IPAC2016 - List of Keywords (undulator)

Paper	Title	Other Keywords	Page
MOXBA01	Beam Commissioning of PAL-XFEL	gun, laser, linac, cathode	6
	J.H. Han PAL, Pohang, Kyungbuk, Republic of Korea
	The Pohang Accelerator Laboratory X-ray Free electron Laser (PAL-XFEL) project aims at the generation of X-ray FEL radiation for photon users. The machine consists of a 10 GeV normal-conducting S-band linear accelerator (linac) and two undulator beamlines initially. The hard X-ray beamline will provide FEL radiation between 0.6 and 0.1 nm or shorter. The soft X-ray line will provide FEL radiation between 4.5 and 1 nm. The linac and hard X-ray beamline construction was complete by the end of 2015. The installation of the soft X-ray line is ongoing. High power RF conditioning of the linac started in late autumn 2015. Beam commissioning of the linac started in April 2016. We report the beam commissioning status.
	Slides MOXBA01 [4.978 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOXBA01
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MOPOR005	Longitudinal Wakefields in the Undulator Section of SXFEL User Facility	FEL, wakefield, vacuum, electron	595
	M. Song, H.X. Deng, C. Feng, D. Huang, B. Liu, D. Wang SINAP, Shanghai, People's Republic of China
	Shanghai soft x-ray free electron laser (SXFEL) user facility based on multi-stage seeded-FEL and self-amplified spontaneous emission (SASE) is recently proposed, which is aiming at generating 4-2nm fully-coherent, high-brightness FEL pulse. In this paper, the wakefields arise from the resistive wall and surface roughness in the vacuum chamber is obtained by theoretical models. And the computations of geometric wakefields are carried out using ABCI. According to the tracked beam profile, the overall wakefields in the undulator section of SXFEL user facility are presented. K. Bane, G. Stupakov, SLAC-PUB-15951, May 2014. ** ABCI website: http://abci.kek.jp/abci.htm
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR005
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MOPOW005	First Electron Beam Measurements on COXINEL	electron, laser, plasma, quadrupole	712
	T. André, I.A. Andriyash, C. Basset, C. Benabderrahmane, P. Berteaud, S. Bonnin, F. Bouvet, F. Briquez, L. Cassinari, L. Chapuis, M.-E. Couprie, D. Dennetière, Y. Dietrich, M. Diop, J.P. Duval, M.E. El Ajjouri, T.K. El Ajjouri, P. Gattoni, C. Herbeaux, N. Hubert, M. Khojoyan, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, P. Pierrot, F. Polack, F. Ribeiro, J.P. Ricaud, P. Rommeluère, M. Sebdaoui, K.T. Tavakoli, M.-A. Tordeux, M. Valléau, J. Vétéran, D. Zerbib, C. de Olivera SOLEIL, Gif-sur-Yvette, France S. Bielawski, C. Evain, C. Szwaj PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France J. Gautier, E. Guillaume, G. Lambert, B. Mahieu, V. Malka, A. Rousse, K. Ta Phuoc, C. Thaury LOA, Palaiseau, France E. Roussel Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The ERC grant COXINEL aims at demonstrating experimentally Free Electron Laser (FEL) amplification with electrons generated by laser plasma acceleration (LPA). Because of the still limited electron beam performance (especially energy spread and divergence) in view of the FEL requirements, the electron beam transfer line has been specifically designed with adequate diagnostics and strong focusing variable strength permanent magnet quadrupoles, an energy de-mixing chicane and second set of quadrupoles for further dedicated focusing in the FEL interaction region, in a U20 in-vacuum undulator, enabling to operate at 200 nm with a 180 MeV electron beam. The first observation and transport of electrons in the COXINEL line is presented here.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW005
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MOPOW008	Reverse Undulator Tapering for Polarization Control at XFELs	FEL, resonance, radiation, bunching	722
	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 afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. We describe a method for such a suppression: an application of the reverse taper in the main undulator. 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. The scheme was successfully tested at LCLS* and is routinely used in user experiments. In this contribution we present the theoretical description of the method as well as the results of experiments with reverse taper at FLASH2. * E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 16, 110702 (2013) ** H.-D. Nuhn et al., "Commissioning of the DELTA polarizing undulator at LCLS", Proc. of FEL2015 Conf., Daejeon, Korea
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW008
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MOPOW009	Studies of Harmonic Lasing Self-seeded FEL at FLASH2	FEL, simulation, electron, radiation	725
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	A concept of the Harmonic Lasing Self-Seeded (HLSS) FEL was proposed in,. A gap-tunable undulator is divided into two parts 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 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 post-saturation tapering would allow to generate higher peak power than in SASE mode due to an improved longitudinal coherence. We present feasibility study of the application of the HLSS FEL scheme at FLASH2 and show that it allows to achieve a higher power and a smaller bandwidth than in a standard SASE regime. First experimental tests are eventually discussed. E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15 (2012) 080702 ** E.A. Schneidmiller and M.V. Yurkov, "Harmonic Lasing Self-Seeded FEL", Proc. of FEL2013 Conf., New York, USA
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW009
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MOPOW011	Operation of Free Electron Laser FLASH Driven by Short Electron Pulses	radiation, electron, simulation, laser	732
	V. Balandin, G. Brenner, C. Gerth, N. Golubeva, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov DESY, Hamburg, Germany E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Rönsch-Schulenburg, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength of 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW011
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MOPOW013	Application of Statistical Methods for Measurements of the Coherence Properties of the Radiation from SASE FEL	radiation, FEL, electron, photon	738
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Radiation of the SASE FEL operating in the linear regime possesses the properties of completely chaotic polarized light which happens due to start up of the amplification properties from the shot noise in the electron beam. One of the features of this statistical object is that probability distribution of the radiation pulse energy follows gamma distribution. Parameter of this distribution is the number of modes in the radiation pulse which is equal to inverse deviation of the energy fluctuations. Statistical analysis of the radiation energies measured within different spatial apertures allows us to determine the number of longitudinal and transverse modes. In addition, knowledge of the saturation length allows to determine the duration of the lasing part of the electron bunch, photon pulse duration, and coherence time. Knowledge of the number of transverse modes allows one to determine the degree of transverse coherence. In this report we present theoretical background of the proposed method and experimental results obtained at free electron laser FLASH. E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 148 (1998) 383. ** C. Behrens et al., Phys. Rev. ST Accel. Beams 15 (2012) 030707.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW013
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MOPOW014	Measurements of Ultrasmall Charges with MCP Detector in FLASH Accelerator	detector, electron, photon, laser	741
	O.I. Brovko, A.Yu. Grebentsov, A.V. Shabunov, E. Syresin JINR, Dubna, Moscow Region, Russia S. Schreiber, M.V. Yurkov DESY, Hamburg, Germany
	Structure of the dark current passed through the undulator is a matter of great concern. Two effects can contribute to the dark current: emission of electrons from "hot" spots in the gun, and generation of "ghost" bunches due to possible leakage of the photoinjector laser. MCP based photon detector has been used for measurements of radiation energy from electron bunch. For small radiation densities the light is detected by direct illumination of the MCP plate, and for large densities a small angle scattering scheme is realized when metallic mesh scatters tiny fraction of light on the MCP plate. In the present experiment we used geometry of direct illumination of MCP plate aiming detection of "ghost" bunches which may generate parasitically from the laser driven electron gun. Reduction of background conditions allowed us to detect light produced by electron bunches with extremely small charges, down to a few femtocoulmb. We measured for the first time structure of the dark current passing through the FLASH undulator. We have also been able to measure a high contrast of radiation produced by the photoinjector laser pulses switched on and off by a 1 MHz repetition rate Pockels cells.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW014
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MOPOW016	Status of Design and Development of Delhi Light Source at IUAC, Delhi	laser, electron, radiation, gun	748
	S. Ghosh, R.K. Bhandari, G.K. Chaudhari, V.J. Joshi, D. Kabiraj, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, P. Patra, B.K. Sahu, A.S. Sharma, A.S. Sthuthikkatt Reghu IUAC, New Delhi, India A. Aryshev, M.K. Fukuda, S. Fukuda, N. Terunuma, J. Urakawa, J. Urakawa KEK, Ibaraki, Japan A. Deshpande SAMEER, Mumbai, India V. Naik, A. Roy VECC, Kolkata, India T. Rao BNL, Upton, Long Island, New York, USA
	Funding: The project is supported jointly by Board of Research in Nuclear Sciences (BRNS) and IUAC The demand for the photon beams for basic research is growing in India. To address the requirements, a project to develop a compact Light Source based on the principle of Free Electron Laser has been initiated at the Inter University Accelerator Centre (IUAC). In the first phase of the project, a normal conducting RF gun will be used to produce electron beam of energy ~ 8 MeV by using copper photocathode and subsequently by Cs2Te photocathode. A high power fiber laser with short pulse length is planned to be used to produce the pre-bunched electron beam by splitting the single laser pulse in to 16 pulses ("comb beam"). The electron beam will be injected in to a compact, variable gap undulator magnet to produce the THz radiation whose frequency can be tuned by varying the undulator field strength and the time separation of the comb beam. In the second and third phases of the project, superconducting RF gun and superconducting accelerating structure will be used to increase the energy of the electron beam up to ~ 40 MeV which will be used to produce IR radiation by using long undulator magnets and to produce X-rays by colliding the electron beam with another high power laser beam.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW016
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MOPOW019	Commissioning Status of the Extreme-Ultraviolet FEL Facility at SACLA	FEL, electron, booster, laser	757
	T. Sakurai, T. Asaka, N. Azumi, T. Hara, T. Hasegawa, T. Inagaki, T. Ishikawa, R. Kinjo, C. Kondo, H. Maesaka, T. Ohshima, Y. Otake, H. Tanaka, T. Tanaka, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan T. Bizen, N. Hosoda, H. Kimura, S. Matsubara, S. Matsui JASRI/SPring-8, Hyogo, Japan
	To equip SACLA with wide ability to provide a laser beams in EUV and soft X-ray regions to experimental users, we have constructed a new free electron laser facility for SACLA beamline-1. Injector components, such as a thermionic electron gun, two buncher cavities, a S-band standing wave accelerator, S-band travelling wave accelerator and their RF sources, were relocated from the SCSS test accelerator, which was a prototype machine of SACLA. At the downstream of a bunch compressor chicane, three C-band 40 MV/m acceleration units were newly installed to effectively boost a beam energy up to 470 MeV. Two in-vacuum undulators were remodeled by changing the period of magnet array from 15 mm to 18 mm to increase SASE intensity by a larger K-value of 2.1. Beam commissioning was started in autumn 2015. So far SASE radiation at a 33 nm wavelength driven by a 470 MeV electron beam was observed. We will install the third undulator in this winter to obtain SASE saturation and additional C-band accelerator units in the next summer to raise the maximum beam energy to 750 MeV. In this presentation, the overview of the facility and the commissioning status will be reported.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW019
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MOPOW020	Power Improvement of Free-Electron Laser Using Transverse-Gradient Undulator with External Focusing	FEL, focusing, radiation, electron	760
	G. Zhou, Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China J. Wu SLAC, Menlo Park, California, USA T. Zhang SINAP, Shanghai, People's Republic of China
	Funding: Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2015009) Resent study [Z. Huang et al., Phys. Rev. Lett. 10⁹, 204801 (2012)] shows that the transverse-gradient undu-lator (TGU) together with electron beams with constant dispersion can reduce the sensitivity to energy spread for FEL. In this study, we numerically study FEL using TGU with external focusing. In spite of the dispersion varia-tion, through parameter optimization, FEL using TGU with TGU achieves similar radiation to that without ex-ternal focusing. To achieve a high energy exaction effi-ciency, the initial dispersion should be set with a shift from that corresponding to the resonant condition, and a variation of the transverse gradient in different undulator section is preferred. Other approaches, such as tapering and detuning frequency control, are also discussed to further improve the radiation power and are demonstrated with global parametric optimizations base on simulation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW020
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MOPOW022	Model-based Algorithm to Tune the LCLS Optics	quadrupole, optics, controls, electron	763
	Z. Zhang TUB, Beijing, People's Republic of China Y. Ding, X. Huang SLAC, Menlo Park, California, USA
	Transverse phase space matching of electron beam to the undulator optics is important for achieving good performance in free-electron lasers. Usually there are dedicated matching quadrupoles distributed in the beamline, by measuring the beam phase space the matching quadrupoles are calculated and adjusted to match to the designed Twiss parameters. Further adjustment of the quadrupoles to overcome collective effects or realistic beamline errors is typically required for performance improvement. In this paper, we studied a method to decompose the Twiss parameters for an independent control of the phase space. Mathematical analysis and numerical simulations are both presented to show that through combining the quadrupoles into some multi-knobs, we can control the Twiss parameters independently. We also show some experimental results at the LCLS.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW022
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MOPOW023	Proposal of an X-band Linearizer for Dalian Coherent Light Source	FEL, laser, electron, radiation	766
	G.L. Wang, X.M. Yang, W.Q. Zhang DICP, Dalian, People's Republic of China H.X. Deng, C. Feng SINAP, Shanghai, People's Republic of China
	Dalian coherent Light Source (DCLS) is a FEL user facility working at 50-150 nm, now under commissioning in Dalian, China. The facility based on HGHG mode, requires high brightness electron beam with small energy spread and low emittance. To linearise the longitudinal phase space before the bunch compression, an X-band linearizer is considered before the bunch compressor. In this paper, we study the performance improvement of DCLS FEL radiation by using such a harmonic cavity, including the jitter of central wavelength induced by arriving time and a larger bunch compression ratio for femtosecond FEL application.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW023
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MOPOW024	Harmonic Lasing Options for Dalian Coherent Light Source	FEL, radiation, laser, electron	770
	G.L. Wang, X.M. Yang, W.Q. Zhang DICP, Dalian, People's Republic of China H.X. Deng, C. Feng SINAP, Shanghai, People's Republic of China
	Harmonic lasing of the Free Electron Laser can be achieved by disrupting the electron interaction with the usually dominant fundamental while allowing the increasing of a harmonic interaction. It's a cheap and relatively efficient way to extend the photon energy range of a particular FEL. In this paper, we discussed the possibility of harmonic lasing concept at Dalian Coherent Light Source by using the combination of tapered undulators and phase shifters. Our calculation shows that it's feasible with the present layout to provide intense, stable, and narrow-band harmonic radiation, the FEL wavelength could be down to 20 nm and the corresponding pulse energy is about 10 μJ.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW024
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MOPOW026	Status of FELiCHEM, a New IR-FEL in China	FEL, radiation, cavity, electron	774
	H.T. Li, Z.G. He, Q.K. Jia, Q. Luo, L. Wang, S.C. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC), whose core device is a FEL oscillator generating middle-infrared and far-infrared laser and covering the spectral range of 2.5-200 μm. It will be a dedicated light source aiming at energy chemistry research, with the photo excitation, photo dissociation and photo detection experimental stations. We present the brief physical and technical design that delivers the required performance for this device and summarize the status of fabrication. Final assembly is scheduled for early in the next year with first light targeted for July 2017.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW026
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MOPOW029	The Soft X-ray Self-seeding System Design for SXFEL User Facility	FEL, electron, simulation, photon	785
	K.Q. Zhang, T. Liu, D. Wang SINAP, Shanghai, People's Republic of China Y. Feng SLAC, Menlo Park, California, USA
	X-ray free electron laser driven by SASE probes the evolution of the new generation light source in high brightness, transverse coherence. However, since SASE achieves lasing from random shotnoise, Poor longitudinal coherence and relative wide bandwidth of SASE FEL limit the operation of many type experiments. Self-seeding as a promising scheme produces longitudinal coherence and even narrower bandwidth radiation by a monochromatic seeding instead of external seeding. The self-seeding system design based on the grating monochromator is carried out for SXFEL user facility across the photon energy from 800-1200 eV. The grating monochromator with a resolution power of 〖10〗^-4 can provide a monochromatic seeding pulse to the seeding undulator. The layout design and simulations of the scheme are presented. It is showing that the self-seeding system for SXFEL user facility is able to improve SASE FEL longitudinal coherence significantly.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW029
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MOPOW035	A Compact, Wavelength Tunable MW-THz FEL Amplifier	FEL, electron, laser, radiation	789
	C.H. Chen, A.P. Lee NSRRC, Hsinchu, Taiwan F.H. Chao, Y.C. Chiu, Y.-C. Huang, M.H. Wu NTHU, Hsinchu, Taiwan G. Zhao PKU, Beijing, People's Republic of China
	We propose a compact scheme of THz free electron laser (FEL) amplifier within a 3.5 m long beam line. The amplification of a tunable THz seed laser in an FEL amplifier is driven by an rf photoinjector. The THz seed laser is an optical parametric amplifier* pumped by a 1064-nm microchip laser and an external-cavity tunable diode laser. By varying the beam energy and undulator parameter, the radiation frequency of the THz FEL amplifier can be tunable in a broad spectral range between 1.5 and 3.0 THz. Moreover, to extract more radiation power from the electron beam within a short undulator, we employ a linearly tapered undulator in our design. The influence of the seed power on the electron-laser interaction in the undulator is studied in some detail for the FEL amplification. Our simulation results show that the radiation power of the THz FEL amplifier can achieve few MW with a 10-W seed power. * D.T. Palmer et al., in Proceedings of Particle Acceleration Conference, Vancouver, 1997, p. 2687, (1997). ** S. Hayashi et al., SCIENTIFIC REPORTS, 4, 5045-1-6, (2014).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW035
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MOPOW037	Developments in the CLARA FEL Test Facility Accelerator Design and Simulations	linac, FEL, space-charge, simulation	797
	P.H. Williams, D. Angal-Kalinin, A.D. Brynes, J.A. Clarke, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.B. Appleby UMAN, Manchester, United Kingdom B. Kyle University of Manchester, Manchester, 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. In order to prioritise FEL schemes requiring the shortest electron bunches, the layout has changed significantly to enable compression at higher energy. Four proposed modes of operation are defined and tracked from cathode to FEL using ASTRA. Supplementing these baseline mode definitions with CSR-enabled codes (such as CSRTRACK) where appropriate is in progress. The FEL layout is re-optimised to include shorter undulators with delay chicanes between each radiator.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW037
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MOPOW040	High Efficiency, High Brightness X-ray Free Electron Lasers via Fresh Bunch Self-Seeding	electron, simulation, extraction, photon	805
	C. Emma, C. Pellegrini UCLA, Los Angeles, USA M.W. Guetg, A.A. Lutman, A. Marinelli, C. Pellegrini, J. Wu SLAC, Menlo Park, California, USA
	High efficiency, terawatt peak power X-ray Free Electron Lasers are a promising tool for enabling single molecule imaging and nonlinear science using X-rays. Increasing the efficiency of XFELs while achieving good longitudinal coherence can be achieved via self-seeding and undulator tapering. The efficiency of self-seeded XFELs is limited by two factors: the ratio of seed power to beam energy spread and the ratio of seed power to shot noise power. We present a method to overcome these limitations by producing a strong X-ray seed and amplifying it with a small energy spread beam. This is achieved by selectively suppressing lasing for part of the bunch in the SASE section. In this manner we can saturate with the seeding electrons and amplify the strong seed with 'fresh' electrons downstream of the monochromator. Simulations of this scenario are presented for two systems, an optimal superconducting undulator design and the LCLS. In the case of the LCLS we examine how betatron oscillations leading to selective suppression are induced by using the transverse wakefield of a parallel plate dechirper. We also discuss extending the selective suppression scheme to chirped electron bunches.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW040
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MOPOW048	Development of the LCLS-II Optics Design	linac, electron, optics, kicker	820
	Y. Nosochkov, P. Emma, T.O. Raubenheimer, M. Woodley SLAC, Menlo Park, California, USA
	Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515. The LCLS-II is a high repetition rate, high average brightness free-electron laser (FEL) under construction at the SLAC National Accelerator Laboratory. The LCLS-II will include new major components: a high repetition-rate injector, a superconducting, CW (continuous wave), 4-GeV linac with a bunch compressor system, a 3-way beam spreader, with independent hard X-ray (HXR) and soft X-ray (SXR) FEL undulators. The design is based on the existing SLAC facilities, including the LCLS linac and beam transport lines. The new SXR line will utilize a variable-gap undulator sharing the same tunnel with the new HXR horizontal-gap vertically polarizing undulator that will replace the existing LCLS undulator. We describe the current state of the electron optics design and the latest developments.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW048
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TUZA01	Soft X-ray Free Electron Laser at SINAP	FEL, laser, electron, radiation	1028
	D. Wang SINAP, Shanghai, People's Republic of China
	Shanghai X-ray FEL (SXFEL) is a test facility at Shanghai Institute of Applied Physics, Chinese Academy of Sciences originally designed for studying XFEL principle and technologies. It is composed of a warm linac to provide up to 840 MeV electron beam, an undulator line with cascaded EEHG-HGHG setup and a short diagnostic beamline. The project started the construction by the end of 2014. Recently a proposal to upgrade it to an user facility at the soft x-ray regime got approved. The talk will give an overview of the test facility construction and upgrade plan.
	Slides TUZA01 [9.344 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUZA01
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TUZA02	Twin-bunch Two-colour FEL at LCLS	electron, laser, free-electron-laser, photon	1032
	A. Marinelli, R.N. Coffee, F.-J. Decker, Y. Ding, R.C. Field, S. Gilevich, Z. Huang, D. Kharakh, H. Loos, A.A. Lutman, T.J. Maxwell, J.L. Turner, S. Vetter SLAC, Menlo Park, California, USA
	Twin electron bunches have been the subject of much investigation at the Linac Coherent Light Source, due to their many applications to X-ray free-electron lasers (X-FEL). Twin bunches are trains of two electron bunches that are accelerated and compressed within the same accelerating RF period. At LCLS, these bunches are used in the downstream FEL undulator to generate two X-ray pulses of different energies for pump/probe applications or de novo phase determination of protein crystals. The spectral and temporal shaping of the two bunches requires exquisite control of the compression system to vary the main parameters of the system in a controlled way (peak current, temporal delay and energy separation). I will discuss recent experimental and theoretical results on this subject. In particular I will focus on the demonstration of mJ-level two-color X-ray pulses using twin bunches, as well as the temporal and spectral control of this new mode of operation. Finally, I will discuss our experience with user experiments as well as our future directions of investigation.
	Slides TUZA02 [5.738 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUZA02
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TUZB02	Challenge of In-vacuum and Cryogenic Undulator Technologies	vacuum, cryogenics, radiation, permanent-magnet	1080
	J.C. Huang, C.-H. Chang, C.H. Chang, T.Y. Chung, C.-S. Hwang, C.K. Yang, Y.T. Yu NSRRC, Hsinchu, Taiwan H. Kitamura RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	An in-vacuum undulator (IVU) opens the utilization of high-brilliance X-rays in the medium energy storage rings. The development of a short-period undulator with low phase error becomes important to bring X-ray into a new unprecedented brilliant light source in an ultimate storage ring (USR). NdFeB or PrFeB cryogenic permanent magnet undulators (CPMUs) with a short period have been developed worldwide to obtain high brilliance of undulator radiation. A CPMU has high resistance against beam-induced heat load and allow to operate at a narrow gap. In a low emittance or ultimate storage ring, not only the performance of an undulator but the choice of the lattice functions is very important to obtain high bril-liance of synchrotron radiation. The optimum betatron functions and zero dispersion function shall be given for a straight section at IVU/CPMUs. In this paper, the relevant factors and design issues for IVU/CPMU will be discussed. Many technological challenges of a short-period undulator associated with beam induced-heat load, phase errors, and the deformation of in-vacuum girders will also be presented herein.
	Slides TUZB02 [5.204 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUZB02
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TUOCB03	Magnet Development for SPring-8 Upgrade	dipole, sextupole, alignment, quadrupole	1093
	T. Watanabe, T. Aoki, K. Fukami, S. Matsubara, C. Mitsuda, S. Takano, T. Taniuchi, K. Tsumaki JASRI/SPring-8, Hyogo-ken, Japan T. Hara, H. Kimura RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	One of the features for newly designed magnets for the SPring-8 major upgrade plan* is permanent magnet based dipole magnets for substantial energy saving. The new dipole magnets have been designed to be equipped with (i) a field variable function by controlling magnetic flux into a beam axis, (ii) a nose structure on iron poles for smooth B-field transition in the longitudinal gradient field, and (iii) a nearly zero temperature coefficient of magnet circuit with the help of a shunt alloy*. Demagnetization due to radiation is also a critical issue. At SPring-8, demagnetization process has been intensively studied, and the effect has been considered in the design of dipole magnets. Although electromagnet based multi-pole magnets are rather conventional technologies, yet new magnets need to be designed to fit in the next generation high packing factor lattice with as reasonably lower energy consumption as possible. Magnet alignment will be a key development as well; in order to secure adequate dynamic apertures, magnets ought to be aligned within tens of microns. Current design and recent progress in the developments of magnets and alignment schemes will be presented. H. Tanaka et al., SPring-8 Upgrade Project, in the abstracts. ** T. Taniuchi et al., Proc. of IPAC2015, WEPMA050.
	Slides TUOCB03 [4.014 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOCB03
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TUPMB011	Calculation and Analysis of the Magnetic Field of a Transverse Gradient Undulator	simulation, electron, FEL, laser	1130
	J. Li, B. Du, Q.K. Jia, H.T. Li USTC/NSRL, Hefei, Anhui, People's Republic of China
	Transverse gradient undulator (TGU) is attracting more and more attentions, especially for the rapid progress of laser plasma accelerator techniques. The transverse gradient of TGU is usually given by an empirical formula simply derived from the empirical formula of a uniform-parameter undulator. In this paper, we numerically investigate the transverse magnetic field of TGUs using the RADIA code. Through many simulations for TGUs with different magnet structures, we have given the dependences of transverse gradient parameter on the cant angle, the undulator period and the average gap. Based on these results, when the cant angle is small and the rate of the gap and period is in the range of 0.4-0.6, the simulation results agree with the empirical formula well. But, with the growing of the cant angle, or with the growing of the deviation of the rate of the gap and period from the range of 0.4-0.6, the difference between the simulation results and the empirical formula becomes larger.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB011
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TUPMB012	Optimization of the Field Integrals of Two Small Gap IDs for CLS	multipole, wiggler, vacuum, synchrotron-radiation	1133
	M.F. Qian, Y.Z. He, H.F. Wang, W. Zhang, Q.G. Zhou SINAP, Shanghai, People's Republic of China
	An in-vacuum undulator and an in-vacuum wiggler have been developed for CLS at SSRF recently. The period lengths of the undulator and the wiggler are 20mm and 80mm respectively. Both IDs have the minimum gap of 5.2mm. The field integrals were measured for each magnet block with two poles and were sorted in-situ as they were installed on to the girders. Finally the field integrals of the undulator and the wiggler were shimmed by using the 'Magic Fingers' at the ends with a special algorithm. This paper reports the procedure and the results of the measurement and the optimization for the field integrals.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB012
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TUPMB013	PAL-XFEL Magnet Design and Magnetic Measurement	dipole, quadrupole, multipole, laser	1136
	H.S. Suh, S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park PAL, Pohang, Kyungbuk, Republic of Korea
	We have designed and tested magnets for PAL-XFEL of 10GeV in Pohang, Korea. These magnets consist of 6 families of 52 dipole magnets, 11 families of 236 quadrupole magnets, and 4 families of 10⁸ corrector magnets. Two hall probe benches are used to measure the magnetic field. This paper reviews the main parameters of these magnets and the results of magnetic field measurements.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB013
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TUPOR018	Design Optimization of Compensation Chicanes in the LCLS-II Transport Lines	simulation, FEL, electron, space-charge	1695
	J. Qiang, C.E. Mitchell, M. Venturini LBNL, Berkeley, California, USA Y. Ding, P. Emma, Z. Huang, G. Marcus, Y. Nosochkov, T.O. Raubenheimer, L. Wang, M. Woodley SLAC, Menlo Park, California, USA
	LCLS-II is a 4th-generation high-repetition rate Free Electron Laser (FEL) based x-ray light source to be built at the SLAC National Accelerator Laboratory. To mitigate the microbunching instability, the transport lines from the exit of the Linac to the undulators will include a number of weak compensation chicanes with the purpose of cancelling the momentum compaction generated by the main bend magnets of the transport lines. In this paper, we will report on our design optimization study of these compensation chicanes in the presence of both longitudinal and transverse space-charge effects.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR018
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TUPOR023	Investigation of Trapped Resonant Modes in Insertion Devices at the Australian Synchrotron	resonance, feedback, vacuum, synchrotron	1710
	R.T. Dowd, M.P. Atkinson, M.J. Boland, G. LeBlanc, Y.E. Tan SLSA, Clayton, Australia D. Teytelman Dimtel, San Jose, USA
	The Australian Synchrotron light Source has 3 variable gap in-vacuum undulators (IVU) in the storage ring. Since installation, these devices have been the source of strong beam instabilities. These instabilities seem to behave as trapped resonant modes of very high Q and high frequency, although a definite source has not been identified. The presence of these instabilities has necessitated operating at unusually high chromaticity for much of the light source's operations. More recently transverse feedback has been able to control the instabilities and recent developments in diagnostics have allowed some investigation of the frequency and mode response of these resonances. The results of this investigation will be presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR023
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TUPOW009	Generation of Coherent Undulator Radiation using Extremely Short Electron Bunch at t-ACTS, Tohoku University	radiation, electron, bunching, injection	1760
	S. Kashiwagi, T. Abe, H. Hama, F. Hinode, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	An accelerator test facility, t-ACTS, was established at Research Center for Electron Photon Science, Tohoku University, in which an intense coherent terahertz (THz) radiation is generated from an extremely short electron bunch. Velocity bunching scheme in a traveling-wave accelerating structure is employed to produce the short electron bunch, and a production of sub-picosecond electron bunch was demonstrated. A long-period linear undulator, which has 25 periods with a period length of 10 cm and a peak magnetic field of 0.41 T, has been developed to produce intense coherent THz radiation. Properties of the radiation from the THz undulator such as radiation fields, spectrum and angular distribution were numerically investigated based on the parameters of short electron bunch and THz undulator. By optimization of bunch compression, it is possible to extract a coherent radiation of fundamental mode excluding higher-order mode. The detail of the numerical studies for the coherent undulator radiation will be reported in the conference.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW009
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TUPOW026	Optimization of Electron Beam Properties for Generation of Coherent THz Undulator Radiation at PBP-CMU Linac Laboratory	radiation, electron, linac, emittance	1803
	N. Chaisueb, S. Rimjaem, J. Saisut, C. Thongbai Chiang Mai University, Chiang Mai, Thailand
	Funding: This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Chiang Mai University, and the Science Achievement Scholarship of Thailand. Relativistic femtosecond electron bunches produced from the linear accelerator at the Plasma and Beam (PBP) Physics Research Facility are currently used to generate THz radiation via transition radiation. An upgrade to increase the intensity of the THz radiation by using a coherent undulator radiation method is conducted. Optimizations, measurements and analysis of the electron beam properties, which include current, energy and energy spread as well as electron bunch length, are performed to investigate the capability of electron beam production from the current accelerator system. This is also to estimate the possibility to produce the coherent undulator radiation of the PBP-CMU linac. Expected characteristics of the coherent undulator radiation are studied and reported in this contribution. The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Material Science and the Graduate School, Chiang Mai University.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW026
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TUPOW051	Optimization of Electron Beam and Laser Pulse Alignment and Focusing at Interaction Point for a Compact FEL Based Inverse-Compton Scattering X-Ray Source	electron, laser, photon, FEL	1881
	P. Niknejadi, J. Madey University of Hawaii, Honolulu,, USA
	Funding: This work was funded under the Department of Homeland Security Grant No. 2010-DN-077-ARI045. In July 2015, the first beam of 10 keV X-rays from our FEL based inverse-Compton scattering X-ray source was detected.* In this setup, 3 micron laser pulses at 2.856 GHz repetition rate from a free electron laser are collided head-on with 40 MeV electron bunches driving the laser. To attain our objective the ebeam was required to have 1) a tight focus at the X-ray interaction point, 2) vertical and horizontal envelopes matched to the downstream undulator, 3) minimized transverse dimensions for low ionizing radiation. Optimization of these quantities required information on the evolution of the beam profiles between the beam spot images on the available insertable screens, leading to the need for a simulator to accurately trace the beam profiles through the system. A simulator was developed and used to optimize the system Twiss parameters by comparing the effectiveness of the beam profiles computed by fitting the profiles to the observed beam spot images along the beamline for different cathode positions. This method proved to be considerably more flexible and effective than the more traditional quadrupole scan technique. Summery of the designed system and results are provided. * John M. J. Madey, ARI final report, December 2015.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW051
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WEOAA03	Experimental Study on Optical Vortex from a Helical Undulator at UVSOR-III	radiation, experiment, synchrotron, synchrotron-radiation	2036
	M. Hosaka Nagoya University, Nagoya, Japan M. Katoh, N.S. Mirian UVSOR, Okazaki, Japan T. Konomi, N. Yamamoto KEK, Ibaraki, Japan K. Kuroda ISSP, Kashiwa-shi, Japan K. Miyamoto, S. Sasaki HSRC, Higashi-Hiroshima, Japan
	A relativistic electron in helical undulator emits an optical vortex which carries orbital angular momentum. Sasaki and McNulty predicted theoretically that higher harmonics of helical undulator is optical vortex* and the experimental verification was made at BESSY and UVSOR-III. Further, we have made a systematic study to characterize the optical vortex from a helical undulator at UVSOR-III. Synchrotron radiation in UV region from an optical klystron undulator system consisting of two APPLE-II helical undulators and a buncher was used for the experiment. Patterns resulting from inferences between two undulator radiation carrying different angular momentums were clearly observed. To investigate the optical properties of the radiation, diffraction experiments were carried out. Specific diffraction patterns due to the phase singularity in the radiation center were clearly observed. The experimental results are compared with simulation. S. Sasaki, I. McNulty, Phys. Rev. Lett. 100, 124801 (2008) J. Bahrdt et al., Phys. Rev. Lett. 111, 034801 (2013) * e.g. S. Sasaki et al., presented in SRI2015 (2015)
	Slides WEOAA03 [11.023 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAA03
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WEPMR048	Hall Element Relative Position and Angle Calibrations for the Cryogenic Permanent Magnet Undulator	vacuum, cryogenics, permanent-magnet, dipole	2386
	L. Gong, W. Chen, W. Kang, L.Z. Li, H.H. Lu, Y.F. Yang IHEP, Beijing, People's Republic of China
	A three dimensions Hall probe will be manufactured for characterizing the magnetic performance of Cryogenic Permanent Magnet Undulator (CPMU) of Chinese High Energy Photon Source and the test facility (HEPS-TF) at Institute of High Energy Physics (IHEP). The positional and angular misalignment errors of the Hall sensors play an important role in the measurement accuracy of CPMU. In order to minimize the misalignment errors, a method of calibrating relative displacements and assembly angles of a 3-D Hall probe is carried out. In this paper, details of the calibration procedures and the data processing are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR048
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WEPMR053	Technical Overview of Cavity BPM Mover for PAL XFEL	cavity, controls, operation, EPICS	2395
	H.-G. Lee, S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, K.W. Kim, S.B. Lee, D.H. Na, B.G. Oh, K.-H. Park, H.S. Suh, Y.J. Suh PAL, Pohang, Kyungbuk, Republic of Korea
	Pohang Accelerator Laboratory(PAL) has been developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. The cavity BPM mover was developed to be used in the intersections of the Undulator Systems. The main specifications include submicron repeatability for a 50 kg cavity BPM adjusting system within compact dimensions and a ±1.5 mm stroke in the vertical and horizontal direction. Compact linear motion guide based on 5-phase stepping motors have been chosen. A closed-loop control system has been developed to achieve this repeatability. For the feedback, one digital probe sensor for each axis was used. Mechanical switches are used to limit movement. In addition, hard-stops are included for emergency. In this report, we describe the design of the stages used for precise movement and results of mechanical measurements including reproducibility will be reported.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR053
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WEPMY025	iMPACT, Undulator-Based Multi-Bunch Plasma Accelerator	plasma, wakefield, electron, simulation	2609
	O. Mete Apsimon, K. Hanahoe, G.X. Xia UMAN, Manchester, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom B. Hidding USTRAT/SUPA, Glasgow, United Kingdom J.D.A. Smith Tech-X, Boulder, Colorado, USA
	Funding: This work is supported by the Cockcroft Institute Core Grant and STFC. The accelerating gradient measured in laser or electron driven wakefield accelerators can be in the range of 10-100GV/m, which is 2-3 orders of magnitude larger than can be achieved by conventional RF-based particle accelerators. However, the beam quality preservation is still an important problem to be tackled to ensure the practicality of this technology. In this global picture, the main goals of this study are planning and coordinating a physics program, the so-called iMPACT, that addresses issues such as emittance growth mechanisms in the transverse and longitudinal planes through scattering from the plasma particles, minimisation of the energy spread and maximising the energy gain while benchmarking the milestones. In this paper, a summary and planning of the project is introduced and initial multi-bunch simulations were presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY025
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WEPOW014	Spectral Studies of Ultrashort and Coherent Radiation Pulses at the DELTA Storage Ring	laser, radiation, electron, bunching	2851
	S. Khan, F.H. Bahnsen, M. Bolsinger, F. Götz, S. Hilbrich, M.A. Jebramcik, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, R. Niemczyk, G. Shayeganrad, P. Ungelenk, D. Zimmermann DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF (05K13PEC, 05K13PE3), the DFG (INST 212/236-1 FUGG), the Stiftung Mercator (Pr-2014-0047) and the state of NRW. At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort and coherent radiation pulses in the VUV and THz regime are routinely generated by the interaction of electron bunches with 45-fs laser pulses. A laser-induced modulation of the electron energy is converted into a density modulation (microbunching) by a magnetic chicane, giving rise to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). As a first step towards active control of the shape and spectrum of CHG pulses, spectral studies were performed under variation of the chicane strength and the laser properties. The spectral phase of the laser pulses was controlled by tuning the compressor of the laser amplifier and was monitored using FROG (frequency-resolved optical gating). In this paper, monochromator scans as well as single-shot spectrograms of the CHG radiation are presented and compared to simulations of the laser-electron interaction and microbunching process. In addition, other results from the short-pulse facility as well as a future upgrade employing the echo-enabled harmonic generation (EEHG) scheme will be outlined.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW014
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WEPOW019	SPring-8 Upgrade Project	emittance, operation, laser, radiation	2867
	H. Tanaka, T. Ishikawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan S. Goto, S. Takano, T. Watanabe, M. Yabashi JASRI/SPring-8, Hyogo, Japan
	Plans are underway for the upgrade of the SPring-8 facility, targeting completion in the early 2020's. Sustainability is a key guiding principle for the fourth-generation X-ray source - a beam emittance of around 100 pm.rad is pursued simultaneously with substantial energy-saving. The three key features of the design are (i) to replace the main dipole electric magnets with permanent magnets, (ii) to reduce the electron beam energy from 8 to 6 GeV, and (iii) to use the SACLA linac as an injector. Lowering the beam energy leads to reduction of (a) beam emittance, (b) magnetic fields, (c) the lengths of ID straight sections to maintain larger spaces for the magnets, and (d) the RF power consumption. Timeshare use of the SACLA linac enables beam injection to the upgraded ring with a low-emittance and short-pulsed beam as well as a reduction of injector power consumption by stopping the present injector consisting of a 1-GeV linac and a booster synchrotron. The outline of the upgrade plan will be reported with the current status of R&D started in 2015.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW019
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WEPOW020	Present Status of KEK Photon Factory and Future Project	emittance, lattice, storage-ring, operation	2871
	T. Honda, M. Adachi, S. Asaoka, K. Haga, K. Harada, Y. Honda, X.J. Jin, T. Kageyama, R. Kato, Y. Kobayashi, K. Marutsuka, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, K.N. Nigorikawa, T. Nogami, T. Obina, M. Ono, T. Ozaki, H. Sagehashi, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, M. Shimada, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, O. Tanaka, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, N. Yamamoto, Ma. Yoshida, S.I. Yoshimoto KEK, Ibaraki, Japan
	Two synchrotron radiation sources of KEK, the PF-ring and the PF-AR, continue their user operation with various improvements. Scrap and build of the first generation undulators of 1980s at the PF-ring is pushed forward year by year. Five new elliptically polarized undulators have been installed in these five years, and we have also installed four very narrow-gap short-period undulators generating high brilliant X-ray. The new beam transport line that enables the 6.5-GeV full energy injection for PF-AR will be completed by the end of 2016 in order to make the top-up operation of the two SR sources compatible with the continuous injection for two main rings of the Super-KEKB. We have proposed a project of further upgrade of the 2.5-GeV PF-ring to improve its horizontal emittance as 8 nm rad using combined bending magnets at the arc sections. And we are also moving ahead on proposal of constructing a new KEK light source of an extremely low emittance as 0.3 nm rad. The progress and detail of our future project will be described in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW020
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WEPOW042	Properties of Synchrotron Radiation from Segmented Undulators based on a Wigner Distribution Function	electron, brilliance, radiation, photon	2933
	H.W. Luo, C.H. Lee NTHU, Hsinchu, Taiwan T.Y. Chung, C.-S. Hwang NSRRC, Hsinchu, Taiwan
	Three long straight sections with a double mini-βy lattice were designed in Taiwan Photon Source. For the purpose to understand whether the brilliance can be enhanced or not when two collinear undulators were installed in the double mini-βy. Therefore, the Wigner distribution function (WDF) is developed to calculate the brilliance in the double mini-βy lattice that is a natural way to describe a synchrotron radiation source. Herein, the brilliance is thereby calculable without a Gaussian approximation used in a conventional manner. Some important optical properties such as the degree of coherence can be directly calculated with this method. We use it as an example to investigate the properties of radiation from a segmented undulator.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW042
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WEPOW043	Accelerator Based Light Source Projects of Turkey	FEL, electron, linac, radiation	2936
	A.A. Aksoy, Ö. Karslı, C. Kaya Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey B. Ketenoğlu, O. Yavaş Ankara University, Faculty of Engineering, Tandogan, Ankara, Turkey Z. Nergiz Nigde University, Nigde, Turkey
	Three light source project is ongoing in Turkey within the frame of Turkish Accelerator Center (TAC) Project which has been supported by Ministry of Development since 2006. As a first facility of TAC, 3-250 μ mm IR-FEL facility (TARLA) based on superconducting accelerator with an energy of maximum 40 MeV is under construction at Institute of Accelerator Technologies of Ankara University. In addition to TARLA, Conceptual/Technical Design Report of a third generation synchrotron radiation facility based on 3 GeV, and a fourth generation FEL facility based 1-6 GeV is being prepared for the next steps of TAC. Therewithal a proton accelerator facility with up 2 GeV and an electron-positron collider as a super charm factory are proposed within the frame of TAC project. In this presentation, current status of TARLA project and main goals, road map of Turkish Light Sources will be explained.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW043
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WEPOW051	R+D Progress Towards a Diffraction Limited Upgrade of the ALS	vacuum, injection, emittance, storage-ring	2962
	C. Steier, A. Anders, J.M. Byrd, K. Chow, S. De Santis, R.M. Duarte, J.-Y. Jung, T.H. Luo, H. Nishimura, T. Oliver, J.R. Osborn, H.A. Padmore, G.C. Pappas, D. Robin, F. Sannibale, D. Schlueter, C. Sun, C.A. Swenson, M. Venturini, W.L. Waldron, E.J. Wallén, W. Wan, Y. Yang LBNL, Berkeley, California, USA
	Funding: This work was supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231. Improvements in brightness and coherent flux of about two orders of magnitude over operational storage ring based light sources are possible using multi bend achromat lattice designs. These improvements can be implemented as upgrades of existing facilities, like the proposed upgrade of the Advanced Light Source, making use of the existing infrastructure, thereby reducing cost and time needed to reach full scientific productivity on a large number of beamlines. An R&D program was started at LBNL to further develop the technologies necessary for diffraction-limited storage rings. It involves many areas, and focuses on the specific needs of soft x-ray facilities: NEG coating of small chambers, swap-out injection, bunch lengthening, magnets/radiation production, x-ray optics, and beam physics design optimization. Hardware prototypes have been built and concepts and equipment was tested in beam tests on the existing ALS.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW051
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WEPOW053	CESR Lattice for Two Beam Operations with Narrow Gap Undulators at CHESS	lattice, injection, operation, simulation	2968
	S. Wang, D. L. Rubin, J.P. Shanks Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work was supported by NSF DMR-0936384 and NSF DMR-1332208. CESR has operated as a dedicated light source since the conclusion of colliding beam program in 2008. Two undulators with a 6.5mm-vertical gap were installed in Fall 2014, replacing a wiggler in the sextant of CESR that is the home to all CHESS beam lines. In order to operate narrow gap undulators with two beams, CESR pretzel lattice was redesigned so that e^- and e⁺ orbits are coincident in one machine sextant but separated in return arcs. In particular both e^- and e⁺ orbits are on axis through undulators. This "arc-pretzel" lattice has been the basis for undulator operation. To better understand the beam dynamics and improve machine performance, we developed many simulation tools: undulator modeling, injection tracking, etc. With installation of an additional quadrupole near undulators, the CESR lattice will be further modified with a low beta waist in the insertion devices, allowing a more than two fold reduction of local beta functions. This reduction is anticipated to mitigate the effects of small aperture and undulator field errors and to enhance the xray brightness. The characterization of the lattice will be compared with measurements of injection efficiency, tune scans, etc.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW053
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WEPOY001	First Field Integral Measurement Campaign for Air Coil	controls, power-supply, operation, LabView	2991
	Z. Zhao, B. Du, Q.K. Jia USTC/NSRL, Hefei, Anhui, People's Republic of China S. Karabekyan, J. Pflüger, M. Yakopov XFEL. EU, Hamburg, Germany
	For the operation of the air coils, which are needed for the undulator segments of the European x-ray free-electron laser (E-XFEL), precise conversion constants are needed to properly convert excitation current to steering strength. This paper describes the measurement of all 200 air coils, needed for this purpose using the short moving wire (MW) system. A LabView program was developed to measure the distribution of first field integral of both vertical (B_y) and horizontal (B_z) magnetic field components in the median plane of an air coil automatically. The program is an adaptation of the existing program, which was used to characterize magnetic properties of the phase shifters (PS). Before doing the measurements the new program automatically finds the centers of B_y and B_z components, which are found to match with the geometrical centers with sufficient accuracy. After the measuring procedure is complete, the results are presented as graphics output and final tables. It shows that the measurement results can fully meet the design requirements of E-XFEL. For all measurements the excitation current of the coils was set to 1 Ampere.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY001
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WEPOY021	Nonlinear Phase Distortion in a Ti:Sapphire Optical Amplifier for Optical Stochastic Cooling	laser, radiation, kicker, pick-up	3024
	M.B. Andorf, P. Piot Northern Illinois University, DeKalb, Illinois, USA V.A. Lebedev, P. Piot, J. Ruan Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the US DOE under contract DE-SC0013761 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359. Optical Stochastic Cooling (OSC) has been considered for future high-luminosity colliders as it offers much faster cooling time in comparison to the micro-wave stochastic cooling. The OSC technique relies on collecting and amplifying a broadband optical signal from a pickup undulator and feeding the amplified signal back to the beam. It creates a corrective kick in a kicker undulator. Owing to its superb gain qualities and broadband amplification features, Titanium:Sapphire medium has been considered as a gain medium for the optical amplifier (OA) needed in the OSC. A limiting factor for any OA used in OSC is the possibility of nonlinear phase distortions. In this paper we experimentally measure phase distortions by inserting a single-pass OA into one leg of a Mach-Zehnder interferometer. The measurement results are used to estimate the reduction of the corrective kick a particle would receive due to these phase distortions in the kicker undulator. A. Zholents, and M. Zolotorev. Proc. PAC'97, 1805 (1998).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY021
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WEPOY022	Light Optics for Optical Stochastic Cooling	radiation, kicker, electron, pick-up	3028
	M.B. Andorf, P. Piot Northern Illinois University, DeKalb, Illinois, USA V.A. Lebedev, P. Piot, J. Ruan Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the US DOE under contract DE-SC0013761 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359. In Optical Stochastic Cooling (OSC) radiation generated by a particle in a "pickup" undulator is amplified and transported to a downstream "kicker" undulator where it interacts with the same particle which radiated it. Fermilab plans to carry out both passive (no optical amplifier) and active (optical amplifier) tests of OSC at the Integrable Optics Test Accelerator (IOTA) currently in construction. The performace of the optical system is analyzed with simulations in Synchrotron Radiation Workshop (SRW) accounting for the specific temporal and spectral properties of undulator radiation and being augmented to include dispersion of lens material. V. Lebedev, et al., Proc. COOL'15 (in press, 2015).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY022
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WEPOY028	Laser Heater System Test at PAL-XFEL ITF	laser, electron, FEL, bunching	3048
	J. H. Lee POSTECH, Pohang, Kyungbuk, Republic of Korea J.H. Han, J.H. Hong, C.H. Kim, I.S. Ko, S.J. Lee PAL, Pohang, Kyungbuk, Republic of Korea
	Coherent x-ray photons are generated by a free electron laser (FEL). In PAL-XFEL, a photon beam with a 0.1 nm wavelength is generated from an electron bunch based on self-amplified spontaneous emission (SASE). An electron bunch with an uncorrelated energy spread in a level of 3 keV, which is generated from the photocathode RF gun, may be sensitive to longitudinal micro-bunching instability. The energy spread of an electron bunch can be increased to suppress the instability by Landau damping. In order to control the uncorrelated energy spread, a laser heater system, which has a chicane with four dipoles chicane and a 0.5 m long undulator, was installed in the injector test facility (ITF) of PAL. In this paper, we introduce the parameters of the laser heater and heating effect on the electron bunch.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY028
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WEPOY035	Free Electron Laser Simulation Tool Based on FDTD/PIC in the Lorentz Boosted Frame	FEL, simulation, radiation, electron	3061
	A. Yahaghi, A. Fallahi, F.X. Kärtner CFEL, Hamburg, Germany F.X. Kärtner MIT, Cambridge, Massachusetts, USA
	Funding: Alexander von Humboldt-Foundation European Research Council(ERC) Free Electron Lasers (FELs) are promising sources capable of generating electromagnetic waves in the whole spectrum. Therefore, it is crucial and additionally very useful to develop sophisticated though complete simulation tools. This goal is mainly motivated by our research focus on the development of compact X-ray sources based on radiation in optical undulators. The currently existing softwares are usually written to tackle special cases with particular approximations, such as 1D FEL theory, steady state, slow wave and forward wave approximation, wiggler-averaged electron motion and slices approximation. Many of the above approximations are hardly valid when sub-femtosecond bunches interact with intense optical lasers. The presented software aims the analysis of the FEL interaction without considering any of the above approximations. The developed tool apparently suffers from long computation times but offers a more accurate picture on the radiation process. In order to overcome the problem of multidimensionality, we exploit Lorentz boosted coordinate system and implement Finite Difference Time Domain (FDTD) method combined with Particle in Cell (PIC) simulation in this frame.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY035
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THPMB013	Proposal of 6 GeV Energy Recovery Linac Hybrid Machine	electron, positron, linac, cavity	3254
	M. Shimada, K. Yokoya KEK, Ibaraki, Japan R. Hajima JAEA, Ibaraki-ken, Japan M. Tecimer University of Hawaii at Manoa, Honolulu, USA
	We proposed 6 GeV Energy Recovery Linac (ERL) as an intense gamma-ray source for the polarized positron source of International Linear Collider (ILC). In this scheme, Coherent Synchrotron Radiation from quasi-CW 6 GeV electron beam is stacked in optical cavity at middle infrared region, and it is used for inverse Compton scattering to generate 10 MeV polarized gamma-ray. The same 6 GeV superconducting linac accelerates both the electron and positron beams up to 5 GeV for injection to the dumping ring. Furthermore, it is available for X-ray light source by adding another recirculation loop. It can be expected as a diffraction limit light source at 10 keV, and the target of the brilliance is 10^22-23 ph/s/mm²/mrad²/b.w.0.1%. M. Shimada, Proceedings of IPAC'13
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB013
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THPMB024	Error Analysis for the Lattice of FELiChEM	FEL, simulation, lattice, emittance	3278
	S. Huang, Z.G. He, W. Xu, S.C. Zhang, T. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC).The facility consists of the middle-infrared (MID-FEL) beam line for 2.5-50 um and the Far-infrared (FAR-FEL) beam line for 40-200um. To achieve the design FEL performance of IR-FEL, the beam with 30 mm-mrad emittance, 5 ps rms length and 1nC bunch charge is required. We conduct error analysis in order to evaluate the tolerances of machine parameters and alignments. In this paper, we simulate the orbit corrections and emittance growth under exist of misalignments and strength errors of magnets. The simulation results show that the trajectory errors can be corrected to mm levels in the whole lattice and the emittance increase is acceptable. At the entrance of undulator, the position and angular errors can be corrected very well. So the trajectory can be controlled in the undulator to meet the requirement of FEL.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB024
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THPMB027	Beam Transport Line of the LPA-FEL Facility Based on Transverse Gradient Undulator	FEL, radiation, beam-transport, laser	3287
	T. Liu, B. Liu, D. Wang, T. Zhang SINAP, Shanghai, People's Republic of China Z. Huang SLAC, Menlo Park, California, USA J.S. Liu Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China
	Free electron lasers (FELs) based on Laser Plasma Accelerators (LPAs) present a main research direction for achieving next generation compact advanced light sources. There are several major challenges of the LPA beam to generate high-brilliance FEL radiation including the large initial angular divergence and the large energy spread. Based on the LPA facility in SIOM that has successfully obtained quasi-monochromatic beam with the central energy of hundreds of MeV, a specific design of a beam transport line is proposed to realize FEL gain using Transverse Gradient Undulator to compensate the relatively large beam energy spread. This beamline uses a single dipole, several strong focusing quadrupoles and correcting sextupoles to match proper beta functions and linear dispersion from the LPA beam to FEL radiation. The corresponding experimental facility of LPA-FEL in SIOM has been set up and will perform first tests to generate FEL radiation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB027
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THPMB050	The Commmissioning of Phase-I Insertion Devices in TPS	storage-ring, coupling, lattice, radiation	3360
	M.-S. Chiu, C.H. Chang, C.H. Chen, J. Chen, J.Y. Chen, Y.-S. Cheng, P.C. Chiu, P.J. Chou, T.Y. Chung, S. Fann, K.H. Hu, C.H. Huang, J.C. Huang, C.-S. Hwang, C.-C. Kuo, T.Y. Lee, C.C. Liang, Y.-C. Liu, H.-J. Tsai, F.H. Tseng, C.Y. Wu NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at Natioal Synchrotron Radiation Research Center, next to the Taiwan Light source (1.5 GeV). On March 26, 2015, the TPS storage ring with two 5-cell PETRA cavities has successfully operated in 100 mA in top-up mode without the installation of insertion devices (IDs). To reach the design goal of 500 mA, the machine was shut down for 5 months to replace PETRA cavitites with superconducting RF (SRF) cavities and to install 10 IDs: 7 in-vacuum undulators (IU) and 3 elliptically polarized undulators (EPU). The commissioning of TPS storage ring with SRF cavities and IDs began in Sep. 2015. In this paper, we present our results and proceedures of ID commissioning.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB050
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THPMB052	Studies on Electron Beam Injector System for Linac-based Coherent Thz Source in Thailand	electron, gun, linac, simulation	3366
	W. Thongpakdi, S. Rimjaem Chiang Mai University, Chiang Mai, Thailand
	Funding: The Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and the Development and Promotion of Science and Technology Talents Project (DPST). At the Plasma and Beam Physics Research Facility, Chiang Mai University, a thermionic cathode RF electron gun and alpha magnet are used together as an injector system for a linac-based THz source. Investigate the optimal performance of the injector system, beam dynamic simulations are performed by computer codes PARMELA, ASTRA and ELEGANT. The input 3D field distributions of the RF-gun for PARMELA and ASTRA simulations are obtained from the RF modeling program CST Microwave Studio. The beam transport calculation using the program ELEGANT is performed to study behavior of electrons from the gun exit through the alpha magnet, a travelling wave linac, magnet elements, drift tubes, and related beam diagnostic components. Energy slits inside the alpha magnet vacuum chamber is used to select electrons with desired kinetic energies. The alpha magnet compresses electron bunches with certain bunch length before the beam entering the linac to obtain minimum energy spread and shortest bunch length at the experimental station. Results of electron beam optimization with appropriated conditions for generation of intense coherent THz radiation will be reported and discussed in this contribution. This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and DPST.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB052
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THPMR017	Resonance Island Experiments at BESSY II for User Applications	photon, operation, resonance, experiment	3427
	P. Goslawski, J. Feikes, K. Holldack, A. Jankowiak, M. Ries, M. Ruprecht, A. Schälicke, G. Wüstefeld HZB, Berlin, Germany R. Ovsyannikov BESSY GmbH, Berlin, Germany
	Beam storage close to a tune resonance (Qx = 1/3, 1/4) can generate resonance island buckets in the x,x' phase space providing a second stable island orbit winding around the standard orbit. Experiments with such an operation mode have been conducted at BESSY II and the Metrology Light Source (MLS),. The two orbits are well separated, with good life time and stability. Such operation mode will offer additional operation flexibility and allows users to choose their radiation source point from one or the other orbit. It has the potential to fulfill simultaneously conflicting user demands, e.g., high vs. low beam current and single or few bunch filling vs. multibunch filling. We discuss the required beam optics setup and present successful measurements taken at photon beamlines at BESSY II. P. Goslawski et al., "Bunch Separation by Transverse Resonance Island Buckets", ESLS XXIII Workshop, 2015, Villigen, Switzerland. ** M. Ries et al., Proc. IPAC 2015, Richmond, USA, MOPWA021.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR017
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THPMY028	Technical Overview of the PAL-XFEL Conventional Facility	site, simulation, linac, survey	3715
	I. Mok, M.S. Hwang, T.-H. Kang, K.W. Kim, K.R. Kim, S.H. Kim, S.N. Kim, Y. C. Kim, B.H. Lee, H.M. Lee, M.S. Lee, B.I. Moon, K.W. Seo, C.H. Son, C.W. Sung, J. Yang PAL, Pohang, Republic of Korea Y.C. Kim, J.H. Lee Haenglim Architecture & Engineering Co. Ltd, Seoul, Republic of Korea I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea S.W. Yong Posco Engineering & Construction., Ltd., Gyeongsangbuk-do, Republic of Korea
	Pohang Accelerator Laboratory (PAL) has finished construction of a 1,110m long 10GeV X-ray free electron laser (XFEL) linear accelerator building in FY2015. In order to secure high-sensitive of XFEL accelerating devices, more advanced and well proven technologies were adopted in the design of the building. These are the ground improvement underneath the tunnel and tunnel structure itself against the possible ground deformation, air conditioning system to maintain the temperature and humidity in the tolerable ranges and architectural zoning. In this paper we describe the features of design and construction of the XFEL accelerator building.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY028
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THPMY043	Collimation System Design for LCLS-II	linac, collimation, gun, electron	3755
	M.W. Guetg, P. Emma, M. Santana-Leitner, J.J. Welch, F. Zhou SLAC, Menlo Park, California, USA
	Funding: DOE contract \#DE-AC02-76SF00515 The planned LCLS-II FEL has an average beam power of up to 1.2 MW and a repetition rate of up to 1 MHz, both of which entail serious challenges for beam halo collimation. This paper summarizes the efforts to assess the proposed collimation system. The undulator section is specifically focused on due to its high loss sensitivity (maximal 12 mW). This proceedings concentrate on field emissions of the gun. Different dark current distribution, linac configurations and simulation programs were used to increase assurance of the results. Filled phase-space tracking further supplemented an independent prove of the collimation system effectiveness and expands to include beam-halo originating from different sources than the gun.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY043
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THPOR036	Updates on the Sliding Contact Cooling ILC Positron Source Target Development	target, vacuum, positron, radiation	3865
	W. Liu, D.S. Doran, R.A. Erck, G.R. Fenske, W. Gai, V.J. Guarino ANL, Argonne, Illinois, USA
	The R&D of the baseline positron source target for ILC is still ongoing after TDR due to the uncertainty of rotating vacuum seal and water cooling system of the fast spinning target wheel. Different institutes around the globe have proposed different approaches to tackle this issue. A spinning target wheel system with sliding contact cooling has been proposed by ANL. The proposed system eliminated the needs of rotating vacuum seal by using magnetic torque coupler to drive the solid spinning wheel target. The energy deposited from positron production process is taken away via cooling pads sliding against the spinning wheel. A full size test wheel has been built and some initial tests have been done with promising outcomes. Results of these tests are presented in this paper along with a plan for developing a prototype.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR036
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THPOW030	ELI Eectron Beam Line for Laser-plasma-driven Undulator X-ray Source	electron, quadrupole, laser, photon	4005
	A.Y. Molodozhentsev KEK, Ibaraki, Japan L. Pribyl Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
	ELI LUX experiment of the ELI-Beamlines Project is based on electron beam, accelerated by the laser plasma wakefield. ELI LUX aims to deliver for users the X-ray beams with radiation length (0.4-4.5)nm and the peak brilliance up to 10²³ photons/(s mrad2 mm2 0.1% B.W.), which makes this source comparable with modern synchrotron sources. To provide small transverse size of the electron beam and small transverse beam divergence in the undulator, permanent quadrupole magnets with high gradient of the magnetic field up to 510 T/m are used in the electron beam line. In frame of this report we present main features of the designed electron beam line. 3D modeling of the magnetic field in the quadrupole magnets has been performed. Effects of the chromatic and spherical aberrations are taken into consideration. The electron beam dynamic is studied by using symplectic integration though the 3D field maps of the permanent quadrupole magnets. Effects of the space charge of the electron beam, beam collimation, injection and alignment errors and realistic field errors are discussed. Finally parameters of the photon beam, generated in compact undulator, are presented in this report.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW030
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THPOW037	Simulated and Measured Magnetic Performance of a Double APPLE-II Undulator at the Canadian Light Source	multipole, polarization, photon, dipole	4025
	C.K. Baribeau, L.O. Dallin, J.M. Helfrich, T.M. Pedersen, M.J. Sigrist, W.A. Wurtz CLS, Saskatoon, Saskatchewan, Canada
	Assembly and shimming are underway for a double APPLE-II type elliptically polarized undulator (i.e. two magnet arrays installed side by side on a single support structure) at the Canadian Light Source. The device is planned to be installed in spring 2017. Extensive preparation was done prior to device assembly, particularly in development of a simulated annealing algorithm for magnet virtual shimming, as well as assembly procedures that minimized positional errors in the installed magnet blocks. In this paper we present measurements taken throughout the shimming process, and compare with predictions from a RADIA model where each magnet block was magnetized uniquely according to individual Helmholtz coil measurements.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW037
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THPOW038	First Results from Two Novel In-vacuum Magnetic Field Measurement Devices as Built at HZB	vacuum, feedback, controls, shielding	4028
	J. Bahrdt, H.-J. Bäcker, J. Bakos, H. Bieder, W. Frentrup, A. Gaupp, S. Gottschlich, C. Kuhn, C. Rethfeldt, M. Scheer, B. Schulz HZB, Berlin, Germany
	The characterization of cryogenic in vacuum permanent magnet undulators with periods less than 20 mm and correspondingly narrow gaps requires new in-vacuum measurement systems. The positioning accuracy of the HZB in-vacuum Hallprobe bench has substantially been improved (a few μm) with appropriate feedback systems. A new in-vacuum cable tray has been developed. Another system for field integral measurements, an in-vacuum moving wire, is under commissioning. Both devices are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW038
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THPOW039	Measurements of the Lattice Modifications for the Cryogenic Undulator CPMU17	betatron, optics, quadrupole, storage-ring	4031
	J. Bahrdt, D.B. Engel, W. Frentrup, P. Goslawski, P. Kuske, R. Müller, M. Ries, M. Ruprecht, A. Schälicke HZB, Berlin, Germany
	A 2 mrad-canted double undulator system is in preparation as the wide energy range light source for the Energy Material in-situ Laboratory EMIL at the HZB storage ring BESSY II. The cryogenic undulator CPMU-17 is the hard X-ray device of the double undulator system. The soft X-ray undulator UE-48 is of the APPLE II type. It was installed and commissioned a few months ago, whereas the CPMU-17 is under fabrication. The CPMU-17 will employ a minimum magnetic gap of 5.5mm. Including a CuNi-foil for RF-shielding and geometric tolerances the free aperture is planned to be 5.0 mm. The BESSY II lattice has been modified locally in order to cope with the small gap device. The adapted betatron functions with a shifted vertical beam waist were measured and fitted with LOCO. The new optics agrees with the predicted performance. The free aperture at the installation place of the CPMU-17 was measured with four vertical scrapers. It is compatible with the projected minimum undulator gap. Finally, the measured injection efficiency with the new EMIL optics switched on is compatible with top-up operation (injection efficiency ≥ 90 %).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW039
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THPOW040	Insertion Devices for Spring-8 Upgrade Project	vacuum, electron, storage-ring, polarization	4035
	T. Tanaka, T. Hasegawa, R. Kinjo RIKEN SPring-8 Center, Hyogo, Japan T. Bizen, A. Kagamihata, H. Kishimoto, H. Ohashi, T. Seike JASRI/SPring-8, Hyogo, Japan S. Yamamoto KEK, Tsukuba, Japan
	In the upcoming major upgrade project of SPring-8 (SPring-8-II) planned in the early 2020's, the electron energy will be reduced from 8 GeV to 6 GeV and the straight sections will be shortened by nearly 2 m to accommodate more magnets, for the purpose of reducing the emittance down to around 100 pm.rad. The insertion devices (IDs) currently installed in SPring-8 are not compatible with the above upgrade plan, and thus most of them should be replaced with new ones optimized in the new storage ring, or at least be shortened to fit into the new straight sections. We report the status of R&Ds toward realization of IDs for SPring-8-II, such as shortening the magnetic period, reforming the fundamental structure of IDs to reduce the total cost and manufacturing lead time, and refurbishment of existing IDs for shorter lengths.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW040
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THPOW041	Field Error Correction Considerations of Cryogenic Permanent Magnet Undulator (CPMU) for High Energy Photon Source Test Facility (HEPS-TF)*	cryogenics, simulation, operation, electron	4038
	Y.F. Yang, H.H. Lu, S.C. Sun, X.Z. Zhang IHEP, Beijing, People's Republic of China
	Considerations are made for field error corrections of a 2m-long CPMU in built for HEPS-TF. Field changes in cooling to liquid nitrogen temperature are simulated. 1st field integral of terminal changes by tens of Gauss cm and RMS of phase errors induced by cold contraction is less than 1° when temperature gradient along girder is below 1.5K/m. Field signature of magic finger is unchanged with temperature. Strategy of the field error correction is discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW041
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THPOW042	Start-to-End Simulation on Terahertz Superradiation of Ultrashort Electron Bunch in an Undulator	radiation, simulation, electron, laser	4041
	X.L. Su, Y.-C. Du, W.-H. Huang, C.-X. Tang, D. Wang, L.X. Yan, Z. Zhang TUB, Beijing, People's Republic of China
	The narrowband, intense and frequency-tunable THz radiation can be generated by letting an ultrashort electron bunch pass through an undulator. Start-to-end simulation of terahertz radiation from electron bunch in an undulator is studied in this paper. GPT code is used to track particle distribution from the photocathode RF gun to the entrance of the undulator and Genesis 1.3 is applied to simulate the radiation. The simulation results agree well with theoretical predictions.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW042
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THPOW045	Development of PAL-XFEL Undulator System	FEL, laser, electron, radiation	4044
	D.E. Kim, Y.-G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, B.G. Oh, K.-H. Park, H.S. Suh PAL, Pohang, Kyungbuk, Republic of Korea J. Pflüger XFEL. EU, Hamburg, Germany
	Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. At the first stage, PAL-XFEL needs two undulator lines for photon source. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator and soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. PAL is developing undulator magnetic structure based on EU-XFEL concepts. In this report, the results of final pole height tuning results, and magnetic measurement results will be presented.
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THPOW046	Status of Insertion Device Measurement Systems at MAX IV Laboratory	insertion, insertion-device, controls, vacuum	4047
	M. Ebbeni, H. Tarawneh, A. Thiel MAX IV Laboratory, Lund University, Lund, Sweden
	An insertion device lab was setup at MAX IV Laboratory and the production of insertion devices, mainly out-of-vacuum is ongoing and aided by new magnetic measurement systems. A new 5.5 m long Hall probe bench is used for field map measurements and a new hybrid flip coil and stretch wire system will be used for field integrals of full devices as well as individual magnet blocks characterisation. This paper describes these magnetic measurement systems and their achieved and expected performance.
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THPOW049	Status of Insertion Devices at Taiwan Photon Source	vacuum, radiation, photon, polarization	4054
	T.Y. Chung, C.-H. Chang, C.H. Chang, M.-S. Chiu, J.C. Huang, C.-S. Hwang, J.C. Jan, C.-C. Kuo, Y.-C. Liu, F.H. Tseng, C.K. Yang NSRRC, Hsinchu, Taiwan
	The storage ring of Taiwan Photon Source (TPS) has eighteen short straight sections (length 7 m) and six long straight sections (length 12 m). In phase I, three elliptically polarized undulators of type APPLE II and seven in-vacuum undulators, which included four in-vacuum undulators and two elliptically polarized undulators in three double mini-βy sections, were installed. Commissioning of the insertion devices began in 2015 November. The influence of insertion devices on the electron beam and the results after compensation are presented. Problems during the commissioning induced by the electron beam and by radiation, and their solutions, are also explained. For insertion devices in phase II and for devices developed in TPS, the preliminary designs are presented herein, to cover from the VUV to the hard X-ray region.
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THPOW051	Design and Construction of Compact Electromagnetic Undulator for THz Radiation Production	radiation, electron, linac, insertion-device	4060
	C. Thongbai, N. Chaisueb, S. Rimjaem, J. Saisut, K. Thaijai-un Chiang Mai University, Chiang Mai, Thailand N. Kangrang Chiang Mai University, PBP Research Facility, Chiang Mai, Thailand P. Wichaisirimongkol Chiang Mai University, Science and Technology Research Institute, Chiang Mai, Thailand
	Funding: Chiang Mai University Research Fellowship Program The goal of this research is to design and construct a compact electromagnetic undulator. This insertion device will be installed at the PBP-CMU-LINAC system of Chiang Mai University (CMU), Thailand, to produce THz radiation. The undulator magnet is designed by using 2D POISSON and 3D RADIA computer code to optimize the magnet dimensions. The width of iron pole (W) should be 12 mm. The length of iron pole (L) should be about 80 mm long and the thickness of return yoke (d) should be more than 10 mm. The magnet design, the in-house con-struction of the magnet, and the measurement results will be presented.
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THPOW052	Recent Magnetic Measurement Activities at NSLS-II Insertion Device Laboratory	electron, vacuum, synchrotron, radiation	4063
	M. Musardo, P.L. Cappadoro, O.V. Chubar, T.M. Corwin, H.C. Fernandes, D.A. Harder, D.A. Hidas, C.A. Kitegi, B.N. Kosciuk, W. Licciardi, J. Rank, C. Rhein, T. Tanabe BNL, Upton, New York, USA
	National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) is a new 3 GeV third generation electron storage ring designated to provide extremely intense beams of X-ray, ultraviolet, and infrared light for basic and applied research. Insertion devices (IDs) play a significant role in achieving the high performance demands of NSLS-II. An accurate magnetic characterization and proper corrections of these devices are essential activities in the development of a state-of-the-art light source facility. This paper describes the results of the latest magnetic measurement activities at the NSLS-II ID laboratory.
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THPOY047	Comprehensive Approach to Synchrotron Radiation Protection of NSLS-II	radiation, synchrotron, synchrotron-radiation, electron	4211
	S. Seletskiy, T.V. Shaftan BNL, Upton, Long Island, New York, USA
	To protect the NSLS-II Storage Ring components from possible damage from synchrotron radiation produced by insertion devices (IDs) and bending magnets (BMs) the Active Interlock System (AIS) keeps electron beam within the AI safe envelope (AIE) in the transverse phase space. The NSLS-II beamlines (BLs) and frontends (FEs) are designed under assumption that above certain safe beam current the ID synchrotron radiation (IDSR) fan is produced by the interlocked e-beam. In this paper we describe a new approach to defining the AIS parameters and settings, which significantly simplifies the process of the FE and BL design.
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THPOY049	Helical Undulator as a Source of Spectromicroscopy Beamline of ILSF	polarization, electron, photon, radiation	4217
	S. Amiri, A. Gholampour, M. Jafarzadeh, M. Lamehi, J. Rahighi ILSF, Tehran, Iran M. Lamehi, J. Rahighi IPM, Tehran, Iran
	Regarding user requirements of spectromicroscopy beamline such as high flux, small spot size, linear and circular polarization light, a helical undulator have been chosen as a source for this beamline. Radiation properties of the source e.g. flux, flux density, brilliance, size and divergence of the photon beam, power, power density, angular distribution of power and flux on the axis of the undulator have been considered by theoretical formula and using SPECTRA code. At the circular polarization, the first harmonic covers the energies in the 100-1300 eV range and for the linear polarization energy ranges, 100-1000 eV and 1000-1500 eV, are provided by the first and third harmonics respectively. In the case of circular and linear polarization mode, maximum flux in the central cone for maximum undulator strength are 4.5 × 10¹⁶ (ph/s) at kX=ky=3.6 and 2.4 × 10¹⁶ (ph/s) at K=5. * James A. Clarke, "The science and technology of undulators and wigglers", 2004. ** H. Onuki, P. Elleaume, "WIGGLERS UNDULATORs and their APLICATIONS", 2003.
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Paper

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MOXBA01

Beam Commissioning of PAL-XFEL

gun, laser, linac, cathode

6

J.H. Han
PAL, Pohang, Kyungbuk, Republic of Korea

The Pohang Accelerator Laboratory X-ray Free electron Laser (PAL-XFEL) project aims at the generation of X-ray FEL radiation for photon users. The machine consists of a 10 GeV normal-conducting S-band linear accelerator (linac) and two undulator beamlines initially. The hard X-ray beamline will provide FEL radiation between 0.6 and 0.1 nm or shorter. The soft X-ray line will provide FEL radiation between 4.5 and 1 nm. The linac and hard X-ray beamline construction was complete by the end of 2015. The installation of the soft X-ray line is ongoing. High power RF conditioning of the linac started in late autumn 2015. Beam commissioning of the linac started in April 2016. We report the beam commissioning status.

Slides MOXBA01 [4.978 MB]

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MOPOR005

Longitudinal Wakefields in the Undulator Section of SXFEL User Facility

FEL, wakefield, vacuum, electron

595

M. Song, H.X. Deng, C. Feng, D. Huang, B. Liu, D. Wang
SINAP, Shanghai, People's Republic of China

Shanghai soft x-ray free electron laser (SXFEL) user facility based on multi-stage seeded-FEL and self-amplified spontaneous emission (SASE) is recently proposed, which is aiming at generating 4-2nm fully-coherent, high-brightness FEL pulse. In this paper, the wakefields arise from the resistive wall and surface roughness in the vacuum chamber is obtained by theoretical models*. And the computations of geometric wakefields are carried out using ABCI**. According to the tracked beam profile, the overall wakefields in the undulator section of SXFEL user facility are presented.
* K. Bane, G. Stupakov, SLAC-PUB-15951, May 2014.
** ABCI website: http://abci.kek.jp/abci.htm

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MOPOW005

First Electron Beam Measurements on COXINEL

electron, laser, plasma, quadrupole

712

T. André, I.A. Andriyash, C. Basset, C. Benabderrahmane, P. Berteaud, S. Bonnin, F. Bouvet, F. Briquez, L. Cassinari, L. Chapuis, M.-E. Couprie, D. Dennetière, Y. Dietrich, M. Diop, J.P. Duval, M.E. El Ajjouri, T.K. El Ajjouri, P. Gattoni, C. Herbeaux, N. Hubert, M. Khojoyan, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, P. Pierrot, F. Polack, F. Ribeiro, J.P. Ricaud, P. Rommeluère, M. Sebdaoui, K.T. Tavakoli, M.-A. Tordeux, M. Valléau, J. Vétéran, D. Zerbib, C. de Olivera
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, C. Evain, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
J. Gautier, E. Guillaume, G. Lambert, B. Mahieu, V. Malka, A. Rousse, K. Ta Phuoc, C. Thaury
LOA, Palaiseau, France
E. Roussel
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The ERC grant COXINEL aims at demonstrating experimentally Free Electron Laser (FEL) amplification with electrons generated by laser plasma acceleration (LPA). Because of the still limited electron beam performance (especially energy spread and divergence) in view of the FEL requirements, the electron beam transfer line has been specifically designed with adequate diagnostics and strong focusing variable strength permanent magnet quadrupoles, an energy de-mixing chicane and second set of quadrupoles for further dedicated focusing in the FEL interaction region, in a U20 in-vacuum undulator, enabling to operate at 200 nm with a 180 MeV electron beam. The first observation and transport of electrons in the COXINEL line is presented here.

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MOPOW008

Reverse Undulator Tapering for Polarization Control at XFELs

FEL, resonance, radiation, bunching

722

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 afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. We describe a method for such a suppression: an application of the reverse taper in the main undulator*. 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. The scheme was successfully tested at LCLS** and is routinely used in user experiments. In this contribution we present the theoretical description of the method as well as the results of experiments with reverse taper at FLASH2.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 16, 110702 (2013)
** H.-D. Nuhn et al., "Commissioning of the DELTA polarizing undulator at LCLS", Proc. of FEL2015 Conf., Daejeon, Korea

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MOPOW009

Studies of Harmonic Lasing Self-seeded FEL at FLASH2

FEL, simulation, electron, radiation

725

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

A concept of the Harmonic Lasing Self-Seeded (HLSS) FEL was proposed in*,**. A gap-tunable undulator is divided into two parts 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 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 post-saturation tapering would allow to generate higher peak power than in SASE mode due to an improved longitudinal coherence. We present feasibility study of the application of the HLSS FEL scheme at FLASH2 and show that it allows to achieve a higher power and a smaller bandwidth than in a standard SASE regime. First experimental tests are eventually discussed.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15 (2012) 080702
** E.A. Schneidmiller and M.V. Yurkov, "Harmonic Lasing Self-Seeded FEL", Proc. of FEL2013 Conf., New York, USA

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MOPOW011

Operation of Free Electron Laser FLASH Driven by Short Electron Pulses

radiation, electron, simulation, laser

732

V. Balandin, G. Brenner, C. Gerth, N. Golubeva, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov
DESY, Hamburg, Germany
E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Rönsch-Schulenburg, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength of 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.

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MOPOW013

Application of Statistical Methods for Measurements of the Coherence Properties of the Radiation from SASE FEL

radiation, FEL, electron, photon

738

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

Radiation of the SASE FEL operating in the linear regime possesses the properties of completely chaotic polarized light which happens due to start up of the amplification properties from the shot noise in the electron beam*. One of the features of this statistical object is that probability distribution of the radiation pulse energy follows gamma distribution. Parameter of this distribution is the number of modes in the radiation pulse which is equal to inverse deviation of the energy fluctuations. Statistical analysis of the radiation energies measured within different spatial apertures allows us to determine the number of longitudinal and transverse modes. In addition, knowledge of the saturation length allows to determine the duration of the lasing part of the electron bunch, photon pulse duration, and coherence time**. Knowledge of the number of transverse modes allows one to determine the degree of transverse coherence. In this report we present theoretical background of the proposed method and experimental results obtained at free electron laser FLASH.
* E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 148 (1998) 383.
** C. Behrens et al., Phys. Rev. ST Accel. Beams 15 (2012) 030707.

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MOPOW014

Measurements of Ultrasmall Charges with MCP Detector in FLASH Accelerator

detector, electron, photon, laser

741

O.I. Brovko, A.Yu. Grebentsov, A.V. Shabunov, E. Syresin
JINR, Dubna, Moscow Region, Russia
S. Schreiber, M.V. Yurkov
DESY, Hamburg, Germany

Structure of the dark current passed through the undulator is a matter of great concern. Two effects can contribute to the dark current: emission of electrons from "hot" spots in the gun, and generation of "ghost" bunches due to possible leakage of the photoinjector laser. MCP based photon detector has been used for measurements of radiation energy from electron bunch. For small radiation densities the light is detected by direct illumination of the MCP plate, and for large densities a small angle scattering scheme is realized when metallic mesh scatters tiny fraction of light on the MCP plate. In the present experiment we used geometry of direct illumination of MCP plate aiming detection of "ghost" bunches which may generate parasitically from the laser driven electron gun. Reduction of background conditions allowed us to detect light produced by electron bunches with extremely small charges, down to a few femtocoulmb. We measured for the first time structure of the dark current passing through the FLASH undulator. We have also been able to measure a high contrast of radiation produced by the photoinjector laser pulses switched on and off by a 1 MHz repetition rate Pockels cells.

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MOPOW016

Status of Design and Development of Delhi Light Source at IUAC, Delhi

laser, electron, radiation, gun

748

S. Ghosh, R.K. Bhandari, G.K. Chaudhari, V.J. Joshi, D. Kabiraj, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, P. Patra, B.K. Sahu, A.S. Sharma, A.S. Sthuthikkatt Reghu
IUAC, New Delhi, India
A. Aryshev, M.K. Fukuda, S. Fukuda, N. Terunuma, J. Urakawa, J. Urakawa
KEK, Ibaraki, Japan
A. Deshpande
SAMEER, Mumbai, India
V. Naik, A. Roy
VECC, Kolkata, India
T. Rao
BNL, Upton, Long Island, New York, USA

Funding: The project is supported jointly by Board of Research in Nuclear Sciences (BRNS) and IUAC
The demand for the photon beams for basic research is growing in India. To address the requirements, a project to develop a compact Light Source based on the principle of Free Electron Laser has been initiated at the Inter University Accelerator Centre (IUAC). In the first phase of the project, a normal conducting RF gun will be used to produce electron beam of energy ~ 8 MeV by using copper photocathode and subsequently by Cs2Te photocathode. A high power fiber laser with short pulse length is planned to be used to produce the pre-bunched electron beam by splitting the single laser pulse in to 16 pulses ("comb beam"). The electron beam will be injected in to a compact, variable gap undulator magnet to produce the THz radiation whose frequency can be tuned by varying the undulator field strength and the time separation of the comb beam. In the second and third phases of the project, superconducting RF gun and superconducting accelerating structure will be used to increase the energy of the electron beam up to ~ 40 MeV which will be used to produce IR radiation by using long undulator magnets and to produce X-rays by colliding the electron beam with another high power laser beam.

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MOPOW019

Commissioning Status of the Extreme-Ultraviolet FEL Facility at SACLA

FEL, electron, booster, laser

757

T. Sakurai, T. Asaka, N. Azumi, T. Hara, T. Hasegawa, T. Inagaki, T. Ishikawa, R. Kinjo, C. Kondo, H. Maesaka, T. Ohshima, Y. Otake, H. Tanaka, T. Tanaka, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Bizen, N. Hosoda, H. Kimura, S. Matsubara, S. Matsui
JASRI/SPring-8, Hyogo, Japan

To equip SACLA with wide ability to provide a laser beams in EUV and soft X-ray regions to experimental users, we have constructed a new free electron laser facility for SACLA beamline-1. Injector components, such as a thermionic electron gun, two buncher cavities, a S-band standing wave accelerator, S-band travelling wave accelerator and their RF sources, were relocated from the SCSS test accelerator, which was a prototype machine of SACLA. At the downstream of a bunch compressor chicane, three C-band 40 MV/m acceleration units were newly installed to effectively boost a beam energy up to 470 MeV. Two in-vacuum undulators were remodeled by changing the period of magnet array from 15 mm to 18 mm to increase SASE intensity by a larger K-value of 2.1. Beam commissioning was started in autumn 2015. So far SASE radiation at a 33 nm wavelength driven by a 470 MeV electron beam was observed. We will install the third undulator in this winter to obtain SASE saturation and additional C-band accelerator units in the next summer to raise the maximum beam energy to 750 MeV. In this presentation, the overview of the facility and the commissioning status will be reported.

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MOPOW020

Power Improvement of Free-Electron Laser Using Transverse-Gradient Undulator with External Focusing

FEL, focusing, radiation, electron

760

G. Zhou, Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China
J. Wu
SLAC, Menlo Park, California, USA
T. Zhang
SINAP, Shanghai, People's Republic of China

Funding: Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2015009)
Resent study [Z. Huang et al., Phys. Rev. Lett. 10⁹, 204801 (2012)] shows that the transverse-gradient undu-lator (TGU) together with electron beams with constant dispersion can reduce the sensitivity to energy spread for FEL. In this study, we numerically study FEL using TGU with external focusing. In spite of the dispersion varia-tion, through parameter optimization, FEL using TGU with TGU achieves similar radiation to that without ex-ternal focusing. To achieve a high energy exaction effi-ciency, the initial dispersion should be set with a shift from that corresponding to the resonant condition, and a variation of the transverse gradient in different undulator section is preferred. Other approaches, such as tapering and detuning frequency control, are also discussed to further improve the radiation power and are demonstrated with global parametric optimizations base on simulation.

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MOPOW022

Model-based Algorithm to Tune the LCLS Optics

quadrupole, optics, controls, electron

763

Z. Zhang
TUB, Beijing, People's Republic of China
Y. Ding, X. Huang
SLAC, Menlo Park, California, USA

Transverse phase space matching of electron beam to the undulator optics is important for achieving good performance in free-electron lasers. Usually there are dedicated matching quadrupoles distributed in the beamline, by measuring the beam phase space the matching quadrupoles are calculated and adjusted to match to the designed Twiss parameters. Further adjustment of the quadrupoles to overcome collective effects or realistic beamline errors is typically required for performance improvement. In this paper, we studied a method to decompose the Twiss parameters for an independent control of the phase space. Mathematical analysis and numerical simulations are both presented to show that through combining the quadrupoles into some multi-knobs, we can control the Twiss parameters independently. We also show some experimental results at the LCLS.

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MOPOW023

Proposal of an X-band Linearizer for Dalian Coherent Light Source

FEL, laser, electron, radiation

766

G.L. Wang, X.M. Yang, W.Q. Zhang
DICP, Dalian, People's Republic of China
H.X. Deng, C. Feng
SINAP, Shanghai, People's Republic of China

Dalian coherent Light Source (DCLS) is a FEL user facility working at 50-150 nm, now under commissioning in Dalian, China. The facility based on HGHG mode, requires high brightness electron beam with small energy spread and low emittance. To linearise the longitudinal phase space before the bunch compression, an X-band linearizer is considered before the bunch compressor. In this paper, we study the performance improvement of DCLS FEL radiation by using such a harmonic cavity, including the jitter of central wavelength induced by arriving time and a larger bunch compression ratio for femtosecond FEL application.

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MOPOW024

Harmonic Lasing Options for Dalian Coherent Light Source

FEL, radiation, laser, electron

770

G.L. Wang, X.M. Yang, W.Q. Zhang
DICP, Dalian, People's Republic of China
H.X. Deng, C. Feng
SINAP, Shanghai, People's Republic of China

Harmonic lasing of the Free Electron Laser can be achieved by disrupting the electron interaction with the usually dominant fundamental while allowing the increasing of a harmonic interaction. It's a cheap and relatively efficient way to extend the photon energy range of a particular FEL. In this paper, we discussed the possibility of harmonic lasing concept at Dalian Coherent Light Source by using the combination of tapered undulators and phase shifters. Our calculation shows that it's feasible with the present layout to provide intense, stable, and narrow-band harmonic radiation, the FEL wavelength could be down to 20 nm and the corresponding pulse energy is about 10 μJ.

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MOPOW026

Status of FELiCHEM, a New IR-FEL in China

FEL, radiation, cavity, electron

774

H.T. Li, Z.G. He, Q.K. Jia, Q. Luo, L. Wang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC), whose core device is a FEL oscillator generating middle-infrared and far-infrared laser and covering the spectral range of 2.5-200 μm. It will be a dedicated light source aiming at energy chemistry research, with the photo excitation, photo dissociation and photo detection experimental stations. We present the brief physical and technical design that delivers the required performance for this device and summarize the status of fabrication. Final assembly is scheduled for early in the next year with first light targeted for July 2017.

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MOPOW029

The Soft X-ray Self-seeding System Design for SXFEL User Facility

FEL, electron, simulation, photon

785

K.Q. Zhang, T. Liu, D. Wang
SINAP, Shanghai, People's Republic of China
Y. Feng
SLAC, Menlo Park, California, USA

X-ray free electron laser driven by SASE probes the evolution of the new generation light source in high brightness, transverse coherence. However, since SASE achieves lasing from random shotnoise, Poor longitudinal coherence and relative wide bandwidth of SASE FEL limit the operation of many type experiments. Self-seeding as a promising scheme produces longitudinal coherence and even narrower bandwidth radiation by a monochromatic seeding instead of external seeding. The self-seeding system design based on the grating monochromator is carried out for SXFEL user facility across the photon energy from 800-1200 eV. The grating monochromator with a resolution power of 〖10〗^-4 can provide a monochromatic seeding pulse to the seeding undulator. The layout design and simulations of the scheme are presented. It is showing that the self-seeding system for SXFEL user facility is able to improve SASE FEL longitudinal coherence significantly.

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MOPOW035

A Compact, Wavelength Tunable MW-THz FEL Amplifier

FEL, electron, laser, radiation

789

C.H. Chen, A.P. Lee
NSRRC, Hsinchu, Taiwan
F.H. Chao, Y.C. Chiu, Y.-C. Huang, M.H. Wu
NTHU, Hsinchu, Taiwan
G. Zhao
PKU, Beijing, People's Republic of China

We propose a compact scheme of THz free electron laser (FEL) amplifier within a 3.5 m long beam line. The amplification of a tunable THz seed laser in an FEL amplifier is driven by an rf photoinjector*. The THz seed laser is an optical parametric amplifier** pumped by a 1064-nm microchip laser and an external-cavity tunable diode laser. By varying the beam energy and undulator parameter, the radiation frequency of the THz FEL amplifier can be tunable in a broad spectral range between 1.5 and 3.0 THz. Moreover, to extract more radiation power from the electron beam within a short undulator, we employ a linearly tapered undulator in our design. The influence of the seed power on the electron-laser interaction in the undulator is studied in some detail for the FEL amplification. Our simulation results show that the radiation power of the THz FEL amplifier can achieve few MW with a 10-W seed power.
* D.T. Palmer et al., in Proceedings of Particle Acceleration Conference, Vancouver, 1997, p. 2687, (1997).
** S. Hayashi et al., SCIENTIFIC REPORTS, 4, 5045-1-6, (2014).

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MOPOW037

Developments in the CLARA FEL Test Facility Accelerator Design and Simulations

linac, FEL, space-charge, simulation

797

P.H. Williams, D. Angal-Kalinin, A.D. Brynes, J.A. Clarke, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.B. Appleby
UMAN, Manchester, United Kingdom
B. Kyle
University of Manchester, Manchester, 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. In order to prioritise FEL schemes requiring the shortest electron bunches, the layout has changed significantly to enable compression at higher energy. Four proposed modes of operation are defined and tracked from cathode to FEL using ASTRA. Supplementing these baseline mode definitions with CSR-enabled codes (such as CSRTRACK) where appropriate is in progress. The FEL layout is re-optimised to include shorter undulators with delay chicanes between each radiator.

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MOPOW040

High Efficiency, High Brightness X-ray Free Electron Lasers via Fresh Bunch Self-Seeding

electron, simulation, extraction, photon

805

C. Emma, C. Pellegrini
UCLA, Los Angeles, USA
M.W. Guetg, A.A. Lutman, A. Marinelli, C. Pellegrini, J. Wu
SLAC, Menlo Park, California, USA

High efficiency, terawatt peak power X-ray Free Electron Lasers are a promising tool for enabling single molecule imaging and nonlinear science using X-rays. Increasing the efficiency of XFELs while achieving good longitudinal coherence can be achieved via self-seeding and undulator tapering. The efficiency of self-seeded XFELs is limited by two factors: the ratio of seed power to beam energy spread and the ratio of seed power to shot noise power. We present a method to overcome these limitations by producing a strong X-ray seed and amplifying it with a small energy spread beam. This is achieved by selectively suppressing lasing for part of the bunch in the SASE section. In this manner we can saturate with the seeding electrons and amplify the strong seed with 'fresh' electrons downstream of the monochromator. Simulations of this scenario are presented for two systems, an optimal superconducting undulator design and the LCLS. In the case of the LCLS we examine how betatron oscillations leading to selective suppression are induced by using the transverse wakefield of a parallel plate dechirper. We also discuss extending the selective suppression scheme to chirped electron bunches.

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MOPOW048

Development of the LCLS-II Optics Design

linac, electron, optics, kicker

820

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

Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515.
The LCLS-II is a high repetition rate, high average brightness free-electron laser (FEL) under construction at the SLAC National Accelerator Laboratory. The LCLS-II will include new major components: a high repetition-rate injector, a superconducting, CW (continuous wave), 4-GeV linac with a bunch compressor system, a 3-way beam spreader, with independent hard X-ray (HXR) and soft X-ray (SXR) FEL undulators. The design is based on the existing SLAC facilities, including the LCLS linac and beam transport lines. The new SXR line will utilize a variable-gap undulator sharing the same tunnel with the new HXR horizontal-gap vertically polarizing undulator that will replace the existing LCLS undulator. We describe the current state of the electron optics design and the latest developments.

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TUZA01

Soft X-ray Free Electron Laser at SINAP

FEL, laser, electron, radiation

1028

D. Wang
SINAP, Shanghai, People's Republic of China

Shanghai X-ray FEL (SXFEL) is a test facility at Shanghai Institute of Applied Physics, Chinese Academy of Sciences originally designed for studying XFEL principle and technologies. It is composed of a warm linac to provide up to 840 MeV electron beam, an undulator line with cascaded EEHG-HGHG setup and a short diagnostic beamline. The project started the construction by the end of 2014. Recently a proposal to upgrade it to an user facility at the soft x-ray regime got approved. The talk will give an overview of the test facility construction and upgrade plan.

Slides TUZA01 [9.344 MB]

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TUZA02

Twin-bunch Two-colour FEL at LCLS

electron, laser, free-electron-laser, photon

1032

A. Marinelli, R.N. Coffee, F.-J. Decker, Y. Ding, R.C. Field, S. Gilevich, Z. Huang, D. Kharakh, H. Loos, A.A. Lutman, T.J. Maxwell, J.L. Turner, S. Vetter
SLAC, Menlo Park, California, USA

Twin electron bunches have been the subject of much investigation at the Linac Coherent Light Source, due to their many applications to X-ray free-electron lasers (X-FEL). Twin bunches are trains of two electron bunches that are accelerated and compressed within the same accelerating RF period. At LCLS, these bunches are used in the downstream FEL undulator to generate two X-ray pulses of different energies for pump/probe applications or de novo phase determination of protein crystals. The spectral and temporal shaping of the two bunches requires exquisite control of the compression system to vary the main parameters of the system in a controlled way (peak current, temporal delay and energy separation). I will discuss recent experimental and theoretical results on this subject. In particular I will focus on the demonstration of mJ-level two-color X-ray pulses using twin bunches, as well as the temporal and spectral control of this new mode of operation. Finally, I will discuss our experience with user experiments as well as our future directions of investigation.

Slides TUZA02 [5.738 MB]

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TUZB02

Challenge of In-vacuum and Cryogenic Undulator Technologies

vacuum, cryogenics, radiation, permanent-magnet

1080

J.C. Huang, C.-H. Chang, C.H. Chang, T.Y. Chung, C.-S. Hwang, C.K. Yang, Y.T. Yu
NSRRC, Hsinchu, Taiwan
H. Kitamura
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

An in-vacuum undulator (IVU) opens the utilization of high-brilliance X-rays in the medium energy storage rings. The development of a short-period undulator with low phase error becomes important to bring X-ray into a new unprecedented brilliant light source in an ultimate storage ring (USR). NdFeB or PrFeB cryogenic permanent magnet undulators (CPMUs) with a short period have been developed worldwide to obtain high brilliance of undulator radiation. A CPMU has high resistance against beam-induced heat load and allow to operate at a narrow gap. In a low emittance or ultimate storage ring, not only the performance of an undulator but the choice of the lattice functions is very important to obtain high bril-liance of synchrotron radiation. The optimum betatron functions and zero dispersion function shall be given for a straight section at IVU/CPMUs. In this paper, the relevant factors and design issues for IVU/CPMU will be discussed. Many technological challenges of a short-period undulator associated with beam induced-heat load, phase errors, and the deformation of in-vacuum girders will also be presented herein.

Slides TUZB02 [5.204 MB]

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TUOCB03

Magnet Development for SPring-8 Upgrade

dipole, sextupole, alignment, quadrupole

1093

T. Watanabe, T. Aoki, K. Fukami, S. Matsubara, C. Mitsuda, S. Takano, T. Taniuchi, K. Tsumaki
JASRI/SPring-8, Hyogo-ken, Japan
T. Hara, H. Kimura
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

One of the features for newly designed magnets for the SPring-8 major upgrade plan* is permanent magnet based dipole magnets for substantial energy saving. The new dipole magnets have been designed to be equipped with (i) a field variable function by controlling magnetic flux into a beam axis, (ii) a nose structure on iron poles for smooth B-field transition in the longitudinal gradient field, and (iii) a nearly zero temperature coefficient of magnet circuit with the help of a shunt alloy**. Demagnetization due to radiation is also a critical issue. At SPring-8, demagnetization process has been intensively studied, and the effect has been considered in the design of dipole magnets. Although electromagnet based multi-pole magnets are rather conventional technologies, yet new magnets need to be designed to fit in the next generation high packing factor lattice with as reasonably lower energy consumption as possible. Magnet alignment will be a key development as well; in order to secure adequate dynamic apertures, magnets ought to be aligned within tens of microns. Current design and recent progress in the developments of magnets and alignment schemes will be presented.
* H. Tanaka et al., SPring-8 Upgrade Project, in the abstracts.
** T. Taniuchi et al., Proc. of IPAC2015, WEPMA050.

Slides TUOCB03 [4.014 MB]

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TUPMB011

Calculation and Analysis of the Magnetic Field of a Transverse Gradient Undulator

simulation, electron, FEL, laser

1130

J. Li, B. Du, Q.K. Jia, H.T. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Transverse gradient undulator (TGU) is attracting more and more attentions, especially for the rapid progress of laser plasma accelerator techniques. The transverse gradient of TGU is usually given by an empirical formula simply derived from the empirical formula of a uniform-parameter undulator. In this paper, we numerically investigate the transverse magnetic field of TGUs using the RADIA code. Through many simulations for TGUs with different magnet structures, we have given the dependences of transverse gradient parameter on the cant angle, the undulator period and the average gap. Based on these results, when the cant angle is small and the rate of the gap and period is in the range of 0.4-0.6, the simulation results agree with the empirical formula well. But, with the growing of the cant angle, or with the growing of the deviation of the rate of the gap and period from the range of 0.4-0.6, the difference between the simulation results and the empirical formula becomes larger.

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TUPMB012

Optimization of the Field Integrals of Two Small Gap IDs for CLS

multipole, wiggler, vacuum, synchrotron-radiation

1133

M.F. Qian, Y.Z. He, H.F. Wang, W. Zhang, Q.G. Zhou
SINAP, Shanghai, People's Republic of China

An in-vacuum undulator and an in-vacuum wiggler have been developed for CLS at SSRF recently. The period lengths of the undulator and the wiggler are 20mm and 80mm respectively. Both IDs have the minimum gap of 5.2mm. The field integrals were measured for each magnet block with two poles and were sorted in-situ as they were installed on to the girders. Finally the field integrals of the undulator and the wiggler were shimmed by using the 'Magic Fingers' at the ends with a special algorithm. This paper reports the procedure and the results of the measurement and the optimization for the field integrals.

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TUPMB013

PAL-XFEL Magnet Design and Magnetic Measurement

dipole, quadrupole, multipole, laser

1136

H.S. Suh, S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park
PAL, Pohang, Kyungbuk, Republic of Korea

We have designed and tested magnets for PAL-XFEL of 10GeV in Pohang, Korea. These magnets consist of 6 families of 52 dipole magnets, 11 families of 236 quadrupole magnets, and 4 families of 10⁸ corrector magnets. Two hall probe benches are used to measure the magnetic field. This paper reviews the main parameters of these magnets and the results of magnetic field measurements.

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TUPOR018

Design Optimization of Compensation Chicanes in the LCLS-II Transport Lines

simulation, FEL, electron, space-charge

1695

J. Qiang, C.E. Mitchell, M. Venturini
LBNL, Berkeley, California, USA
Y. Ding, P. Emma, Z. Huang, G. Marcus, Y. Nosochkov, T.O. Raubenheimer, L. Wang, M. Woodley
SLAC, Menlo Park, California, USA

LCLS-II is a 4th-generation high-repetition rate Free Electron Laser (FEL) based x-ray light source to be built at the SLAC National Accelerator Laboratory. To mitigate the microbunching instability, the transport lines from the exit of the Linac to the undulators will include a number of weak compensation chicanes with the purpose of cancelling the momentum compaction generated by the main bend magnets of the transport lines. In this paper, we will report on our design optimization study of these compensation chicanes in the presence of both longitudinal and transverse space-charge effects.

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TUPOR023

Investigation of Trapped Resonant Modes in Insertion Devices at the Australian Synchrotron

resonance, feedback, vacuum, synchrotron

1710

R.T. Dowd, M.P. Atkinson, M.J. Boland, G. LeBlanc, Y.E. Tan
SLSA, Clayton, Australia
D. Teytelman
Dimtel, San Jose, USA

The Australian Synchrotron light Source has 3 variable gap in-vacuum undulators (IVU) in the storage ring. Since installation, these devices have been the source of strong beam instabilities. These instabilities seem to behave as trapped resonant modes of very high Q and high frequency, although a definite source has not been identified. The presence of these instabilities has necessitated operating at unusually high chromaticity for much of the light source's operations. More recently transverse feedback has been able to control the instabilities and recent developments in diagnostics have allowed some investigation of the frequency and mode response of these resonances. The results of this investigation will be presented in this paper.

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TUPOW009

Generation of Coherent Undulator Radiation using Extremely Short Electron Bunch at t-ACTS, Tohoku University

radiation, electron, bunching, injection

1760

S. Kashiwagi, T. Abe, H. Hama, F. Hinode, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

An accelerator test facility, t-ACTS, was established at Research Center for Electron Photon Science, Tohoku University, in which an intense coherent terahertz (THz) radiation is generated from an extremely short electron bunch. Velocity bunching scheme in a traveling-wave accelerating structure is employed to produce the short electron bunch, and a production of sub-picosecond electron bunch was demonstrated. A long-period linear undulator, which has 25 periods with a period length of 10 cm and a peak magnetic field of 0.41 T, has been developed to produce intense coherent THz radiation. Properties of the radiation from the THz undulator such as radiation fields, spectrum and angular distribution were numerically investigated based on the parameters of short electron bunch and THz undulator. By optimization of bunch compression, it is possible to extract a coherent radiation of fundamental mode excluding higher-order mode. The detail of the numerical studies for the coherent undulator radiation will be reported in the conference.

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TUPOW026

Optimization of Electron Beam Properties for Generation of Coherent THz Undulator Radiation at PBP-CMU Linac Laboratory

radiation, electron, linac, emittance

1803

N. Chaisueb, S. Rimjaem, J. Saisut, C. Thongbai
Chiang Mai University, Chiang Mai, Thailand

Funding: This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Chiang Mai University, and the Science Achievement Scholarship of Thailand.
Relativistic femtosecond electron bunches produced from the linear accelerator at the Plasma and Beam (PBP) Physics Research Facility are currently used to generate THz radiation via transition radiation. An upgrade to increase the intensity of the THz radiation by using a coherent undulator radiation method is conducted. Optimizations, measurements and analysis of the electron beam properties, which include current, energy and energy spread as well as electron bunch length, are performed to investigate the capability of electron beam production from the current accelerator system. This is also to estimate the possibility to produce the coherent undulator radiation of the PBP-CMU linac. Expected characteristics of the coherent undulator radiation are studied and reported in this contribution.
The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Material Science and the Graduate School, Chiang Mai University.

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TUPOW051

Optimization of Electron Beam and Laser Pulse Alignment and Focusing at Interaction Point for a Compact FEL Based Inverse-Compton Scattering X-Ray Source

electron, laser, photon, FEL

1881

P. Niknejadi, J. Madey
University of Hawaii, Honolulu,, USA

Funding: This work was funded under the Department of Homeland Security Grant No. 2010-DN-077-ARI045.
In July 2015, the first beam of 10 keV X-rays from our FEL based inverse-Compton scattering X-ray source was detected.* In this setup, 3 micron laser pulses at 2.856 GHz repetition rate from a free electron laser are collided head-on with 40 MeV electron bunches driving the laser. To attain our objective the ebeam was required to have 1) a tight focus at the X-ray interaction point, 2) vertical and horizontal envelopes matched to the downstream undulator, 3) minimized transverse dimensions for low ionizing radiation. Optimization of these quantities required information on the evolution of the beam profiles between the beam spot images on the available insertable screens, leading to the need for a simulator to accurately trace the beam profiles through the system. A simulator was developed and used to optimize the system Twiss parameters by comparing the effectiveness of the beam profiles computed by fitting the profiles to the observed beam spot images along the beamline for different cathode positions. This method proved to be considerably more flexible and effective than the more traditional quadrupole scan technique. Summery of the designed system and results are provided.
* John M. J. Madey, ARI final report, December 2015.

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WEOAA03

Experimental Study on Optical Vortex from a Helical Undulator at UVSOR-III

radiation, experiment, synchrotron, synchrotron-radiation

2036

M. Hosaka
Nagoya University, Nagoya, Japan
M. Katoh, N.S. Mirian
UVSOR, Okazaki, Japan
T. Konomi, N. Yamamoto
KEK, Ibaraki, Japan
K. Kuroda
ISSP, Kashiwa-shi, Japan
K. Miyamoto, S. Sasaki
HSRC, Higashi-Hiroshima, Japan

A relativistic electron in helical undulator emits an optical vortex which carries orbital angular momentum. Sasaki and McNulty predicted theoretically that higher harmonics of helical undulator is optical vortex* and the experimental verification was made at BESSY** and UVSOR-III***. Further, we have made a systematic study to characterize the optical vortex from a helical undulator at UVSOR-III. Synchrotron radiation in UV region from an optical klystron undulator system consisting of two APPLE-II helical undulators and a buncher was used for the experiment. Patterns resulting from inferences between two undulator radiation carrying different angular momentums were clearly observed. To investigate the optical properties of the radiation, diffraction experiments were carried out. Specific diffraction patterns due to the phase singularity in the radiation center were clearly observed. The experimental results are compared with simulation.
* S. Sasaki, I. McNulty, Phys. Rev. Lett. 100, 124801 (2008)
** J. Bahrdt et al., Phys. Rev. Lett. 111, 034801 (2013)
*** e.g. S. Sasaki et al., presented in SRI2015 (2015)

Slides WEOAA03 [11.023 MB]

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WEPMR048

Hall Element Relative Position and Angle Calibrations for the Cryogenic Permanent Magnet Undulator

vacuum, cryogenics, permanent-magnet, dipole

2386

L. Gong, W. Chen, W. Kang, L.Z. Li, H.H. Lu, Y.F. Yang
IHEP, Beijing, People's Republic of China

A three dimensions Hall probe will be manufactured for characterizing the magnetic performance of Cryogenic Permanent Magnet Undulator (CPMU) of Chinese High Energy Photon Source and the test facility (HEPS-TF) at Institute of High Energy Physics (IHEP). The positional and angular misalignment errors of the Hall sensors play an important role in the measurement accuracy of CPMU. In order to minimize the misalignment errors, a method of calibrating relative displacements and assembly angles of a 3-D Hall probe is carried out. In this paper, details of the calibration procedures and the data processing are presented.

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WEPMR053

Technical Overview of Cavity BPM Mover for PAL XFEL

cavity, controls, operation, EPICS

2395

H.-G. Lee, S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, K.W. Kim, S.B. Lee, D.H. Na, B.G. Oh, K.-H. Park, H.S. Suh, Y.J. Suh
PAL, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory(PAL) has been developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. The cavity BPM mover was developed to be used in the intersections of the Undulator Systems. The main specifications include submicron repeatability for a 50 kg cavity BPM adjusting system within compact dimensions and a ±1.5 mm stroke in the vertical and horizontal direction. Compact linear motion guide based on 5-phase stepping motors have been chosen. A closed-loop control system has been developed to achieve this repeatability. For the feedback, one digital probe sensor for each axis was used. Mechanical switches are used to limit movement. In addition, hard-stops are included for emergency. In this report, we describe the design of the stages used for precise movement and results of mechanical measurements including reproducibility will be reported.

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WEPMY025

iMPACT, Undulator-Based Multi-Bunch Plasma Accelerator

plasma, wakefield, electron, simulation

2609

O. Mete Apsimon, K. Hanahoe, G.X. Xia
UMAN, Manchester, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
B. Hidding
USTRAT/SUPA, Glasgow, United Kingdom
J.D.A. Smith
Tech-X, Boulder, Colorado, USA

Funding: This work is supported by the Cockcroft Institute Core Grant and STFC.
The accelerating gradient measured in laser or electron driven wakefield accelerators can be in the range of 10-100GV/m, which is 2-3 orders of magnitude larger than can be achieved by conventional RF-based particle accelerators. However, the beam quality preservation is still an important problem to be tackled to ensure the practicality of this technology. In this global picture, the main goals of this study are planning and coordinating a physics program, the so-called iMPACT, that addresses issues such as emittance growth mechanisms in the transverse and longitudinal planes through scattering from the plasma particles, minimisation of the energy spread and maximising the energy gain while benchmarking the milestones. In this paper, a summary and planning of the project is introduced and initial multi-bunch simulations were presented.

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WEPOW014

Spectral Studies of Ultrashort and Coherent Radiation Pulses at the DELTA Storage Ring

laser, radiation, electron, bunching

2851

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

Funding: Work supported by the BMBF (05K13PEC, 05K13PE3), the DFG (INST 212/236-1 FUGG), the Stiftung Mercator (Pr-2014-0047) and the state of NRW.
At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort and coherent radiation pulses in the VUV and THz regime are routinely generated by the interaction of electron bunches with 45-fs laser pulses. A laser-induced modulation of the electron energy is converted into a density modulation (microbunching) by a magnetic chicane, giving rise to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). As a first step towards active control of the shape and spectrum of CHG pulses, spectral studies were performed under variation of the chicane strength and the laser properties. The spectral phase of the laser pulses was controlled by tuning the compressor of the laser amplifier and was monitored using FROG (frequency-resolved optical gating). In this paper, monochromator scans as well as single-shot spectrograms of the CHG radiation are presented and compared to simulations of the laser-electron interaction and microbunching process. In addition, other results from the short-pulse facility as well as a future upgrade employing the echo-enabled harmonic generation (EEHG) scheme will be outlined.

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WEPOW019

SPring-8 Upgrade Project

emittance, operation, laser, radiation

2867

H. Tanaka, T. Ishikawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
S. Goto, S. Takano, T. Watanabe, M. Yabashi
JASRI/SPring-8, Hyogo, Japan

Plans are underway for the upgrade of the SPring-8 facility, targeting completion in the early 2020's. Sustainability is a key guiding principle for the fourth-generation X-ray source - a beam emittance of around 100 pm.rad is pursued simultaneously with substantial energy-saving. The three key features of the design are (i) to replace the main dipole electric magnets with permanent magnets, (ii) to reduce the electron beam energy from 8 to 6 GeV, and (iii) to use the SACLA linac as an injector. Lowering the beam energy leads to reduction of (a) beam emittance, (b) magnetic fields, (c) the lengths of ID straight sections to maintain larger spaces for the magnets, and (d) the RF power consumption. Timeshare use of the SACLA linac enables beam injection to the upgraded ring with a low-emittance and short-pulsed beam as well as a reduction of injector power consumption by stopping the present injector consisting of a 1-GeV linac and a booster synchrotron. The outline of the upgrade plan will be reported with the current status of R&D started in 2015.

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WEPOW020

Present Status of KEK Photon Factory and Future Project

emittance, lattice, storage-ring, operation

2871

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

Two synchrotron radiation sources of KEK, the PF-ring and the PF-AR, continue their user operation with various improvements. Scrap and build of the first generation undulators of 1980s at the PF-ring is pushed forward year by year. Five new elliptically polarized undulators have been installed in these five years, and we have also installed four very narrow-gap short-period undulators generating high brilliant X-ray. The new beam transport line that enables the 6.5-GeV full energy injection for PF-AR will be completed by the end of 2016 in order to make the top-up operation of the two SR sources compatible with the continuous injection for two main rings of the Super-KEKB. We have proposed a project of further upgrade of the 2.5-GeV PF-ring to improve its horizontal emittance as 8 nm rad using combined bending magnets at the arc sections. And we are also moving ahead on proposal of constructing a new KEK light source of an extremely low emittance as 0.3 nm rad. The progress and detail of our future project will be described in this paper.

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WEPOW042

Properties of Synchrotron Radiation from Segmented Undulators based on a Wigner Distribution Function

electron, brilliance, radiation, photon

2933

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

Three long straight sections with a double mini-βy lattice were designed in Taiwan Photon Source. For the purpose to understand whether the brilliance can be enhanced or not when two collinear undulators were installed in the double mini-βy. Therefore, the Wigner distribution function (WDF) is developed to calculate the brilliance in the double mini-βy lattice that is a natural way to describe a synchrotron radiation source. Herein, the brilliance is thereby calculable without a Gaussian approximation used in a conventional manner. Some important optical properties such as the degree of coherence can be directly calculated with this method. We use it as an example to investigate the properties of radiation from a segmented undulator.

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WEPOW043

Accelerator Based Light Source Projects of Turkey

FEL, electron, linac, radiation

2936

A.A. Aksoy, Ö. Karslı, C. Kaya
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
B. Ketenoğlu, O. Yavaş
Ankara University, Faculty of Engineering, Tandogan, Ankara, Turkey
Z. Nergiz
Nigde University, Nigde, Turkey

Three light source project is ongoing in Turkey within the frame of Turkish Accelerator Center (TAC) Project which has been supported by Ministry of Development since 2006. As a first facility of TAC, 3-250 μ mm IR-FEL facility (TARLA) based on superconducting accelerator with an energy of maximum 40 MeV is under construction at Institute of Accelerator Technologies of Ankara University. In addition to TARLA, Conceptual/Technical Design Report of a third generation synchrotron radiation facility based on 3 GeV, and a fourth generation FEL facility based 1-6 GeV is being prepared for the next steps of TAC. Therewithal a proton accelerator facility with up 2 GeV and an electron-positron collider as a super charm factory are proposed within the frame of TAC project. In this presentation, current status of TARLA project and main goals, road map of Turkish Light Sources will be explained.

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WEPOW051

R+D Progress Towards a Diffraction Limited Upgrade of the ALS

vacuum, injection, emittance, storage-ring

2962

C. Steier, A. Anders, J.M. Byrd, K. Chow, S. De Santis, R.M. Duarte, J.-Y. Jung, T.H. Luo, H. Nishimura, T. Oliver, J.R. Osborn, H.A. Padmore, G.C. Pappas, D. Robin, F. Sannibale, D. Schlueter, C. Sun, C.A. Swenson, M. Venturini, W.L. Waldron, E.J. Wallén, W. Wan, Y. Yang
LBNL, Berkeley, California, USA

Funding: This work was supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231.
Improvements in brightness and coherent flux of about two orders of magnitude over operational storage ring based light sources are possible using multi bend achromat lattice designs. These improvements can be implemented as upgrades of existing facilities, like the proposed upgrade of the Advanced Light Source, making use of the existing infrastructure, thereby reducing cost and time needed to reach full scientific productivity on a large number of beamlines. An R&D program was started at LBNL to further develop the technologies necessary for diffraction-limited storage rings. It involves many areas, and focuses on the specific needs of soft x-ray facilities: NEG coating of small chambers, swap-out injection, bunch lengthening, magnets/radiation production, x-ray optics, and beam physics design optimization. Hardware prototypes have been built and concepts and equipment was tested in beam tests on the existing ALS.

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WEPOW053

CESR Lattice for Two Beam Operations with Narrow Gap Undulators at CHESS

lattice, injection, operation, simulation

2968

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

Funding: Work was supported by NSF DMR-0936384 and NSF DMR-1332208.
CESR has operated as a dedicated light source since the conclusion of colliding beam program in 2008. Two undulators with a 6.5mm-vertical gap were installed in Fall 2014, replacing a wiggler in the sextant of CESR that is the home to all CHESS beam lines. In order to operate narrow gap undulators with two beams, CESR pretzel lattice was redesigned so that e^- and e⁺ orbits are coincident in one machine sextant but separated in return arcs. In particular both e^- and e⁺ orbits are on axis through undulators. This "arc-pretzel" lattice has been the basis for undulator operation. To better understand the beam dynamics and improve machine performance, we developed many simulation tools: undulator modeling, injection tracking, etc. With installation of an additional quadrupole near undulators, the CESR lattice will be further modified with a low beta waist in the insertion devices, allowing a more than two fold reduction of local beta functions. This reduction is anticipated to mitigate the effects of small aperture and undulator field errors and to enhance the xray brightness. The characterization of the lattice will be compared with measurements of injection efficiency, tune scans, etc.

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WEPOY001

First Field Integral Measurement Campaign for Air Coil

controls, power-supply, operation, LabView

2991

Z. Zhao, B. Du, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China
S. Karabekyan, J. Pflüger, M. Yakopov
XFEL. EU, Hamburg, Germany

For the operation of the air coils, which are needed for the undulator segments of the European x-ray free-electron laser (E-XFEL), precise conversion constants are needed to properly convert excitation current to steering strength. This paper describes the measurement of all 200 air coils, needed for this purpose using the short moving wire (MW) system. A LabView program was developed to measure the distribution of first field integral of both vertical (B_y) and horizontal (B_z) magnetic field components in the median plane of an air coil automatically. The program is an adaptation of the existing program, which was used to characterize magnetic properties of the phase shifters (PS). Before doing the measurements the new program automatically finds the centers of B_y and B_z components, which are found to match with the geometrical centers with sufficient accuracy. After the measuring procedure is complete, the results are presented as graphics output and final tables. It shows that the measurement results can fully meet the design requirements of E-XFEL. For all measurements the excitation current of the coils was set to 1 Ampere.

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WEPOY021

Nonlinear Phase Distortion in a Ti:Sapphire Optical Amplifier for Optical Stochastic Cooling

laser, radiation, kicker, pick-up

3024

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
V.A. Lebedev, P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the US DOE under contract DE-SC0013761 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
Optical Stochastic Cooling (OSC) has been considered for future high-luminosity colliders as it offers much faster cooling time in comparison to the micro-wave stochastic cooling. The OSC technique relies on collecting and amplifying a broadband optical signal from a pickup undulator and feeding the amplified signal back to the beam. It creates a corrective kick in a kicker undulator. Owing to its superb gain qualities and broadband amplification features, Titanium:Sapphire medium has been considered as a gain medium for the optical amplifier (OA) needed in the OSC*. A limiting factor for any OA used in OSC is the possibility of nonlinear phase distortions. In this paper we experimentally measure phase distortions by inserting a single-pass OA into one leg of a Mach-Zehnder interferometer. The measurement results are used to estimate the reduction of the corrective kick a particle would receive due to these phase distortions in the kicker undulator.
* A. Zholents, and M. Zolotorev. Proc. PAC'97, 1805 (1998).

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WEPOY022

Light Optics for Optical Stochastic Cooling

radiation, kicker, electron, pick-up

3028

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
V.A. Lebedev, P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the US DOE under contract DE-SC0013761 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
In Optical Stochastic Cooling (OSC) radiation generated by a particle in a "pickup" undulator is amplified and transported to a downstream "kicker" undulator where it interacts with the same particle which radiated it. Fermilab plans to carry out both passive (no optical amplifier) and active (optical amplifier) tests of OSC at the Integrable Optics Test Accelerator (IOTA) currently in construction*. The performace of the optical system is analyzed with simulations in Synchrotron Radiation Workshop (SRW) accounting for the specific temporal and spectral properties of undulator radiation and being augmented to include dispersion of lens material.
* V. Lebedev, et al., Proc. COOL'15 (in press, 2015).

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WEPOY028

Laser Heater System Test at PAL-XFEL ITF

laser, electron, FEL, bunching

3048

J. H. Lee
POSTECH, Pohang, Kyungbuk, Republic of Korea
J.H. Han, J.H. Hong, C.H. Kim, I.S. Ko, S.J. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

Coherent x-ray photons are generated by a free electron laser (FEL). In PAL-XFEL, a photon beam with a 0.1 nm wavelength is generated from an electron bunch based on self-amplified spontaneous emission (SASE). An electron bunch with an uncorrelated energy spread in a level of 3 keV, which is generated from the photocathode RF gun, may be sensitive to longitudinal micro-bunching instability. The energy spread of an electron bunch can be increased to suppress the instability by Landau damping. In order to control the uncorrelated energy spread, a laser heater system, which has a chicane with four dipoles chicane and a 0.5 m long undulator, was installed in the injector test facility (ITF) of PAL. In this paper, we introduce the parameters of the laser heater and heating effect on the electron bunch.

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WEPOY035

Free Electron Laser Simulation Tool Based on FDTD/PIC in the Lorentz Boosted Frame

FEL, simulation, radiation, electron

3061

A. Yahaghi, A. Fallahi, F.X. Kärtner
CFEL, Hamburg, Germany
F.X. Kärtner
MIT, Cambridge, Massachusetts, USA

Funding: Alexander von Humboldt-Foundation European Research Council(ERC)
Free Electron Lasers (FELs) are promising sources capable of generating electromagnetic waves in the whole spectrum. Therefore, it is crucial and additionally very useful to develop sophisticated though complete simulation tools. This goal is mainly motivated by our research focus on the development of compact X-ray sources based on radiation in optical undulators. The currently existing softwares are usually written to tackle special cases with particular approximations, such as 1D FEL theory, steady state, slow wave and forward wave approximation, wiggler-averaged electron motion and slices approximation. Many of the above approximations are hardly valid when sub-femtosecond bunches interact with intense optical lasers. The presented software aims the analysis of the FEL interaction without considering any of the above approximations. The developed tool apparently suffers from long computation times but offers a more accurate picture on the radiation process. In order to overcome the problem of multidimensionality, we exploit Lorentz boosted coordinate system and implement Finite Difference Time Domain (FDTD) method combined with Particle in Cell (PIC) simulation in this frame.

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THPMB013

Proposal of 6 GeV Energy Recovery Linac Hybrid Machine

electron, positron, linac, cavity

3254

M. Shimada, K. Yokoya
KEK, Ibaraki, Japan
R. Hajima
JAEA, Ibaraki-ken, Japan
M. Tecimer
University of Hawaii at Manoa, Honolulu, USA

We proposed 6 GeV Energy Recovery Linac (ERL) as an intense gamma-ray source for the polarized positron source of International Linear Collider (ILC)*. In this scheme, Coherent Synchrotron Radiation from quasi-CW 6 GeV electron beam is stacked in optical cavity at middle infrared region, and it is used for inverse Compton scattering to generate 10 MeV polarized gamma-ray. The same 6 GeV superconducting linac accelerates both the electron and positron beams up to 5 GeV for injection to the dumping ring. Furthermore, it is available for X-ray light source by adding another recirculation loop. It can be expected as a diffraction limit light source at 10 keV, and the target of the brilliance is 10^22-23 ph/s/mm²/mrad²/b.w.0.1%.
* M. Shimada, Proceedings of IPAC'13

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THPMB024

Error Analysis for the Lattice of FELiChEM

FEL, simulation, lattice, emittance

3278

S. Huang, Z.G. He, W. Xu, S.C. Zhang, T. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC).The facility consists of the middle-infrared (MID-FEL) beam line for 2.5-50 um and the Far-infrared (FAR-FEL) beam line for 40-200um. To achieve the design FEL performance of IR-FEL, the beam with 30 mm-mrad emittance, 5 ps rms length and 1nC bunch charge is required. We conduct error analysis in order to evaluate the tolerances of machine parameters and alignments. In this paper, we simulate the orbit corrections and emittance growth under exist of misalignments and strength errors of magnets. The simulation results show that the trajectory errors can be corrected to mm levels in the whole lattice and the emittance increase is acceptable. At the entrance of undulator, the position and angular errors can be corrected very well. So the trajectory can be controlled in the undulator to meet the requirement of FEL.

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THPMB027

Beam Transport Line of the LPA-FEL Facility Based on Transverse Gradient Undulator

FEL, radiation, beam-transport, laser

3287

T. Liu, B. Liu, D. Wang, T. Zhang
SINAP, Shanghai, People's Republic of China
Z. Huang
SLAC, Menlo Park, California, USA
J.S. Liu
Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China

Free electron lasers (FELs) based on Laser Plasma Accelerators (LPAs) present a main research direction for achieving next generation compact advanced light sources. There are several major challenges of the LPA beam to generate high-brilliance FEL radiation including the large initial angular divergence and the large energy spread. Based on the LPA facility in SIOM that has successfully obtained quasi-monochromatic beam with the central energy of hundreds of MeV, a specific design of a beam transport line is proposed to realize FEL gain using Transverse Gradient Undulator to compensate the relatively large beam energy spread. This beamline uses a single dipole, several strong focusing quadrupoles and correcting sextupoles to match proper beta functions and linear dispersion from the LPA beam to FEL radiation. The corresponding experimental facility of LPA-FEL in SIOM has been set up and will perform first tests to generate FEL radiation.

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THPMB050

The Commmissioning of Phase-I Insertion Devices in TPS

storage-ring, coupling, lattice, radiation

3360

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

The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at Natioal Synchrotron Radiation Research Center, next to the Taiwan Light source (1.5 GeV). On March 26, 2015, the TPS storage ring with two 5-cell PETRA cavities has successfully operated in 100 mA in top-up mode without the installation of insertion devices (IDs). To reach the design goal of 500 mA, the machine was shut down for 5 months to replace PETRA cavitites with superconducting RF (SRF) cavities and to install 10 IDs: 7 in-vacuum undulators (IU) and 3 elliptically polarized undulators (EPU). The commissioning of TPS storage ring with SRF cavities and IDs began in Sep. 2015. In this paper, we present our results and proceedures of ID commissioning.

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THPMB052

Studies on Electron Beam Injector System for Linac-based Coherent Thz Source in Thailand

electron, gun, linac, simulation

3366

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

Funding: The Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and the Development and Promotion of Science and Technology Talents Project (DPST).
At the Plasma and Beam Physics Research Facility, Chiang Mai University, a thermionic cathode RF electron gun and alpha magnet are used together as an injector system for a linac-based THz source. Investigate the optimal performance of the injector system, beam dynamic simulations are performed by computer codes PARMELA, ASTRA and ELEGANT. The input 3D field distributions of the RF-gun for PARMELA and ASTRA simulations are obtained from the RF modeling program CST Microwave Studio. The beam transport calculation using the program ELEGANT is performed to study behavior of electrons from the gun exit through the alpha magnet, a travelling wave linac, magnet elements, drift tubes, and related beam diagnostic components. Energy slits inside the alpha magnet vacuum chamber is used to select electrons with desired kinetic energies. The alpha magnet compresses electron bunches with certain bunch length before the beam entering the linac to obtain minimum energy spread and shortest bunch length at the experimental station. Results of electron beam optimization with appropriated conditions for generation of intense coherent THz radiation will be reported and discussed in this contribution.
This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and DPST.

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THPMR017

Resonance Island Experiments at BESSY II for User Applications

photon, operation, resonance, experiment

3427

P. Goslawski, J. Feikes, K. Holldack, A. Jankowiak, M. Ries, M. Ruprecht, A. Schälicke, G. Wüstefeld
HZB, Berlin, Germany
R. Ovsyannikov
BESSY GmbH, Berlin, Germany

Beam storage close to a tune resonance (Qx = 1/3, 1/4) can generate resonance island buckets in the x,x' phase space providing a second stable island orbit winding around the standard orbit. Experiments with such an operation mode have been conducted at BESSY II and the Metrology Light Source (MLS)*,**. The two orbits are well separated, with good life time and stability. Such operation mode will offer additional operation flexibility and allows users to choose their radiation source point from one or the other orbit. It has the potential to fulfill simultaneously conflicting user demands, e.g., high vs. low beam current and single or few bunch filling vs. multibunch filling. We discuss the required beam optics setup and present successful measurements taken at photon beamlines at BESSY II.
* P. Goslawski et al., "Bunch Separation by Transverse Resonance Island Buckets", ESLS XXIII Workshop, 2015, Villigen, Switzerland.
** M. Ries et al., Proc. IPAC 2015, Richmond, USA, MOPWA021.

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THPMY028

Technical Overview of the PAL-XFEL Conventional Facility

site, simulation, linac, survey

3715

I. Mok, M.S. Hwang, T.-H. Kang, K.W. Kim, K.R. Kim, S.H. Kim, S.N. Kim, Y. C. Kim, B.H. Lee, H.M. Lee, M.S. Lee, B.I. Moon, K.W. Seo, C.H. Son, C.W. Sung, J. Yang
PAL, Pohang, Republic of Korea
Y.C. Kim, J.H. Lee
Haenglim Architecture & Engineering Co. Ltd, Seoul, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.W. Yong
Posco Engineering & Construction., Ltd., Gyeongsangbuk-do, Republic of Korea

Pohang Accelerator Laboratory (PAL) has finished construction of a 1,110m long 10GeV X-ray free electron laser (XFEL) linear accelerator building in FY2015. In order to secure high-sensitive of XFEL accelerating devices, more advanced and well proven technologies were adopted in the design of the building. These are the ground improvement underneath the tunnel and tunnel structure itself against the possible ground deformation, air conditioning system to maintain the temperature and humidity in the tolerable ranges and architectural zoning. In this paper we describe the features of design and construction of the XFEL accelerator building.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY028

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THPMY043

Collimation System Design for LCLS-II

linac, collimation, gun, electron

3755

M.W. Guetg, P. Emma, M. Santana-Leitner, J.J. Welch, F. Zhou
SLAC, Menlo Park, California, USA

Funding: DOE contract \#DE-AC02-76SF00515
The planned LCLS-II FEL has an average beam power of up to 1.2 MW and a repetition rate of up to 1 MHz, both of which entail serious challenges for beam halo collimation. This paper summarizes the efforts to assess the proposed collimation system. The undulator section is specifically focused on due to its high loss sensitivity (maximal 12 mW). This proceedings concentrate on field emissions of the gun. Different dark current distribution, linac configurations and simulation programs were used to increase assurance of the results. Filled phase-space tracking further supplemented an independent prove of the collimation system effectiveness and expands to include beam-halo originating from different sources than the gun.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY043

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THPOR036

Updates on the Sliding Contact Cooling ILC Positron Source Target Development

target, vacuum, positron, radiation

3865

W. Liu, D.S. Doran, R.A. Erck, G.R. Fenske, W. Gai, V.J. Guarino
ANL, Argonne, Illinois, USA

The R&D of the baseline positron source target for ILC is still ongoing after TDR due to the uncertainty of rotating vacuum seal and water cooling system of the fast spinning target wheel. Different institutes around the globe have proposed different approaches to tackle this issue. A spinning target wheel system with sliding contact cooling has been proposed by ANL. The proposed system eliminated the needs of rotating vacuum seal by using magnetic torque coupler to drive the solid spinning wheel target. The energy deposited from positron production process is taken away via cooling pads sliding against the spinning wheel. A full size test wheel has been built and some initial tests have been done with promising outcomes. Results of these tests are presented in this paper along with a plan for developing a prototype.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR036

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THPOW030

ELI Eectron Beam Line for Laser-plasma-driven Undulator X-ray Source

electron, quadrupole, laser, photon

4005

A.Y. Molodozhentsev
KEK, Ibaraki, Japan
L. Pribyl
Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic

ELI LUX experiment of the ELI-Beamlines Project is based on electron beam, accelerated by the laser plasma wakefield. ELI LUX aims to deliver for users the X-ray beams with radiation length (0.4-4.5)nm and the peak brilliance up to 10²³ photons/(s mrad2 mm2 0.1% B.W.), which makes this source comparable with modern synchrotron sources. To provide small transverse size of the electron beam and small transverse beam divergence in the undulator, permanent quadrupole magnets with high gradient of the magnetic field up to 510 T/m are used in the electron beam line. In frame of this report we present main features of the designed electron beam line. 3D modeling of the magnetic field in the quadrupole magnets has been performed. Effects of the chromatic and spherical aberrations are taken into consideration. The electron beam dynamic is studied by using symplectic integration though the 3D field maps of the permanent quadrupole magnets. Effects of the space charge of the electron beam, beam collimation, injection and alignment errors and realistic field errors are discussed. Finally parameters of the photon beam, generated in compact undulator, are presented in this report.

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THPOW037

Simulated and Measured Magnetic Performance of a Double APPLE-II Undulator at the Canadian Light Source

multipole, polarization, photon, dipole

4025

C.K. Baribeau, L.O. Dallin, J.M. Helfrich, T.M. Pedersen, M.J. Sigrist, W.A. Wurtz
CLS, Saskatoon, Saskatchewan, Canada

Assembly and shimming are underway for a double APPLE-II type elliptically polarized undulator (i.e. two magnet arrays installed side by side on a single support structure) at the Canadian Light Source. The device is planned to be installed in spring 2017. Extensive preparation was done prior to device assembly, particularly in development of a simulated annealing algorithm for magnet virtual shimming, as well as assembly procedures that minimized positional errors in the installed magnet blocks. In this paper we present measurements taken throughout the shimming process, and compare with predictions from a RADIA model where each magnet block was magnetized uniquely according to individual Helmholtz coil measurements.

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THPOW038

First Results from Two Novel In-vacuum Magnetic Field Measurement Devices as Built at HZB

vacuum, feedback, controls, shielding

4028

J. Bahrdt, H.-J. Bäcker, J. Bakos, H. Bieder, W. Frentrup, A. Gaupp, S. Gottschlich, C. Kuhn, C. Rethfeldt, M. Scheer, B. Schulz
HZB, Berlin, Germany

The characterization of cryogenic in vacuum permanent magnet undulators with periods less than 20 mm and correspondingly narrow gaps requires new in-vacuum measurement systems. The positioning accuracy of the HZB in-vacuum Hallprobe bench has substantially been improved (a few μm) with appropriate feedback systems. A new in-vacuum cable tray has been developed. Another system for field integral measurements, an in-vacuum moving wire, is under commissioning. Both devices are presented.

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THPOW039

Measurements of the Lattice Modifications for the Cryogenic Undulator CPMU17

betatron, optics, quadrupole, storage-ring

4031

J. Bahrdt, D.B. Engel, W. Frentrup, P. Goslawski, P. Kuske, R. Müller, M. Ries, M. Ruprecht, A. Schälicke
HZB, Berlin, Germany

A 2 mrad-canted double undulator system is in preparation as the wide energy range light source for the Energy Material in-situ Laboratory EMIL at the HZB storage ring BESSY II. The cryogenic undulator CPMU-17 is the hard X-ray device of the double undulator system. The soft X-ray undulator UE-48 is of the APPLE II type. It was installed and commissioned a few months ago, whereas the CPMU-17 is under fabrication. The CPMU-17 will employ a minimum magnetic gap of 5.5mm. Including a CuNi-foil for RF-shielding and geometric tolerances the free aperture is planned to be 5.0 mm. The BESSY II lattice has been modified locally in order to cope with the small gap device. The adapted betatron functions with a shifted vertical beam waist were measured and fitted with LOCO. The new optics agrees with the predicted performance. The free aperture at the installation place of the CPMU-17 was measured with four vertical scrapers. It is compatible with the projected minimum undulator gap. Finally, the measured injection efficiency with the new EMIL optics switched on is compatible with top-up operation (injection efficiency ≥ 90 %).

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THPOW040

Insertion Devices for Spring-8 Upgrade Project

vacuum, electron, storage-ring, polarization

4035

T. Tanaka, T. Hasegawa, R. Kinjo
RIKEN SPring-8 Center, Hyogo, Japan
T. Bizen, A. Kagamihata, H. Kishimoto, H. Ohashi, T. Seike
JASRI/SPring-8, Hyogo, Japan
S. Yamamoto
KEK, Tsukuba, Japan

In the upcoming major upgrade project of SPring-8 (SPring-8-II) planned in the early 2020's, the electron energy will be reduced from 8 GeV to 6 GeV and the straight sections will be shortened by nearly 2 m to accommodate more magnets, for the purpose of reducing the emittance down to around 100 pm.rad. The insertion devices (IDs) currently installed in SPring-8 are not compatible with the above upgrade plan, and thus most of them should be replaced with new ones optimized in the new storage ring, or at least be shortened to fit into the new straight sections. We report the status of R&Ds toward realization of IDs for SPring-8-II, such as shortening the magnetic period, reforming the fundamental structure of IDs to reduce the total cost and manufacturing lead time, and refurbishment of existing IDs for shorter lengths.

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THPOW041

Field Error Correction Considerations of Cryogenic Permanent Magnet Undulator (CPMU) for High Energy Photon Source Test Facility (HEPS-TF)*

cryogenics, simulation, operation, electron

4038

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

Considerations are made for field error corrections of a 2m-long CPMU in built for HEPS-TF. Field changes in cooling to liquid nitrogen temperature are simulated. 1st field integral of terminal changes by tens of Gauss cm and RMS of phase errors induced by cold contraction is less than 1° when temperature gradient along girder is below 1.5K/m. Field signature of magic finger is unchanged with temperature. Strategy of the field error correction is discussed.

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THPOW042

Start-to-End Simulation on Terahertz Superradiation of Ultrashort Electron Bunch in an Undulator

radiation, simulation, electron, laser

4041

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

The narrowband, intense and frequency-tunable THz radiation can be generated by letting an ultrashort electron bunch pass through an undulator. Start-to-end simulation of terahertz radiation from electron bunch in an undulator is studied in this paper. GPT code is used to track particle distribution from the photocathode RF gun to the entrance of the undulator and Genesis 1.3 is applied to simulate the radiation. The simulation results agree well with theoretical predictions.

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THPOW045

Development of PAL-XFEL Undulator System

FEL, laser, electron, radiation

4044

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

Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. At the first stage, PAL-XFEL needs two undulator lines for photon source. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator and soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. PAL is developing undulator magnetic structure based on EU-XFEL concepts. In this report, the results of final pole height tuning results, and magnetic measurement results will be presented.

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THPOW046

Status of Insertion Device Measurement Systems at MAX IV Laboratory

insertion, insertion-device, controls, vacuum

4047

M. Ebbeni, H. Tarawneh, A. Thiel
MAX IV Laboratory, Lund University, Lund, Sweden

An insertion device lab was setup at MAX IV Laboratory and the production of insertion devices, mainly out-of-vacuum is ongoing and aided by new magnetic measurement systems. A new 5.5 m long Hall probe bench is used for field map measurements and a new hybrid flip coil and stretch wire system will be used for field integrals of full devices as well as individual magnet blocks characterisation. This paper describes these magnetic measurement systems and their achieved and expected performance.

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THPOW049

Status of Insertion Devices at Taiwan Photon Source

vacuum, radiation, photon, polarization

4054

T.Y. Chung, C.-H. Chang, C.H. Chang, M.-S. Chiu, J.C. Huang, C.-S. Hwang, J.C. Jan, C.-C. Kuo, Y.-C. Liu, F.H. Tseng, C.K. Yang
NSRRC, Hsinchu, Taiwan

The storage ring of Taiwan Photon Source (TPS) has eighteen short straight sections (length 7 m) and six long straight sections (length 12 m). In phase I, three elliptically polarized undulators of type APPLE II and seven in-vacuum undulators, which included four in-vacuum undulators and two elliptically polarized undulators in three double mini-βy sections, were installed. Commissioning of the insertion devices began in 2015 November. The influence of insertion devices on the electron beam and the results after compensation are presented. Problems during the commissioning induced by the electron beam and by radiation, and their solutions, are also explained. For insertion devices in phase II and for devices developed in TPS, the preliminary designs are presented herein, to cover from the VUV to the hard X-ray region.

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THPOW051

Design and Construction of Compact Electromagnetic Undulator for THz Radiation Production

radiation, electron, linac, insertion-device

4060

C. Thongbai, N. Chaisueb, S. Rimjaem, J. Saisut, K. Thaijai-un
Chiang Mai University, Chiang Mai, Thailand
N. Kangrang
Chiang Mai University, PBP Research Facility, Chiang Mai, Thailand
P. Wichaisirimongkol
Chiang Mai University, Science and Technology Research Institute, Chiang Mai, Thailand

Funding: Chiang Mai University Research Fellowship Program
The goal of this research is to design and construct a compact electromagnetic undulator. This insertion device will be installed at the PBP-CMU-LINAC system of Chiang Mai University (CMU), Thailand, to produce THz radiation. The undulator magnet is designed by using 2D POISSON and 3D RADIA computer code to optimize the magnet dimensions. The width of iron pole (W) should be 12 mm. The length of iron pole (L) should be about 80 mm long and the thickness of return yoke (d) should be more than 10 mm. The magnet design, the in-house con-struction of the magnet, and the measurement results will be presented.

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THPOW052

Recent Magnetic Measurement Activities at NSLS-II Insertion Device Laboratory

electron, vacuum, synchrotron, radiation

4063

M. Musardo, P.L. Cappadoro, O.V. Chubar, T.M. Corwin, H.C. Fernandes, D.A. Harder, D.A. Hidas, C.A. Kitegi, B.N. Kosciuk, W. Licciardi, J. Rank, C. Rhein, T. Tanabe
BNL, Upton, New York, USA

National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) is a new 3 GeV third generation electron storage ring designated to provide extremely intense beams of X-ray, ultraviolet, and infrared light for basic and applied research. Insertion devices (IDs) play a significant role in achieving the high performance demands of NSLS-II. An accurate magnetic characterization and proper corrections of these devices are essential activities in the development of a state-of-the-art light source facility. This paper describes the results of the latest magnetic measurement activities at the NSLS-II ID laboratory.

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THPOY047

Comprehensive Approach to Synchrotron Radiation Protection of NSLS-II

radiation, synchrotron, synchrotron-radiation, electron

4211

S. Seletskiy, T.V. Shaftan
BNL, Upton, Long Island, New York, USA

To protect the NSLS-II Storage Ring components from possible damage from synchrotron radiation produced by insertion devices (IDs) and bending magnets (BMs) the Active Interlock System (AIS) keeps electron beam within the AI safe envelope (AIE) in the transverse phase space. The NSLS-II beamlines (BLs) and frontends (FEs) are designed under assumption that above certain safe beam current the ID synchrotron radiation (IDSR) fan is produced by the interlocked e-beam. In this paper we describe a new approach to defining the AIS parameters and settings, which significantly simplifies the process of the FE and BL design.

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THPOY049

Helical Undulator as a Source of Spectromicroscopy Beamline of ILSF

polarization, electron, photon, radiation

4217

S. Amiri, A. Gholampour, M. Jafarzadeh, M. Lamehi, J. Rahighi
ILSF, Tehran, Iran
M. Lamehi, J. Rahighi
IPM, Tehran, Iran

Regarding user requirements of spectromicroscopy beamline such as high flux, small spot size, linear and circular polarization light, a helical undulator have been chosen as a source for this beamline. Radiation properties of the source e.g. flux, flux density, brilliance, size and divergence of the photon beam, power, power density, angular distribution of power and flux on the axis of the undulator have been considered by theoretical formula and using SPECTRA code. At the circular polarization, the first harmonic covers the energies in the 100-1300 eV range and for the linear polarization energy ranges, 100-1000 eV and 1000-1500 eV, are provided by the first and third harmonics respectively. In the case of circular and linear polarization mode, maximum flux in the central cone for maximum undulator strength are 4.5 × 10¹⁶ (ph/s) at kX=ky=3.6 and 2.4 × 10¹⁶ (ph/s) at K=5.
* James A. Clarke, "The science and technology of undulators and wigglers", 2004.
** H. Onuki, P. Elleaume, "WIGGLERS UNDULATORs and their APLICATIONS", 2003.

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