FLS2018 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
TUA2WB04	Ion Instability in the HEPS Storage Ring	ion, simulation, storage-ring, emittance	34
	S.K. Tian, N. Wang IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS), a kilometre scale storage ring light source, with a beam energy of 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing and now is under design. We investigate the ion instability in the storage ring with high beam intensity and low-emittance. We performe a weak-strong simulation to show characteristic phenomena of the instability in the storage ring.
	Slides TUA2WB04 [3.446 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUA2WB04
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TUP1WD02	A Study on the Improved Cavity Bunch Length Monitor for FEL	ion, cavity, simulation, FEL	39
	Q. Wang, X.Y. Liu, P. Lu, Q. Luo, B.G. Sun, L.L. Tang, J.H. Wei, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046) Bunch length monitors based on cavities have great potential especially for future high quality beam sources because of many advantages such as simple structure, wide application rage, and high signal-to-noise ratio (SNR). The traditional way to measure bunch length needs two cavities at least. One is reference cavity, whose function is to get the beam intensity. The other one is defined as main cavity, which is used to calculate the bunch length. There are some drawbacks. To improve performance, the mode and the cavity shape are changed. At the same time, the position and orientation of coaxial probe are designed to avoid interference modes which come from the cavity and beam tube according to the analytic formula of the electromagnetic field distribution. A series simulation based on CST is performed to verify the feasibility, and the simulation results reveal that the improved monitor shows good performance in bunch length measurement.
	Slides TUP1WD02 [3.505 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUP1WD02
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TUA2WC01	Transportation and Manipulation of a Laser Plasma Acceleration Beam	ion, laser, undulator, plasma	56
	A. Ghaith, T. André, I.A. Andriyash, F. Blache, F. Bouvet, F. Briquez, M.-E. Couprie, Y. Dietrich, J.P. Duval, C. Herbeaux, N. Hubert, C.A. Kitegi, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, D. Oumbarek, P. Rommeluère, E. Roussel, M. Sebdaoui, K.T. Tavakoli, M. Valléau SOLEIL, Gif-sur-Yvette, France S. Bielawski, C. Evain, C. Szwaj PhLAM/CERLA, Villeneuve d'Ascq, France S. Corde, J. Gautier, G. Lambert, B. Mahieu, V. Malka, K.T. Phuoc, C. Thaury LOA, Palaiseau, France
	Funding: European Research Council advanced grant COXINEL - 340015 The ERC Advanced Grant COXINEL aims at demonstrating free electron laser amplification, at a resonant wavelength of 200 nm, based on a laser plasma acceleration source. To achieve the amplification, a 10 m long dedicated transport line was designed to manipulate the beam qualities. It starts with a triplet of permanent magnet with tunable gradient quadrupoles (QUAPEVA) that handles the highly divergent electron beam, a demixing chicane with a slit to reduce the energy spread per slice, and a set of electromagnetic quadrupoles to provide a chromatic focusing in a 2 m long cryogenic undulator. Electrons of energy 176 MeV were successfully transported throughout the line, where the beam positioning and dispersion were controlled efficiently thanks to a specific beam based alignment method, as well as the energy range by varying the slit width. Observations of undulator radiation for different undulator gaps are reported.
	Slides TUA2WC01 [2.465 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUA2WC01
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TUA2WC02	"LWFA-driven" Free Electron Laser for ELI-Beamlines	ion, FEL, undulator, photon	62
	A.Y. Molodozhentsev, G. Korn, L. Pribyl Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic A.R. Maier University of Hamburg, Hamburg, Germany
	Free-electron lasers (FEL) are unique light source for different applications on the femto-second scale, including for instance the most basic reaction mechanisms in chemistry, structural biology and condense physics. Laser wake field acceleration (LWFA) mechanism allow to produce extremely short electron bunches of a few fs length with the energy up to a few GeV providing peak current of many kA in extremely compact geometries. This novel acceleration method therefore opens a new way to develop compact "laser-based" FELs. ELI beamlines is an international user facility for fundamental and applied research using ultra-intense lasers and ultra-short high-energy electron beams. In frame of this report we present conceptual solutions for an compact "LFWA" based soft X-ray FEL, which can deliver a photon peak brightness of 10³¹ ph/sec/mm²/mrad²/0.1%bw. A combination of this achievement with novel laser technologies will open a new perspective for the development of extremely compact FELs with few or even sub-femtosecond photon bunches for a very wide user community.
	Slides TUA2WC02 [3.882 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUA2WC02
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TUP2WA03	Harmonic Lasing in X-Ray FELs: Theory and Experiment	ion, FEL, undulator, radiation	68
	E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov DESY, Hamburg, Germany
	Harmonic lasing in XFELs is an opportunity to extend operating range of existing and planned X-ray FEL user facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental. Another interesting application of harmonic lasing is Harmonic Lasing Self-Seeded (HLSS) FEL, that allows to improve longitudinal coherence and spectral power of a SASE FEL. Recently* this concept was successfully tested at FLASH2 in the range 4.5 - 15 nm. That was also the first experimental demonstration of harmonic lasing in a high-gain FEL and at a short wavelength (before it worked only in infrared FEL oscillators). In this contribution we describe the concepts of harmonic lasing and of HLSS FEL, and present the experimental results from FLASH2. * E.Schneidmiller and M.Yurkov, Phys. Rev. ST-AB 15(2012)080702 E.Schneidmiller and M.Yurkov, Proc. of FEL2013, p.700 * E.Schneidmiller et al., Phys. Rev. Accel. Beams 20(2017)020705
	Slides TUP2WA03 [3.378 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUP2WA03
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WEA1PL02	Dielectric Accelerators and Other Non-Plasma Accelerator Based Compact Light Sources	ion, laser, undulator, radiation	74
	R.J. England, Z. Huang SLAC, Menlo Park, California, USA
	Funding: U.S. Department of Energy DE-AC02-76SF00515; Gordon and Betty Moore Foundation GBMF4744 We review recent experimental progress in developing nanofabricated dielectric laser-driven accelerators and discuss the possibility of utilizing the unique sub-femtosecond electron pulse format these accelerators would provide to create ultra-compact EUV and X-ray radiation sources.
	Slides WEA1PL02 [16.828 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEA1PL02
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WEA1PL03	Attosecond Timing	ion, laser, timing, FEL	79
	F.X. Kärtner Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany K. Shafak CFEL, Hamburg, Germany K. Shafak Cycle GmbH, Hamburg, Germany M. Xin DESY, Hamburg, Germany
	Funding: This work was supported by DESY and the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement No. 609920. Photon-science facilities such as X-ray free-electron lasers (XFELs) and intense-laser facilities are emerging world-wide with some of them producing sub-fs X-ray pulses. These facilities are in need of a high-precision timing distribution system, which can synchronize various microwave and optical sub-sources across multi-km distances with attosecond precision. Here, we report on a synchronous laser-microwave network that permits attosecond precision across km-scale distances. This was achieved by developing new ultrafast timing metrology devices and carefully balancing the fiber nonlinearities and fundamental noise contributions in the system. New polarization-noise-suppressed balanced optical crosscorrelators and free-space-coupled balanced optical-microwave phase detectors for improved noise performance have been implemented. Residual second- and third-order dispersion in the fiber links are carefully compensated with additional dispersion-compensating fiber to suppress link-induced Gordon-Haus jitter and to minimize output pulse duration; the link power is stabilized to minimize the nonlinearity-induced jitter as well as to maximize the signal to noise ratio for locking.
	Slides WEA1PL03 [5.888 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEA1PL03
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WEP1WC02	CompactLight Design Study	ion, undulator, FEL, gun	85
	A. Latina, D. Schulte, S. Stapnes, W. Wuensch CERN, Geneva, Switzerland M. Aicheler HIP, University of Helsinki, Finland A.A. Aksoy Ankara University Institute of Accelerator Technologies, Golbasi, Turkey A. Bernhard KIT, Karlsruhe, Germany J.A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.W. Cross USTRAT/SUPA, Glasgow, United Kingdom G. D'Auria, R. Geometrante Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy R.T. Dowd AS - ANSTO, Clayton, Australia D. Esperante Pereira IFIC, Valencia, Spain W. Fang SINAP, Shanghai, People's Republic of China A. Faus-Golfe LAL, Orsay, France M. Ferrario INFN/LNF, Frascati (Roma), Italy E.N. Gazis National Technical University of Athens, Athens, Greece R. Geometrante KYMA, Trieste, Italy M. Jacewicz Uppsala University, Uppsala, Sweden A. Mostacci Sapienza University of Rome, Rome, Italy F. Nguyen ENEA C.R. Frascati, Frascati (Roma), Italy F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain J.M.A. Priem VDL ETG, Eindhoven, The Netherlands T. Schmidt PSI, Villigen PSI, Switzerland
	H2020 CompactLight Project aims at designing the next generation of compact hard X-Rays Free-Electron Lasers, relying on very high accelerating gradients and on novel undulator concepts. CompactLight intends to design a compact Hard X-ray FEL facility based on very high-gradient acceleration in the X band of frequencies, on a very bright photo injector, and on short-period/superconductive undulators to enable smaller electron beam energy. If compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, be significantly more compact, as a consequence both of the lower energy and of the high-gradient X-band structures, have lower electrical power demand and a smaller footprint. CompactLight is a consortium of 24 institutes (21 European + 3 extra Europeans), gathering the world-leading experts both in the domains of X-band acceleration and undulator design.
	Slides WEP1WC02 [12.831 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP1WC02
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WEA2WD01	QUAPEVA: Variable High Gradient Permanent Magnet Quadrupole	ion, quadrupole, laser, multipole	89
	C.A. Kitegi, T. André, M.-E. Couprie, A. Ghaith, J. Idam, A. Loulergue, F. Marteau, D. Oumbarek, M. Sebdaoui, M. Valléau, J. Vétéran SOLEIL, Gif-sur-Yvette, France C. Benabderrahmane, J. Chavanne, G. Le Bec ESRF, Grenoble, France O. Cosson, F. Forest, P. Jivkov, J.L. Lancelot Sigmaphi, Vannes, France P. N'gotta MAX IV Laboratory, Lund University, Lund, Sweden C. Vallerand LAL, Orsay, France
	We present the magnetic and the mechanical design of tunable high gradient permanent magnet (PM) quadrupoles. The tunable gradient of the so-called QUAPEVAS extends from 100T/m up to 200T/m. Seven of them with various lengths, ranging from 26mm up to 100mm, for different integrated quadrupole strengths were manufactured. The measured magnetic performance of these devices is also reported. These devices were successfully developed to transport laser plasma accelerated electron beam. Such applications have however less stringent multipole harmonic content constraints than diffraction limited Light sources. Trails for lowering the multipole harmonics will be discussed.
	Slides WEA2WD01 [3.093 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEA2WD01
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WEA2WD03	Analysis of Electron Trajectories in Harmonic Undulator with SCILAB's Model Based Design Codes	ion, undulator, simulation, FEL	93
	H. Jeevakhan, S. Kumar NITTTR, Bhopal, India G. Mishra Devi Ahilya University, Indore, India
	Scilab's X-cos model-based simulation blocks has been used to simulate the trajectories of an electron traversing through an Harmonic undulator. The trajectory of electron along X and Y directions has been simulated from Numerical and analytical methods. Analysis given in the present paper is compared with the other codes. Parallel simulation of Harmonic undulator magnetic field along with trajectories of electron is given in the present analysis.
	Slides WEA2WD03 [0.652 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEA2WD03
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WEA2WD04	Harmonic Undulator Radiation with Dual Non Periodic Magnetic Components	ion, undulator, radiation, FEL	98
	H. Jeevakhan NITTTR, Bhopal, India G. Mishra Devi Ahilya University, Indore, India
	Undulator radiation at third harmonics generated by harmonic undulator in the presence dual non periodic constant magnetic field. Electron trajectories along the x and y direction has been determined analytical and numerical methods. Generalized Bessel function is used to determine the intensity of radiation and Simpson's numerical method of integration is used to find the effect of constant magnetic fields. Comparison with previous analysis has also been presented.
	Slides WEA2WD04 [1.050 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEA2WD04
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WEP2PT003	Undulator Phase Matching for the the European XFEL	ion, undulator, FEL, radiation	103
	Y. Li, J. Pflüger XFEL. EU, Hamburg, Germany
	The undulator system in the European XFEL is mainly comprised 5-m long undulator segments and 1.1 m long intersections in between. In intersections the electron velocity is faster than it inside an undulator and the optical phase is detuned. The detune effect is also from the undulator fringe field where electron longitudinal speed also deviates from the oscillation condition. The total detune effect is compensated by a magnetic device called phase shifter, which is correspondingly set for a specific undulator gap. In this paper we introduce the method to set the phase shifter gap for each K parameter according to the measured magnetic field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP2PT003
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WEP2PT008	Microbunching Instability Study in the Linac-Driven FERMI FEL Spreader Beam Line	ion, linac, laser, FEL	108
	S. Di Mitri, S. Spampinati Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	Suppression of microbunching instability (MBI) along high brightness electron beam delivery systems is a priority for Free Electron lasers (FELs) aiming at very narrow bandwidth. The impact of MBI on FEL spectral brilliance is aggravated by the growing demand for multi-user FEL facilities, which adopt multi-bend switchyard lines traversed by high charge density electron beams. This study provides practical guidelines to switchyards design largely immune to MBI, by focusing on the FERMI FEL Spreader line. First, two MBI analytical models [1, 2] are successfully benchmarked along the accelerator. Being the second model flexible enough to describe an arbitrary multi-bend line, and found it in agreement with particle tracking and experimental results, it was used to demonstrate that a newly proposed Spreader optics provides unitary MBI gain while preserving the electron beam brightness. [1] Z. Huang and K.-J. Kim, Phys. Rev. Special Topics - Accel. Beams 5, 074401 (2002) [2] R.A. Bosch, K.J. Kleman, and J. Wu, Phys. Rev. Special Topics - Accel. Beams 11, 090702 (2008)
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WEP2PT014	Strong Focusing Lattice Design for SSMB	ion, lattice, photon, dipole	113
	T. Rui, X.J. Deng, W.-H. Huang, C.-X. Tang TUB, Beijing, People's Republic of China A. Chao SLAC, Menlo Park, California, USA
	A storage ring applicable for SSMB operation is a critical part of a high average power SSMB EUV light source. A lattice for SSMB based on longitudinal strong focusing is under design in Tsinghua University. To generate and maintain micro-bunching in a storage ring in this scenario, the momentum compaction has to be small. A lattice with low momentum compaction factor is presented in this work. The lattice of the current design consists of two MBA cells with isochronous unit cells to minimize local and global momentum compaction, and two straight sections for insertion devices. The design energy of the ring is 400MeV and the circumference is 94 meters. Nonlinear effects such as higher order momentum compactions will continue to be optimized.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP2PT014
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WEP2PT022	PHASE SHIFTER APPLICATION IN DOUBLE UNDULATOR CONFIGURATION OF HEPS	ion, undulator, brilliance, radiation	120
	X.Y. Li, Y. Jiao, S.K. Tian IHEP, Beijing, People's Republic of China
	For over 6 meters long straight-section of HEPS, collinear double-cryogenic permanent magnet undulator(CPMU) is designed for high energy photon users to achieve higher brightness. Angular and spatial profiles of radiation produced by the double undulator configuration have been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread and emittance are taken into account. Optimized beta-functions of electron beam are obtained.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP2PT022
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WEP2PT033	Conceptual Design of Superconducting Transverse Gradient Undulator for PAL-XFEL Beamline	ion, FEL, undulator, operation	142
	S.J. Lee, J.H. Han PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT \& Future Planning(2017R1C1B1012852) Recently, the transverse gradient undulator (TGU) applications are suggested from the laser plasma wake-field accelerator (LPWA) to ultimate storage ring (USR). Especially for X-ray FEL, TGU can be used to generate the large bandwidth radiation (up to §I10{\percent}). In this proceeding, the review of PAL-XFEL beam parameters and TGU requirements was done to apply a variable large bandwidth operation to the PAL-XFEL beamlines. Also, the conceptual design of TGU, based on superconducting undulator (SCU) was proposed, and B-field calculation results were introduced for PAL-XFEL large bandwidth operation mode.
	Poster WEP2PT033 [0.927 MB]
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WEP2PT050	Status of CAEP THz Free Electron Laser Oscillator	ion, FEL, laser, free-electron-laser	154
	M. Li, T.H. He, C.L. Lao, P. Li, S.F. Lin, X. Luo, Q. Pan, L.J. Shan, X. Shen, H. Wang, J. Wang, D. Wu, D.X. Xiao, Y. Xu, X. Yang, P. Zhang, K. Zhou CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	China Academy of Engineering Physics tera-hertz free electron laser (CAEP THz FEL, CTFEL) is the first THz FEL oscillator in China, which was jointly built by CAEP, Peking university and Tsinghua university. The stimulated saturation of the CTFEL was reached in August, 2017. This THz FEL facility consists of a GaAs photocathode high-voltage DC gun, a superconducting RF linac, a planar undulator and a quasi-concentric optical resonator. The terahertz laser's frequency is continuous adjustable from 2 THz to 3 THz. The average power is more than 10 W and the micro-pulse power is more than 0.1 MW.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP2PT050
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THA1WA03	GPT-CSR: A New Simulation Code for CSR Effects	ion, simulation, radiation, bunching	157
	S.B. van der Geer, M.J. de Loos Pulsar Physics, Eindhoven, The Netherlands I. Setija, P.W. Smorenburg ASML Netherlands B.V., Veldhoven, The Netherlands P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	For future applications of high-brightness electron beams, including the design of next generation FEL's, correct correct simulation of Coherent Synchrotron Radiation (CSR) is essential as it potentially degrades beam quality to unacceptable levels. However, the long interaction lengths compared to the bunch length, numerical cancellation, and difficult 3D retardation conditions make accurate simulation of CSR effects notoriously difficult. To ease the computational burden, CSR codes often make severe simplifications such as an ultra relativistic bunch travelling on a prescribed reference trajectory. Here we report on a new CSR model, implemented in the General Particle Tracer (GPT) code, that avoids most of the usual assumptions: It directly evaluates the Lienard-Wiechert potentials based on the stored history of the beam, it makes no assumptions about reference trajectories, while also taking into account the transverse size of the beam. First results demonstrating microbunching gain in a chicane are presented.
	Slides THA1WA03 [1.799 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THA1WA03
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THP2WB04	Laser Seeding of Electron Bunches for Future Ring-Based Light Sources	ion, laser, radiation, storage-ring	177
	S. Khan, B. Büsing, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, B. Riemann, B. Sawadski, M. Schmutzler, P. Ungelenk DELTA, Dortmund, Germany
	Funding: Funded by BMBF (05K16PEA, 05K16PEB), MERCUR (Pr-2014-0047), DFG (INST 212/236-1 FUGG) and the Land NRW. In contrast to free-electron lasers (FELs), ring-based light sources are limited in intensity by incoherent emission and in pulse duration by the bunch length. However, FEL seeding schemes can be adopted to generate intense and ultrashort radiation pulses in storage rings by creating laser-induced microbunches within a short slice of the electron bunch. Microbunching gives rise to coherent emission at harmonics of the seed wavelength. In addition, terahertz (THz) radiation is coherently emitted over many turns. At DELTA, a storage ring operated by the TU Dortmund University, coherent harmonic generation (CHG) with single and double 40-fs pulses is routinely performed at seed wavelengths of 800 and 400 nm. Seeding with intensity-modulated pulses to generate tunable narrowband THz radiation is also studied. As a preparation for echo-enabled harmonic generation (EEHG), simultaneous seeding with 800/400-nm pulses in two undulators has been demonstrated. The DELTA storage ring is an excellent testbed to study many aspects of laser seeding and related diagnostics. In addition to short-pulse generation, steady-state microbunching at ring-based light sources will be discussed in the paper.
	Slides THP2WB04 [5.103 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THP2WB04
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THA1WC01	Compact Arc Compressor for FEL-Driven Compton Light Source and ERL-Driven UV FEL	ion, FEL, emittance, dipole	183
	S. Di Mitri Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy J.A.G. Akkermans, I. Setija ASML Netherlands B.V., Veldhoven, The Netherlands D. Douglas JLab, Newport News, Virginia, USA C. Pellegrini SLAC, Menlo Park, California, USA G. Penn, M. Placidi LBNL, Berkeley, California, USA
	Many research and applications areas require photon sources capable of producing extreme ultra-violet (EUV) to gamma-ray beams with reasonably high fluxes and compact footprints. We explore the feasibility of a compact energy-recovery linac EUV free electron laser (FEL), and of a multi-MeV gamma-rays source based on inverse Compton scattering from a high intensity UV FEL emitted by the electron beam itself. In the latter scenario, the same electron beam is used to produce gamma-rays in the 10-20 MeV range and UV radiation in the 10¹⁵ eV range, in a ~4x22 m² footprint system.* * J.Akkermans, S.Di Mitri, D.Douglas, I.Setija, PRAB 20, 080705 (2017). ** M. Placidi, S. Di Mitri,⁎, C. Pellegrini, G. Penn, NIM A 855 (2017) 55-60.
	Slides THA1WC01 [5.258 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THA1WC01
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THP1WD02	LCLS-II Beam Containment System for Radiation Safety	ion, cavity, FEL, radiation	187
	C.I. Clarke, J. Bauer, M. Boyes, Y. Feng, A.S. Fisher, R.A. Kadyrov, J.C. Liu, E. Rodriguez, M. Rowen, M. Santana-Leitner, F. Tao, J.J. Welch, S. Xiao SLAC, Menlo Park, California, USA T.L. Allison, J. Musson JLab, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 and DE-AC05-06OR23177. LCLS-II is a new xFEL facility under construction at SLAC National Accelerator Laboratory with a superconducting electron linac designed to operate up to §I{1.2}{MW} of beam power. This generates more serious beam hazards than the typical sub-kW linac operation of the existing xFEL facility, Linac Coherent Light Source (LCLS). SLAC uses a set of safety controls termed the Beam Containment System (BCS) to limit beam power and losses to prevent excessive radiation in occupied areas. The high beam power hazards of LCLS-II necessitate the development of new BCS devices and a larger scale deployment than previously done at LCLS. We present the new radiation hazards introduced by LCLS-II and the design development for the BCS.
	Slides THP1WD02 [2.244 MB]
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THP2WD01	Construction and Optimization of Cryogenic Undulators at SOLEIL	ion, undulator, cryogenics, vacuum	193
	M. Valléau, P. Berteaud, F. Briquez, P. Brunelle, N. Béchu, M.-E. Couprie, J. Da Silva Castro, J.M. Dubuisson, A. Ghaith, C. Herbeaux, J. Idam, C.A. Kitegi, F. Lepage, A. Lestrade, M. Louvet, O. Marcouillé, F. Marteau, A. Mary, A. Nadji, L.S. Nadolski, P. Rommeluère, M. Sebdaoui, A. Somogyi, K.T. Tavakoli, M. Tilmont, T. Weitkamp SOLEIL, Gif-sur-Yvette, France
	Funding: Synchrotron SOLEIL, L'Orme des Merisiers, 91 192 BP 34 Gif-sur-Yvette, France, With permanent magnets undulator operation at cryogenic temperature, the magnetic field and the coercivity can be enhanced, enabling shorter periods with high magnetic fields. The first full scale (2 m long, 18 mm period) hybrid cryogenic undulator [1] using PrFeB [2] magnets operating at 77 K was installed at SOLEIL in 2011. Photon spectra measurements, in good agreement with the ex-pectations from magnetic measurements, were used for precise alignment and taper optimization. The second and third 18 mm PrFeB cryogenic undulators, modified to a half-pole/magnet/half-pole structure, were optimized without any magnet or pole shimming after assembly but mechanical sortings and some geometrical corrections had been done before assembly. A systematic error on individual magnets on the third U18 was also compensated. In-situ measurement benches, including a Hall probe and a stretched wire to optimize the undulator field at room and cryogenic temperature are presented. An upgrade of these in-situ benches will be detailed with the fabrication of a 15 mm 3 m long PrFeB cryogenic undulator at SOLEIL. [1] C. Benabderrahmane, M. Valléau, M. E. Couprie, Phys. Rev. Accel. Beams 20, 033201(2017) [2] C. Benabderrahmane, M. Valléau, M. E. Couprie, NIMA 669, 1-6, (2012)
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TUA2WB04

Ion Instability in the HEPS Storage Ring

ion, simulation, storage-ring, emittance

34

S.K. Tian, N. Wang
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS), a kilometre scale storage ring light source, with a beam energy of 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing and now is under design. We investigate the ion instability in the storage ring with high beam intensity and low-emittance. We performe a weak-strong simulation to show characteristic phenomena of the instability in the storage ring.

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TUP1WD02

A Study on the Improved Cavity Bunch Length Monitor for FEL

ion, cavity, simulation, FEL

39

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

Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046)
Bunch length monitors based on cavities have great potential especially for future high quality beam sources because of many advantages such as simple structure, wide application rage, and high signal-to-noise ratio (SNR). The traditional way to measure bunch length needs two cavities at least. One is reference cavity, whose function is to get the beam intensity. The other one is defined as main cavity, which is used to calculate the bunch length. There are some drawbacks. To improve performance, the mode and the cavity shape are changed. At the same time, the position and orientation of coaxial probe are designed to avoid interference modes which come from the cavity and beam tube according to the analytic formula of the electromagnetic field distribution. A series simulation based on CST is performed to verify the feasibility, and the simulation results reveal that the improved monitor shows good performance in bunch length measurement.

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TUA2WC01

Transportation and Manipulation of a Laser Plasma Acceleration Beam

ion, laser, undulator, plasma

56

A. Ghaith, T. André, I.A. Andriyash, F. Blache, F. Bouvet, F. Briquez, M.-E. Couprie, Y. Dietrich, J.P. Duval, C. Herbeaux, N. Hubert, C.A. Kitegi, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, D. Oumbarek, P. Rommeluère, E. Roussel, M. Sebdaoui, K.T. Tavakoli, M. Valléau
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, C. Evain, C. Szwaj
PhLAM/CERLA, Villeneuve d'Ascq, France
S. Corde, J. Gautier, G. Lambert, B. Mahieu, V. Malka, K.T. Phuoc, C. Thaury
LOA, Palaiseau, France

Funding: European Research Council advanced grant COXINEL - 340015
The ERC Advanced Grant COXINEL aims at demonstrating free electron laser amplification, at a resonant wavelength of 200 nm, based on a laser plasma acceleration source. To achieve the amplification, a 10 m long dedicated transport line was designed to manipulate the beam qualities. It starts with a triplet of permanent magnet with tunable gradient quadrupoles (QUAPEVA) that handles the highly divergent electron beam, a demixing chicane with a slit to reduce the energy spread per slice, and a set of electromagnetic quadrupoles to provide a chromatic focusing in a 2 m long cryogenic undulator. Electrons of energy 176 MeV were successfully transported throughout the line, where the beam positioning and dispersion were controlled efficiently thanks to a specific beam based alignment method, as well as the energy range by varying the slit width. Observations of undulator radiation for different undulator gaps are reported.

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TUA2WC02

"LWFA-driven" Free Electron Laser for ELI-Beamlines

ion, FEL, undulator, photon

62

A.Y. Molodozhentsev, G. Korn, L. Pribyl
Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
A.R. Maier
University of Hamburg, Hamburg, Germany

Free-electron lasers (FEL) are unique light source for different applications on the femto-second scale, including for instance the most basic reaction mechanisms in chemistry, structural biology and condense physics. Laser wake field acceleration (LWFA) mechanism allow to produce extremely short electron bunches of a few fs length with the energy up to a few GeV providing peak current of many kA in extremely compact geometries. This novel acceleration method therefore opens a new way to develop compact "laser-based" FELs. ELI beamlines is an international user facility for fundamental and applied research using ultra-intense lasers and ultra-short high-energy electron beams. In frame of this report we present conceptual solutions for an compact "LFWA" based soft X-ray FEL, which can deliver a photon peak brightness of 10³¹ ph/sec/mm²/mrad²/0.1%bw. A combination of this achievement with novel laser technologies will open a new perspective for the development of extremely compact FELs with few or even sub-femtosecond photon bunches for a very wide user community.

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TUP2WA03

Harmonic Lasing in X-Ray FELs: Theory and Experiment

ion, FEL, undulator, radiation

68

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

Harmonic lasing in XFELs is an opportunity to extend operating range of existing and planned X-ray FEL user facilities*. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental. Another interesting application of harmonic lasing is Harmonic Lasing Self-Seeded (HLSS) FEL*,** that allows to improve longitudinal coherence and spectral power of a SASE FEL. Recently*** this concept was successfully tested at FLASH2 in the range 4.5 - 15 nm. That was also the first experimental demonstration of harmonic lasing in a high-gain FEL and at a short wavelength (before it worked only in infrared FEL oscillators). In this contribution we describe the concepts of harmonic lasing and of HLSS FEL, and present the experimental results from FLASH2.
* E.Schneidmiller and M.Yurkov, Phys. Rev. ST-AB 15(2012)080702
** E.Schneidmiller and M.Yurkov, Proc. of FEL2013, p.700
*** E.Schneidmiller et al., Phys. Rev. Accel. Beams 20(2017)020705

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WEA1PL02

Dielectric Accelerators and Other Non-Plasma Accelerator Based Compact Light Sources

ion, laser, undulator, radiation

74

R.J. England, Z. Huang
SLAC, Menlo Park, California, USA

Funding: U.S. Department of Energy DE-AC02-76SF00515; Gordon and Betty Moore Foundation GBMF4744
We review recent experimental progress in developing nanofabricated dielectric laser-driven accelerators and discuss the possibility of utilizing the unique sub-femtosecond electron pulse format these accelerators would provide to create ultra-compact EUV and X-ray radiation sources.

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WEA1PL03

Attosecond Timing

ion, laser, timing, FEL

79

F.X. Kärtner
Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
K. Shafak
CFEL, Hamburg, Germany
K. Shafak
Cycle GmbH, Hamburg, Germany
M. Xin
DESY, Hamburg, Germany

Funding: This work was supported by DESY and the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement No. 609920.
Photon-science facilities such as X-ray free-electron lasers (XFELs) and intense-laser facilities are emerging world-wide with some of them producing sub-fs X-ray pulses. These facilities are in need of a high-precision timing distribution system, which can synchronize various microwave and optical sub-sources across multi-km distances with attosecond precision. Here, we report on a synchronous laser-microwave network that permits attosecond precision across km-scale distances. This was achieved by developing new ultrafast timing metrology devices and carefully balancing the fiber nonlinearities and fundamental noise contributions in the system. New polarization-noise-suppressed balanced optical crosscorrelators and free-space-coupled balanced optical-microwave phase detectors for improved noise performance have been implemented. Residual second- and third-order dispersion in the fiber links are carefully compensated with additional dispersion-compensating fiber to suppress link-induced Gordon-Haus jitter and to minimize output pulse duration; the link power is stabilized to minimize the nonlinearity-induced jitter as well as to maximize the signal to noise ratio for locking.

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WEP1WC02

CompactLight Design Study

ion, undulator, FEL, gun

85

A. Latina, D. Schulte, S. Stapnes, W. Wuensch
CERN, Geneva, Switzerland
M. Aicheler
HIP, University of Helsinki, Finland
A.A. Aksoy
Ankara University Institute of Accelerator Technologies, Golbasi, Turkey
A. Bernhard
KIT, Karlsruhe, Germany
J.A. Clarke
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.W. Cross
USTRAT/SUPA, Glasgow, United Kingdom
G. D'Auria, R. Geometrante
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
R.T. Dowd
AS - ANSTO, Clayton, Australia
D. Esperante Pereira
IFIC, Valencia, Spain
W. Fang
SINAP, Shanghai, People's Republic of China
A. Faus-Golfe
LAL, Orsay, France
M. Ferrario
INFN/LNF, Frascati (Roma), Italy
E.N. Gazis
National Technical University of Athens, Athens, Greece
R. Geometrante
KYMA, Trieste, Italy
M. Jacewicz
Uppsala University, Uppsala, Sweden
A. Mostacci
Sapienza University of Rome, Rome, Italy
F. Nguyen
ENEA C.R. Frascati, Frascati (Roma), Italy
F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
J.M.A. Priem
VDL ETG, Eindhoven, The Netherlands
T. Schmidt
PSI, Villigen PSI, Switzerland

H2020 CompactLight Project aims at designing the next generation of compact hard X-Rays Free-Electron Lasers, relying on very high accelerating gradients and on novel undulator concepts. CompactLight intends to design a compact Hard X-ray FEL facility based on very high-gradient acceleration in the X band of frequencies, on a very bright photo injector, and on short-period/superconductive undulators to enable smaller electron beam energy. If compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, be significantly more compact, as a consequence both of the lower energy and of the high-gradient X-band structures, have lower electrical power demand and a smaller footprint. CompactLight is a consortium of 24 institutes (21 European + 3 extra Europeans), gathering the world-leading experts both in the domains of X-band acceleration and undulator design.

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WEA2WD01

QUAPEVA: Variable High Gradient Permanent Magnet Quadrupole

ion, quadrupole, laser, multipole

89

C.A. Kitegi, T. André, M.-E. Couprie, A. Ghaith, J. Idam, A. Loulergue, F. Marteau, D. Oumbarek, M. Sebdaoui, M. Valléau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France
C. Benabderrahmane, J. Chavanne, G. Le Bec
ESRF, Grenoble, France
O. Cosson, F. Forest, P. Jivkov, J.L. Lancelot
Sigmaphi, Vannes, France
P. N'gotta
MAX IV Laboratory, Lund University, Lund, Sweden
C. Vallerand
LAL, Orsay, France

We present the magnetic and the mechanical design of tunable high gradient permanent magnet (PM) quadrupoles. The tunable gradient of the so-called QUAPEVAS extends from 100T/m up to 200T/m. Seven of them with various lengths, ranging from 26mm up to 100mm, for different integrated quadrupole strengths were manufactured. The measured magnetic performance of these devices is also reported. These devices were successfully developed to transport laser plasma accelerated electron beam. Such applications have however less stringent multipole harmonic content constraints than diffraction limited Light sources. Trails for lowering the multipole harmonics will be discussed.

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WEA2WD03

Analysis of Electron Trajectories in Harmonic Undulator with SCILAB's Model Based Design Codes

ion, undulator, simulation, FEL

93

H. Jeevakhan, S. Kumar
NITTTR, Bhopal, India
G. Mishra
Devi Ahilya University, Indore, India

Scilab's X-cos model-based simulation blocks has been used to simulate the trajectories of an electron traversing through an Harmonic undulator. The trajectory of electron along X and Y directions has been simulated from Numerical and analytical methods. Analysis given in the present paper is compared with the other codes. Parallel simulation of Harmonic undulator magnetic field along with trajectories of electron is given in the present analysis.

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WEA2WD04

Harmonic Undulator Radiation with Dual Non Periodic Magnetic Components

ion, undulator, radiation, FEL

98

H. Jeevakhan
NITTTR, Bhopal, India
G. Mishra
Devi Ahilya University, Indore, India

Undulator radiation at third harmonics generated by harmonic undulator in the presence dual non periodic constant magnetic field. Electron trajectories along the x and y direction has been determined analytical and numerical methods. Generalized Bessel function is used to determine the intensity of radiation and Simpson's numerical method of integration is used to find the effect of constant magnetic fields. Comparison with previous analysis has also been presented.

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WEP2PT003

Undulator Phase Matching for the the European XFEL

ion, undulator, FEL, radiation

103

Y. Li, J. Pflüger
XFEL. EU, Hamburg, Germany

The undulator system in the European XFEL is mainly comprised 5-m long undulator segments and 1.1 m long intersections in between. In intersections the electron velocity is faster than it inside an undulator and the optical phase is detuned. The detune effect is also from the undulator fringe field where electron longitudinal speed also deviates from the oscillation condition. The total detune effect is compensated by a magnetic device called phase shifter, which is correspondingly set for a specific undulator gap. In this paper we introduce the method to set the phase shifter gap for each K parameter according to the measured magnetic field.

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WEP2PT008

Microbunching Instability Study in the Linac-Driven FERMI FEL Spreader Beam Line

ion, linac, laser, FEL

108

S. Di Mitri, S. Spampinati
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Suppression of microbunching instability (MBI) along high brightness electron beam delivery systems is a priority for Free Electron lasers (FELs) aiming at very narrow bandwidth. The impact of MBI on FEL spectral brilliance is aggravated by the growing demand for multi-user FEL facilities, which adopt multi-bend switchyard lines traversed by high charge density electron beams. This study provides practical guidelines to switchyards design largely immune to MBI, by focusing on the FERMI FEL Spreader line. First, two MBI analytical models [1, 2] are successfully benchmarked along the accelerator. Being the second model flexible enough to describe an arbitrary multi-bend line, and found it in agreement with particle tracking and experimental results, it was used to demonstrate that a newly proposed Spreader optics provides unitary MBI gain while preserving the electron beam brightness.
[1] Z. Huang and K.-J. Kim, Phys. Rev. Special Topics - Accel. Beams 5, 074401 (2002)
[2] R.A. Bosch, K.J. Kleman, and J. Wu, Phys. Rev. Special Topics - Accel. Beams 11, 090702 (2008)

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WEP2PT014

Strong Focusing Lattice Design for SSMB

ion, lattice, photon, dipole

113

T. Rui, X.J. Deng, W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China
A. Chao
SLAC, Menlo Park, California, USA

A storage ring applicable for SSMB operation is a critical part of a high average power SSMB EUV light source. A lattice for SSMB based on longitudinal strong focusing is under design in Tsinghua University. To generate and maintain micro-bunching in a storage ring in this scenario, the momentum compaction has to be small. A lattice with low momentum compaction factor is presented in this work. The lattice of the current design consists of two MBA cells with isochronous unit cells to minimize local and global momentum compaction, and two straight sections for insertion devices. The design energy of the ring is 400MeV and the circumference is 94 meters. Nonlinear effects such as higher order momentum compactions will continue to be optimized.

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WEP2PT022

PHASE SHIFTER APPLICATION IN DOUBLE UNDULATOR CONFIGURATION OF HEPS

ion, undulator, brilliance, radiation

120

X.Y. Li, Y. Jiao, S.K. Tian
IHEP, Beijing, People's Republic of China

For over 6 meters long straight-section of HEPS, collinear double-cryogenic permanent magnet undulator(CPMU) is designed for high energy photon users to achieve higher brightness. Angular and spatial profiles of radiation produced by the double undulator configuration have been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread and emittance are taken into account. Optimized beta-functions of electron beam are obtained.

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WEP2PT033

Conceptual Design of Superconducting Transverse Gradient Undulator for PAL-XFEL Beamline

ion, FEL, undulator, operation

142

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

Funding: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT \& Future Planning(2017R1C1B1012852)
Recently, the transverse gradient undulator (TGU) applications are suggested from the laser plasma wake-field accelerator (LPWA) to ultimate storage ring (USR). Especially for X-ray FEL, TGU can be used to generate the large bandwidth radiation (up to §I10{\percent}). In this proceeding, the review of PAL-XFEL beam parameters and TGU requirements was done to apply a variable large bandwidth operation to the PAL-XFEL beamlines. Also, the conceptual design of TGU, based on superconducting undulator (SCU) was proposed, and B-field calculation results were introduced for PAL-XFEL large bandwidth operation mode.

Poster WEP2PT033 [0.927 MB]

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WEP2PT050

Status of CAEP THz Free Electron Laser Oscillator

ion, FEL, laser, free-electron-laser

154

M. Li, T.H. He, C.L. Lao, P. Li, S.F. Lin, X. Luo, Q. Pan, L.J. Shan, X. Shen, H. Wang, J. Wang, D. Wu, D.X. Xiao, Y. Xu, X. Yang, P. Zhang, K. Zhou
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

China Academy of Engineering Physics tera-hertz free electron laser (CAEP THz FEL, CTFEL) is the first THz FEL oscillator in China, which was jointly built by CAEP, Peking university and Tsinghua university. The stimulated saturation of the CTFEL was reached in August, 2017. This THz FEL facility consists of a GaAs photocathode high-voltage DC gun, a superconducting RF linac, a planar undulator and a quasi-concentric optical resonator. The terahertz laser's frequency is continuous adjustable from 2 THz to 3 THz. The average power is more than 10 W and the micro-pulse power is more than 0.1 MW.

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THA1WA03

GPT-CSR: A New Simulation Code for CSR Effects

ion, simulation, radiation, bunching

157

S.B. van der Geer, M.J. de Loos
Pulsar Physics, Eindhoven, The Netherlands
I. Setija, P.W. Smorenburg
ASML Netherlands B.V., Veldhoven, The Netherlands
P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

For future applications of high-brightness electron beams, including the design of next generation FEL's, correct correct simulation of Coherent Synchrotron Radiation (CSR) is essential as it potentially degrades beam quality to unacceptable levels. However, the long interaction lengths compared to the bunch length, numerical cancellation, and difficult 3D retardation conditions make accurate simulation of CSR effects notoriously difficult. To ease the computational burden, CSR codes often make severe simplifications such as an ultra relativistic bunch travelling on a prescribed reference trajectory. Here we report on a new CSR model, implemented in the General Particle Tracer (GPT) code, that avoids most of the usual assumptions: It directly evaluates the Lienard-Wiechert potentials based on the stored history of the beam, it makes no assumptions about reference trajectories, while also taking into account the transverse size of the beam. First results demonstrating microbunching gain in a chicane are presented.

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THP2WB04

Laser Seeding of Electron Bunches for Future Ring-Based Light Sources

ion, laser, radiation, storage-ring

177

S. Khan, B. Büsing, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, B. Riemann, B. Sawadski, M. Schmutzler, P. Ungelenk
DELTA, Dortmund, Germany

Funding: Funded by BMBF (05K16PEA, 05K16PEB), MERCUR (Pr-2014-0047), DFG (INST 212/236-1 FUGG) and the Land NRW.
In contrast to free-electron lasers (FELs), ring-based light sources are limited in intensity by incoherent emission and in pulse duration by the bunch length. However, FEL seeding schemes can be adopted to generate intense and ultrashort radiation pulses in storage rings by creating laser-induced microbunches within a short slice of the electron bunch. Microbunching gives rise to coherent emission at harmonics of the seed wavelength. In addition, terahertz (THz) radiation is coherently emitted over many turns. At DELTA, a storage ring operated by the TU Dortmund University, coherent harmonic generation (CHG) with single and double 40-fs pulses is routinely performed at seed wavelengths of 800 and 400 nm. Seeding with intensity-modulated pulses to generate tunable narrowband THz radiation is also studied. As a preparation for echo-enabled harmonic generation (EEHG), simultaneous seeding with 800/400-nm pulses in two undulators has been demonstrated. The DELTA storage ring is an excellent testbed to study many aspects of laser seeding and related diagnostics. In addition to short-pulse generation, steady-state microbunching at ring-based light sources will be discussed in the paper.

Slides THP2WB04 [5.103 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THP2WB04

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THA1WC01

Compact Arc Compressor for FEL-Driven Compton Light Source and ERL-Driven UV FEL

ion, FEL, emittance, dipole

183

S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
J.A.G. Akkermans, I. Setija
ASML Netherlands B.V., Veldhoven, The Netherlands
D. Douglas
JLab, Newport News, Virginia, USA
C. Pellegrini
SLAC, Menlo Park, California, USA
G. Penn, M. Placidi
LBNL, Berkeley, California, USA

Many research and applications areas require photon sources capable of producing extreme ultra-violet (EUV) to gamma-ray beams with reasonably high fluxes and compact footprints. We explore the feasibility of a compact energy-recovery linac EUV free electron laser (FEL)*, and of a multi-MeV gamma-rays source based on inverse Compton scattering from a high intensity UV FEL emitted by the electron beam itself. In the latter scenario, the same electron beam is used to produce gamma-rays in the 10-20 MeV range and UV radiation in the 10¹⁵ eV range, in a ~4x22 m² footprint system.**
* J.Akkermans, S.Di Mitri, D.Douglas, I.Setija, PRAB 20, 080705 (2017).
** M. Placidi, S. Di Mitri,⁎, C. Pellegrini, G. Penn, NIM A 855 (2017) 55-60.

Slides THA1WC01 [5.258 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THA1WC01

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THP1WD02

LCLS-II Beam Containment System for Radiation Safety

ion, cavity, FEL, radiation

187

C.I. Clarke, J. Bauer, M. Boyes, Y. Feng, A.S. Fisher, R.A. Kadyrov, J.C. Liu, E. Rodriguez, M. Rowen, M. Santana-Leitner, F. Tao, J.J. Welch, S. Xiao
SLAC, Menlo Park, California, USA
T.L. Allison, J. Musson
JLab, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 and DE-AC05-06OR23177.
LCLS-II is a new xFEL facility under construction at SLAC National Accelerator Laboratory with a superconducting electron linac designed to operate up to §I{1.2}{MW} of beam power. This generates more serious beam hazards than the typical sub-kW linac operation of the existing xFEL facility, Linac Coherent Light Source (LCLS). SLAC uses a set of safety controls termed the Beam Containment System (BCS) to limit beam power and losses to prevent excessive radiation in occupied areas. The high beam power hazards of LCLS-II necessitate the development of new BCS devices and a larger scale deployment than previously done at LCLS. We present the new radiation hazards introduced by LCLS-II and the design development for the BCS.

Slides THP1WD02 [2.244 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THP1WD02

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THP2WD01

Construction and Optimization of Cryogenic Undulators at SOLEIL

ion, undulator, cryogenics, vacuum

193

M. Valléau, P. Berteaud, F. Briquez, P. Brunelle, N. Béchu, M.-E. Couprie, J. Da Silva Castro, J.M. Dubuisson, A. Ghaith, C. Herbeaux, J. Idam, C.A. Kitegi, F. Lepage, A. Lestrade, M. Louvet, O. Marcouillé, F. Marteau, A. Mary, A. Nadji, L.S. Nadolski, P. Rommeluère, M. Sebdaoui, A. Somogyi, K.T. Tavakoli, M. Tilmont, T. Weitkamp
SOLEIL, Gif-sur-Yvette, France

Funding: Synchrotron SOLEIL, L'Orme des Merisiers, 91 192 BP 34 Gif-sur-Yvette, France,
With permanent magnets undulator operation at cryogenic temperature, the magnetic field and the coercivity can be enhanced, enabling shorter periods with high magnetic fields. The first full scale (2 m long, 18 mm period) hybrid cryogenic undulator [1] using PrFeB [2] magnets operating at 77 K was installed at SOLEIL in 2011. Photon spectra measurements, in good agreement with the ex-pectations from magnetic measurements, were used for precise alignment and taper optimization. The second and third 18 mm PrFeB cryogenic undulators, modified to a half-pole/magnet/half-pole structure, were optimized without any magnet or pole shimming after assembly but mechanical sortings and some geometrical corrections had been done before assembly. A systematic error on individual magnets on the third U18 was also compensated. In-situ measurement benches, including a Hall probe and a stretched wire to optimize the undulator field at room and cryogenic temperature are presented. An upgrade of these in-situ benches will be detailed with the fabrication of a 15 mm 3 m long PrFeB cryogenic undulator at SOLEIL.
[1] C. Benabderrahmane, M. Valléau, M. E. Couprie, Phys. Rev. Accel. Beams 20, 033201(2017)
[2] C. Benabderrahmane, M. Valléau, M. E. Couprie, NIMA 669, 1-6, (2012)

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reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THP2WD01

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