FEL2019 - List of Keywords (linac)

Paper	Title	Other Keywords	Page
MOA07	Commissioning and First Lasing of the FELiChEM: A New IR and THz FEL Oscillator in China	FEL, electron, cavity, undulator	15
	H.T. Li, Q.K. Jia USTC/NSRL, Hefei, Anhui, People’s Republic of China
	A new infrared FEL named FELiChEM aiming at the energy chemistry has been constructed and commissioned at NSRL in Hefei. It consists of two FEL oscillators driven by one normal-conducting S-Band linac with maximum beam energy of 60 MeV. The two oscillators generate the midinfrared and far-infrared lasers covering the spectral range of 2.5-50 µm and 40-200 µm, respectively. First lasing was achieved at a wavelength of 15 µm with an electron energy of 35 MeV. Till now, we have observed the FEL signal from 3.5 µm to 30 µm and achieved the maximum micropulse energy up to 27 µJ at 15 µm.
	Slides MOA07 [2.434 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-MOA07
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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TUP008	Concept of High-Power CW IR-THz Source for the Radiation Source Elbe Upgrade	undulator, electron, radiation, FEL	59
	P.E. Evtushenko, T.E. Cowan, U. Lehnert, P. Michel HZDR, Dresden, Germany
	The Radiation Source ELBE at HZDR is a user facility based on a 1 mA, 40 MeV CW SRF LINAC. HZDR is considering upgrade options for the ELBE or its replacement with a new user facility. A part of the user requirements is the capability to generate IR and THz pulse in the frequency range from 0.1 through 30 THz, with pulse energies in the range from 100 uJ through a few mJ, at the repetition rate between 100 kHz and 1 MHz. In this contribution, we outline key aspects of a concept, which would allow achieving such parameters. Such key aspects are: use of a beam with longitudinal density modulation and bunching factor of about 0.5 at the fundamental frequency; achieving the density modulation through the mechanism similar to the one used in optical klystron (OK) and HGHG FEL, generation necessary for the modulation optical beam by an FEL oscillator, using two electron injectors, where one injector provides a beam for the FEL oscillator while second high charge injector provides beam for the high energy per pulse generation for user experiments. All-in-all the concept of the new radiation source is very similar to an OK, but operating with two beams simultaneously.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP008
About •	paper received ※ 29 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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TUP066	Start-to-End Simulations for the Soft X-Ray FEL at the MAX IV Laboratory	FEL, simulation, electron, undulator	210
	W. Qin, J. Andersson, F. Curbis, L. Isaksson, M. Kotur, E. Mansten, M.A. Pop, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden F. Curbis, S. Werin SLF, Lund, Sweden
	Funding: The work is supported by Knut and Alice Wallenberg foundation. A Soft X-ray FEL (the SXL) using the existing 3 GeV linac at the MAX IV Laboratory is currently in the design phase. In this contribution, start-to-end simulations, including the photo-injector simulations using ASTRA, the linac simulations using ELEGANT and the FEL simulations using GENESIS, are presented for 100 pC and 10 pC operation modes. The features of the electron beam from the MAX IV linac and their impact on the FEL performance are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP066
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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WEP009	Long Term Stability and Slow Feedback Performance at the European XFEL	feedback, FEL, operation, undulator	339
	R. Kammering DESY, Hamburg, Germany
	The European XFEL is now routinely running in user operation since more than two years. Up to 8 longitudinal and 9 transversal slow feedback loops are routinely used to keep the accelerators chosen operation conditions. First tests of comparing the machine ’free-floating’ state versus fully fixing all relevant monitoring signals have been carried out and show interesting results. Here we will review the feedback systems in terms of software architecture and conceptual layout but also in respect to feedback and FEL performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP009
About •	paper received ※ 20 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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WEP010	Femtosecond Laser-to-RF Synchronization and RF Reference Distribution at the European XFEL	laser, FEL, feedback, FEM	343
	T. Lamb, M. Felber, T. Kozak, J. Müller, H. Schlarb, S. Schulz, C. Sydlo, M. Titberidze, F. Zummack DESY, Hamburg, Germany
	At the European XFEL, optical pulses from a mode-locked laser are distributed in an optical fiber network providing femtosecond stability throughout the accelerator facility. Due to the large number of RF reference clients and because of the expected higher reliability, the 1.3 GHz RF reference signals are distributed by a conventional coaxial RF distribution system. However, the provided ultra-low phase noise 1.3 GHz RF reference signals may drift over time. To remove these drifts, an optical reference module (REFM-OPT) has been developed to detect and correct environmentally induced phase errors of the RF reference. It uses a femtosecond long-term stable laser-to-RF phase detector, based on an integrated Mach-Zehnder amplitude modulator (MZM), to measure and resynchronize the RF phase with respect to the laser pulses from the optical synchronization system with high accuracy. Currently nine REFM-OPTs are permanently operated at the European XFEL, delivering femtosecond stable RF reference signals for critical accelerating field control stations. The operation experience will be reported together with a detailed evaluation of the REFM-OPT performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP010
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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WEP037	RF Jitter and Electron Beam Stability in the SwissFEL Linac	FEL, klystron, feedback, booster	400
	Z.G. Geng, J. Alex, V.R. Arsov, P. Craievich, C.H. Gough, R. Kalt, T. Lippuner, F. Löhl, M. Pedrozzi, E. Prat, S. Reiche PSI, Villigen PSI, Switzerland
	The X-ray FEL machine SwissFEL at the Paul Scherrer Institut in Switzerland is commissioned and transiting to user operation smoothly. FEL operation requires stringent requirements for the beam stability at the linac output, such as the electron bunch arrival time, peak current and energy. Among other things, a highly stable RF system is required to guarantee the beam stability. The SwissFEL RF system is designed based on the state-of-the-art technologies that have allowed achieving excellent RF stability. The propagation of RF amplitude and phase jitter to the electron beam are analyzed theoretically and compared with the measurements performed at SwissFEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP037
About •	paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
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WEP043	Multi-Energy Operation Analysis in a Superconducting Linac Based on off-Frequency Detune Method	SRF, undulator, electron, acceleration	416
	Z. Zhang, C. Adolphsen, Y. Ding, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	The free-electron laser facilities driven by a superconducting radio-frequency (SRF) linac provide high-repetition-rate electron beam, which makes it feasible to feed multiple undulator lines at the same time. In this paper, we study a method of controlling the beam energy of multiple electron bunches by off-frequency detuning of the SRF linac. Based on the theoretical analysis, we present the optimal solutions of the method and the strategy to allocate linac energy for each possible off-frequency detune. The initial acceleration phases before detuning of the SRF linac can be optimized to reduce the necessary SRF linac energy overhead. We adopt the LCLS-II-HE configuration as an example to discuss possible schemes for two undulator lines.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP043
About •	paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
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WEP045	Status of the Klystrons for the European XFEL after Commissioning and First User Operation Phase	FEL, klystron, operation, cathode	420
	V. Vogel (Fogel), M. Bousonville, A. Cherepenko, S. Choroba, H.-J. Eckoldt, T. Grevsmühl, V.V. Katalev, K. Machau, P. Morozov, B. Yildirim DESY, Hamburg, Germany
	At present 26 RF stations for the European XFEL are in operation. Each of the RF stations consists of a HV modulator located on the DESY campus, up to 1600 m long 10 kV HV cables that connect the modulators and the HV pulse transformers located in the underground tunnel, the horizontal multi-beam klystron (MBK), and an air filled waveguide distribution system (WG) between the klystron and the cavities input couplers. The klystrons can produce RF power up to 10 MW, 1.5 ms RF pulse length and 10 Hz repetition rate. Two RF stations of the injector have already achieved about 30,000 hours of operation, RF stations of the XFEL bunch compressor area have operated up to 20,000 hours and the klystrons in the XFEL main linac already have about 18,000 hours of operation. To increase the lifetime of the klystrons we are using a fast protection system (KLM) that is in routine operation since 2018 in addition to the common interlock system. In this article we will give a summary of the present klystrons operation status including the number of HV and RF arcs in the klystrons and in the WG system and operation statistics for the high power RF part of machine.
	Poster WEP045 [0.757 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP045
About •	paper received ※ 20 August 2019 paper accepted ※ 12 September 2019 issue date ※ 05 November 2019
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WEP056	Engineering Design of Low-Emittance DC-SRF Photocathode Injector	SRF, cathode, cavity, shielding	460
	Y.Q. Liu, M. Chen, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, S. Zhao PKU, Beijing, People’s Republic of China
	An upgraded version of DC-SRF photocathode injector (DC-SRF-II) is under development at Peking University. The goal is to achieve an emittance below 0.5 mm-mrad at the bunch charge of 100 pC and repetition rate of 1 MHz. The engineering design of the DC-SRF-II photoinjector was accomplished in this May and the fabrication is ongoing now. This paper presents some details of the engineering design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP056
About •	paper received ※ 19 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019
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THB04	Longitudinal Phase Space Study on Injector Beam of High Repetition Rate X-Ray FEL	electron, cavity, bunching, laser	584
	Q. Gu SSRF, Shanghai, People’s Republic of China Z. Wang SARI-CAS, Pudong, Shanghai, People’s Republic of China
	The longitudinal phase space of the high repetition rate injector beam usually twisted and deteriorated by the space charge force. It causes the correlated energy spread and the local chirp within the beam, which could not compensated by the harmonic correction. As a consequence of this problem, one could not get ideal beam with a peak current more than kiloamperes. In this paper several approaches have been studied to relieve this effect and get the well compressed beam for the lasing.
	Slides THB04 [3.151 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THB04
About •	paper received ※ 26 August 2019 paper accepted ※ 16 September 2019 issue date ※ 05 November 2019
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THP001	Steffen Hard-Edge Model for Quadrupoles with Extended Fringe-Fields at the European XFEL	quadrupole, FEL, focusing, optics	588
	N. Golubeva, V. Balandin, W. Decking, L. Fröhlich, M. Scholz DESY, Hamburg, Germany
	For modeling of linear focusing properties of quadrupole magnets the conventional rectangular model is commonly used for the design and calculations of the linear beam optics for accelerators. At the European XFEL the quadrupole magnets are described using a more accurate Steffen hard-edge model. In this paper we discuss the application of the Steffen approach for the European XFEL quadrupoles and present the examination of the model with the orbit response matrix technique.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP001
About •	paper received ※ 20 August 2019 paper accepted ※ 25 August 2019 issue date ※ 05 November 2019
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THP008	Design of a Multi-Cell SRF Reduced-Beta Cavity for the Acceleration of Low Energy Electron Beams	cavity, electron, SRF, operation	603
	D.B. Bazyl, H. De Gersem, W.F.O. Müller TEMF, TU Darmstadt, Darmstadt, Germany J. Enders, S. Weih TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG (GRK 2128) Recently, the S-DALINAC has successfully passed the first ERL tests. One of the critical requirements for further operation in the ERL regime is minimising the longitudinal energy spread of the electron beam. One of the major sources for the current energy spread at the S-DALINAC is the low energy accelerating section. In order to overcome this problem an SRF reduced-beta cavity has been designed. The new cavity will replace the existing capture section and will allow to accelerate low energy electron beams with a minimised energy spread growth. In this work we discuss the electromagnetic and mechanical design of the SRF 3 GHz 6-cell reduced-beta cavity of elliptic type. In addition, we present the results of beam dynamics simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP008
About •	paper received ※ 19 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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THP011	Experimental Benchmarking of Wakefields at the FERMI FEL Linac and Undulator Line	wakefield, electron, undulator, FEL	613
	S. Di Mitri, L. Sturari Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy C. Venier, R. Vescovo University of Trieste, Trieste, Italy
	Collective effects such as wakefields affect the dynamics of high brightness electron beams in linear accelerators (linacs), and can degrade the performance of short wavelength free-electron lasers (FELs). If a reliable model of wakefields is made available, the accelerator can be designed and configured with parameters that minimize their disrupting effect. In this work, the simulated effect of geometric (diffractive) wakefields and of coherent synchrotron radiation on the electron beam energy distribution at the FERMI FEL is benchmarked with measurements, so quantifying the accuracy of the model. Wakefields modelling is then extended to the undulator line, where particle tracking confirms the limited impact of the resistive wall wakefield on the lasing process. The study reveals an overall good understanding of collective effects in the facility [1]. [1] S. Di Mitri et al., Phys. Rev. Accel. and Beams, 22, 014401 (2019)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP011
About •	paper received ※ 29 July 2019 paper accepted ※ 25 August 2019 issue date ※ 05 November 2019
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THP013	User Operation of Sub-Picosecond THz Coherent Transition Radiation Parasitic to a VUV FEL	electron, target, radiation, FEL	621
	S. Di Mitri, N. Adhlakha, E. Allaria, L. Badano, G. De Ninno, P. Di Pietro, G. Gaio, L. Giannessi, G. Penco, A. Perucchi, P. Rebernik Ribič, E. Roussel, S. Spampinati, C. Spezzani, M. Trovò, M. Veronese Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno University of Nova Gorica, Nova Gorica, Slovenia L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy S. Lupi Coherentia, Naples, Italy S. Lupi Sapienza University of Rome, Roma, Italy F. Piccirilli IOM-CNR, Trieste, Italy E. Roussel PhLAM/CERLA, Villeneuve d’Ascq, France E. Roussel PhLAM/CERCLA, Villeneuve d’Ascq Cedex, France
	Coherent transition radiation is enhanced in intensity and extended in frequency spectral range by the electron beam manipulation in the beam dump beam line of the FERMI FEL, by exploiting the interplay of coherent synchrotron radiation instability and electron beam optics [1]. Experimental observations at the TeraFERMI beamline [2] confirm intensity peaks at around 1 THz and extending up to 8.5 THz, for up to 80 µJ pulse energy integrated over the full bandwidth. By virtue of its implementation in an FEL beam dump line, this work might stimulate the development of user-oriented multi-THz beamlines parasitic and self-synchronized to VUV and X-ray FELs. [1] S. Di Mitri et al., Scientific Reports, 8, 11661 (2018). [2] A. Perucchi et al., Synch. Rad. News 4, 30 (2017).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP013
About •	paper received ※ 29 July 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
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THP015	The X-Band Linear Compression System in Dalian Coherent Light Source	electron, FEL, simulation, RF-structure	625
	Y. Yu, Z. Chen, G.K. Cheng, D.X. Dai, H.L. Ding, Z.G. He, L. Huang, Q.M. Li, Z.B. Li, L. Shi, J.T. Sun, K. Tao, Y.H. Tian, G.L. Wang, Z.Q. Wang, G.R. Wu, J.Y. Yang, X.M. Yang, W.Q. Zhang DICP, Dalian, People’s Republic of China
	Dalian Coherent Light Source (DCLS) is a free-electron laser (FEL) user facility working in the extreme ultraviolet (EUV) wavelength region from 50 to 150 nm. It mainly operates on the High Gain Harmonic Generation (HGHG) mode with the seed laser, although it can also run in the Self Amplified Spontaneous Emission (SASE) mode. The brightness and bandwidth of FEL radiation strongly depends on electron bunch quality, such as normalized transverse emittance, electron bunch energy, energy spread, peak current, etc. The high peak current with uniform longitudinal distribution is especially helpful for high peak power and narrow bandwidth of FEL, although it is not easy to achieve, due to the nonlinearity of sinusoidal accelerating radio frequency (RF) field and the 2nd-order momentum compaction coefficient T566 of bunch compressor. An X-band linearizer will be installed before the bunch compressor in order to correct this nonlinearity properly. In this paper, the beam dynamics design of the X-band linear compression system in DCLS is focused, and the simulation results with Elegant are presented and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP015
About •	paper received ※ 19 August 2019 paper accepted ※ 25 August 2019 issue date ※ 05 November 2019
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THP016	Study of Microbunching Instability in SHINE Linac	laser, bunching, simulation, electron	629
	D. Huang SINAP, Shanghai, People’s Republic of China D. Gu SARI-CAS, Pudong, Shanghai, People’s Republic of China M. Zhang Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
	The SHINE project in China aims at the next generation high repetation rate and high power hard X-ray free electron laser facility. The high quality electron beam is thus requested in the linac to generate such a high quality FEL lasing. As the prerequisite, the microbuncing instability introduced by the nonlinear effects such as the LSC, CSR and wakefields in the bunch compressing process must be taken care of, otherwise the electron beam will not meet the requirements of lasing. In this article, the microbunching effects including the gain of the instability in the linac of SHINE are estimated, and several ways for the control of the instability are proposed.
	Poster THP016 [0.536 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP016
About •	paper received ※ 24 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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THP030	An Updated Design of the NSRRC Seeded VUV Free Electron Laser Test Facility	undulator, laser, FEL, radiation	651
	W.K. Lau, C.K. Chan, C.-H. Chang, C.-C. Chang, L.-H. Chang, C.H. Chen, M.C. Chou, P.J. Chou, F.Z. Hsiao, K.T. Hsu, H.P. Hsueh, K.H. Hu, C.-S. Hwang, J.-Y. Hwang, J.C. Jan, C.K. Kuan, A.P. Lee, M.-C. Lin, G.-H. Luo, K.L. Tsai NSRRC, Hsinchu, Taiwan A. Chao, J. Wu SLAC, Menlo Park, California, USA S.Y. Teng NTHU, Hsinchu, Taiwan
	In this report, we present an updated design of the facility which is a 200 nm seeded, HGHG FEL driven by a 250 MeV high brightness electron linac system with dogleg bunch compressor for generation of ultrashort intense coherent radiation in the vacuum ultraviolet region. It employs a 10-periods helical undulator for enhancement of beam energy modulation and a helical undulator of 20 mm period length as the radiator (i.e. THU20) to produce hundreds of megawatts radiation with wavelength as short as 66.7 nm. An optional planar undulator can be added to generate odd harmonics (e.g. 22.2 nm, 13.3 nm etc.) of the fundamental. The facility layout and expected FEL output performance is reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP030
About •	paper received ※ 20 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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THP031	Simulation and Optimization of Injector System for the Pre-bunched THz FEL	electron, gun, radiation, simulation	654
	N. Chaisueb, S. Rimjaem Chiang Mai University, Chiang Mai, Thailand S. Rimjaem ThEP Center, Commission on Higher Education, Bangkok, Thailand
	A linac-based light source for generation of infrared free-electron laser is under the development at Chiang Mai University, Thailand. The injector system of the facility consists mainly of an S-band thermionic cathode RF electron gun, a pre-bunch compressor in a form of an alpha magnet and a travelling-wave linac structure. Two 180-degree magnetic bunch compressors are installed downstream the injector system. Two separate radiation beamlines for mid-infrared (MIR) and terahertz (THz) free-electron laser (FEL) are located following the bunch compressor systems. In this contribution, we focus only on the coherent and high-power pre-bunch THz FEL that is generated from electron bunches with a femtosecond length. Electron beam dynamic simulations with program ASTRA were performed to obtain optimal electron beam properties. Optimization of the injector system for the THz FEL is thus presented. The simulated results show that the beam at the linac exit has a bunch length of 282 fs with a charge of 200 pC when the linac RF phase is 90° and the alpha gradient is 300 G/cm. This optimal condition will be used as an input for simulation in the 180-degree bunch compressor system and in the THz undulator magnet.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP031
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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THP035	Beam Shaping for High-Repetition-Rate X-Ray FELs	octupole, electron, emittance, FEL	661
	Y. Ding, K.L.F. Bane, Y.M. Nosochkov SLAC, Menlo Park, California, USA
	Beam shaping at normal-conducting, accelerator-based FELs, such as LCLS, plays an important role for improving lasing performance and for supporting special operating modes, such as the self-seeding scheme. Beam shaping methods include horn-collimation and dechirper manipulation. Applying the beam shaping concept to high-repetition-rate FELs driven by a superconducting linac, such as LCLS-II, beam invasive methods are not preferred due to concerns about high power deposition. We have recently studied a few shaping options for LCLS-II, such as manipulating the beam chirp before compression using corrugated devices, and modifying higher order optics terms in a chicane using octupoles. In this report we will discuss the results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP035
About •	paper received ※ 23 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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THP044	The Simulation Study for Single and Multi Turn ERL Based EUV FEL	simulation, electron, FEL, laser	677
	K.M. Nam, G.S. Yun POSTECH, Pohang, Kyungbuk, Republic of Korea Y.W. Parc PAL, Pohang, Kyungbuk, Republic of Korea
	Photolithography technology is the core part of the semiconductor manufacturing process. It has required light having stronger power for higher throughput. ERL based EUV FEL is emerging as a next generation EUV source which can produce the light over 10 kW. In this study, first, EUV-FEL design, which is based on single turn, is represented. It accelerates 40 pC electron beam to 600 MeV and produces EUV, whose wavelength and power are 13.5 nm and 37 kW. Second, multiturn based design is represented. It improved compactness to make it more suitable for industrial use. As a result, the electron beam was able to obtain the kinetic energy and circulate, and the size was reduced to about half without reducing the power greatly. This study is expected to increase the practical industrialization potential of ERL-based photolithography.
	Poster THP044 [0.584 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP044
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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THP066	XARA: X-Band Accelerator for Research and Applications	FEL, electron, undulator, photon	715
	D.J. Dunning, L.S. Cowie, J.K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom L.S. Cowie, J.K. Jones Cockcroft Institute, Warrington, Cheshire, United Kingdom L.S. Cowie Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	XARA (X-band Accelerator for Research and Applications) is a proposal for a compact ~1 GeV/c accelerator to produce attosecond light pulses in the EUV to soft X-ray region. It is under consideration as a potential future upgrade to the CLARA facility at Daresbury Laboratory, utilising high-performance X-band RF technology to increase the electron beam momentum from 250 MeV/c. Emerging techniques for generating single-cycle undulator light [1] would give access to attosecond timescales, enabling studies of ultra-fast dynamics, while also being very compact. XARA would also enhance the existing capabilities for accelerator science R&D by incorporating X-band development and increasing the electron beam momentum for novel acceleration studies. [1] Alan Mak et al., Rep. Prog. Phys. 82 025901 (2019)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP066
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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THP078	Status of the CompactLight Design Study	FEL, electron, undulator, gun	738
	G. D’Auria, S. Di Mitri, R.A. Rochow Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy M. Aicheler HIP, University of Helsinki, Finland A. Aksoy Ankara University Institute of Accelerator Technologies, Golbasi, Turkey D. Alesini, M. Bellaveglia, B. Buonomo, F. Cardelli, M. Croia, M. Diomede, M. Ferrario, A. Gallo, A. Giribono, L. Piersanti, J. Scifo, B. Spataro, C. Vaccarezza INFN/LNF, Frascati, Italy R. Apsimon, G. Burt, A. Castilla Cockcroft Institute, Lancaster University, Lancaster, United Kingdom J.M. Arnesano, F. Bosco, L. Ficcadenti, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy A. Bernhard, J. Gethmann KIT, Karlsruhe, Germany M. Calvi, T. Schmidt, K. Zhang PSI, Villigen PSI, Switzerland H.M. Castañeda Cortés, J.A. Clarke, D.J. Dunning, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.W. Cross, L. Zhang USTRAT/SUPA, Glasgow, United Kingdom G. Dattoli, F. Nguyen, A. Petralia ENEA C.R. Frascati, Frascati (Roma), Italy R.T. Dowd, D. Zhu AS - ANSTO, Clayton, Australia D. Esperante Pereira, J. Fuster, D. Gonzalez-Iglesias IFIC, Valencia, Spain W. Fang SINAP, Shanghai, People’s Republic of China A. Faus-Golfe, Y. Han LAL, Orsay, France E.N. Gazis, N. Gazis National Technical University of Athens, Athens, Greece R. Geometrante, M. Kokole KYMA, Trieste, Italy B. Gimeno UVEG, Burjasot (Valencia), Spain V.A. Goryashko, M. Jacewicz, R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden R. Hoekstra ARCNL, Amsterdam, The Netherlands X.J.A. Janssen, J.M.A. Priem VDL ETG, Eindhoven, The Netherlands A. Latina, X. Liu, C. Rossi, D. Schulte, S. Stapnes, X.W. Wu, W. Wuensch CERN, Geneva, Switzerland O.J. Luiten, P.H.A. Mutsaers, X.F.D. Stragier TUE, Eindhoven, The Netherlands J. Marcos, E. Marín, R. Muñoz Horta, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain Z. Nergiz Ankara University, Faculty of Sciences, Ankara, Turkey L.J.R. Nix University of Strathclyde, Glasgow, United Kingdom E. Tanke, E. Trachnas ESS, Lund, Sweden G. Taylor The University of Melbourne, Melbourne, Victoria, Australia
	Funding: This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 777431. CompactLight (XLS) is an International Collaboration of 24 partners and 5 third parties, funded by the European Union through the Horizon 2020 Research and Innovation Programme. The main goal of the project, which started in January 2018 with a duration of 36 months, is the design of an hard X-ray FEL facility beyond today’s state of the art, using the latest concepts for bright electron photo-injectors, high-gradient accelerating structures, and innovative short-period undulators. The specifications of the facility and the parameters of the future FEL are driven by the demands of potential users and the associated science cases. In this paper we will give an overview on the ongoing activities and the major results achieved until now.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP078
About •	paper received ※ 19 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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THP079	Status and Perspectives of the FERMI FEL Facility (2019)	FEL, laser, electron, free-electron-laser	742
	L. Giannessi, E. Allaria, L. Badano, S. Bassanese, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, F. Cilento, P. Cinquegrana, M. Coreno, I. Cudin, G. D’Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, M. Di Fraia, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, L. Foglia, P. Furlan Radivo, G. Gaio, F. Gelmetti, F. Iazzourene, S. Krecic, G. Kurdi, M. Lonza, N. Mahne, M. Malvestuto, M. Manfredda, C. Masciovecchio, M. Milloch, R. Mincigrucci, N.S. Mirian, I. Nikolov, F.H. O’Shea, G. Penco, A. Perucchi, O. Plekan, M. Predonzani, K.C. Prince, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, N. Shafqat, P. Sigalotti, A. Simoncig, S. Spampinati, C. Spezzani, M. Svandrlik, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste, operating in the VUV to EUV and soft X-rays spectral range; the radiation produced by the seeded FEL is characterized by wavelength stability, low temporal jitter and longitudinal coherence in the range 100-4 nm. During 2018 a dedicated experiment has shown the potential of the Echo Enabled Harmonic Generation (EEHG) scheme [1] to cover most of this spectral range with a single stage cascade [2]. Such a scheme, combined to an increment of the beam energy and of the accelerator performances, could extend the FERMI operating range toward the oxygen k-edge. With this perspective, we present the development plans under consideration for the next 3 to 5 years. These include an upgrade of the linac and of the existing FEL lines, consisting in the conversion of FEL-1 first, and FEL-2 successively, into EEHG seeded FELs. [1] G. Stupakov, Phys. Rev. Lett. 102, 74801 (2009) [2] P. Rebernik et al., Nature Photonics https://doi.org/10.1038/s41566-019-0427-1
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP079
About •	paper received ※ 28 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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THP084	Status of the Soft X-Ray Laser (SXL) Project at MAX IV Laboratory	FEL, simulation, experiment, undulator	749
	F. Curbis, J. Andersson, L. Isaksson, M. Kotur, F. Lindau, E. Mansten, M.A. Pop, H. Tarawneh, P.F. Tavares, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden S. Bonetti, A. Nilsson Stockholm University, Stockholm, Sweden V.A. Goryashko Uppsala University, Uppsala, Sweden P. Johnsson, W. Qin Lund University, Lund, Sweden M. Larsson, P.M. Salén FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden J.A. Sellberg KTH Physics, Stockholm, Sweden
	Funding: The work is supported by Knut and Alice Wallenberg foundation. A Soft X-ray Laser project (the SXL) aiming to produce FEL radiation in the range of 1 to 5 nm is currently in a conceptual design phase and a report on the design is expected to be delivered by March 2021. The FEL will be driven by the existing 3 GeV linac at MAX IV laboratory, which also serves as injector for the two storage rings. The science case has been pushed by a large group of mainly Swedish users and consists of experiments ranging from AMO physics to condensed matter, chemistry and imaging in life science. In this contribution, we will present the current conceptual design of the accelerator and the FEL operation modes together with a general overview of the beamline and experimental station. In particular design options for the FEL will be discussed in conjunction with the features of the electron beam from the MAX IV linac and the connection with the proposed experiments.
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About •	paper received ※ 21 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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FRA02	LCLS-II - Status and Upgrades	undulator, electron, operation, photon	772
	A. Brachmann, M. Dunham, J.F. Schmerge SLAC, Menlo Park, California, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-76SF00515. The LCLS-II FEL is under construction at the SLAC National Accelerator Laboratory. This facility is based on a superconducting accelerator, providing a cw e^- beam of 4 GeV at ~1 MHz. This beam drives two variable gap undulator (VGU) beam lines to generate photons in the soft and hard X-ray regime. High repetition rate photon beams will be available up to ~5 keV. The normal conducting accelerator will remain in operation, delivering milli-joule pulses up to ~20 keV for LCLS science. We anticipate to start the LCLS user program in the spring of 2020 using the new undulator systems. Superconducting accelerator operation will start in 2021 and will achieve full design-performance over the course of several years. Approximately a quarter of the superconducting accelerator is installed now and the associated cryoplant construction is near completion. The VGU systems will be installed and ready for beam delivery in early 2020. We will report on the project status, commissioning and ramp-up plans to achieve design performance and discuss plans to take advantage of the new facilities potential including our longer term strategy to extend the capability of SLAC’s LCLS FEL facility.
	Slides FRA02 [24.207 MB]
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Paper

Title

Other Keywords

Page

MOA07

Commissioning and First Lasing of the FELiChEM: A New IR and THz FEL Oscillator in China

FEL, electron, cavity, undulator

15

H.T. Li, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People’s Republic of China

A new infrared FEL named FELiChEM aiming at the energy chemistry has been constructed and commissioned at NSRL in Hefei. It consists of two FEL oscillators driven by one normal-conducting S-Band linac with maximum beam energy of 60 MeV. The two oscillators generate the midinfrared and far-infrared lasers covering the spectral range of 2.5-50 µm and 40-200 µm, respectively. First lasing was achieved at a wavelength of 15 µm with an electron energy of 35 MeV. Till now, we have observed the FEL signal from 3.5 µm to 30 µm and achieved the maximum micropulse energy up to 27 µJ at 15 µm.

Slides MOA07 [2.434 MB]

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TUP008

Concept of High-Power CW IR-THz Source for the Radiation Source Elbe Upgrade

undulator, electron, radiation, FEL

59

P.E. Evtushenko, T.E. Cowan, U. Lehnert, P. Michel
HZDR, Dresden, Germany

The Radiation Source ELBE at HZDR is a user facility based on a 1 mA, 40 MeV CW SRF LINAC. HZDR is considering upgrade options for the ELBE or its replacement with a new user facility. A part of the user requirements is the capability to generate IR and THz pulse in the frequency range from 0.1 through 30 THz, with pulse energies in the range from 100 uJ through a few mJ, at the repetition rate between 100 kHz and 1 MHz. In this contribution, we outline key aspects of a concept, which would allow achieving such parameters. Such key aspects are: use of a beam with longitudinal density modulation and bunching factor of about 0.5 at the fundamental frequency; achieving the density modulation through the mechanism similar to the one used in optical klystron (OK) and HGHG FEL, generation necessary for the modulation optical beam by an FEL oscillator, using two electron injectors, where one injector provides a beam for the FEL oscillator while second high charge injector provides beam for the high energy per pulse generation for user experiments. All-in-all the concept of the new radiation source is very similar to an OK, but operating with two beams simultaneously.

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paper received ※ 29 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

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TUP066

Start-to-End Simulations for the Soft X-Ray FEL at the MAX IV Laboratory

FEL, simulation, electron, undulator

210

W. Qin, J. Andersson, F. Curbis, L. Isaksson, M. Kotur, E. Mansten, M.A. Pop, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden
F. Curbis, S. Werin
SLF, Lund, Sweden

Funding: The work is supported by Knut and Alice Wallenberg foundation.
A Soft X-ray FEL (the SXL) using the existing 3 GeV linac at the MAX IV Laboratory is currently in the design phase. In this contribution, start-to-end simulations, including the photo-injector simulations using ASTRA, the linac simulations using ELEGANT and the FEL simulations using GENESIS, are presented for 100 pC and 10 pC operation modes. The features of the electron beam from the MAX IV linac and their impact on the FEL performance are discussed.

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WEP009

Long Term Stability and Slow Feedback Performance at the European XFEL

feedback, FEL, operation, undulator

339

R. Kammering
DESY, Hamburg, Germany

The European XFEL is now routinely running in user operation since more than two years. Up to 8 longitudinal and 9 transversal slow feedback loops are routinely used to keep the accelerators chosen operation conditions. First tests of comparing the machine ’free-floating’ state versus fully fixing all relevant monitoring signals have been carried out and show interesting results. Here we will review the feedback systems in terms of software architecture and conceptual layout but also in respect to feedback and FEL performance.

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WEP010

Femtosecond Laser-to-RF Synchronization and RF Reference Distribution at the European XFEL

laser, FEL, feedback, FEM

343

T. Lamb, M. Felber, T. Kozak, J. Müller, H. Schlarb, S. Schulz, C. Sydlo, M. Titberidze, F. Zummack
DESY, Hamburg, Germany

At the European XFEL, optical pulses from a mode-locked laser are distributed in an optical fiber network providing femtosecond stability throughout the accelerator facility. Due to the large number of RF reference clients and because of the expected higher reliability, the 1.3 GHz RF reference signals are distributed by a conventional coaxial RF distribution system. However, the provided ultra-low phase noise 1.3 GHz RF reference signals may drift over time. To remove these drifts, an optical reference module (REFM-OPT) has been developed to detect and correct environmentally induced phase errors of the RF reference. It uses a femtosecond long-term stable laser-to-RF phase detector, based on an integrated Mach-Zehnder amplitude modulator (MZM), to measure and resynchronize the RF phase with respect to the laser pulses from the optical synchronization system with high accuracy. Currently nine REFM-OPTs are permanently operated at the European XFEL, delivering femtosecond stable RF reference signals for critical accelerating field control stations. The operation experience will be reported together with a detailed evaluation of the REFM-OPT performance.

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WEP037

RF Jitter and Electron Beam Stability in the SwissFEL Linac

FEL, klystron, feedback, booster

400

Z.G. Geng, J. Alex, V.R. Arsov, P. Craievich, C.H. Gough, R. Kalt, T. Lippuner, F. Löhl, M. Pedrozzi, E. Prat, S. Reiche
PSI, Villigen PSI, Switzerland

The X-ray FEL machine SwissFEL at the Paul Scherrer Institut in Switzerland is commissioned and transiting to user operation smoothly. FEL operation requires stringent requirements for the beam stability at the linac output, such as the electron bunch arrival time, peak current and energy. Among other things, a highly stable RF system is required to guarantee the beam stability. The SwissFEL RF system is designed based on the state-of-the-art technologies that have allowed achieving excellent RF stability. The propagation of RF amplitude and phase jitter to the electron beam are analyzed theoretically and compared with the measurements performed at SwissFEL.

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WEP043

Multi-Energy Operation Analysis in a Superconducting Linac Based on off-Frequency Detune Method

SRF, undulator, electron, acceleration

416

Z. Zhang, C. Adolphsen, Y. Ding, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The free-electron laser facilities driven by a superconducting radio-frequency (SRF) linac provide high-repetition-rate electron beam, which makes it feasible to feed multiple undulator lines at the same time. In this paper, we study a method of controlling the beam energy of multiple electron bunches by off-frequency detuning of the SRF linac. Based on the theoretical analysis, we present the optimal solutions of the method and the strategy to allocate linac energy for each possible off-frequency detune. The initial acceleration phases before detuning of the SRF linac can be optimized to reduce the necessary SRF linac energy overhead. We adopt the LCLS-II-HE configuration as an example to discuss possible schemes for two undulator lines.

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WEP045

Status of the Klystrons for the European XFEL after Commissioning and First User Operation Phase

FEL, klystron, operation, cathode

420

V. Vogel (Fogel), M. Bousonville, A. Cherepenko, S. Choroba, H.-J. Eckoldt, T. Grevsmühl, V.V. Katalev, K. Machau, P. Morozov, B. Yildirim
DESY, Hamburg, Germany

At present 26 RF stations for the European XFEL are in operation. Each of the RF stations consists of a HV modulator located on the DESY campus, up to 1600 m long 10 kV HV cables that connect the modulators and the HV pulse transformers located in the underground tunnel, the horizontal multi-beam klystron (MBK), and an air filled waveguide distribution system (WG) between the klystron and the cavities input couplers. The klystrons can produce RF power up to 10 MW, 1.5 ms RF pulse length and 10 Hz repetition rate. Two RF stations of the injector have already achieved about 30,000 hours of operation, RF stations of the XFEL bunch compressor area have operated up to 20,000 hours and the klystrons in the XFEL main linac already have about 18,000 hours of operation. To increase the lifetime of the klystrons we are using a fast protection system (KLM) that is in routine operation since 2018 in addition to the common interlock system. In this article we will give a summary of the present klystrons operation status including the number of HV and RF arcs in the klystrons and in the WG system and operation statistics for the high power RF part of machine.

Poster WEP045 [0.757 MB]

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WEP056

Engineering Design of Low-Emittance DC-SRF Photocathode Injector

SRF, cathode, cavity, shielding

460

Y.Q. Liu, M. Chen, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, S. Zhao
PKU, Beijing, People’s Republic of China

An upgraded version of DC-SRF photocathode injector (DC-SRF-II) is under development at Peking University. The goal is to achieve an emittance below 0.5 mm-mrad at the bunch charge of 100 pC and repetition rate of 1 MHz. The engineering design of the DC-SRF-II photoinjector was accomplished in this May and the fabrication is ongoing now. This paper presents some details of the engineering design.

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paper received ※ 19 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019

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THB04

Longitudinal Phase Space Study on Injector Beam of High Repetition Rate X-Ray FEL

electron, cavity, bunching, laser

584

Q. Gu
SSRF, Shanghai, People’s Republic of China
Z. Wang
SARI-CAS, Pudong, Shanghai, People’s Republic of China

The longitudinal phase space of the high repetition rate injector beam usually twisted and deteriorated by the space charge force. It causes the correlated energy spread and the local chirp within the beam, which could not compensated by the harmonic correction. As a consequence of this problem, one could not get ideal beam with a peak current more than kiloamperes. In this paper several approaches have been studied to relieve this effect and get the well compressed beam for the lasing.

Slides THB04 [3.151 MB]

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paper received ※ 26 August 2019 paper accepted ※ 16 September 2019 issue date ※ 05 November 2019

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THP001

Steffen Hard-Edge Model for Quadrupoles with Extended Fringe-Fields at the European XFEL

quadrupole, FEL, focusing, optics

588

N. Golubeva, V. Balandin, W. Decking, L. Fröhlich, M. Scholz
DESY, Hamburg, Germany

For modeling of linear focusing properties of quadrupole magnets the conventional rectangular model is commonly used for the design and calculations of the linear beam optics for accelerators. At the European XFEL the quadrupole magnets are described using a more accurate Steffen hard-edge model. In this paper we discuss the application of the Steffen approach for the European XFEL quadrupoles and present the examination of the model with the orbit response matrix technique.

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THP008

Design of a Multi-Cell SRF Reduced-Beta Cavity for the Acceleration of Low Energy Electron Beams

cavity, electron, SRF, operation

603

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

Funding: Work supported by DFG (GRK 2128)
Recently, the S-DALINAC has successfully passed the first ERL tests. One of the critical requirements for further operation in the ERL regime is minimising the longitudinal energy spread of the electron beam. One of the major sources for the current energy spread at the S-DALINAC is the low energy accelerating section. In order to overcome this problem an SRF reduced-beta cavity has been designed. The new cavity will replace the existing capture section and will allow to accelerate low energy electron beams with a minimised energy spread growth. In this work we discuss the electromagnetic and mechanical design of the SRF 3 GHz 6-cell reduced-beta cavity of elliptic type. In addition, we present the results of beam dynamics simulations.

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THP011

Experimental Benchmarking of Wakefields at the FERMI FEL Linac and Undulator Line

wakefield, electron, undulator, FEL

613

S. Di Mitri, L. Sturari
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
C. Venier, R. Vescovo
University of Trieste, Trieste, Italy

Collective effects such as wakefields affect the dynamics of high brightness electron beams in linear accelerators (linacs), and can degrade the performance of short wavelength free-electron lasers (FELs). If a reliable model of wakefields is made available, the accelerator can be designed and configured with parameters that minimize their disrupting effect. In this work, the simulated effect of geometric (diffractive) wakefields and of coherent synchrotron radiation on the electron beam energy distribution at the FERMI FEL is benchmarked with measurements, so quantifying the accuracy of the model. Wakefields modelling is then extended to the undulator line, where particle tracking confirms the limited impact of the resistive wall wakefield on the lasing process. The study reveals an overall good understanding of collective effects in the facility [1].
[1] S. Di Mitri et al., Phys. Rev. Accel. and Beams, 22, 014401 (2019)

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THP013

User Operation of Sub-Picosecond THz Coherent Transition Radiation Parasitic to a VUV FEL

electron, target, radiation, FEL

621

S. Di Mitri, N. Adhlakha, E. Allaria, L. Badano, G. De Ninno, P. Di Pietro, G. Gaio, L. Giannessi, G. Penco, A. Perucchi, P. Rebernik Ribič, E. Roussel, S. Spampinati, C. Spezzani, M. Trovò, M. Veronese
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno
University of Nova Gorica, Nova Gorica, Slovenia
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
S. Lupi
Coherentia, Naples, Italy
S. Lupi
Sapienza University of Rome, Roma, Italy
F. Piccirilli
IOM-CNR, Trieste, Italy
E. Roussel
PhLAM/CERLA, Villeneuve d’Ascq, France
E. Roussel
PhLAM/CERCLA, Villeneuve d’Ascq Cedex, France

Coherent transition radiation is enhanced in intensity and extended in frequency spectral range by the electron beam manipulation in the beam dump beam line of the FERMI FEL, by exploiting the interplay of coherent synchrotron radiation instability and electron beam optics [1]. Experimental observations at the TeraFERMI beamline [2] confirm intensity peaks at around 1 THz and extending up to 8.5 THz, for up to 80 µJ pulse energy integrated over the full bandwidth. By virtue of its implementation in an FEL beam dump line, this work might stimulate the development of user-oriented multi-THz beamlines parasitic and self-synchronized to VUV and X-ray FELs.
[1] S. Di Mitri et al., Scientific Reports, 8, 11661 (2018).
[2] A. Perucchi et al., Synch. Rad. News 4, 30 (2017).

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paper received ※ 29 July 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

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THP015

The X-Band Linear Compression System in Dalian Coherent Light Source

electron, FEL, simulation, RF-structure

625

Y. Yu, Z. Chen, G.K. Cheng, D.X. Dai, H.L. Ding, Z.G. He, L. Huang, Q.M. Li, Z.B. Li, L. Shi, J.T. Sun, K. Tao, Y.H. Tian, G.L. Wang, Z.Q. Wang, G.R. Wu, J.Y. Yang, X.M. Yang, W.Q. Zhang
DICP, Dalian, People’s Republic of China

Dalian Coherent Light Source (DCLS) is a free-electron laser (FEL) user facility working in the extreme ultraviolet (EUV) wavelength region from 50 to 150 nm. It mainly operates on the High Gain Harmonic Generation (HGHG) mode with the seed laser, although it can also run in the Self Amplified Spontaneous Emission (SASE) mode. The brightness and bandwidth of FEL radiation strongly depends on electron bunch quality, such as normalized transverse emittance, electron bunch energy, energy spread, peak current, etc. The high peak current with uniform longitudinal distribution is especially helpful for high peak power and narrow bandwidth of FEL, although it is not easy to achieve, due to the nonlinearity of sinusoidal accelerating radio frequency (RF) field and the 2nd-order momentum compaction coefficient T566 of bunch compressor. An X-band linearizer will be installed before the bunch compressor in order to correct this nonlinearity properly. In this paper, the beam dynamics design of the X-band linear compression system in DCLS is focused, and the simulation results with Elegant are presented and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP015

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paper received ※ 19 August 2019 paper accepted ※ 25 August 2019 issue date ※ 05 November 2019

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THP016

Study of Microbunching Instability in SHINE Linac

laser, bunching, simulation, electron

629

D. Huang
SINAP, Shanghai, People’s Republic of China
D. Gu
SARI-CAS, Pudong, Shanghai, People’s Republic of China
M. Zhang
Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China

The SHINE project in China aims at the next generation high repetation rate and high power hard X-ray free electron laser facility. The high quality electron beam is thus requested in the linac to generate such a high quality FEL lasing. As the prerequisite, the microbuncing instability introduced by the nonlinear effects such as the LSC, CSR and wakefields in the bunch compressing process must be taken care of, otherwise the electron beam will not meet the requirements of lasing. In this article, the microbunching effects including the gain of the instability in the linac of SHINE are estimated, and several ways for the control of the instability are proposed.

Poster THP016 [0.536 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP016

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paper received ※ 24 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

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THP030

An Updated Design of the NSRRC Seeded VUV Free Electron Laser Test Facility

undulator, laser, FEL, radiation

651

W.K. Lau, C.K. Chan, C.-H. Chang, C.-C. Chang, L.-H. Chang, C.H. Chen, M.C. Chou, P.J. Chou, F.Z. Hsiao, K.T. Hsu, H.P. Hsueh, K.H. Hu, C.-S. Hwang, J.-Y. Hwang, J.C. Jan, C.K. Kuan, A.P. Lee, M.-C. Lin, G.-H. Luo, K.L. Tsai
NSRRC, Hsinchu, Taiwan
A. Chao, J. Wu
SLAC, Menlo Park, California, USA
S.Y. Teng
NTHU, Hsinchu, Taiwan

In this report, we present an updated design of the facility which is a 200 nm seeded, HGHG FEL driven by a 250 MeV high brightness electron linac system with dogleg bunch compressor for generation of ultrashort intense coherent radiation in the vacuum ultraviolet region. It employs a 10-periods helical undulator for enhancement of beam energy modulation and a helical undulator of 20 mm period length as the radiator (i.e. THU20) to produce hundreds of megawatts radiation with wavelength as short as 66.7 nm. An optional planar undulator can be added to generate odd harmonics (e.g. 22.2 nm, 13.3 nm etc.) of the fundamental. The facility layout and expected FEL output performance is reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP030

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paper received ※ 20 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

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THP031

Simulation and Optimization of Injector System for the Pre-bunched THz FEL

electron, gun, radiation, simulation

654

N. Chaisueb, S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand
S. Rimjaem
ThEP Center, Commission on Higher Education, Bangkok, Thailand

A linac-based light source for generation of infrared free-electron laser is under the development at Chiang Mai University, Thailand. The injector system of the facility consists mainly of an S-band thermionic cathode RF electron gun, a pre-bunch compressor in a form of an alpha magnet and a travelling-wave linac structure. Two 180-degree magnetic bunch compressors are installed downstream the injector system. Two separate radiation beamlines for mid-infrared (MIR) and terahertz (THz) free-electron laser (FEL) are located following the bunch compressor systems. In this contribution, we focus only on the coherent and high-power pre-bunch THz FEL that is generated from electron bunches with a femtosecond length. Electron beam dynamic simulations with program ASTRA were performed to obtain optimal electron beam properties. Optimization of the injector system for the THz FEL is thus presented. The simulated results show that the beam at the linac exit has a bunch length of 282 fs with a charge of 200 pC when the linac RF phase is 90° and the alpha gradient is 300 G/cm. This optimal condition will be used as an input for simulation in the 180-degree bunch compressor system and in the THz undulator magnet.

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP031

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paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

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THP035

Beam Shaping for High-Repetition-Rate X-Ray FELs

octupole, electron, emittance, FEL

661

Y. Ding, K.L.F. Bane, Y.M. Nosochkov
SLAC, Menlo Park, California, USA

Beam shaping at normal-conducting, accelerator-based FELs, such as LCLS, plays an important role for improving lasing performance and for supporting special operating modes, such as the self-seeding scheme. Beam shaping methods include horn-collimation and dechirper manipulation. Applying the beam shaping concept to high-repetition-rate FELs driven by a superconducting linac, such as LCLS-II, beam invasive methods are not preferred due to concerns about high power deposition. We have recently studied a few shaping options for LCLS-II, such as manipulating the beam chirp before compression using corrugated devices, and modifying higher order optics terms in a chicane using octupoles. In this report we will discuss the results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP035

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paper received ※ 23 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

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THP044

The Simulation Study for Single and Multi Turn ERL Based EUV FEL

simulation, electron, FEL, laser

677

K.M. Nam, G.S. Yun
POSTECH, Pohang, Kyungbuk, Republic of Korea
Y.W. Parc
PAL, Pohang, Kyungbuk, Republic of Korea

Photolithography technology is the core part of the semiconductor manufacturing process. It has required light having stronger power for higher throughput. ERL based EUV FEL is emerging as a next generation EUV source which can produce the light over 10 kW. In this study, first, EUV-FEL design, which is based on single turn, is represented. It accelerates 40 pC electron beam to 600 MeV and produces EUV, whose wavelength and power are 13.5 nm and 37 kW. Second, multiturn based design is represented. It improved compactness to make it more suitable for industrial use. As a result, the electron beam was able to obtain the kinetic energy and circulate, and the size was reduced to about half without reducing the power greatly. This study is expected to increase the practical industrialization potential of ERL-based photolithography.

Poster THP044 [0.584 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP044

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paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

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THP066

XARA: X-Band Accelerator for Research and Applications

FEL, electron, undulator, photon

715

D.J. Dunning, L.S. Cowie, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
L.S. Cowie, J.K. Jones
Cockcroft Institute, Warrington, Cheshire, United Kingdom
L.S. Cowie
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

XARA (X-band Accelerator for Research and Applications) is a proposal for a compact ~1 GeV/c accelerator to produce attosecond light pulses in the EUV to soft X-ray region. It is under consideration as a potential future upgrade to the CLARA facility at Daresbury Laboratory, utilising high-performance X-band RF technology to increase the electron beam momentum from 250 MeV/c. Emerging techniques for generating single-cycle undulator light [1] would give access to attosecond timescales, enabling studies of ultra-fast dynamics, while also being very compact. XARA would also enhance the existing capabilities for accelerator science R&D by incorporating X-band development and increasing the electron beam momentum for novel acceleration studies.
[1] Alan Mak et al., Rep. Prog. Phys. 82 025901 (2019)

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP066

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paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

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THP078

Status of the CompactLight Design Study

FEL, electron, undulator, gun

738

G. D’Auria, S. Di Mitri, R.A. Rochow
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
M. Aicheler
HIP, University of Helsinki, Finland
A. Aksoy
Ankara University Institute of Accelerator Technologies, Golbasi, Turkey
D. Alesini, M. Bellaveglia, B. Buonomo, F. Cardelli, M. Croia, M. Diomede, M. Ferrario, A. Gallo, A. Giribono, L. Piersanti, J. Scifo, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
R. Apsimon, G. Burt, A. Castilla
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
J.M. Arnesano, F. Bosco, L. Ficcadenti, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
A. Bernhard, J. Gethmann
KIT, Karlsruhe, Germany
M. Calvi, T. Schmidt, K. Zhang
PSI, Villigen PSI, Switzerland
H.M. Castañeda Cortés, J.A. Clarke, D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.W. Cross, L. Zhang
USTRAT/SUPA, Glasgow, United Kingdom
G. Dattoli, F. Nguyen, A. Petralia
ENEA C.R. Frascati, Frascati (Roma), Italy
R.T. Dowd, D. Zhu
AS - ANSTO, Clayton, Australia
D. Esperante Pereira, J. Fuster, D. Gonzalez-Iglesias
IFIC, Valencia, Spain
W. Fang
SINAP, Shanghai, People’s Republic of China
A. Faus-Golfe, Y. Han
LAL, Orsay, France
E.N. Gazis, N. Gazis
National Technical University of Athens, Athens, Greece
R. Geometrante, M. Kokole
KYMA, Trieste, Italy
B. Gimeno
UVEG, Burjasot (Valencia), Spain
V.A. Goryashko, M. Jacewicz, R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden
R. Hoekstra
ARCNL, Amsterdam, The Netherlands
X.J.A. Janssen, J.M.A. Priem
VDL ETG, Eindhoven, The Netherlands
A. Latina, X. Liu, C. Rossi, D. Schulte, S. Stapnes, X.W. Wu, W. Wuensch
CERN, Geneva, Switzerland
O.J. Luiten, P.H.A. Mutsaers, X.F.D. Stragier
TUE, Eindhoven, The Netherlands
J. Marcos, E. Marín, R. Muñoz Horta, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
Z. Nergiz
Ankara University, Faculty of Sciences, Ankara, Turkey
L.J.R. Nix
University of Strathclyde, Glasgow, United Kingdom
E. Tanke, E. Trachnas
ESS, Lund, Sweden
G. Taylor
The University of Melbourne, Melbourne, Victoria, Australia

Funding: This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 777431.
CompactLight (XLS) is an International Collaboration of 24 partners and 5 third parties, funded by the European Union through the Horizon 2020 Research and Innovation Programme. The main goal of the project, which started in January 2018 with a duration of 36 months, is the design of an hard X-ray FEL facility beyond today’s state of the art, using the latest concepts for bright electron photo-injectors, high-gradient accelerating structures, and innovative short-period undulators. The specifications of the facility and the parameters of the future FEL are driven by the demands of potential users and the associated science cases. In this paper we will give an overview on the ongoing activities and the major results achieved until now.

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP078

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paper received ※ 19 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

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THP079

Status and Perspectives of the FERMI FEL Facility (2019)

FEL, laser, electron, free-electron-laser

742

L. Giannessi, E. Allaria, L. Badano, S. Bassanese, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, F. Cilento, P. Cinquegrana, M. Coreno, I. Cudin, G. D’Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, M. Di Fraia, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, L. Foglia, P. Furlan Radivo, G. Gaio, F. Gelmetti, F. Iazzourene, S. Krecic, G. Kurdi, M. Lonza, N. Mahne, M. Malvestuto, M. Manfredda, C. Masciovecchio, M. Milloch, R. Mincigrucci, N.S. Mirian, I. Nikolov, F.H. O’Shea, G. Penco, A. Perucchi, O. Plekan, M. Predonzani, K.C. Prince, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, N. Shafqat, P. Sigalotti, A. Simoncig, S. Spampinati, C. Spezzani, M. Svandrlik, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste, operating in the VUV to EUV and soft X-rays spectral range; the radiation produced by the seeded FEL is characterized by wavelength stability, low temporal jitter and longitudinal coherence in the range 100-4 nm. During 2018 a dedicated experiment has shown the potential of the Echo Enabled Harmonic Generation (EEHG) scheme [1] to cover most of this spectral range with a single stage cascade [2]. Such a scheme, combined to an increment of the beam energy and of the accelerator performances, could extend the FERMI operating range toward the oxygen k-edge. With this perspective, we present the development plans under consideration for the next 3 to 5 years. These include an upgrade of the linac and of the existing FEL lines, consisting in the conversion of FEL-1 first, and FEL-2 successively, into EEHG seeded FELs.
[1] G. Stupakov, Phys. Rev. Lett. 102, 74801 (2009)
[2] P. Rebernik et al., Nature Photonics https://doi.org/10.1038/s41566-019-0427-1

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP079

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paper received ※ 28 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

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THP084

Status of the Soft X-Ray Laser (SXL) Project at MAX IV Laboratory

FEL, simulation, experiment, undulator

749

F. Curbis, J. Andersson, L. Isaksson, M. Kotur, F. Lindau, E. Mansten, M.A. Pop, H. Tarawneh, P.F. Tavares, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden
S. Bonetti, A. Nilsson
Stockholm University, Stockholm, Sweden
V.A. Goryashko
Uppsala University, Uppsala, Sweden
P. Johnsson, W. Qin
Lund University, Lund, Sweden
M. Larsson, P.M. Salén
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
J.A. Sellberg
KTH Physics, Stockholm, Sweden

Funding: The work is supported by Knut and Alice Wallenberg foundation.
A Soft X-ray Laser project (the SXL) aiming to produce FEL radiation in the range of 1 to 5 nm is currently in a conceptual design phase and a report on the design is expected to be delivered by March 2021. The FEL will be driven by the existing 3 GeV linac at MAX IV laboratory, which also serves as injector for the two storage rings. The science case has been pushed by a large group of mainly Swedish users and consists of experiments ranging from AMO physics to condensed matter, chemistry and imaging in life science. In this contribution, we will present the current conceptual design of the accelerator and the FEL operation modes together with a general overview of the beamline and experimental station. In particular design options for the FEL will be discussed in conjunction with the features of the electron beam from the MAX IV linac and the connection with the proposed experiments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP084

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paper received ※ 21 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

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FRA02

LCLS-II - Status and Upgrades

undulator, electron, operation, photon

772

A. Brachmann, M. Dunham, J.F. Schmerge
SLAC, Menlo Park, California, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-76SF00515.
The LCLS-II FEL is under construction at the SLAC National Accelerator Laboratory. This facility is based on a superconducting accelerator, providing a cw e^- beam of 4 GeV at ~1 MHz. This beam drives two variable gap undulator (VGU) beam lines to generate photons in the soft and hard X-ray regime. High repetition rate photon beams will be available up to ~5 keV. The normal conducting accelerator will remain in operation, delivering milli-joule pulses up to ~20 keV for LCLS science. We anticipate to start the LCLS user program in the spring of 2020 using the new undulator systems. Superconducting accelerator operation will start in 2021 and will achieve full design-performance over the course of several years. Approximately a quarter of the superconducting accelerator is installed now and the associated cryoplant construction is near completion. The VGU systems will be installed and ready for beam delivery in early 2020. We will report on the project status, commissioning and ramp-up plans to achieve design performance and discuss plans to take advantage of the new facilities potential including our longer term strategy to extend the capability of SLAC’s LCLS FEL facility.

Slides FRA02 [24.207 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-FRA02

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paper received ※ 04 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

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