upgraded SRF electron gun bunch charges up to 1nC will become available. For the beam energies in the 20-30 MeV range buch compression into the sub-200 fs range becomes a major challenge. We present beam dynamics calculation of the attempted bunch compression scheme as well as first measurements obtained during the commissioning.
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TUPRO047	Betatron Oscillations in Planar Dipole Field	betatron, dipole, focusing, longitudinal-dynamics	1132
	V. Balandin, W. Decking, N. Golubeva DESY, Hamburg, Germany
	In this paper, in preparation to the European XFEL commissioning, we consider the procedure of calculation of focusing properties of chicane-type bunch compressors and planar undulators using 2D magnetic field model (approximation of infinitely wide poles).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO047
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TUPRO084	Magnetic Tuning of FLASH2 Undulators	multipole, quadrupole, radiation, pick-up	1235
	O. Bilani, P. Neumann, A. Schöps, M. Tischer, S. Tripathi, P. Vagin, T. Vielitz DESY, Hamburg, Germany
	The present fixed-gap undulator system for FLASH1 and the new FLASH2 undulators will share the same electron beam accelerator, thus 12 variable gap undulators are needed in order to provide radiation of different wavelengths to both experimental halls independently. Each of the 12 devices has a length of 2.5m. The magnet structure with a period length of 31.4mm provides a maximum field of 0.96T with an effective K-parameter of 2.81 at minimum gap. Phase, vertical and horizontal trajectories have been tuned based on Hall probe and stretched wire measurements. Remaining multipoles were optimized with moderate gap dependence by using magic fingers. At some magnet structures, shims were placed to correct gap dependent field integrals. All undulators have an rms vertical and horizontal trajectory flatness <6Tmm2 for all gaps corresponding to an rms trajectory roughness (at 1GeV) along the structure of ~2um. The rms phase error is below 2° over the entire gap range.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO084
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TUPRO085	Properties, Options and Limitations of PrFeB-magnets for Cryogenic Undulators	cryogenics, permanent-magnet, induction, polarization	1238
	F.-J. Börgermann, C. Brombacher, K. Üstüner Vacuumschmelze GmbH & Co. KG, Hanau, Germany
	The gap induction and thus the K-factor of permanent magnet undulators may be increased by cooling them to cryogenic temperatures. The use of NdFeB-magnets in cryogenic undulators, however, is limited to temperatures above 140 K due to the spin-reorientation transition (SRT) which leads to a reduction of the magnetization level. A further increase of the gap induction in undulators may be achieved by use of PrFeB-magnets at even lower temperatures, as this alloy does not show the SRT phenomenon. Although the effects are well known, up to now only a few undulator prototypes were built using this class of material since the coercivity of ternary PrFeB-magnets is not sufficient to minimize the risk of partial demagnetization when the undulator structure is kept at room temperature. This problem can be solved by applying actual technologies like grain-boundary diffusion in order to achieve coercivities exceeding 20 kOe at RT without sacrificing the high remanence Br of about 1.6 T at 77 K. We will provide actual data of the magnet performance achieved and show up the technological limitations in building PrFeB-based CPMU’s.
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TUPRO103	Novel Magnet Production Technique used for an Elliptically Polarizing Undulator	controls, multipole, radiation, permanent-magnet	1286
	E.J. Wallén, K.I. Blomqvist MAX-lab, Lund, Sweden J. Bahrdt HZB, Berlin, Germany F.-J. Börgermann Vacuumschmelze GmbH & Co. KG, Hanau, Germany
	A common problem for elliptically polarizing undulators (EPUs) is that the magnetic forces give a mechanical deflection in the magnet holder construction when changing the undulator phase. Gluing horizontally and vertically magnetized blocks together can increase the mechanical stability of the magnet holders. The gluing process of pairs of magnetized magnet blocks is time-consuming, expensive and difficult to carry out with high positional precision. A novel magnet production technique has been developed where un-magnetized pairs of blocks are glued together before magnetization. The large number of parts, the time for assembly, and the cost of the EPU can be reduced with the novel magnet production technique. The novel magnet production method has been used for a 2.6 m long EPU of APPLE-II type, which has been built in-house at the MAX IV Laboratory. The frame for the EPU is made of cast iron in order to get a small mechanical deformation when changing phase in the inclined mode. The paper includes detailed descriptions of the novel magnet production technique, including measurements of the magnetization, and the new EPU.
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TUPRO109	Calculation of Heat Load on Double Mini-beta Y Undulators	radiation, synchrotron, synchrotron-radiation, vacuum	1304
	J.C. Huang, T.Y. Chung, C.-S. Hwang, Y.T. Yu NSRRC, Hsinchu, Taiwan
	Two collinear in-vacuum undulators (IU22) are adopted for light source of X-ray coherence beamline in Taiwan photon source. Each undulator is 3 meter and the drift space between two undulator is 3.991m. The synchrotron radiation is propagating in the longitudinal direction and will result in a serious heat load problem for undualtor downstream. The magnet array of undualtor downstream will received the synchrotron radiation of 142W from upstream bending magnet and undualtor. Heat load is a critical challenge for in-vacuum undulator in double mini-beta Y lattice and therefore details analysis in this paper.
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TUPME001	Heat Load, Stress and Reaction Force Studies of a Polarized Positron Production Target for the Future International Linear Collider	target, positron, photon, vacuum	1331
	F. Staufenbiel, S. Riemann DESY Zeuthen, Zeuthen, Germany G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany
	The International Linear Collider requires an intense polarized positron beam with yields of about 10¹⁴ positrons per second. A polarized positron beam can be produced with a helical undulator passed by the accelerated electron beam to create a high power polarized photon beam. The photon beam penetrates a thin titanium-alloy rotating target wheel of 1m diameter with 500 to 2000 rpm rotation speed and produces polarized positrons. The system should run for 1-2 years without failure. A break down can occur due to the huge heat load in a short time (<1ms). The target design must keep the resulting thermo-mechanical stress below the yield strength and the fatigue limit of the material. FEM ANSYS simulations are used to evaluate the thermo-mechanical stress as well as the vibrations at the bearings of the rotating system. Results are presented with the goal to optimize the target wheel design parameters for a long lifetime.
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TUPRI037	Some Features of Wave Distribution in the Thin-Wall Waveguide	vacuum, impedance, shielding, radiation	1641
	M. Ivanyan, L.V. Hovakimyan, A. Sargsyan CANDLE SRI, Yerevan, Armenia
	In this report we derive rigorous and approximate dispersion relations for the round resistive thin-wall waveguide. The features of the distributions of dispersion curves of the waveguide axisymmetric TM modes are obtained. Cases of splitting and degeneracy of modes under consideration are detected and regularities of their behaviours are established.
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TUPRI040	New BBA Algorithm for Electron Beam Orbit Steering in Linear Accelerators	quadrupole, lattice, simulation, alignment	1650
	A. Sargsyan, V. Sahakyan, G.S. Zanyan CANDLE SRI, Yerevan, Armenia W. Decking DESY, Hamburg, Germany
	In linear accelerators or transfer lines beam-based alignment (BBA) techniques are important tools for beam orbit steering. In this paper BBA correction algorithm based on difference orbit multiple measurements is proposed. Numerical simulation results for European XFEL SASE1 and FLASH undulator section are presented, according to which the orbit alignment can be achieved within accuracy of about 2 microns and 5 microns respectively. The influence of quadrupole gradient errors is also discussed.
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TUPRI041	Study of Collective Beam Instabilities for Sirius	impedance, vacuum, operation, feedback	1653
	F.H. de Sá, H.O.C. Duarte, L. Liu, N. Milas, X.R. Resende LNLS, Campinas, Brazil
	In this paper we present the on going work of construction of the Sirius impedance budget and instability threshold estimates for several machine operation scenarios.
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TUPRI052	Analysis of Single Bunch Measurements at the ALBA Storage Ring	impedance, synchrotron, vacuum, simulation	1686
	T.F.G. Günzel, U. Iriso, F. Pérez CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain E. Koukovini-Platia, G. Rumolo CERN, Geneva, Switzerland
	Measurements of the vertical single bunch mode detuning and the TMCI threshold at zero chromaticity were carried out and their results were compared to the theoretical expectation. Around 65% of the found mode detuning can be explained by a developed transverse impedance model. A good bunch length parametrisation with current contributed essentially to this result. The analysis of single bunch measurements at non-zero chromaticity will also be presented.
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TUPRI081	Feed-forward and Feedback Schemes applied to the Diamond Light Source Storage Ring	feedback, photon, optics, storage-ring	1757
	M.T. Heron, M.G. Abbott, M.J. Furseman, D.G. Hickin, E.C. Longhi, I.P.S. Martin, G. Rehm, W.A.H. Rogers, A.J. Rose, B. Singh DLS, Oxfordshire, United Kingdom
	Since initial operation for users in Jan 2007, Diamond Light Source has developed to support a suite of 22 experimental stations. These stations have resulted in the installation of 24 undulators and two superconducting wigglers in the storage ring. To preserve optics, tune and coupling with the operation of these devices has necessitated the implementation of a number of feed-forward and feedback schemes. The implementation and operation of these correction schemes will be described.
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TUPRI100	Present Status of the Cherenkov Beam Loss Monitor at SACLA	electron, detector, status, laser	1808
	T. Itoga JASRI/SPring-8, Hyogo, Japan Y. Asano RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	Since 2011, high power lasers have been delivered stably to the users at SACLA, the SPring-8 Angstrom compact free electron laser, and the upgrades have been performing to obtain the high quality of the laser continuously. Optical fiber based Cherenkov beam loss monitors have been successfully operated from the commissioning phase. This monitor covers the undulator section of beam lines and the electron beam transporting tunnel from SACLA to SPring-8. This monitor is made good use of not only beam transport but also detection of the small beam loss such as electron halos hitting the magnets of undulator. In this presentation, we will report the present status of the Cherenkov beam loss monitor and its usage experience.
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WEOAA02	Development of the Very Short Period Undulators	radiation, electron, photon, vacuum	1845
	S. Yamamoto KEK, Ibaraki, Japan
	We have been exploring a method to fabricate very short period undulators, a period length of which is one order-of-magnitude shorter than the ordinary period of several cm. We are developing a plate-type magnet some 100mm long with a period length of 4mm. We selected this period length since we can generate 12-keV radiation with the first harmonic of this undulator in the 2.5-GeV storage ring. A multi-pole magnetizing method was applied to magnetizing this plate: a periodic undulator field (of 4-mm period in this case) was generated by pulsed electro-magnets, and was transcribed into the plate. The magnetization procedure allows the undulator field to be obtained in a very short gap between the pair of opposing plates, which is also one order-of-magnitude shorter than a gap in the ordinary undulators. We report the magnetization method to obtain a very short period and present the test results. The calculated spectrum of the radiation from the measured field compares well with that from an ideal magnetic field in the region of the fundamental radiation in case of 2.5-GeV energy of the electron beam.
	Slides WEOAA02 [5.189 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOAA02
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WEOAA03	Ultrashort and Coherent Radiation for Pump-probe Experiments at the DELTA Storage Ring	radiation, laser, experiment, electron	1848
	M. Huck, S. Hilbrich, H. Huck, M. Höner, S. Khan, C. Mai, A. Meyer auf der Heide, R. Molo, H. Rast, A. Schick, P. Ungelenk DELTA, Dortmund, Germany
	Funding: Work supported by DFG, BMBF, and by the Federal State NRW. A light source facility employing the coherent harmonic generation (CHG) principle is being commissioned and operated since 2011 at DELTA, a 1.5-GeV electron storage ring at the TU Dortmund University, with the purpose of providing ultrashort coherent VUV radiation for time-resolved experiments. CHG is based on the interaction of ultrashort laser pulses with electrons in an undulator to generate coherent harmonics of the laser wavelength. Different methods have been used to optimize, detect and characterize the CHG radiation. One example is the study of transverse and longitudinal coherence properties in double-slit and Michelson experiments. Moreover, final steps towards performing pump-probe experiments to study ultrafast magnetic phenomena have been taken.
	Slides WEOAA03 [4.139 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOAA03
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WEPRO008	A Beam-driven Microwave Undulator for FEL	wakefield, electron, FEL, linac	1956
	A. Kanareykin, C.-J. Jing, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA S. Baturin LETI, Saint-Petersburg, Russia A. Zholents ANL, Argonne, Ilinois, USA
	Funding: DOE SBIR Microwave waveguides can in principle be used for undulators with periods less than 1 cm. Intensive work has been done on the recently proposed design that operates at the HE11 hybrid mode of a corrugated waveguide; successful experimental results have been reported recently [S.Tantawi Talk at POSIPOL 2012]. In this presentation we propose a beam driven design for an undulator based on an electron bunch train powering a microwave or mm waveguide. The drive bunch train propagates towards the undulating beam inside a dielectric loaded structure or corrugated waveguide generating high power RF. The “smart” waveguide design and a proper bunch spacing of the electron drive beam train provide single mode generation of the high magnitude undulating field that gives an undulator parameter in the range of K~1 for a high frequency device.* *A. Zholents, HBEB Workshop, Puerto-Rico, 2013.
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WEPRO022	Modal Analysis of Helical Undulator Radiation In Cylindrical Waveguide	radiation, vacuum, FEL, linac	1989
	T.L. Vardanyan, M. Ivanyan, V. Sahakyan, A.V. Tsakanian, G.S. Zanyan CANDLE SRI, Yerevan, Armenia
	The coherent radiation of the relativistic electron beam with helical orbit in circular waveguide is studied. The radiation field configuration is obtained using modal expansion technique. For short electron bunches the coherent part of radiation is evaluated. The coherent radiation effects on the bunch performance are analyzed.
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WEPRO029	Developing of Advanced Magnet Structures for Cryogenic in Vacuum Permanent Magnet Undulators	permanent-magnet, cryogenics, vacuum, electron	2004
	C. Kuhn, J. Bahrdt, A. Gaupp, M. Scheer, B. Schulz HZB, Berlin, Germany
	Cryogenic in vacuum permanent magnet undulators with periods less than 10 mm and correspondingly narrow gaps require tighter geometric and magnetic tolerances and complex pole designs from different materials to achieve the needed high field strengths. We use new mechanic designs and manufacturing technologies for magnet and pole assembly. We develop new precise and UHV-compatible joining methods which are different from the current approaches which are based on mechanical clamping or gluing. . We examine the mechanical and magnetic properties by performing tests and discuss the results.
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WEPRO031	Design and Commissioning of the FLASH2 Undulators	FEL, controls, operation, vacuum	2007
	A. Schöps, O. Bilani, T. Ramm, M. Tischer, S. Tripathi, P. Vagin DESY, Hamburg, Germany
	This paper reports about aspects of design, manufacturing, and commissioning of the 12 FLASH2 variable gap undulator segments. The accuracy of gap drive and encoder systems was tested by magnetic measurements; changes in the phase error proved to be a highly sensitive probe to verify a reproducibility of 1 μm. After magnetic tuning of the IDs, the remaining gap dependence in the field integrals could be successfully compensated by corrector coils. Inconsiderate handling of components during assembling necessitated an elaborate demagnetisation process before the tuning could start.
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WEPRO032	Phase Shifters for the FLASH2 FEL	electron, operation, quadrupole, FEL	2010
	M. Tischer, P. Neumann, A. Schöps, P. Vagin DESY, Hamburg, Germany
	The FLASH2 SASE undulator section consists of 12 IDs. Each of them is followed by an intersection component comprising a phase shifter and various parts for diagnostics and beam steering. The phase shifter is a compact and simple electromagnetic chicane and has to assure constructive interference of the radiation of adjacent undulators for all wavelengths. The magnetic performance, field errors and the hysteresis behavior have been investigated and were found to be within the required accuracy. The results are discussed in relation to the undulator conditions. From these data tables for steering the phase shifter current as function of undulator gap were derived and implemented in the control system.
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WEPRO033	Design and Magnetic Measurements on Bi-harmonic Undulators	laser, free-electron-laser, electron, synchrotron	2013
	G. Sharma, G. Mishra Devi Ahilya University, Indore, India S. Tripathi DESY, Hamburg, Germany
	In recent years there exists interests in harmonic lasing of free electron lasers for short wavelength operation with low energy electron beams. In a planar undulator , the electron radiates at odd harmonics on axis however the harmonic gain of the FEL is much less than that of fundamental. It has been shown in earlier works that it is possible to enhance the harmonic radiation by increasing the harmonic wiggler field to the fundamental by putting high permeability shims inside the undulator. The common material is the vanadium permendur (μ ~800) , which has been used effectively to design the harmonic undulator. In this paper, we report the design and fabrication of seventh and ninth harmonic undulator for free electron laser applications. We use CRGO shims with μ ~ 2-3. The permanent magnet undulator is a four block per period design. The undulator is a variable gap type and consists of NdFeB magnets with six periods, each period is of 5cm length. The undulator has been measured in hall probe and pulsed wire bench. It is shown that the pulsed wire magnetic measurements yields results in close agreement with hall probe results.
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WEPRO034	Magnetic Measurement Developments for Undulators	quadrupole, laser, vacuum, alignment	2016
	P. Vagin, P. Neumann, M. Tischer DESY, Hamburg, Germany
	FLASH2 is an extension of the present VUV-FEL facility at DESY. It includes a separate tunnel with a 12 x 2.5m = 30m long planar hybrid undulator. The undulators have 31.4mm period length and 1T field at a minimum gap of 9mm. The paper presents recent progress in the magnetic measurements of these undulators. Several specific details of the measurement tools will be discussed like peculiarities in the Hall probe calibration and noise, positioning accuracy and synchronization of voltage measurement with probes movement during scan, noise issues of various voltage integrators for stretched wire and search coil measurements.
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WEPRO035	Radiation Damage of Undulators at PETRA III	radiation, wiggler, damping, vacuum	2019
	P. Vagin, O. Bilani, A. Schöps, M. Tischer, S. Tripathi, T. Vielitz DESY, Hamburg, Germany
	In the new octant of PETRA~III, there are 14 undulator beamlines covering photon energy range from 0.3keV to 150keV. There are also 80m of damping wigglers in order to achieve a low emittance of 1nmrad. Some of these devices, operating at PETRAIII since 2008, accumulated total radiation doses of about 100kGy. Visible corrosion at the magnet structures of some permanent magnet undulators setting in after a few years and a high dose rate measured regularly by thermoluminescent dosimeters (TLDs) gave reason to inspect the magnetic field of all insertion devices in the PETRA tunnel. This paper presents details of the magnetic field degradation caused by radiation damage to the undulator magnets. For some undulators changes in the spectral properties of the generated light were observed. It was measured with different taper settings in order to partly compensate the nonuniform demagnetization along the structure. The results are compared with the data from the sFLASH undulators and measurements of special 3 pole "sacrificial" undulator, installed in FLASH. Its magnetic field is periodically remeasured and shows field amplitude decrease of 1% per 16kGy accumulated dose.
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WEPRO036	Construction and First Magnetic Field Test of a Superconducting Transversal Gradient Undulator for the Laser Wakefield Accelerator in Jena.	electron, laser, radiation, wakefield	2022
	V. Afonso Rodríguez, A. Bernhard, A.W. Grau, P. Peiffer, R. Rossmanith, M. Weber, C. Widmann, A. Will KIT, Karlsruhe, Germany M. Kaluza, M. Nicolai, A. Sävert IOQ, Jena, Germany M. Reuter HIJ, Jena, Germany
	Funding: This work is funded by the German Federal Ministry for Education and Research under contract no. 05K10VK2 and 05K10SJ2. A superconducting transversal gradient undulator (TGU), tailored to the particular beam properties of the laser wakefield accelerator (LWFA) at the University of Jena, has been designed and constructed at KIT. This undulator in combination with a specialized beam transport line will be employed to produce undulator radiation with natural bandwidth despite the relatively large energy spread of the electrons produced by the LWFA. The fabrication of this undulator and first results of the magnetic field measurement are discussed in this paper.
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WEPRO038	Possibility for Quasi-periodic Knot-APPLE Undulator	radiation, polarization, synchrotron, synchrotron-radiation	2026
	S. Sasaki, A. Miyamoto HSRC, Higashi-Hiroshima, Japan N. Kawata, T. Mitsuyasu Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan S. Qiao SIMIT, Shanghai, People's Republic of China
	An intense on-axis radiation power from an undulator is a serious problem especially for a low-photon-energy beamline in a facility with high or medium energy storage ring. This problem may be solved by using a Figure-8, a Pera, or a Knot undulator configuration,. However, these schemes are useless for variably polarizing undulators such as an APPLE undulator and other similar variations since such devices are not capable for reducing on-axis power density in the linear mode. In these circumstances, we have completed a conceptual magnet design of Knot-APPLE udulator which is capable to generate elliptically polarized radiation as well as linearly polarized radiation. This pure permanent magnet device is equipped with a motion mechanism of APPLE undulator. In this paper, we present detailed magnet design feature, magnetic field distributions, and radiation properties including variations of polarization in comparisons with other exotic devices. In addition, a possibility to introduce a quasi-periodicity in this type of undulator is considered in order to achieve further reduction of second and third harmonic radiation intensities. S. Sasaki, "Undulators, wigglers and their applications," p.237-243 (Ed. by H. Onuki and P. Elleaume, Taylor & Francis Inc, New York, 2003). **S. Qiao, et. al, Rev. Sci. Instrum., 80, 085108 (2009).
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WEPRO039	Status of PAL-XFEL Undulator Program	FEL, controls, radiation, electron	2029
	D.E. Kim, H.-S. Kang, W.W. Lee, K.-H. Park PAL, Pohang, Kyungbuk, Republic of Korea M.-H. Cho, I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea S. Karabekyan, J. Pflüger XFEL. EU, Hamburg, Germany
	Pohang Accelerator Laboratory (PAL) is developing 10 GeV, 0.1 nm SASE based FEL for high power, short pulse X-ray coherent photon sources named PAL-XFEL. At the first stage PAL-XFEL needs two undulator lines for photon source. PAL is developing undulator magnetic structure based on EU-XFEL design. Recently, the hard X-ray undulator changed its minimum magnetic gap to 8.3 mm from the previous 7.2 mm to alleviate the wake field impact, and to increase the allowances for the re alignment. Accordingly, the period is also changed from 24.4 mm to 26.0 mm to generate 0.1 nm at 10 GeV electron energy. In this report, the modification efforts and the progress on the prototyping of hard x-ray undulator system will be presented.
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WEPRO040	Field Measurement Facility for PAL-XFEL Undulators	controls, FEL, laser, software	2032
	K.-H. Park, Y.-G. Jung, D.E. Kim, S.N. Kim, I.S. Ko, B.H. Lee, H.-G. Lee, M.S. Lee, S.B. Lee, H.S. Suh, C.W. Sung PAL, Pohang, Kyungbuk, Republic of Korea
	Pohang Accelerator Laboratory (PAL) is developing the SASE based FEL for X-ray coherent photon sources. The PAL developed the prototype undulator that was 5.0 m magnetic length. The PAL has constructed the undulator field measurement facility to confirm the field qualities of the XFEL undulators in the assembly building. The temperature stability of the measurement rooms was controlled within ±0.1°C. Two field measurement benches that included Hall probe scan, flip coil and stretched wire system were installed and evaluated their performances. The field profile of the prototype undulator was characterized and shimmed using the installed measurement system. This paper described the field measurement facility with the performance test results of the two benches.
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WEPRO041	Undulator Radiation Spectral Broadening Due To Radiation Energy Loss	radiation, electron, simulation, photon	2035
	N.V. Smolyakov NRC, Moscow, Russia
	A relativistic electron passing through an undulator generates electromagnetic radiation at the expenses of its own kinetic energy. This effect is usually not taken into account if the number of periods of the undulator is relatively small (100 - 200). However, at FEL facilities, long installations have been built, planned or are under construction, where many undulators are installed one after another for a total of several thousand undulator periods. For instance, the SASE1 and SASE2 lines at the European XFEL will consist of 35 undulators with 124 periods each. In this case, because of the electron energy decrease along its trajectory, the radiation from different undulators will drop out of synchronism. As a result, the radiation spectral line will be much wider. In the presented report, this effect was analyzed analytically and numerically. An expression for the critical number of undulator periods, when the effect of electron energy loss should be properly taken into account, is derived. It is found that, for the case of the European XFEL, this number is about 1200 periods.
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WEPRO045	Design of a System at NSRRC to Measure the Field for an In-vacuum Cryogenic Undulator with Permanent Magnet	vacuum, laser, alignment, timing	2041
	C.K. Yang, C.-H. Chang, T.Y. Chung, J.C. Huang, C.-S. Hwang, Y.Y. Lin NSRRC, Hsinchu, Taiwan
	A cryogenic undulator with a permanent magnet (CPMU) is an important insertion device now under construction at NSRRC. For an undulator of this kind, the distribution of the magnetic field must be measured along the axis; the phase error, trajectory and photon flux must be calculated after the magnetic arrays are installed in the vacuum chamber and cooled to cryogenic temperature. We developed a Hall-probe system to measure the magnetic field in an evacuated environment; this system uses lasers and stages to monitor and to correct dynamically the positions of the Hall probe. All components installed inside the vacuum chamber are compatible with an environment of high vacuum and low temperature. The details of the design and completed fabrication are presented in this paper.
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WEPRO047	A New Cooling System for Cryocooled Permanent Magnet Undulators at Diamond Light Source	vacuum, operation, cryogenics, electron	2047
	E.C. Longhi, A.G. Miller, E.C.M. Rial, A.J. Rose, J.C. Schouten, C.W. Thompson, A. Thomson, J.H. Williams DLS, Oxfordshire, United Kingdom C. Monroe Monroe Brothers Ltd., Moreton-in-Marsh, United Kingdom
	Cryocooled permanent magnet undulators (CPMUs) using NdFeB magnets around 150K were first proposed by Hara. These are cooled by using either GM cryocoolers or circulating sub-cooled liquid nitrogen. Due to the heat load from radiation and wakefield heating from the electron beam, temperature gradients can develop along the length of the magnet girders which could be as large as several degrees for the Diamond Light Source (DLS) storage ring operating parameters. Some grades of the magnetic material (NdxPr1-x)2Fe14B have remanence curves versus temperature which increase significantly for temperatures below 150K with peaks below 80K. This means that the operating temperature of a CPMU using this material can be close to the boiling point of liquid nitrogen. The proposed cooling system for the new DLS CPMU is based on a thermosiphon allowing nitrogen to boil inside the cooling channels without a circulating pump. This has the advantage of absorbing large amounts (>250W) of heat with very small temperature gradients. We report here the results of a prototype magnet beam cooled with a thermosiphon producing a temperature gradient of less than 0.05K along a 2m beam at ~77K. T. Hara et al., Phys Rev Spec Top. Accelerator & Beam, Vol 7, 2004. ** J. Bahrdt et al., AIP Conf. Proc., SRI 2009, Melbourne Australia, vol. 1234, pp. 499-502, 2010.
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WEPRO048	A Concept of a Universal Superconducting Undulator	simulation, electron, storage-ring, FEL	2050
	Y. Ivanyushenkov ANL, Argonne, Ilinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Tiny round electron beams of free-electron lasers and relatively new diffraction-limited storage rings make possible utilization of electromagnetic helical undulators based on double-helical windings. It has been understood for a while that a coaxial pair of double-helical windings can generate helical as well as planar magnetic fields. Such a coil structure can potentially be realized with superconducting windings thus forming the concept of a universal superconducting undulator (Universal SCU). An example of a possible universal SCU for the recently suggested Advanced Photon Source multi-bend achromat storage ring is given in this paper. The results of the magnetic simulation together with initial cryogenic considerations are presented. D.F. Alferov, Yu.A. Bashamakov, E. G. Bessonov, Sov. J. Tech. Phys. 21(11), (1976) 1408.
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WEPRO049	Experience of Operating a Superconducting Undulator at the Advanced Photon Source	photon, operation, storage-ring, vacuum	2053
	Y. Ivanyushenkov, K.C. Harkay ANL, Argonne, Ilinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. A superconducting test undulator SCU0 was installed into the storage ring of the Advanced Photon Source (APS) in December 2012 and has been in user operation since January 2013. The first year's experience of operating such a novel insertion device at the APS is summarized in this paper. The performance of the SCU0 as a photon source is presented. The measured heat load from the electron beam is described together with the observed cryogenic behavior of the device. The effect of the SCU0 on the APS electron beam is also presented.
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WEPRO053	All-optical Free Electron Lasers using Travelling-wave Thomson Scattering	electron, laser, FEL, scattering	2065
	K. Steiniger, M.H. Bussmann, A.D. Debus, A. Irman, A. Jochmann, R.G. Pausch, U. Schramm Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany T.E. Cowan HZDR, Dresden, Germany
	In Travelling-Wave Thomson Scattering (TWTS) the pulse front of a high-power, short-pulse laser is tilted and the dispersion of the pulse is controlled in such a way that electrons can interact over a long distance with a quasi-monochromatic electromagnetic wave. We present a complete three dimensional analytic time-dependent description of the TWTS field and use this description to derive an analytic FEL equation that shows that TWTS indeed provides for an all-optical FEL. We further derive conditions for optimum operation of the TWTS FEL, showing that EUV and XUV FEL sources are in reach using Petawatt lasers and conventional few-hundred MeV electron sources. Future laser-wakefield accelerators could potentially drive all-optical TWTS-FELs in the X-ray and beyond. TWTS itself is optimum to provide full flexibility in terms of the wavelength and bandwidth of the scattered radiation, allowing for application-optimized, highly-brilliant Thomson Scattering sources for a broad range of wavelengths from the EUV to the gamma ray spectral region.
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WEPRO057	Effect of the Electron Beam Emittance on the ILSF Radiation of Sources and Beamline Design	emittance, photon, brilliance, electron	2075
	A. Gholampour, S. Amiri, H. Ghasem, H. Khosroabadi, J. Rahighi ILSF, Tehran, Iran H. Ghasem, M. Lamehi Rashti, J. Rahighi IPM, Tehran, Iran
	At the Iranian Light Source Facility (ILSF), two different storage ring options are being studied. The designs differ in emittance. In the first option the calculated emittance is 3.278 nm-rad whereas for the second option emittance is 0.937 nm-rad. In this paper the electron beam emittance effects on the source radiation properties from bending magnet, wiggler and undulator, X-ray optics and the beamline design are carefully studied. The present calculations demonstrate that in the case of 0.937 nm-rad brilliance of undulator is increased by a factor of about 5. For bending magnet, flux is reduced almost 1 order of magnitude for hard x-ray regime. Because of smaller size of the source for undulator at the case of 0.937 nm-rad, we can achieve to a smaller spot size and higher resolution with easier focusing systems and usual kind of monochromator than the emittance of 3.278 nm-rad and for the bending magnet hard x-ray beamline, size of the mirrors reduced 30% in the 0.937 nm-rad emittance case, so its result is shorter mirror, low cost and perhaps more challengeable heat load.
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WEPRO058	Photoemission Electron Microscopy Branch of Spectromicroscopy Beamline of the Iranian Light Source Facility	electron, photon, focusing, brilliance	2078
	S. Amiri, H. Ghasem, A. Gholampour, H. Khosroabadi, J. Rahighi ILSF, Tehran, Iran H. Ghasem, M. Lamehi Rashti IPM, Tehran, Iran
	The Spectromicroscopy beamline is one of the day one beamlines of the Iranian Light Source Facility project in the field of soft x-ray spectroscopy. This beamline is designed to cover the 90-2500eV energy range with about 8000 resolving power, and the minimum spot size of about 10×4 micrometer 2 at sample position. Brilliance, flux and photon size and divergence in the whole range of energy has been calculated for a 4.3m linear undulator using SPECTRA code. This undulator has 10¹⁵ ph/s(0.1% B.W.) photon flux at 96 eV energy & 400 mA electron current. A circular pinhole with maximum diameter size of 2.52mm has been inserted in a distance of 10m from the source to pass 95% radiated. Primary layout of this branch includes a collimating mirror, a varied included-angle plane grating monochromator, and a KB bendable elliptical cylinder mirror. The ray tracing calculation by using computational software SHADOW has been done to determine and optimize of the important optical parameters. Three plane gratings with different uniform line density (700, 900, 1200 lines/mm) have been used to cover the whole energy range with the resolving power of 0.75-0.8×104 depending on the photon energy.
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WEPRO093	Possibility of Application of THz Wiggler in Low Energy FEL for Measurements of Electron Bunch Longitudinal Structure	electron, wiggler, laser, radiation	2177
	E. Syresin, S.A. Kostromin, R.S. Makarov, N.A. Morozov, D. Petrov JINR, Dubna, Moscow Region, Russia M. Krasilnikov DESY Zeuthen, Zeuthen, Germany
	Funding: The work is funded by HGDF-RFBR Grant HRJRG-400 The infrared undulator constructed at JINR and installed at FLASH in 2007 is used for longitudinal bunch shape measurements in the range of several tenths of μm. The presented below electromagnetic wiggler is applied for a narrow-band THz radiation for measurements of electron bunch longitudinal structure in FEL with electron energy of several tenths of MeV. This is a planar electromagnetic device with 6 regular periods, each of 30 cm long. The K parameter is varied in the range 0.5- 7.12 corresponding to a range B=0.025- 0.356 T of the peak field on axis. The wiggler is simulated for 19.8 MeV/c FEL. The bunch compression scheme allows the whole wavelength range to be covered by super-radiant emission with a sufficient form factor. The wavelength range corresponds to 126 μm - 5.3 mm for the electron beam momentum of 19.8 MeV/c. The 3D Opera simulations of THz wiggler will be discussed.
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WEPME031	Magnetic Design of the First Prototype Pure Permanent Magnet Undulator for the ILSF	brilliance, radiation, permanent-magnet, electron	2326
	A. Ramezani Moghaddam, J. Rahighi ILSF, Tehran, Iran H. Ghasem IPM, Tehran, Iran M. Lamehi Rashti Nuclear Science & Technology Research Institute, Tehran, Iran A. Ramezani Moghaddam NSTRI, Tehran, Iran
	Iranian light source facility (ILSF) is a 3GeV, 400 mA, 3rd generation light source under design and construction. This paper describes the details of the preliminary magnetic design of the first prototype PPM undulator for the ILSF. In the preliminary design, the undulator period and some other parameters have been determined to reach desired x-ray spectrum to be used for soft x-ray application. A PPM layout and a model undulator with 16 poles is used to calculate the properties of the designs.
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WEPRI095	Modelling of a Short-period Superconducting Undulator	simulation, alignment, software, radiation	2716
	B.J.A. Shepherd, J.A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V. Bayliss, T.W. Bradshaw STFC/RAL, Chilton, Didcot, Oxon, United Kingdom E.C. Longhi DLS, Oxfordshire, United Kingdom
	STFC, in collaboration with Diamond Light Source, are designing and building a 15.5 mm period, 1.26 T superconducting undulator. This paper describes the modelling of the undulator, using Radia and Opera. Extensive numerical modelling has been carried out to simulate the effect of manufacturing tolerances on the quality of the magnetic field, in order to meet the demanding 3° rms phase error specification.
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WEPRI105	Preliminary Design of Cooling System for a PrFeB-based Cryogenic Permanent Magnet Undulator Prototype at IHEP	vacuum, cryogenics, permanent-magnet, simulation	2743
	Y.C. Zhang, S.P. Li, H.H. Lu, S.C. Sun, Y.F. Yang IHEP, Beijing, People's Republic of China
	A circulation cooling system is under progress for a 2-m-long PrFeB-based cryogenic permanent magnet undulator (CPMU) prototype at IHEP. Sub-cooled liquid nitrogen flows through each in-vacuum girder back and forth once. Refrigerant channels for both girders are parallel connected in vacuum chamber. Numerical simulation shows that the cooling system is able to cool down magnet array from 300 K to 83 K. Meanwhile, phase error increases about 0.1 degree.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI105
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THOBA03	Beam Transport System from a Laser Wakefield Accelerator to a Transverse Gradient Undulator	electron, laser, beam-transport, radiation	2803
	C. Widmann, V. Afonso Rodríguez, A. Bernhard, N. Braun, A.-S. Müller, A.I. Papash, R. Rossmanith, W. Werner KIT, Karlsruhe, Germany M. Kaluza, M. Reuter HIJ, Jena, Germany M. Kaluza, M. Nicolai, A. Sävert IOQ, Jena, Germany
	Funding: This work is funded by the German Federal Ministry for Education and Research under contract no. 05K10VK2. The transport and matching of electron beams generated by a laser wakefield accelerator (LWFA) is a major challenge due to their large energy spread and divergence. Strong focussing magnets and a chromatic correction are required. This contribution discusses the layout of the beam transport optics for a diagnostic beamline at the LWFA in Jena, Germany. The aim of this optics is to match the betatron functions and the dispersion to the field of a transverse gradient undulator (TGU) such that monochromatic undulator radiation is generated despite the large energy spread.
	Slides THOBA03 [2.891 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THOBA03
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THPPA01	FEL R&D Initiatives at the SLAC National Accelerator Laboratory	FEL, electron, laser, free-electron-laser	2842
	A. Marinelli SLAC, Menlo Park, California, USA
	The successful lasing of the linac coherent light source in 2009, the first x-ray free-electron laser (xFEL) in the world, has opened a new era for x-ray photon science. The unprecedented intensity and coherence of the LCLS photon pulses have enabled groundbreaking experiments in a wide variety of fields ranging from coherent x-ray imaging to molecular and atomic physics. Despite the success of x-ray free-electron lasers, there is a steady push to extend and improve their capabilities fueled by the users' demands for new modes of operation and more precise photon and electron diagnostics. In my talk I will present several R&D initiatives at the SLAC National Accelerator Laboratory geared towards improving the performance and extending the capabilities of x-ray FELs. In particular I will focus on the spectral manipulation of FELs and our recent development of the multibunch and multicolor x-ray FEL modes at LCLS as well as our demonstration of the longitudinal space-charge amplifier as a broadband coherent light source at the NLCTA test accelerator.
	Slides THPPA01 [10.793 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPPA01
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THPRO003	Progress of the LUNEX5 demonstator Project	FEL, electron, operation, laser	2856
	M.-E. Couprie, C. Benabderrahmane, P. Berteaud, C. Bourassin-Bouchet, F. Bouvet, L. Cassinari, L. Chapuis, J. Daillant, M. Diop, M.E. El Ajjouri, C. Evain, C. Herbeaux, N. Hubert, M. Labat, P. Lebasque, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Polack, F. Ribeiro, J.P. Ricaud, P. Roy, K. Tavakoli, M. Valléau, D. Zerbib SOLEIL, Gif-sur-Yvette, France S. Bielawski, E. Roussel, C. Szwaj PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France B. Carré, D. Garzella CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France X. Davoine CEA/DAM/DIF, Arpajon, France N. Delerue LAL, Orsay, France G. Devanz CEA/DSM/IRFU, France A. Dubois, J. Lüning CCPMR, Paris, France G. Lambert, R. Lehé, V. Malka, A. Rousse, C. Thaury LOA, Palaiseau, France C. Madec, A. Mosnier CEA/IRFU, Gif-sur-Yvette, France
	LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, coherent pulses in the 40-4 nm spectral range [1]. It comprises two types of accelerators connected to a single Free Electron Laser (FEL) for advanced seeding configurations (seeding with High order Harmonic in Gas, echo). A 400 MeV superconducting Linear Accelerator, adapted for studies of advanced FEL schemes, will enable future upgrade towards high repetition rate and multi-user operation by splitting part of the macropulse to different FEL lines. A 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA) [2] will also be qualified by the FEL application. After the Conceptual Design Report, R&D has been launched on different sub components. Following transport theoretical studies of longitudinal and transverse manipulation of a LWFA electron beam enabling to provide theoretical amplification, a test experiment is under preparation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO003
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THPRO004	Study of the CLIO FEL in the Far-infrared in a Partially Guided Mode	vacuum, FEL, cavity, simulation	2859
	J.-M. Ortega, J.P. Berthet, F. Glotin, R. Prazeres LCP/CLIO, Orsay, Cedex, France
	The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to unity. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. A solution is to use this chamber as a waveguide by adaptating the radius of curvature of the cavity mirrors to this regime. Then, as has been shown before* a minimum appears in the spectrum that can be produced by the FEL. We discuss the physical mechanism of this particular regime and compare it to experiments using vacuum chambers of different tranverse sizes. A good agreement is found with results of simulations and with a simple analytical formula. * Analysis of the periodic power gaps observed in the tuning range of FELs with a partial waveguide, R. Prazeres, F. Glotin, J.-M. Ortega, Phys. Rev. STAB12, 010701 (2009)
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THPRO007	Beam-based Alignment in the European XFEL SASE1	radiation, quadrupole, simulation, FEL	2867
	H. Jin, W. Decking, T. Limberg DESY, Hamburg, Germany
	The European X-ray Free Electron Laser (E-XFEL) provides an ultra-short and high-brilliant photon pulses of spatially coherent X-rays with wavelengths down to 0.05 nm by using three undulator systems. Within these undulator systems, the orbit trajectory is required to be straight to a few micron over each gain length, so that the photon beam is capable of overlapping efficiently with the electron beam. However, this requirement is not obtainable with ordinary mechanical alignment methods. For this reason, a beam-based alignment (BBA) method using BPM readings of different beam energies is applied to the E-XFEL SASE1 undulators. In this report, we describe the BBA simulation for SASE1 including alignment errors of quadrupoles and BPMs. After correction, the desired range of the orbit trajectory is attained with high confidence. In addition, to identify the reliability of an aligned orbit trajectory acquired from the BBA simulation, we present here the SASE FEL radiation simulation, in which we observe a slight decrease of radiation energy and power.
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THPRO008	Obtaining High Degree of Circular Polarization at X-ray FELs via a Reverse Undulator Taper	FEL, radiation, bunching, polarization	2870
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft X-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced. Phys. Rev. ST-AB 16(2013)110702
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO008
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THPRO009	Harmonic Lasing in X-ray FELs	FEL, electron, photon, operation	2873
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Contrary to nonlinear harmonic generation, harmonic lasing in a high-gain FEL can provide much more intense, stable, and narrow-band FEL beam which is easier to handle if the fundamental is suppressed. We perform a parametrization of the solution of eigenvalue equation for lasing at odd harmonics, and present explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam. We discover that in a part of the parameter space, corresponding to the operating range of soft X-ray beamlines of X-ray FEL facilities, harmonics can grow faster than the fundamental. We suggest that harmonic lasing can be widely used in the existing or planned X-ray FEL facilities. LCLS after a minor modification can lase at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level. At the European XFEL the harmonic lasing would allow to extend operating range up to 100 keV, to reduce bandwidth and increase brilliance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO009
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THPRO010	Analysis of Operation of Harmonic Lasing Self-seeded FEL	FEL, simulation, radiation, electron	2876
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Harmonic lasing self-seeded FEL holds great potential for significant improvement of the the longitudinal coherence of the radiation. A gap-tunable undulator is divided into two parts by setting two different undulator parameters such that the first part is tuned to a sub-harmonic of the second part. Harmonic lasing occurs in the exponential gain regime in the first part of the undulator, also the fundamental stays well below saturation. In the second part of the undulator the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is defined by the harmonic lasing (i.e. it is reduced by a significant factor depending on harmonic number) but the saturation power is still as high as in the reference case of lasing at the fundamental in the whole undulator, i.e. the spectral brightness increases. Application of the undulator tapering in the deep nonlinear regime would allow to generate higher peak powers approaching TW level. The scheme is illustrated with the parameters of the European XFEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO010
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THPRO011	Investigation of the Coherence Properties of the Radiation at FLASH	radiation, emittance, electron, FEL	2879
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	We present the results of the studies of coherence properties of the radiation from FLASH for fundamental harmonic and higher odd harmonics. General overview of the parameter space is performed including peak current, emittance, and external focusing. The results of our studies show that present configuration of FLASH free electron laser is not optimal for providing ultimate quality of the output radiation. We find that the physical origin of the problem is mode degeneration. The way for improving quality of the radiation is proposed.
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THPRO016	Stable Generation of High Power Self-seeded XFEL at SACLA	radiation, electron, photon, FEL	2888
	T. Inagaki, N. Adumi, T. Fukui, T. Hara, Y. Inubushi, T. Ishikawa, H. Kimura, R. Kinjo, H. Maesaka, Y. Otake, H. Tanaka, T. Tanaka, K. Togawa, M. Yabashi RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan S. Goto, T.K. Kameshima, T. Ohata, K. Tono JASRI/SPring-8, Hyogo, Japan T. Hasegawa, S. Tanaka SES, Hyogo-pref., Japan A. Miura, H. Ohashi, H. Yamazaki Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Hyogo, Japan
	A self-seeded XFEL system using a transmitted beam under Bragg diffraction has been developed at the first compact XFEL facility SACLA in order to generate a brilliant single-mode XFEL with high temporal coherence. High stability and unique beam characteristics of SACLA should significantly contribute to achieve reliable, high-quality seeded XFEL operation. In particular, the short-pulse property that has been achieved in routine operation enables us to switch SASE and seeded mode quickly, without changing the electron beam parameters. This is also useful for delivering different modes to multiple beamlines simultaneously. In the test experiments carried out in autumn 2013, spectral narrowing was observed at 10 keV using diamond 400 reflection. Systematic optimization on beam properties is now in progress towards experimental use of seeded XFELs in summer 2014. This talk gives the overview of the plan, achieved results and ongoing R&D.
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THPRO019	Current Status of PAL-XFEL Project	klystron, linac, quadrupole, cavity	2897
	H.-S. Kang, K.W. Kim, I.S. Ko PAL, Pohang, Kyungbuk, Republic of Korea
	The PAL-XFEL, a 0.1-nm hard X-ray FEL facility consisting of a 10-GeV S-band linac, is being constructed in Pohang, South Korea. The installation of linac, undulator, and beam line will be completed by 2015. Its building construction is at its peak moment to be completed by December 2014. The major procurement contract was made in 2013 for the critical components of S-band linac modules and hard X-ray undulators. The commissioning will start in January 2016. We hope the first lasing will be achieved in early 2016.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO019
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THPRO024	Progress of the EU-XFEL Laser Heater	laser, vacuum, electron, photon	2912
	M. Hamberg, V.G. Ziemann Uppsala University, Uppsala, Sweden
	Funding: Swedish research council under Project number DNR-828-2008-1093 for financial support. We describe the technical layout and report the status of the installation of the undulator, optical and vacuum systems of the laser heater for the EUXFEL. The laser heater is a device to increase the overall X-ray brightness stability. This is achieved by an optical laser system which induce an additional momentum spread in the electron bunches to reduce micro-bunching instabilities.
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THPRO026	Design Parameters and Current Status of the TARLA Project	FEL, electron, linac, radiation	2918
	A.A. Aksoy, Ö. Karslı, C. Kaya, E. Kazancı, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey P. Arıkan Gazi University, Faculty of Arts and Sciences, Teknikokullar, Ankara, Turkey S. Özkorucuklu Istanbul University, Istanbul, Turkey
	Funding: Work is supported by Ministry of Development of Turkey with Grand No: DPT2006K-120470 The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) will operate two InfraRed Free Electron Lasers (IR-FEL) covering the range of 3-250 microns. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating ELBE modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. In this paper, we discuss design goals of the project and present status and road map of the project. On behalf of TARLA Team
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THPRO030	Developments in CLARA Accelerator Design and Simulations	FEL, wakefield, simulation, electron	2930
	S. Spampinati Cockcroft Institute, Warrington, Cheshire, United Kingdom D. Angal-Kalinin, A.D. Brynes, D.J. Dunning, J.K. Jones, K.B. Marinov, J.W. McKenzie, B.L. Militsyn, N. Thompson, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom I.P.S. Martin DLS, Oxfordshire, 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. Updates on the electron beam simulations and code comparisons including wakefields are described. Simulations of the effects of geometric wakefields in the small-aperture FEL undulator are shown, as well as further simulations on potential FEL experiments using chirped beams. We also present the results of simulations on post-FEL diagnostics.
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THPRO031	Short Pulses THz FEL for the Oxford Accelerator Science Laboratory	FEL, radiation, cavity, gun	2934
	T. Chanwattana, R. Bartolini, A. Seryi JAI, Oxford, United Kingdom R. Bartolini DLS, Oxfordshire, United Kingdom E. Tsesmelis CERN, Geneva, Switzerland
	The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a short pulse THz FEL based on a conventional RF accelerator driven by a RF photocathode gun is being investigated. This report presents the concept of the facility, the accelerator physics and FEL studies and engineering integration in the University physics department.
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THPRO032	Studies on LPWA-based Light Sources driven by a Transverse Gradient Undulator	FEL, laser, electron, simulation	2937
	T. Chanwattana, R. Bartolini, A. Seryi JAI, Oxford, United Kingdom R. Bartolini DLS, Oxfordshire, United Kingdom
	The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a LPWA based light source driven by a transverse gradient undulator is being investigated. This report presents the accelerator physics, FEL studies and the performance expected from such a facility.
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THPRO034	Design of the LCLS-II Electron Optics	linac, quadrupole, electron, optics	2940
	Y. Nosochkov, P. Emma, T.O. Raubenheimer, M. Woodley SLAC, Menlo Park, California, USA
	Funding: Work supported by the US Department of Energy Contract DE-AC02-76SF00515. The LCLS-II project is a high repetition rate, high average brightness free-electron laser based on the existing facilities at the SLAC National Accelerator Laboratory. The LCLS-II will be driven by a new CW superconducting RF (SCRF) 4-GeV linac replacing the existing Cu-linac in the 1st km of the linac tunnel. The SCRF linac will include chicanes for providing full compression of the electron bunch length. After the linac, the electron beam will be directed into the existing 2-km bypass line connecting to the Beam Switch Yard (BSY), where a new spreader system will allow a high rate bunch-by-bunch deflection into the hard X-ray (HXR) or soft X-ray (SXR) transport lines, or towards the BSY high power dump. The HXR line will include a new variable gap undulator replacing the existing LCLS-I undulator and will reuse the existing LCLS-I linac-to-undulator and dump transport lines. The SXR will require a new transport line sharing the same tunnel with the HXR and will include a new variable gap undulator. Overview of the electron beam transport and the optics design are presented.
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THPRO035	Improving and Maintaining FEL Beam Stability of the LCLS	FEL, feedback, timing, high-voltage	2943
	F.-J. Decker, A.L. Benwell, W.S. Colocho, Z. Huang, A. Krasnykh, J.R. Lewandowski, T.J. Maxwell, J. Sheppard, J.L. Turner SLAC, Menlo Park, California, USA
	Funding: *Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. The beam stability of the Linac Coherent Light Source (LCLS) has seen many improvements over the years and has matured to a state where progress is slow and maintaining the best stability is becoming the main challenge. Single sources which are identified by various means contribute to only about 10 to 20% of the whole jitter power, meaning that their elimination gives only a small improvement of 5 to 10%. New sources need to be identified fast. Especially slow variations of a few seconds to minutes time scale are often hidden and partially corrected by feedback systems. A few episodes of increased jitter have shown the limitations of some of the feedback systems. Stability for all dimensions, transverse, longitudinal, and intensity are presented.
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THPRO039	Model-independent Description of Shot-noise, Amplification and Saturation	FEL, bunching, electron, simulation	2949
	Y.C. Jing, V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. High-gain FEL is one of many electron-beam instabilities, which have a number of common features linking the shot noise, the amplification and the saturation. In this paper we present a new, model-independent description of the interplay between these effects and derivation of a simple formula determining the saturation and maximum attainable gain in such instabilities. Application of this model-independent formula to FEL is compared with FEL theory and simulations. We describe limitations resulting from these finding for FEL amplifiers used for seeded FELs and for Coherent electron Cooling.
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THPRO050	Study of a THz/VUV Free Electron Laser Facility in Taiwan	FEL, laser, radiation, linac	2980
	N.Y. Huang, M.C. Chou, C.-S. Hwang, W.K. Lau, A.P. Lee NSRRC, Hsinchu, Taiwan A. Chao, J. Wu SLAC, Menlo Park, California, USA C.H. Chen, Y.-C. Huang NTHU, Hsinchu, Taiwan X.M. Yang DICP, Dalian, People's Republic of China
	A free electron laser (FEL) facility aimed for VUV and THz radiation is being studied at National Synchrotron Radiation Research Center (NSRRC) in Taiwan. Strong consideration has been given to minimize the cost by making maximum use of existing hardware at NSRRC. One unique consideration is to use an existing undulator for the dual functions of the THz radiator and the modulator of a HGHG section. Design emphasizes versatility of operation and beam quality control and compensation of nonlinearities, with a vision that it will allow as much as possible future upgrades as well as later R&D of FEL physics. The polarization control of the THz radiation provides novel application for the users. The facility is to be housed in the existing 38-m by 5-m tunnel of the TPS Linac Test Laboratory.
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THPRO107	Application Programs of Elettra and FERMI@Elettra	controls, optics, booster, software	3146
	F. Iazzourene, C. Scafuri Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	At Elettra we have high level software application programs used on the ring and others, based on the TANGO control, a new High Level Framework and a beam optics module, firstly developed and successfully used for the commissioning and operation of the Elettra booster and now for FERMI@Elettra transfer lines. The paper describes the present status and some of the application programs.
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THPRI074	Colorado State University (CSU) Accelerator and FEL Facility	laser, electron, controls, linac	3937
	S. Biedron, C. Carrico, A. D'Audney, J.P. Edelen, J. Einstein, C.C. Hall, J.R. Harris, K. Horovitz, J. Martinez, S.V. Milton, A.L. Morin, N. Sipahi, T. Sipahi, J.E. Williams, P.J.M. van der Slot CSU, Fort Collins, Colorado, USA P.J.M. van der Slot Mesa+, Enschede, The Netherlands P.J.M. van der Slot Twente University, Laser Physics and Non-Linear Optics Group, Enschede, The Netherlands
	The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test stand, and a magnetic test stand. The photocathode drive linac will be used in conjunction with a hybrid undulator capable of producing THz radiation. Details of the systems used in CSU Accelerator Facility are discussed.
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Paper

Title

Other Keywords

Page

MOYAA01

Innovative Ideas for Single-pass FELs

electron, FEL, operation, photon

12

T. Hara
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

SASE FELs are a powerful light source in short wavelengths from VUV to X-ray regions to investigate matters and phenomena. SASE was first experimentally obtained in 2000 at DESY TTF with an output wavelength of 10⁹ nm. Subsequently, FLASH, LCLS and SACLA have achieved lasing in VUV, soft X-rays and hard X-rays. Although SASE has already been widely used for many application experiments in broad scientific fields, its spiky spectrum and time structures due to the lack of longitudinal coherence sometimes become problematic. To improve its longitudinal coherence, various ideas have been proposed and some of them are already demonstrated experimentally, such as a self-seeded scheme, high-gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG). There is also another direction of developments to enhance the capability and potentiality of SASE, for example short pulse generation and two-color lasing. This talk will review recent innovative ideas of short wavelength FELs together with their experimental results.

Slides MOYAA01 [10.701 MB]

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MOPRO057

Undulator Photon Beams with Orbital Angular Momentum

emittance, photon, experiment, storage-ring

213

J. Bahrdt, K. Holldack, P. Kuske, R. Müller, M. Scheer, P.O. Schmid
HZB, Berlin, Germany

Photons carrying orbital angular momentum (OAM) are present in the off-axis radiation of higher harmonics of helical undulators. Usually, the purity and visibility of OAM photons is blurred by electron beam emittance. However, high brightness OAM beams are expected in ultimate storage rings and FELs, and they may trigger a new class of experiments utilizing the variability of the topological charge, a 3rd degree of freedom besides wavelength and polarization. We report on the first detection of OAM photons in helical undulator radiation in the 3rd generation storage ring BESSY II. Measurements and simulations are compared and the impact of emittance and energy spread is discussed.

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MOPRO084

Recent Development and Operational Status of PF-Ring and PF-AR

vacuum, injection, photon, operation

286

T. Honda, M. Adachi, S. Asaoka, K. Haga, K. Harada, Y. Honda, M. Izawa, T. Kageyama, Y. Kamiya, Y. Kobayashi, K. Marutsuka, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, M. Ono, T. Ozaki, H. Sagehashi, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, M. Shimada, K. Shinoe, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Ma. Yoshida, S.I. Yoshimoto
KEK, Ibaraki, Japan

Update of the first-generation undulators installed in 1980s is pushed forward at PF-Ring, a 2.5-GeV SR source of KEK, taking advantage of the expanded straight sections reconstructed in 2005. New undulators have been designed as elliptically polarizing undulators each has 6 magnetic arrays to obtain various polarization states, not only circular polarization but also linear (horizontal and vertical) polarization. Three undulators will be installed in FY2013 and FY2014 for BL02, BL13 and BL28. For BL02, the longest straight section of about 9 m, the new undulator will be installed in tandem with the existing planar undulator, in order to cover the wide photon energy range from 15 eV to 2 keV. At PF-AR, a 6.5-GeV SR source, a new direct beam transport (BT) line from the injector LINAC is under construction. Super KEKB which shares the injector LINAC with PF-Ring and PF-AR will be commissioned at the end of FY2014. The full-energy continuous injection of PF-AR will be available as a simultaneous injection with the 7-GeV HER, the 4-GeV LER and PF-Ring not so later than the commissioning of Super KEKB.

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MOPME021

Vicky: Computer Code Update

quadrupole, optics, multipole, sextupole

421

F. Iazzourene
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Vicky is a computer code for designing and simulating charged particle accelerators*. We recall mainly that Vicky is a very user friendly code, the particle motion is described by 10 parameters: four beta-functions, four alpha-functions and two phase advances, and a large variety of insertion devices, wigglers and undulators, linearly and elliptically polarized, are treated. The features include Twiss functions matching, orbit correction, tune and chromaticity adjustment, dynamic aperture and phase space tracking. The paper describes new aspects and the present status.
* F. IAZZOURENE, “Vicky: A Computer Code for Use in the Design and Simulation of Particle Accelerators”, proceedings IPAC 2011.

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MOPRI006

Possible Uses of Gamma-rays at Future Intense Positron Sources

positron, synchrotron, software, electron

586

A.O. Alrashdi, I.R. Bailey
Lancaster University, Lancaster, United Kingdom
A.O. Alrashdi, I.R. Bailey, D. Newton
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A.O. Alrashdi
KACST, Riyadh, Kingdom of Saudi Arabia
D. Newton
The University of Liverpool, Liverpool, United Kingdom

Funding: This research is funded in part by STFC grant ST/G008248/1
The baseline design of the ILC (International Linear Collider) positron source requires the production of an intense flux of gamma rays. In this paper we present an investigation of using the gamma ray beam of the ILC for additional applications, including nuclear physics. As a result of changing the collimator shape, as well as the parameters of the undulator magnets, we obtained spectra from numerical simulations using the HUSR/GSR software package. We present results from simulations and a discussion of possible future investigations in this paper.

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TUOCA01

The Linac Coherent Light Source-II Project

linac, electron, cryomodule, laser

935

J.N. Galayda
SLAC, Menlo Park, California, USA

Funding: Work supported by US DOE Contract DE-AC02-766SF00515
The “Linac Coherent Light Source–II” Project, initiated in September 2010, has gone through a radical transformation beginning in August 2013. In its new form, LCLS-II will construct a 4 GeV CW superconducting linac in the first kilometre of the existing linac tunnel. A new undulator, optimized as a soft x-ray (200-1,300 eV) source, will receive electrons from the new SC linac. The existing undulator system will be replaced with a new variable gap device, which will receive electrons from either the new SC linac (providing 1-5 keV photons) or the copper linac presently used by LCLS (providing 1-25 keV x-rays). First light from the new facility is expected in September 2019.
galayda@slac.stanford.edu

Slides TUOCA01 [9.380 MB]

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TUOCA03

Production of Quasi-monochromatic GeV Photons by Compton Scattering using Undulator X-ray Radiation at SPring-8

photon, electron, laser, experiment

941

H. Ohkuma, A. Mochihashi, M. Oishi, S. Suzuki, K. Tamura
JASRI/SPring-8, Hyogo-ken, Japan
N. Muramatsu, H. Shimizu
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
T. Nakano
RCNP, Osaka, Japan

Funding: This work is supported by JSPS KAKENHI (Grant-in-Aid for Scientific Research) Grant Number 24241035.
Backward Compton scattering (BCS) of X-ray photons emitted by undulator and reflected back by a single crystal from the electron beam can produce a quasi-monochromatic gamma-ray beam up to an energy very close to the electron beam energy. The SPring-8 beam diagnostics beamline (BL05SS) is used to inject a reflected undulator X-ray radiation against 8 GeV stored electron beam and to extract a quasi-monochromatic 8 GeV gamma-ray produced by BCS. BL05SS has conditions to do a pilot experiment to obtain the gamma-ray beam using BCS of X-ray photons from existing undulator. Experimental setup including a Bragg mirror system is now under construction. Preliminary reflectivity measurement of a silicon Bragg mirror using around 10keV photons has been done. Status of the experimental preparation and the future outlook is presented.

Slides TUOCA03 [1.889 MB]

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TUZB01

Prospects for the use of Permanent Magnets in Future Accelerator Facilities

permanent-magnet, radiation, lattice, dipole

968

J. Chavanne, G. Le Bec
ESRF, Grenoble, France

Permanent magnet based accelerator magnets may offer a viable alternative to their conventional electromagnetic pairs for many applications, especially where strong gradients and low power consumption is needed. As an example, the development of future light sources based on ultimate storage ring needs to be done in an important energy saving context aiming at a significant reduction of operational costs. After more than two decades of continuous developments in the field of permanent insertion devices, a knowledge capital on different issues such as aging effects has been gained. This technology seems ready to jump into the design and construction of advanced accelerator magnets. This talk reviews the status of the permanent magnet technology and the perspectives for its implementations in standard lattice magnets, highlighting both the advantages and the challenges as compared to electromagnetic magnets.

Slides TUZB01 [9.341 MB]

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TUOCB03

Performance of Elliptical Polarization Undulators at TPS

polarization, multipole, photon, FEL

987

T.Y. Chung, C.-H. Chang, C.H. Chang, J.C. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin, C.Y. Wu
NSRRC, Hsinchu, Taiwan

Design, assembly, field shimming, and performance of APPLE-II type undulators in NSRRC are described in this article. Essentially, the mechanical error has been well controlled based on the optimize design and mechanical arts. Effectively initial sorting of permanent magnets is developed to minimize several adverse effects, such as magnetic inhomogeneities, no perfection geometry of blocks, and mechanical frame issue, those challenge the sorting expectation, especially for an adjusted polarization undulator. The sorting algorithm shows a quantitative prediction of magnetic field and is verified by measurement results. 2D virtual shimming algorithm has been developed to optimize field quality, including multipole, phase error, and particle trajectory. We describe the considering of each procedure and demonstrate the optimization together with measurement results.

Slides TUOCB03 [1.503 MB]

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TUPRO036

Start-to-end Optic of the FSF Multi-turn ERL Project

emittance, linac, injection, simulation

1099

T. Atkinson, A.V. Bondarenko, A.N. Matveenko, Y. Petenev
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association VH NG 636 and HRJRG-214
Advanced magnetic optic designs are required to meet the heavy demands of future light sources: diffraction limited emittance, femto-second pulses and low energy spread. This paper highlights the magnetic optic that is presently being investigated in the ERL-simulation group at HZB. The injector optic is based on subtle emittance compensation techniques of space charge dominated beams. The high energy arcs are designed to suppress emittance growth due to CSR through horizontal phase advance manipulation, ISR effects by keeping the radiation integrals small and reduce the degradation due to chromatic aberrations. Optimised Start-to-End beam dynamic simulations are presented.

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TUPRO044

Bunch Compression of the Low-energy ELBE Electron Beam for Super-radiant THz Sources

radiation, electron, linac, emittance

1123

U. Lehnert, P. Michel, R. Schurig
HZDR, Dresden, Germany
A.A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
P.E. Evtushenko
JLab, Newport News, Virginia, USA
J.M. Krämer
Danfysik A/S, Taastrup, Denmark

At the ELBE radiation source two super-radiant THz sources, a broad-band trasnsition/diffraction radiation source and a planar undulator narrow-band sourc are under commissioning. At present the facility is driven from the ELBE linac with a CW electron beam of 100kHz repetition rate and up to 100pC of bunch charge. With the upgraded SRF electron gun bunch charges up to 1nC will become available. For the beam energies in the 20-30 MeV range buch compression into the sub-200 fs range becomes a major challenge. We present beam dynamics calculation of the attempted bunch compression scheme as well as first measurements obtained during the commissioning.

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TUPRO047

Betatron Oscillations in Planar Dipole Field

betatron, dipole, focusing, longitudinal-dynamics

1132

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

In this paper, in preparation to the European XFEL commissioning, we consider the procedure of calculation of focusing properties of chicane-type bunch compressors and planar undulators using 2D magnetic field model (approximation of infinitely wide poles).

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TUPRO084

Magnetic Tuning of FLASH2 Undulators

multipole, quadrupole, radiation, pick-up

1235

O. Bilani, P. Neumann, A. Schöps, M. Tischer, S. Tripathi, P. Vagin, T. Vielitz
DESY, Hamburg, Germany

The present fixed-gap undulator system for FLASH1 and the new FLASH2 undulators will share the same electron beam accelerator, thus 12 variable gap undulators are needed in order to provide radiation of different wavelengths to both experimental halls independently. Each of the 12 devices has a length of 2.5m. The magnet structure with a period length of 31.4mm provides a maximum field of 0.96T with an effective K-parameter of 2.81 at minimum gap. Phase, vertical and horizontal trajectories have been tuned based on Hall probe and stretched wire measurements. Remaining multipoles were optimized with moderate gap dependence by using magic fingers. At some magnet structures, shims were placed to correct gap dependent field integrals. All undulators have an rms vertical and horizontal trajectory flatness <6Tmm2 for all gaps corresponding to an rms trajectory roughness (at 1GeV) along the structure of ~2um. The rms phase error is below 2° over the entire gap range.

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TUPRO085

Properties, Options and Limitations of PrFeB-magnets for Cryogenic Undulators

cryogenics, permanent-magnet, induction, polarization

1238

F.-J. Börgermann, C. Brombacher, K. Üstüner
Vacuumschmelze GmbH & Co. KG, Hanau, Germany

The gap induction and thus the K-factor of permanent magnet undulators may be increased by cooling them to cryogenic temperatures. The use of NdFeB-magnets in cryogenic undulators, however, is limited to temperatures above 140 K due to the spin-reorientation transition (SRT) which leads to a reduction of the magnetization level. A further increase of the gap induction in undulators may be achieved by use of PrFeB-magnets at even lower temperatures, as this alloy does not show the SRT phenomenon. Although the effects are well known, up to now only a few undulator prototypes were built using this class of material since the coercivity of ternary PrFeB-magnets is not sufficient to minimize the risk of partial demagnetization when the undulator structure is kept at room temperature. This problem can be solved by applying actual technologies like grain-boundary diffusion in order to achieve coercivities exceeding 20 kOe at RT without sacrificing the high remanence Br of about 1.6 T at 77 K. We will provide actual data of the magnet performance achieved and show up the technological limitations in building PrFeB-based CPMU’s.

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TUPRO103

Novel Magnet Production Technique used for an Elliptically Polarizing Undulator

controls, multipole, radiation, permanent-magnet

1286

E.J. Wallén, K.I. Blomqvist
MAX-lab, Lund, Sweden
J. Bahrdt
HZB, Berlin, Germany
F.-J. Börgermann
Vacuumschmelze GmbH & Co. KG, Hanau, Germany

A common problem for elliptically polarizing undulators (EPUs) is that the magnetic forces give a mechanical deflection in the magnet holder construction when changing the undulator phase. Gluing horizontally and vertically magnetized blocks together can increase the mechanical stability of the magnet holders. The gluing process of pairs of magnetized magnet blocks is time-consuming, expensive and difficult to carry out with high positional precision. A novel magnet production technique has been developed where un-magnetized pairs of blocks are glued together before magnetization. The large number of parts, the time for assembly, and the cost of the EPU can be reduced with the novel magnet production technique. The novel magnet production method has been used for a 2.6 m long EPU of APPLE-II type, which has been built in-house at the MAX IV Laboratory. The frame for the EPU is made of cast iron in order to get a small mechanical deformation when changing phase in the inclined mode. The paper includes detailed descriptions of the novel magnet production technique, including measurements of the magnetization, and the new EPU.

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TUPRO109

Calculation of Heat Load on Double Mini-beta Y Undulators

radiation, synchrotron, synchrotron-radiation, vacuum

1304

J.C. Huang, T.Y. Chung, C.-S. Hwang, Y.T. Yu
NSRRC, Hsinchu, Taiwan

Two collinear in-vacuum undulators (IU22) are adopted for light source of X-ray coherence beamline in Taiwan photon source. Each undulator is 3 meter and the drift space between two undulator is 3.991m. The synchrotron radiation is propagating in the longitudinal direction and will result in a serious heat load problem for undualtor downstream. The magnet array of undualtor downstream will received the synchrotron radiation of 142W from upstream bending magnet and undualtor. Heat load is a critical challenge for in-vacuum undulator in double mini-beta Y lattice and therefore details analysis in this paper.

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TUPME001

Heat Load, Stress and Reaction Force Studies of a Polarized Positron Production Target for the Future International Linear Collider

target, positron, photon, vacuum

1331

F. Staufenbiel, S. Riemann
DESY Zeuthen, Zeuthen, Germany
G.A. Moortgat-Pick, A. Ushakov
University of Hamburg, Hamburg, Germany

The International Linear Collider requires an intense polarized positron beam with yields of about 10¹⁴ positrons per second. A polarized positron beam can be produced with a helical undulator passed by the accelerated electron beam to create a high power polarized photon beam. The photon beam penetrates a thin titanium-alloy rotating target wheel of 1m diameter with 500 to 2000 rpm rotation speed and produces polarized positrons. The system should run for 1-2 years without failure. A break down can occur due to the huge heat load in a short time (<1ms). The target design must keep the resulting thermo-mechanical stress below the yield strength and the fatigue limit of the material. FEM ANSYS simulations are used to evaluate the thermo-mechanical stress as well as the vibrations at the bearings of the rotating system. Results are presented with the goal to optimize the target wheel design parameters for a long lifetime.

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TUPRI037

Some Features of Wave Distribution in the Thin-Wall Waveguide

vacuum, impedance, shielding, radiation

1641

M. Ivanyan, L.V. Hovakimyan, A. Sargsyan
CANDLE SRI, Yerevan, Armenia

In this report we derive rigorous and approximate dispersion relations for the round resistive thin-wall waveguide. The features of the distributions of dispersion curves of the waveguide axisymmetric TM modes are obtained. Cases of splitting and degeneracy of modes under consideration are detected and regularities of their behaviours are established.

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TUPRI040

New BBA Algorithm for Electron Beam Orbit Steering in Linear Accelerators

quadrupole, lattice, simulation, alignment

1650

A. Sargsyan, V. Sahakyan, G.S. Zanyan
CANDLE SRI, Yerevan, Armenia
W. Decking
DESY, Hamburg, Germany

In linear accelerators or transfer lines beam-based alignment (BBA) techniques are important tools for beam orbit steering. In this paper BBA correction algorithm based on difference orbit multiple measurements is proposed. Numerical simulation results for European XFEL SASE1 and FLASH undulator section are presented, according to which the orbit alignment can be achieved within accuracy of about 2 microns and 5 microns respectively. The influence of quadrupole gradient errors is also discussed.

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TUPRI041

Study of Collective Beam Instabilities for Sirius

impedance, vacuum, operation, feedback

1653

F.H. de Sá, H.O.C. Duarte, L. Liu, N. Milas, X.R. Resende
LNLS, Campinas, Brazil

In this paper we present the on going work of construction of the Sirius impedance budget and instability threshold estimates for several machine operation scenarios.

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TUPRI052

Analysis of Single Bunch Measurements at the ALBA Storage Ring

impedance, synchrotron, vacuum, simulation

1686

T.F.G. Günzel, U. Iriso, F. Pérez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
E. Koukovini-Platia, G. Rumolo
CERN, Geneva, Switzerland

Measurements of the vertical single bunch mode detuning and the TMCI threshold at zero chromaticity were carried out and their results were compared to the theoretical expectation. Around 65% of the found mode detuning can be explained by a developed transverse impedance model. A good bunch length parametrisation with current contributed essentially to this result. The analysis of single bunch measurements at non-zero chromaticity will also be presented.

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TUPRI081

Feed-forward and Feedback Schemes applied to the Diamond Light Source Storage Ring

feedback, photon, optics, storage-ring

1757

M.T. Heron, M.G. Abbott, M.J. Furseman, D.G. Hickin, E.C. Longhi, I.P.S. Martin, G. Rehm, W.A.H. Rogers, A.J. Rose, B. Singh
DLS, Oxfordshire, United Kingdom

Since initial operation for users in Jan 2007, Diamond Light Source has developed to support a suite of 22 experimental stations. These stations have resulted in the installation of 24 undulators and two superconducting wigglers in the storage ring. To preserve optics, tune and coupling with the operation of these devices has necessitated the implementation of a number of feed-forward and feedback schemes. The implementation and operation of these correction schemes will be described.

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TUPRI100

Present Status of the Cherenkov Beam Loss Monitor at SACLA

electron, detector, status, laser

1808

T. Itoga
JASRI/SPring-8, Hyogo, Japan
Y. Asano
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

Since 2011, high power lasers have been delivered stably to the users at SACLA, the SPring-8 Angstrom compact free electron laser, and the upgrades have been performing to obtain the high quality of the laser continuously. Optical fiber based Cherenkov beam loss monitors have been successfully operated from the commissioning phase. This monitor covers the undulator section of beam lines and the electron beam transporting tunnel from SACLA to SPring-8. This monitor is made good use of not only beam transport but also detection of the small beam loss such as electron halos hitting the magnets of undulator. In this presentation, we will report the present status of the Cherenkov beam loss monitor and its usage experience.

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WEOAA02

Development of the Very Short Period Undulators

radiation, electron, photon, vacuum

1845

S. Yamamoto
KEK, Ibaraki, Japan

We have been exploring a method to fabricate very short period undulators, a period length of which is one order-of-magnitude shorter than the ordinary period of several cm. We are developing a plate-type magnet some 100mm long with a period length of 4mm. We selected this period length since we can generate 12-keV radiation with the first harmonic of this undulator in the 2.5-GeV storage ring. A multi-pole magnetizing method was applied to magnetizing this plate: a periodic undulator field (of 4-mm period in this case) was generated by pulsed electro-magnets, and was transcribed into the plate. The magnetization procedure allows the undulator field to be obtained in a very short gap between the pair of opposing plates, which is also one order-of-magnitude shorter than a gap in the ordinary undulators. We report the magnetization method to obtain a very short period and present the test results. The calculated spectrum of the radiation from the measured field compares well with that from an ideal magnetic field in the region of the fundamental radiation in case of 2.5-GeV energy of the electron beam.

Slides WEOAA02 [5.189 MB]

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WEOAA03

Ultrashort and Coherent Radiation for Pump-probe Experiments at the DELTA Storage Ring

radiation, laser, experiment, electron

1848

M. Huck, S. Hilbrich, H. Huck, M. Höner, S. Khan, C. Mai, A. Meyer auf der Heide, R. Molo, H. Rast, A. Schick, P. Ungelenk
DELTA, Dortmund, Germany

Funding: Work supported by DFG, BMBF, and by the Federal State NRW.
A light source facility employing the coherent harmonic generation (CHG) principle is being commissioned and operated since 2011 at DELTA, a 1.5-GeV electron storage ring at the TU Dortmund University, with the purpose of providing ultrashort coherent VUV radiation for time-resolved experiments. CHG is based on the interaction of ultrashort laser pulses with electrons in an undulator to generate coherent harmonics of the laser wavelength. Different methods have been used to optimize, detect and characterize the CHG radiation. One example is the study of transverse and longitudinal coherence properties in double-slit and Michelson experiments. Moreover, final steps towards performing pump-probe experiments to study ultrafast magnetic phenomena have been taken.

Slides WEOAA03 [4.139 MB]

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WEPRO008

A Beam-driven Microwave Undulator for FEL

wakefield, electron, FEL, linac

1956

A. Kanareykin, C.-J. Jing, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Baturin
LETI, Saint-Petersburg, Russia
A. Zholents
ANL, Argonne, Ilinois, USA

Funding: DOE SBIR
Microwave waveguides can in principle be used for undulators with periods less than 1 cm. Intensive work has been done on the recently proposed design that operates at the HE11 hybrid mode of a corrugated waveguide; successful experimental results have been reported recently [S.Tantawi Talk at POSIPOL 2012]. In this presentation we propose a beam driven design for an undulator based on an electron bunch train powering a microwave or mm waveguide. The drive bunch train propagates towards the undulating beam inside a dielectric loaded structure or corrugated waveguide generating high power RF. The “smart” waveguide design and a proper bunch spacing of the electron drive beam train provide single mode generation of the high magnitude undulating field that gives an undulator parameter in the range of K~1 for a high frequency device.*
*A. Zholents, HBEB Workshop, Puerto-Rico, 2013.

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WEPRO022

Modal Analysis of Helical Undulator Radiation In Cylindrical Waveguide

radiation, vacuum, FEL, linac

1989

T.L. Vardanyan, M. Ivanyan, V. Sahakyan, A.V. Tsakanian, G.S. Zanyan
CANDLE SRI, Yerevan, Armenia

The coherent radiation of the relativistic electron beam with helical orbit in circular waveguide is studied. The radiation field configuration is obtained using modal expansion technique. For short electron bunches the coherent part of radiation is evaluated. The coherent radiation effects on the bunch performance are analyzed.

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WEPRO029

Developing of Advanced Magnet Structures for Cryogenic in Vacuum Permanent Magnet Undulators

permanent-magnet, cryogenics, vacuum, electron

2004

C. Kuhn, J. Bahrdt, A. Gaupp, M. Scheer, B. Schulz
HZB, Berlin, Germany

Cryogenic in vacuum permanent magnet undulators with periods less than 10 mm and correspondingly narrow gaps require tighter geometric and magnetic tolerances and complex pole designs from different materials to achieve the needed high field strengths. We use new mechanic designs and manufacturing technologies for magnet and pole assembly. We develop new precise and UHV-compatible joining methods which are different from the current approaches which are based on mechanical clamping or gluing. . We examine the mechanical and magnetic properties by performing tests and discuss the results.

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WEPRO031

Design and Commissioning of the FLASH2 Undulators

FEL, controls, operation, vacuum

2007

A. Schöps, O. Bilani, T. Ramm, M. Tischer, S. Tripathi, P. Vagin
DESY, Hamburg, Germany

This paper reports about aspects of design, manufacturing, and commissioning of the 12 FLASH2 variable gap undulator segments. The accuracy of gap drive and encoder systems was tested by magnetic measurements; changes in the phase error proved to be a highly sensitive probe to verify a reproducibility of 1 μm. After magnetic tuning of the IDs, the remaining gap dependence in the field integrals could be successfully compensated by corrector coils. Inconsiderate handling of components during assembling necessitated an elaborate demagnetisation process before the tuning could start.

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WEPRO032

Phase Shifters for the FLASH2 FEL

electron, operation, quadrupole, FEL

2010

M. Tischer, P. Neumann, A. Schöps, P. Vagin
DESY, Hamburg, Germany

The FLASH2 SASE undulator section consists of 12 IDs. Each of them is followed by an intersection component comprising a phase shifter and various parts for diagnostics and beam steering. The phase shifter is a compact and simple electromagnetic chicane and has to assure constructive interference of the radiation of adjacent undulators for all wavelengths. The magnetic performance, field errors and the hysteresis behavior have been investigated and were found to be within the required accuracy. The results are discussed in relation to the undulator conditions. From these data tables for steering the phase shifter current as function of undulator gap were derived and implemented in the control system.

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WEPRO033

Design and Magnetic Measurements on Bi-harmonic Undulators

laser, free-electron-laser, electron, synchrotron

2013

G. Sharma, G. Mishra
Devi Ahilya University, Indore, India
S. Tripathi
DESY, Hamburg, Germany

In recent years there exists interests in harmonic lasing of free electron lasers for short wavelength operation with low energy electron beams. In a planar undulator , the electron radiates at odd harmonics on axis however the harmonic gain of the FEL is much less than that of fundamental. It has been shown in earlier works that it is possible to enhance the harmonic radiation by increasing the harmonic wiggler field to the fundamental by putting high permeability shims inside the undulator. The common material is the vanadium permendur (μ ~800) , which has been used effectively to design the harmonic undulator. In this paper, we report the design and fabrication of seventh and ninth harmonic undulator for free electron laser applications. We use CRGO shims with μ ~ 2-3. The permanent magnet undulator is a four block per period design. The undulator is a variable gap type and consists of NdFeB magnets with six periods, each period is of 5cm length. The undulator has been measured in hall probe and pulsed wire bench. It is shown that the pulsed wire magnetic measurements yields results in close agreement with hall probe results.

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WEPRO034

Magnetic Measurement Developments for Undulators

quadrupole, laser, vacuum, alignment

2016

P. Vagin, P. Neumann, M. Tischer
DESY, Hamburg, Germany

FLASH2 is an extension of the present VUV-FEL facility at DESY. It includes a separate tunnel with a 12 x 2.5m = 30m long planar hybrid undulator. The undulators have 31.4mm period length and 1T field at a minimum gap of 9mm. The paper presents recent progress in the magnetic measurements of these undulators. Several specific details of the measurement tools will be discussed like peculiarities in the Hall probe calibration and noise, positioning accuracy and synchronization of voltage measurement with probes movement during scan, noise issues of various voltage integrators for stretched wire and search coil measurements.

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WEPRO035

Radiation Damage of Undulators at PETRA III

radiation, wiggler, damping, vacuum

2019

P. Vagin, O. Bilani, A. Schöps, M. Tischer, S. Tripathi, T. Vielitz
DESY, Hamburg, Germany

In the new octant of PETRA~III, there are 14 undulator beamlines covering photon energy range from 0.3keV to 150keV. There are also 80m of damping wigglers in order to achieve a low emittance of 1nmrad. Some of these devices, operating at PETRAIII since 2008, accumulated total radiation doses of about 100kGy. Visible corrosion at the magnet structures of some permanent magnet undulators setting in after a few years and a high dose rate measured regularly by thermoluminescent dosimeters (TLDs) gave reason to inspect the magnetic field of all insertion devices in the PETRA tunnel. This paper presents details of the magnetic field degradation caused by radiation damage to the undulator magnets. For some undulators changes in the spectral properties of the generated light were observed. It was measured with different taper settings in order to partly compensate the nonuniform demagnetization along the structure. The results are compared with the data from the sFLASH undulators and measurements of special 3 pole "sacrificial" undulator, installed in FLASH. Its magnetic field is periodically remeasured and shows field amplitude decrease of 1% per 16kGy accumulated dose.

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WEPRO036

Construction and First Magnetic Field Test of a Superconducting Transversal Gradient Undulator for the Laser Wakefield Accelerator in Jena.

electron, laser, radiation, wakefield

2022

V. Afonso Rodríguez, A. Bernhard, A.W. Grau, P. Peiffer, R. Rossmanith, M. Weber, C. Widmann, A. Will
KIT, Karlsruhe, Germany
M. Kaluza, M. Nicolai, A. Sävert
IOQ, Jena, Germany
M. Reuter
HIJ, Jena, Germany

Funding: This work is funded by the German Federal Ministry for Education and Research under contract no. 05K10VK2 and 05K10SJ2.
A superconducting transversal gradient undulator (TGU), tailored to the particular beam properties of the laser wakefield accelerator (LWFA) at the University of Jena, has been designed and constructed at KIT. This undulator in combination with a specialized beam transport line will be employed to produce undulator radiation with natural bandwidth despite the relatively large energy spread of the electrons produced by the LWFA. The fabrication of this undulator and first results of the magnetic field measurement are discussed in this paper.

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WEPRO038

Possibility for Quasi-periodic Knot-APPLE Undulator

radiation, polarization, synchrotron, synchrotron-radiation

2026

S. Sasaki, A. Miyamoto
HSRC, Higashi-Hiroshima, Japan
N. Kawata, T. Mitsuyasu
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
S. Qiao
SIMIT, Shanghai, People's Republic of China

An intense on-axis radiation power from an undulator is a serious problem especially for a low-photon-energy beamline in a facility with high or medium energy storage ring. This problem may be solved by using a Figure-8, a Pera, or a Knot undulator configuration*,**. However, these schemes are useless for variably polarizing undulators such as an APPLE undulator and other similar variations since such devices are not capable for reducing on-axis power density in the linear mode. In these circumstances, we have completed a conceptual magnet design of Knot-APPLE udulator which is capable to generate elliptically polarized radiation as well as linearly polarized radiation. This pure permanent magnet device is equipped with a motion mechanism of APPLE undulator. In this paper, we present detailed magnet design feature, magnetic field distributions, and radiation properties including variations of polarization in comparisons with other exotic devices. In addition, a possibility to introduce a quasi-periodicity in this type of undulator is considered in order to achieve further reduction of second and third harmonic radiation intensities.
*S. Sasaki, "Undulators, wigglers and their applications," p.237-243 (Ed. by H. Onuki and P. Elleaume, Taylor & Francis Inc, New York, 2003).
**S. Qiao, et. al, Rev. Sci. Instrum., 80, 085108 (2009).

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WEPRO039

Status of PAL-XFEL Undulator Program

FEL, controls, radiation, electron

2029

D.E. Kim, H.-S. Kang, W.W. Lee, K.-H. Park
PAL, Pohang, Kyungbuk, Republic of Korea
M.-H. Cho, I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
S. Karabekyan, J. Pflüger
XFEL. EU, Hamburg, Germany

Pohang Accelerator Laboratory (PAL) is developing 10 GeV, 0.1 nm SASE based FEL for high power, short pulse X-ray coherent photon sources named PAL-XFEL. At the first stage PAL-XFEL needs two undulator lines for photon source. PAL is developing undulator magnetic structure based on EU-XFEL design. Recently, the hard X-ray undulator changed its minimum magnetic gap to 8.3 mm from the previous 7.2 mm to alleviate the wake field impact, and to increase the allowances for the re alignment. Accordingly, the period is also changed from 24.4 mm to 26.0 mm to generate 0.1 nm at 10 GeV electron energy. In this report, the modification efforts and the progress on the prototyping of hard x-ray undulator system will be presented.

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WEPRO040

Field Measurement Facility for PAL-XFEL Undulators

controls, FEL, laser, software

2032

K.-H. Park, Y.-G. Jung, D.E. Kim, S.N. Kim, I.S. Ko, B.H. Lee, H.-G. Lee, M.S. Lee, S.B. Lee, H.S. Suh, C.W. Sung
PAL, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory (PAL) is developing the SASE based FEL for X-ray coherent photon sources. The PAL developed the prototype undulator that was 5.0 m magnetic length. The PAL has constructed the undulator field measurement facility to confirm the field qualities of the XFEL undulators in the assembly building. The temperature stability of the measurement rooms was controlled within ±0.1°C. Two field measurement benches that included Hall probe scan, flip coil and stretched wire system were installed and evaluated their performances. The field profile of the prototype undulator was characterized and shimmed using the installed measurement system. This paper described the field measurement facility with the performance test results of the two benches.

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WEPRO041

Undulator Radiation Spectral Broadening Due To Radiation Energy Loss

radiation, electron, simulation, photon

2035

N.V. Smolyakov
NRC, Moscow, Russia

A relativistic electron passing through an undulator generates electromagnetic radiation at the expenses of its own kinetic energy. This effect is usually not taken into account if the number of periods of the undulator is relatively small (100 - 200). However, at FEL facilities, long installations have been built, planned or are under construction, where many undulators are installed one after another for a total of several thousand undulator periods. For instance, the SASE1 and SASE2 lines at the European XFEL will consist of 35 undulators with 124 periods each. In this case, because of the electron energy decrease along its trajectory, the radiation from different undulators will drop out of synchronism. As a result, the radiation spectral line will be much wider. In the presented report, this effect was analyzed analytically and numerically. An expression for the critical number of undulator periods, when the effect of electron energy loss should be properly taken into account, is derived. It is found that, for the case of the European XFEL, this number is about 1200 periods.

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WEPRO045

Design of a System at NSRRC to Measure the Field for an In-vacuum Cryogenic Undulator with Permanent Magnet

vacuum, laser, alignment, timing

2041

C.K. Yang, C.-H. Chang, T.Y. Chung, J.C. Huang, C.-S. Hwang, Y.Y. Lin
NSRRC, Hsinchu, Taiwan

A cryogenic undulator with a permanent magnet (CPMU) is an important insertion device now under construction at NSRRC. For an undulator of this kind, the distribution of the magnetic field must be measured along the axis; the phase error, trajectory and photon flux must be calculated after the magnetic arrays are installed in the vacuum chamber and cooled to cryogenic temperature. We developed a Hall-probe system to measure the magnetic field in an evacuated environment; this system uses lasers and stages to monitor and to correct dynamically the positions of the Hall probe. All components installed inside the vacuum chamber are compatible with an environment of high vacuum and low temperature. The details of the design and completed fabrication are presented in this paper.

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WEPRO047

A New Cooling System for Cryocooled Permanent Magnet Undulators at Diamond Light Source

vacuum, operation, cryogenics, electron

2047

E.C. Longhi, A.G. Miller, E.C.M. Rial, A.J. Rose, J.C. Schouten, C.W. Thompson, A. Thomson, J.H. Williams
DLS, Oxfordshire, United Kingdom
C. Monroe
Monroe Brothers Ltd., Moreton-in-Marsh, United Kingdom

Cryocooled permanent magnet undulators (CPMUs) using NdFeB magnets around 150K were first proposed by Hara*. These are cooled by using either GM cryocoolers or circulating sub-cooled liquid nitrogen. Due to the heat load from radiation and wakefield heating from the electron beam, temperature gradients can develop along the length of the magnet girders which could be as large as several degrees for the Diamond Light Source (DLS) storage ring operating parameters. Some grades of the magnetic material (NdxPr1-x)2Fe14B have remanence curves versus temperature which increase significantly for temperatures below 150K with peaks below 80K**. This means that the operating temperature of a CPMU using this material can be close to the boiling point of liquid nitrogen. The proposed cooling system for the new DLS CPMU is based on a thermosiphon allowing nitrogen to boil inside the cooling channels without a circulating pump. This has the advantage of absorbing large amounts (>250W) of heat with very small temperature gradients. We report here the results of a prototype magnet beam cooled with a thermosiphon producing a temperature gradient of less than 0.05K along a 2m beam at ~77K.
* T. Hara et al., Phys Rev Spec Top. Accelerator & Beam, Vol 7, 2004.
** J. Bahrdt et al., AIP Conf. Proc., SRI 2009, Melbourne Australia, vol. 1234, pp. 499-502, 2010.

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WEPRO048

A Concept of a Universal Superconducting Undulator

simulation, electron, storage-ring, FEL

2050

Y. Ivanyushenkov
ANL, Argonne, Ilinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Tiny round electron beams of free-electron lasers and relatively new diffraction-limited storage rings make possible utilization of electromagnetic helical undulators based on double-helical windings. It has been understood for a while that a coaxial pair of double-helical windings can generate helical as well as planar magnetic fields*. Such a coil structure can potentially be realized with superconducting windings thus forming the concept of a universal superconducting undulator (Universal SCU). An example of a possible universal SCU for the recently suggested Advanced Photon Source multi-bend achromat storage ring is given in this paper. The results of the magnetic simulation together with initial cryogenic considerations are presented.
* D.F. Alferov, Yu.A. Bashamakov, E. G. Bessonov, Sov. J. Tech. Phys. 21(11), (1976) 1408.

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WEPRO049

Experience of Operating a Superconducting Undulator at the Advanced Photon Source

photon, operation, storage-ring, vacuum

2053

Y. Ivanyushenkov, K.C. Harkay
ANL, Argonne, Ilinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
A superconducting test undulator SCU0 was installed into the storage ring of the Advanced Photon Source (APS) in December 2012 and has been in user operation since January 2013. The first year's experience of operating such a novel insertion device at the APS is summarized in this paper. The performance of the SCU0 as a photon source is presented. The measured heat load from the electron beam is described together with the observed cryogenic behavior of the device. The effect of the SCU0 on the APS electron beam is also presented.

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WEPRO053

All-optical Free Electron Lasers using Travelling-wave Thomson Scattering

electron, laser, FEL, scattering

2065

K. Steiniger, M.H. Bussmann, A.D. Debus, A. Irman, A. Jochmann, R.G. Pausch, U. Schramm
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
T.E. Cowan
HZDR, Dresden, Germany

In Travelling-Wave Thomson Scattering (TWTS) the pulse front of a high-power, short-pulse laser is tilted and the dispersion of the pulse is controlled in such a way that electrons can interact over a long distance with a quasi-monochromatic electromagnetic wave. We present a complete three dimensional analytic time-dependent description of the TWTS field and use this description to derive an analytic FEL equation that shows that TWTS indeed provides for an all-optical FEL. We further derive conditions for optimum operation of the TWTS FEL, showing that EUV and XUV FEL sources are in reach using Petawatt lasers and conventional few-hundred MeV electron sources. Future laser-wakefield accelerators could potentially drive all-optical TWTS-FELs in the X-ray and beyond. TWTS itself is optimum to provide full flexibility in terms of the wavelength and bandwidth of the scattered radiation, allowing for application-optimized, highly-brilliant Thomson Scattering sources for a broad range of wavelengths from the EUV to the gamma ray spectral region.

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WEPRO057

Effect of the Electron Beam Emittance on the ILSF Radiation of Sources and Beamline Design

emittance, photon, brilliance, electron

2075

A. Gholampour, S. Amiri, H. Ghasem, H. Khosroabadi, J. Rahighi
ILSF, Tehran, Iran
H. Ghasem, M. Lamehi Rashti, J. Rahighi
IPM, Tehran, Iran

At the Iranian Light Source Facility (ILSF), two different storage ring options are being studied. The designs differ in emittance. In the first option the calculated emittance is 3.278 nm-rad whereas for the second option emittance is 0.937 nm-rad. In this paper the electron beam emittance effects on the source radiation properties from bending magnet, wiggler and undulator, X-ray optics and the beamline design are carefully studied. The present calculations demonstrate that in the case of 0.937 nm-rad brilliance of undulator is increased by a factor of about 5. For bending magnet, flux is reduced almost 1 order of magnitude for hard x-ray regime. Because of smaller size of the source for undulator at the case of 0.937 nm-rad, we can achieve to a smaller spot size and higher resolution with easier focusing systems and usual kind of monochromator than the emittance of 3.278 nm-rad and for the bending magnet hard x-ray beamline, size of the mirrors reduced 30% in the 0.937 nm-rad emittance case, so its result is shorter mirror, low cost and perhaps more challengeable heat load.

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WEPRO058

Photoemission Electron Microscopy Branch of Spectromicroscopy Beamline of the Iranian Light Source Facility

electron, photon, focusing, brilliance

2078

S. Amiri, H. Ghasem, A. Gholampour, H. Khosroabadi, J. Rahighi
ILSF, Tehran, Iran
H. Ghasem, M. Lamehi Rashti
IPM, Tehran, Iran

The Spectromicroscopy beamline is one of the day one beamlines of the Iranian Light Source Facility project in the field of soft x-ray spectroscopy. This beamline is designed to cover the 90-2500eV energy range with about 8000 resolving power, and the minimum spot size of about 10×4 micrometer 2 at sample position. Brilliance, flux and photon size and divergence in the whole range of energy has been calculated for a 4.3m linear undulator using SPECTRA code. This undulator has 10¹⁵ ph/s(0.1% B.W.) photon flux at 96 eV energy & 400 mA electron current. A circular pinhole with maximum diameter size of 2.52mm has been inserted in a distance of 10m from the source to pass 95% radiated. Primary layout of this branch includes a collimating mirror, a varied included-angle plane grating monochromator, and a KB bendable elliptical cylinder mirror. The ray tracing calculation by using computational software SHADOW has been done to determine and optimize of the important optical parameters. Three plane gratings with different uniform line density (700, 900, 1200 lines/mm) have been used to cover the whole energy range with the resolving power of 0.75-0.8×104 depending on the photon energy.

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WEPRO093

Possibility of Application of THz Wiggler in Low Energy FEL for Measurements of Electron Bunch Longitudinal Structure

electron, wiggler, laser, radiation

2177

E. Syresin, S.A. Kostromin, R.S. Makarov, N.A. Morozov, D. Petrov
JINR, Dubna, Moscow Region, Russia
M. Krasilnikov
DESY Zeuthen, Zeuthen, Germany

Funding: The work is funded by HGDF-RFBR Grant HRJRG-400
The infrared undulator constructed at JINR and installed at FLASH in 2007 is used for longitudinal bunch shape measurements in the range of several tenths of μm. The presented below electromagnetic wiggler is applied for a narrow-band THz radiation for measurements of electron bunch longitudinal structure in FEL with electron energy of several tenths of MeV. This is a planar electromagnetic device with 6 regular periods, each of 30 cm long. The K parameter is varied in the range 0.5- 7.12 corresponding to a range B=0.025- 0.356 T of the peak field on axis. The wiggler is simulated for 19.8 MeV/c FEL. The bunch compression scheme allows the whole wavelength range to be covered by super-radiant emission with a sufficient form factor. The wavelength range corresponds to 126 μm - 5.3 mm for the electron beam momentum of 19.8 MeV/c. The 3D Opera simulations of THz wiggler will be discussed.

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WEPME031

Magnetic Design of the First Prototype Pure Permanent Magnet Undulator for the ILSF

brilliance, radiation, permanent-magnet, electron

2326

A. Ramezani Moghaddam, J. Rahighi
ILSF, Tehran, Iran
H. Ghasem
IPM, Tehran, Iran
M. Lamehi Rashti
Nuclear Science & Technology Research Institute, Tehran, Iran
A. Ramezani Moghaddam
NSTRI, Tehran, Iran

Iranian light source facility (ILSF) is a 3GeV, 400 mA, 3rd generation light source under design and construction. This paper describes the details of the preliminary magnetic design of the first prototype PPM undulator for the ILSF. In the preliminary design, the undulator period and some other parameters have been determined to reach desired x-ray spectrum to be used for soft x-ray application. A PPM layout and a model undulator with 16 poles is used to calculate the properties of the designs.

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WEPRI095

Modelling of a Short-period Superconducting Undulator

simulation, alignment, software, radiation

2716

B.J.A. Shepherd, J.A. Clarke
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V. Bayliss, T.W. Bradshaw
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
E.C. Longhi
DLS, Oxfordshire, United Kingdom

STFC, in collaboration with Diamond Light Source, are designing and building a 15.5 mm period, 1.26 T superconducting undulator. This paper describes the modelling of the undulator, using Radia and Opera. Extensive numerical modelling has been carried out to simulate the effect of manufacturing tolerances on the quality of the magnetic field, in order to meet the demanding 3° rms phase error specification.

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WEPRI105

Preliminary Design of Cooling System for a PrFeB-based Cryogenic Permanent Magnet Undulator Prototype at IHEP

vacuum, cryogenics, permanent-magnet, simulation

2743

Y.C. Zhang, S.P. Li, H.H. Lu, S.C. Sun, Y.F. Yang
IHEP, Beijing, People's Republic of China

A circulation cooling system is under progress for a 2-m-long PrFeB-based cryogenic permanent magnet undulator (CPMU) prototype at IHEP. Sub-cooled liquid nitrogen flows through each in-vacuum girder back and forth once. Refrigerant channels for both girders are parallel connected in vacuum chamber. Numerical simulation shows that the cooling system is able to cool down magnet array from 300 K to 83 K. Meanwhile, phase error increases about 0.1 degree.

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THOBA03

Beam Transport System from a Laser Wakefield Accelerator to a Transverse Gradient Undulator

electron, laser, beam-transport, radiation

2803

C. Widmann, V. Afonso Rodríguez, A. Bernhard, N. Braun, A.-S. Müller, A.I. Papash, R. Rossmanith, W. Werner
KIT, Karlsruhe, Germany
M. Kaluza, M. Reuter
HIJ, Jena, Germany
M. Kaluza, M. Nicolai, A. Sävert
IOQ, Jena, Germany

Funding: This work is funded by the German Federal Ministry for Education and Research under contract no. 05K10VK2.
The transport and matching of electron beams generated by a laser wakefield accelerator (LWFA) is a major challenge due to their large energy spread and divergence. Strong focussing magnets and a chromatic correction are required. This contribution discusses the layout of the beam transport optics for a diagnostic beamline at the LWFA in Jena, Germany. The aim of this optics is to match the betatron functions and the dispersion to the field of a transverse gradient undulator (TGU) such that monochromatic undulator radiation is generated despite the large energy spread.

Slides THOBA03 [2.891 MB]

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THPPA01

FEL R&D Initiatives at the SLAC National Accelerator Laboratory

FEL, electron, laser, free-electron-laser

2842

A. Marinelli
SLAC, Menlo Park, California, USA

The successful lasing of the linac coherent light source in 2009, the first x-ray free-electron laser (xFEL) in the world, has opened a new era for x-ray photon science. The unprecedented intensity and coherence of the LCLS photon pulses have enabled groundbreaking experiments in a wide variety of fields ranging from coherent x-ray imaging to molecular and atomic physics. Despite the success of x-ray free-electron lasers, there is a steady push to extend and improve their capabilities fueled by the users' demands for new modes of operation and more precise photon and electron diagnostics. In my talk I will present several R&D initiatives at the SLAC National Accelerator Laboratory geared towards improving the performance and extending the capabilities of x-ray FELs. In particular I will focus on the spectral manipulation of FELs and our recent development of the multibunch and multicolor x-ray FEL modes at LCLS as well as our demonstration of the longitudinal space-charge amplifier as a broadband coherent light source at the NLCTA test accelerator.

Slides THPPA01 [10.793 MB]

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THPRO003

Progress of the LUNEX5 demonstator Project

FEL, electron, operation, laser

2856

M.-E. Couprie, C. Benabderrahmane, P. Berteaud, C. Bourassin-Bouchet, F. Bouvet, L. Cassinari, L. Chapuis, J. Daillant, M. Diop, M.E. El Ajjouri, C. Evain, C. Herbeaux, N. Hubert, M. Labat, P. Lebasque, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Polack, F. Ribeiro, J.P. Ricaud, P. Roy, K. Tavakoli, M. Valléau, D. Zerbib
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, E. Roussel, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
B. Carré, D. Garzella
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
X. Davoine
CEA/DAM/DIF, Arpajon, France
N. Delerue
LAL, Orsay, France
G. Devanz
CEA/DSM/IRFU, France
A. Dubois, J. Lüning
CCPMR, Paris, France
G. Lambert, R. Lehé, V. Malka, A. Rousse, C. Thaury
LOA, Palaiseau, France
C. Madec, A. Mosnier
CEA/IRFU, Gif-sur-Yvette, France

LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, coherent pulses in the 40-4 nm spectral range [1]. It comprises two types of accelerators connected to a single Free Electron Laser (FEL) for advanced seeding configurations (seeding with High order Harmonic in Gas, echo). A 400 MeV superconducting Linear Accelerator, adapted for studies of advanced FEL schemes, will enable future upgrade towards high repetition rate and multi-user operation by splitting part of the macropulse to different FEL lines. A 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA) [2] will also be qualified by the FEL application. After the Conceptual Design Report, R&D has been launched on different sub components. Following transport theoretical studies of longitudinal and transverse manipulation of a LWFA electron beam enabling to provide theoretical amplification, a test experiment is under preparation.

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THPRO004

Study of the CLIO FEL in the Far-infrared in a Partially Guided Mode

vacuum, FEL, cavity, simulation

2859

J.-M. Ortega, J.P. Berthet, F. Glotin, R. Prazeres
LCP/CLIO, Orsay, Cedex, France

The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to unity. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. A solution is to use this chamber as a waveguide by adaptating the radius of curvature of the cavity mirrors to this regime. Then, as has been shown before* a minimum appears in the spectrum that can be produced by the FEL. We discuss the physical mechanism of this particular regime and compare it to experiments using vacuum chambers of different tranverse sizes. A good agreement is found with results of simulations and with a simple analytical formula.
* Analysis of the periodic power gaps observed in the tuning range of FELs with a partial waveguide, R. Prazeres, F. Glotin, J.-M. Ortega, Phys. Rev. STAB12, 010701 (2009)

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THPRO007

Beam-based Alignment in the European XFEL SASE1

radiation, quadrupole, simulation, FEL

2867

H. Jin, W. Decking, T. Limberg
DESY, Hamburg, Germany

The European X-ray Free Electron Laser (E-XFEL) provides an ultra-short and high-brilliant photon pulses of spatially coherent X-rays with wavelengths down to 0.05 nm by using three undulator systems. Within these undulator systems, the orbit trajectory is required to be straight to a few micron over each gain length, so that the photon beam is capable of overlapping efficiently with the electron beam. However, this requirement is not obtainable with ordinary mechanical alignment methods. For this reason, a beam-based alignment (BBA) method using BPM readings of different beam energies is applied to the E-XFEL SASE1 undulators. In this report, we describe the BBA simulation for SASE1 including alignment errors of quadrupoles and BPMs. After correction, the desired range of the orbit trajectory is attained with high confidence. In addition, to identify the reliability of an aligned orbit trajectory acquired from the BBA simulation, we present here the SASE FEL radiation simulation, in which we observe a slight decrease of radiation energy and power.

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THPRO008

Obtaining High Degree of Circular Polarization at X-ray FELs via a Reverse Undulator Taper

FEL, radiation, bunching, polarization

2870

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

Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft X-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced.
Phys. Rev. ST-AB 16(2013)110702

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THPRO009

Harmonic Lasing in X-ray FELs

FEL, electron, photon, operation

2873

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

Contrary to nonlinear harmonic generation, harmonic lasing in a high-gain FEL can provide much more intense, stable, and narrow-band FEL beam which is easier to handle if the fundamental is suppressed. We perform a parametrization of the solution of eigenvalue equation for lasing at odd harmonics, and present explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam. We discover that in a part of the parameter space, corresponding to the operating range of soft X-ray beamlines of X-ray FEL facilities, harmonics can grow faster than the fundamental. We suggest that harmonic lasing can be widely used in the existing or planned X-ray FEL facilities. LCLS after a minor modification can lase at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level. At the European XFEL the harmonic lasing would allow to extend operating range up to 100 keV, to reduce bandwidth and increase brilliance.

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THPRO010

Analysis of Operation of Harmonic Lasing Self-seeded FEL

FEL, simulation, radiation, electron

2876

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

Harmonic lasing self-seeded FEL holds great potential for significant improvement of the the longitudinal coherence of the radiation. A gap-tunable undulator is divided into two parts by setting two different undulator parameters such that the first part is tuned to a sub-harmonic of the second part. Harmonic lasing occurs in the exponential gain regime in the first part of the undulator, also the fundamental stays well below saturation. In the second part of the undulator the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is defined by the harmonic lasing (i.e. it is reduced by a significant factor depending on harmonic number) but the saturation power is still as high as in the reference case of lasing at the fundamental in the whole undulator, i.e. the spectral brightness increases. Application of the undulator tapering in the deep nonlinear regime would allow to generate higher peak powers approaching TW level. The scheme is illustrated with the parameters of the European XFEL.

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THPRO011

Investigation of the Coherence Properties of the Radiation at FLASH

radiation, emittance, electron, FEL

2879

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

We present the results of the studies of coherence properties of the radiation from FLASH for fundamental harmonic and higher odd harmonics. General overview of the parameter space is performed including peak current, emittance, and external focusing. The results of our studies show that present configuration of FLASH free electron laser is not optimal for providing ultimate quality of the output radiation. We find that the physical origin of the problem is mode degeneration. The way for improving quality of the radiation is proposed.

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THPRO016

Stable Generation of High Power Self-seeded XFEL at SACLA

radiation, electron, photon, FEL

2888

T. Inagaki, N. Adumi, T. Fukui, T. Hara, Y. Inubushi, T. Ishikawa, H. Kimura, R. Kinjo, H. Maesaka, Y. Otake, H. Tanaka, T. Tanaka, K. Togawa, M. Yabashi
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
S. Goto, T.K. Kameshima, T. Ohata, K. Tono
JASRI/SPring-8, Hyogo, Japan
T. Hasegawa, S. Tanaka
SES, Hyogo-pref., Japan
A. Miura, H. Ohashi, H. Yamazaki
Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Hyogo, Japan

A self-seeded XFEL system using a transmitted beam under Bragg diffraction has been developed at the first compact XFEL facility SACLA in order to generate a brilliant single-mode XFEL with high temporal coherence. High stability and unique beam characteristics of SACLA should significantly contribute to achieve reliable, high-quality seeded XFEL operation. In particular, the short-pulse property that has been achieved in routine operation enables us to switch SASE and seeded mode quickly, without changing the electron beam parameters. This is also useful for delivering different modes to multiple beamlines simultaneously. In the test experiments carried out in autumn 2013, spectral narrowing was observed at 10 keV using diamond 400 reflection. Systematic optimization on beam properties is now in progress towards experimental use of seeded XFELs in summer 2014. This talk gives the overview of the plan, achieved results and ongoing R&D.

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THPRO019

Current Status of PAL-XFEL Project

klystron, linac, quadrupole, cavity

2897

H.-S. Kang, K.W. Kim, I.S. Ko
PAL, Pohang, Kyungbuk, Republic of Korea

The PAL-XFEL, a 0.1-nm hard X-ray FEL facility consisting of a 10-GeV S-band linac, is being constructed in Pohang, South Korea. The installation of linac, undulator, and beam line will be completed by 2015. Its building construction is at its peak moment to be completed by December 2014. The major procurement contract was made in 2013 for the critical components of S-band linac modules and hard X-ray undulators. The commissioning will start in January 2016. We hope the first lasing will be achieved in early 2016.

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THPRO024

Progress of the EU-XFEL Laser Heater

laser, vacuum, electron, photon

2912

M. Hamberg, V.G. Ziemann
Uppsala University, Uppsala, Sweden

Funding: Swedish research council under Project number DNR-828-2008-1093 for financial support.
We describe the technical layout and report the status of the installation of the undulator, optical and vacuum systems of the laser heater for the EUXFEL. The laser heater is a device to increase the overall X-ray brightness stability. This is achieved by an optical laser system which induce an additional momentum spread in the electron bunches to reduce micro-bunching instabilities.

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THPRO026

Design Parameters and Current Status of the TARLA Project

FEL, electron, linac, radiation

2918

A.A. Aksoy, Ö. Karslı, C. Kaya, E. Kazancı, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
P. Arıkan
Gazi University, Faculty of Arts and Sciences, Teknikokullar, Ankara, Turkey
S. Özkorucuklu
Istanbul University, Istanbul, Turkey

Funding: Work is supported by Ministry of Development of Turkey with Grand No: DPT2006K-120470
The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) will operate two InfraRed Free Electron Lasers (IR-FEL) covering the range of 3-250 microns. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating ELBE modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. In this paper, we discuss design goals of the project and present status and road map of the project.
On behalf of TARLA Team

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THPRO030

Developments in CLARA Accelerator Design and Simulations

FEL, wakefield, simulation, electron

2930

S. Spampinati
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D. Angal-Kalinin, A.D. Brynes, D.J. Dunning, J.K. Jones, K.B. Marinov, J.W. McKenzie, B.L. Militsyn, N. Thompson, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
I.P.S. Martin
DLS, Oxfordshire, 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. Updates on the electron beam simulations and code comparisons including wakefields are described. Simulations of the effects of geometric wakefields in the small-aperture FEL undulator are shown, as well as further simulations on potential FEL experiments using chirped beams. We also present the results of simulations on post-FEL diagnostics.

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THPRO031

Short Pulses THz FEL for the Oxford Accelerator Science Laboratory

FEL, radiation, cavity, gun

2934

T. Chanwattana, R. Bartolini, A. Seryi
JAI, Oxford, United Kingdom
R. Bartolini
DLS, Oxfordshire, United Kingdom
E. Tsesmelis
CERN, Geneva, Switzerland

The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a short pulse THz FEL based on a conventional RF accelerator driven by a RF photocathode gun is being investigated. This report presents the concept of the facility, the accelerator physics and FEL studies and engineering integration in the University physics department.

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THPRO032

Studies on LPWA-based Light Sources driven by a Transverse Gradient Undulator

FEL, laser, electron, simulation

2937

T. Chanwattana, R. Bartolini, A. Seryi
JAI, Oxford, United Kingdom
R. Bartolini
DLS, Oxfordshire, United Kingdom

The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a LPWA based light source driven by a transverse gradient undulator is being investigated. This report presents the accelerator physics, FEL studies and the performance expected from such a facility.

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THPRO034

Design of the LCLS-II Electron Optics

linac, quadrupole, electron, optics

2940

Y. Nosochkov, P. Emma, T.O. Raubenheimer, M. Woodley
SLAC, Menlo Park, California, USA

Funding: Work supported by the US Department of Energy Contract DE-AC02-76SF00515.
The LCLS-II project is a high repetition rate, high average brightness free-electron laser based on the existing facilities at the SLAC National Accelerator Laboratory. The LCLS-II will be driven by a new CW superconducting RF (SCRF) 4-GeV linac replacing the existing Cu-linac in the 1st km of the linac tunnel. The SCRF linac will include chicanes for providing full compression of the electron bunch length. After the linac, the electron beam will be directed into the existing 2-km bypass line connecting to the Beam Switch Yard (BSY), where a new spreader system will allow a high rate bunch-by-bunch deflection into the hard X-ray (HXR) or soft X-ray (SXR) transport lines, or towards the BSY high power dump. The HXR line will include a new variable gap undulator replacing the existing LCLS-I undulator and will reuse the existing LCLS-I linac-to-undulator and dump transport lines. The SXR will require a new transport line sharing the same tunnel with the HXR and will include a new variable gap undulator. Overview of the electron beam transport and the optics design are presented.

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THPRO035

Improving and Maintaining FEL Beam Stability of the LCLS

FEL, feedback, timing, high-voltage

2943

F.-J. Decker, A.L. Benwell, W.S. Colocho, Z. Huang, A. Krasnykh, J.R. Lewandowski, T.J. Maxwell, J. Sheppard, J.L. Turner
SLAC, Menlo Park, California, USA

Funding: *Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The beam stability of the Linac Coherent Light Source (LCLS) has seen many improvements over the years and has matured to a state where progress is slow and maintaining the best stability is becoming the main challenge. Single sources which are identified by various means contribute to only about 10 to 20% of the whole jitter power, meaning that their elimination gives only a small improvement of 5 to 10%. New sources need to be identified fast. Especially slow variations of a few seconds to minutes time scale are often hidden and partially corrected by feedback systems. A few episodes of increased jitter have shown the limitations of some of the feedback systems. Stability for all dimensions, transverse, longitudinal, and intensity are presented.

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THPRO039

Model-independent Description of Shot-noise, Amplification and Saturation

FEL, bunching, electron, simulation

2949

Y.C. Jing, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
High-gain FEL is one of many electron-beam instabilities, which have a number of common features linking the shot noise, the amplification and the saturation. In this paper we present a new, model-independent description of the interplay between these effects and derivation of a simple formula determining the saturation and maximum attainable gain in such instabilities. Application of this model-independent formula to FEL is compared with FEL theory and simulations. We describe limitations resulting from these finding for FEL amplifiers used for seeded FELs and for Coherent electron Cooling.

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THPRO050

Study of a THz/VUV Free Electron Laser Facility in Taiwan

FEL, laser, radiation, linac

2980

N.Y. Huang, M.C. Chou, C.-S. Hwang, W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan
A. Chao, J. Wu
SLAC, Menlo Park, California, USA
C.H. Chen, Y.-C. Huang
NTHU, Hsinchu, Taiwan
X.M. Yang
DICP, Dalian, People's Republic of China

A free electron laser (FEL) facility aimed for VUV and THz radiation is being studied at National Synchrotron Radiation Research Center (NSRRC) in Taiwan. Strong consideration has been given to minimize the cost by making maximum use of existing hardware at NSRRC. One unique consideration is to use an existing undulator for the dual functions of the THz radiator and the modulator of a HGHG section. Design emphasizes versatility of operation and beam quality control and compensation of nonlinearities, with a vision that it will allow as much as possible future upgrades as well as later R&D of FEL physics. The polarization control of the THz radiation provides novel application for the users. The facility is to be housed in the existing 38-m by 5-m tunnel of the TPS Linac Test Laboratory.

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THPRO107

Application Programs of Elettra and FERMI@Elettra

controls, optics, booster, software

3146

F. Iazzourene, C. Scafuri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

At Elettra we have high level software application programs used on the ring and others, based on the TANGO control, a new High Level Framework and a beam optics module, firstly developed and successfully used for the commissioning and operation of the Elettra booster and now for FERMI@Elettra transfer lines. The paper describes the present status and some of the application programs.

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THPRI074

Colorado State University (CSU) Accelerator and FEL Facility

laser, electron, controls, linac

3937

S. Biedron, C. Carrico, A. D'Audney, J.P. Edelen, J. Einstein, C.C. Hall, J.R. Harris, K. Horovitz, J. Martinez, S.V. Milton, A.L. Morin, N. Sipahi, T. Sipahi, J.E. Williams, P.J.M. van der Slot
CSU, Fort Collins, Colorado, USA
P.J.M. van der Slot
Mesa+, Enschede, The Netherlands
P.J.M. van der Slot
Twente University, Laser Physics and Non-Linear Optics Group, Enschede, The Netherlands

The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test stand, and a magnetic test stand. The photocathode drive linac will be used in conjunction with a hybrid undulator capable of producing THz radiation. Details of the systems used in CSU Accelerator Facility are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI074

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