Keyword: simulation
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TUP009 Integration of an XFELO at the European XFEL Facility FEL, electron, radiation, cavity 62
 
  • P. Rauer, I. Bahns, W. Hillert, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • W. Decking
    DESY, Hamburg, Germany
  • H. Sinn
    EuXFEL, Schenefeld, Germany
  
  Funding: Work supported by BMBF (FKZ 05K16GU4)
An X-ray free-electron laser oscillator (XFELO) is a fourth generation X-ray source promising radiation with full three dimensional coherence, nearly constant pulse to pulse stability and more than an order of magnitude higher peak brilliance compared to SASE FELs. Proposed by Kim et al. in 2008 [1] an XFELO follows the concept of circulating the light in an optical cavity - as known from FEL oscillators in longer wavelength regimes - but uses Bragg reflecting crystals instead of classical mirrors. With the new European X-ray Free-Electron Laser (XFEL) facility recently gone into operation, the realization of an XFELO with radiation in the Angstrom regime seems feasible. Though, the high thermal load of the radiation on the cavity crystals, the high sensibility of the Bragg-reflection on reflection angle and crystal temperature as well as the very demanding tolerances of the at least 60 m long optical resonator path pose challenges which need to be considered. In this work these problems shall be summarized and results regarding the possible integration of an XFELO at the European XFEL facility will be presented.
[1] K.-J. Kim, Y. Shvyd’ko and S. Reiche, Phys. Rev. Lett. 100 (2008), 244802. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP009  
About • paper received ※ 20 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
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TUP017 Terahertz FEL Simulation in PAL XFEL FEL, electron, undulator, radiation 77
 
  • J.H. Ko, H.-S. Kang
    PAL, Pohang, Republic of Korea
  
  Terahertz radiation is being used in various fields such as imaging, diagnosis, inspection, etc. For the terahertz research, the Pohang accelerator laboratory (PAL) is planning to make a terahertz free electron laser based on self-amplified spontaneous emission (SASE). Using free electron laser method, we can conduct the THz-pump X-ray probe experiment. For the terahertz free electron laser, we conducted the simulation on accelerators below 40 MeV, using photo-cathode RF gun, S-band accelerator and undulator below 4 meters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP017  
About • paper received ※ 20 August 2019       paper accepted ※ 25 August 2019       issue date ※ 05 November 2019  
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TUP018 Superradiant Emission of Electron Bunches Based on Cherenkov Excitation of Surface Waves in 1D and 2D Periodical Lattices: Theory and Experiments electron, GUI, experiment, radiation 80
 
  • A. Malkin, N.S. Ginzburg, A. Sergeev, I.V. Zheleznov, I.V. Zotova
    IAP/RAS, Nizhny Novgorod, Russia
  • M.I. Yalandin
    RAS/IEP, Ekaterinburg, Russia
  • V.Yu. Zaslavsky
    UNN, Nizhny Novgorod, Russia
  
  Funding: The work was supported by RFBR grant no. 17-08-01072
In recent years, significant progress was achieved in generation of high-power ultrashort microwave pulses based on superradiance (SR) of electron bunches extended in the wavelength scale. In this process, coherent emission from the entire volume of the bunch occurs due to the development of microbunching and slippage of the wave with respect to electrons. An obvious method for generation of high-power sub-THz radiation is the implementation of oversized periodical slow-wave structures where evanescent surface waves can be excited. We report of the experiments on Cherenkov generation of 150 ps SR pulses with a central frequency of 0.14 THz, and an extremely high peak power up to 70 MW. In order to generate spatially coherent radiation in shorter wavelength ranges (including THz band) in strongly oversized waveguiding systems, we propose a slow wave structure with double periodic corrugation (2D SWS). Using the quasi-optical theory and PIC simulations, we demonstrate the applicability of such 2D SWS and its advantages against traditional 1D SWS. Proof of principle experiments on observation G-band Cherenkov SR in 2D SWS are currently in progress. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP018  
About • paper received ※ 20 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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TUP020 Terahertz Free Electron Maser Based on Excitation of a Talbot-Type Super-Mode in an Oversized Microwave System electron, cavity, GUI, resonance 87
 
  • A.V. Savilov, Yu.S. Oparina, N.Yu. Peskov
    IAP/RAS, Nizhny Novgorod, Russia
  
  Funding: The work is supported by the Russian Science Foundation, Project # 19-12-00212.
A natural problem arising in the case of realization of a THz FEM with a high-current relativistic e-beam is an inevitable use of an oversized microwave system, which characteristic transverse size significantly exceeds the wavelength of the operating wave. In this situation, it becomes difficult to provide selective excitation of a chosen transverse mode of the operating cavity. Our basic idea is to give up working on a fixed transverse mode. Instead, we propose to work on a supermode, which is a fixed set of several transverse modes of an oversized wavegude. We propose to use the Talbot effect [1,2,3] as a way to create an oversized microwave system of an electron maser that provides a high Q-factor for this supermode. On the basis of a multi-mode set of self-consistent equations of the electron-wave interaction we demonstrate the possibility of the selective self-excitation of the supermode both in the simplest 2-D model and in the detailed modeling of a THz FEM fed by a 10 MeV / 2 kA / 200 e-beam based on excitation of a Talbot-type supermode at a frequency close to 2 THz. The calculated efficiency at the level of 5-10% corresponds to the GW level of the output power.
[1] L. A. Rivlin, Laser Focus, p. 82, 1981
[2] G. G. Denisov, D. A. Lukovnikov, M. Yu. Shmelyov, Digest of 18 Int. Conf. on IR MM Waves, p. 485, 1993
[3] V. L. Bratman et al., Nucl. Instr. Meth. Phys. Res. A, vol. 407, pp. 40-44, 1998 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP020  
About • paper received ※ 14 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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TUP021 Development of Powerful Long-Pulse Terahertz Band FELs Based on Linear Induction Accelerators electron, FEL, radiation, feedback 91
 
  • V.Yu. Zaslavsky, N.S. Ginzburg, A. Malkin, N.Yu. Peskov, A. Sergeev
    IAP/RAS, Nizhny Novgorod, Russia
  • A.V. Arzhannikov, E.S. Sandalov, S.L. Sinitsky, D.I. Skovorodin, A.A. Starostenko
    BINP SB RAS, Novosibirsk, Russia
  
  Funding: This work was supported by the Russian Scientific Foundation (RSCF), grant No. 19-12-00212.
The paper is devoted to development of high-power long-pulse THz-band FELs based on new generation of linear induction accelerators which have been elaborated recently at Budker Institute (Novosibirsk). These accelerators generate microsecond electron beams with current at kA-level and energy of 2 to 5 MeV (with a possibility to increase electrons energy up to 20 MeV). Based on this beam, we initiated a new project of multi-MW long-pulse FEL operating in the frequency range of 1 to 10 THz using a wiggler period of 3 to 6 cm. For this FEL oscillator, we suggest a hybrid planar two-mirror resonator consisting of an upstream highly selective advanced Bragg reflector and a downstream weakly reflecting conventional Bragg reflector. Simulations demonstrate that the advanced Bragg reflector based on coupling of propagating and quasi-cutoff waves ensures the mode control at the values of the gap between the corrugated plates forming such resonator up to 20 wavelengths. Simulations of the FEL driven by electron beam generated by the LIU¿2 in the frame of both averaged approach and 3D PIC code demonstrate that the THz radiation power can reach the level of 10 to 20 MW. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP021  
About • paper received ※ 28 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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TUP023 Analytical and Numerical Comparison of Different Approaches to the Description of SASE in High Gain FELs FEL, radiation, undulator, bunching 94
 
  • O.A. Shevchenko, N.A. Vinokurov
    BINP SB RAS, Novosibirsk, Russia
  • N.A. Vinokurov
    NSU, Novosibirsk, Russia
  
  Correlation function theory which has been developed recently gives rigorous statistical description of the SASE FEL operation. It directly deals with the values averaged over many shots. There are two other approaches which are based either on Vlasov equation or on direct solution of particle motion equations. Both of them use random functions which relate to single shot. To check the validity of these three approaches it might be interesting to compare them with each other. In this paper we present the results of such comparison obtained for the 1-D FEL model. We show that two-particle correlation function approximation is equivalent to the quasilinear approximation of the Vlasov equation approach. These two approximations are in a good agreement with the results of direct solution of particle motion equations at linear and early saturation stages. To obtain this agreement at strong saturation high order harmonics in Vlasov equation have to be taken into account which corresponds to taking into account of three and more particle correlations in the correlation function approach.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP023  
About • paper received ※ 19 August 2019       paper accepted ※ 25 August 2019       issue date ※ 05 November 2019  
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TUP026 Unaveraged Simulation of a Regenerative Amplifier Free Electron Laser FEL, undulator, cavity, electron 106
 
  • P. Pongchalee, B.W.J. MᶜNeil
    USTRAT/SUPA, Glasgow, United Kingdom
  • B.W.J. MᶜNeil
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  A regenerative amplifier free-electron laser (RAFEL) design and simulation requires the modelling of both the electron-light interaction in the FEL undulator and the optical propagation within the cavity. An unaveraged 3D simulation was used to model the FEL interaction within the undulator using the Puffin code. This allows a broadband, high temporal-resolution of the FEL interaction. The Optical Propagation Code (OPC) was used to model the optical beam propagation within the cavity and diagnostics at the cavity mirrors. This paper presents the optical field conversion method between Puffin and the OPC codes and demonstrates the full model via a VUV-RAFEL simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP026  
About • paper received ※ 19 August 2019       paper accepted ※ 25 August 2019       issue date ※ 05 November 2019  
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TUP027 Modelling Crystal Misaligments for the X-ray FEL Oscillator FEL, cavity, alignment, undulator 110
 
  • R.R. Lindberg
    ANL, Lemont, Illinois, USA
  
  Funding: Work supported by U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357.
The X-ray FEL oscillator has the potential to be a revolutionary new light source providing unprecedented stability in a narrow bandwidth [1]. However, a detailed understanding of cavity tolerance and stability has only begun, and there are presently no suitable simulation tools. To address this issue, we have developed a fast FEL oscillator code that discretizes the field using a Gauss-Hermite mode expansion of the oscillator cavity. Errors in crystal alignment result in a mixing of the modes that is easily modeled with a loss and coupling matrix. We show first results from our code, including the effects of static and time-varying crystal misalignments.
[1] K.-J. Kim, Y. Shvyd’ko, and S. Reiche, PRL 100 244802 (2008) 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP027  
About • paper received ※ 20 August 2019       paper accepted ※ 25 August 2019       issue date ※ 05 November 2019  
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TUP028 Power Variations of an X-ray FEL Oscillator in Saturation FEL, electron, cavity, undulator 114
 
  • R.R. Lindberg, K. Kim
    ANL, Lemont, Illinois, USA
  
  Funding: Work supported by U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357.
Basic FEL theory predicts that the fractional power fluctuations of an ideal oscillator in steady state should be given by the ratio of the spontaneous power in the oscillator bandwidth to that stored in the cavity at saturation. For the X-ray FEL oscillator with its narrow bandwidth Bragg crystal mirrors, this ratio is typically a few parts per million, but some simulations have shown evidence of power oscillations on the percent level. We show that this is not related to the well-known sideband instability, but rather is purely numerical and can be eliminated by changing the particle loading. We then briefly discuss to what extent variations in electron beam arrival time may degrade the power stability. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP028  
About • paper received ※ 20 August 2019       paper accepted ※ 25 August 2019       issue date ※ 05 November 2019  
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TUP041 X-cos SCILAB Model for Simulation of Intensity and Gain of Planar Undulator Radiation undulator, electron, radiation, FEL 138
 
  • H. Jeevakhan
    NITTTR, Bhopal, India
  • G. Mishra
    Devi Ahilya University, Indore, India
  
  SCILAB X-cos based model has been designed to simulate the Intensity and Gain of planar undulator radiation. Numerical approach has been used to determine the trajectories of an electron along x and z direction, traversing through a planar undulator. The present paper describes the technical details of the different blocks, parameters and possibility of combined model used for trajectory and intensity simulation Results are compared with the previous conventional syntax based codes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP041  
About • paper received ※ 01 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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TUP049 Simulating Shot-Noise of ’Real’ Electron Bunches micro-particles, electron, FEL, bunching 149
 
  • P. Traczykowski, L.T. Campbell, B.W.J. MᶜNeil
    USTRAT/SUPA, Glasgow, United Kingdom
  • L.T. Campbell, B.W.J. MᶜNeil, P. Traczykowski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • L.T. Campbell, P. Traczykowski
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  An algorithm and numerical code for the up-sampling of a system of particles, from a smaller to a larger number, is described. The method introduces a Poissonian ’shot-noise’ to the up-sampled distribution [1], typical of the noise statistics arising in a bunch of particles generated by a particle accelerator. The algorithm is applied on a phase-space distribution of relatively few simulation particles representing an electron beam generated by particle accelerator modelling software, for subsequent injection into an Free Electron Laser (FEL) amplifier which is used here to describe the model. A much larger number of particles is usually required to model the FEL lasing process than is required in the simulation models of the electron beam accelerators that drive it. A numerical code developed from the algorithm was then used to generate electron bunches for injection into to an unaveraged 3D FEL simulation code, Puffin [2]. Results show good qualitative and quantitative agreement with analytical theory. The program and usage manual is available to download from GitHub [3].
[1] B.W.J. McNeil, M.W. Poole and G.R.M. Robb, Physical Review Special Topics - Accelerators and Beams Vol 6, 070701 (2003).
[2] L.T. Campbell and B.W.J. McNeil, Phys. Plasmas 19, 093119 (2012).
[3] https://github.com/UKFELs/JDF
 		 
poster icon Poster TUP049 [1.419 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP049  
About • paper received ※ 20 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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TUP050 Comparison Between, and Validation Against an Experiment of, a Slowly-varying Envelope Approximation Code and a Particle-in-Cell Simulation Code for Free-Electron Lasers undulator, FEL, experiment, electron 153
 
  • P. Traczykowski, L.T. Campbell, J. Henderson, B.W.J. MᶜNeil
    USTRAT/SUPA, Glasgow, United Kingdom
  • L.T. Campbell, J. Henderson, P. Traczykowski
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • H. Freund
    University of New Mexico, Albuquerque, USA
  • B.W.J. MᶜNeil, P. Traczykowski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • P.J.M. van der Slot
    Mesa+, Enschede, The Netherlands
  
  Free-electron laser simulation codes employ either the Slowly-Varying Envelope Approximation (SVEA) or a Particle-in-Cell (PiC) formulation. Maxwell’s equations are averaged over the fast time scale in the SVEA so that there is no need to resolve the wave period. In contrast, the fast oscillation is retained in PiC codes. As a result, the SVEA codes are much less computationally intensive and are used more frequently than PiC codes. While the orbit dynamics in PiC codes and some SVEA Codes (MEDUSA and MINERVA) use the full unaveraged Lorentz force equations, some SVEA codes use the Kroll-Morton-Rosenbluth (KMR) approximation (GENESIS, GINGER, FAST, and TDA3D). Steady-state simulation comparisons [1] have appeared in the literature between different codes using the averaged and unaveraged particle dynamics. Recently, a comparison between three KMR SVEA codes (GENESIS, GINGER, and FAST) and the PUFFIN PiC code in the time-dependent regime has been reported [2]. In this paper, we present a comparison between the unaveraged PiC code PUFFIN, the unaveraged SVEA code MINERVA for the time-dependent simulation of SASE free-electron lasers with the experimental measurements from SPARC SASE FEL at ENEA Frascati.
[1] S.G. Biedron et al., NIMA 445, 110 (2000).
[2] B. Garcia et al., paper presented at the 38th International Free Electron Laser Conference, Santa Fe, New Mexico, 20 - 25 August 2017.
 		 
poster icon Poster TUP050 [0.908 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP050  
About • paper received ※ 02 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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TUP061 Super-X: Simulations for Extremely Hard X-Ray Generation With Short Period Superconducting Undulators for the European XFEL FEL, undulator, electron, photon 191
 
  • S. Serkez, G. Geloni, S. Karabekyan, Y. Li, T. Tanikawa, S. Tomin, F. Wolff-Fabris
    EuXFEL, Schenefeld, Germany
  • C. Boffo
    Bilfinger Noell GmbH, Wuerzburg, Germany
  • S. Casalbuoni
    KIT, Eggenstein-Leopoldshafen, Germany
  • M. Dohlus, E. Schneidmiller, M.V. Yurkov, I. Zagorodnov
    DESY, Hamburg, Germany
  • A. Trebushinin
    BINP, Novosibirsk, Russia
  
  The European XFEL is a high-repetition multi-user facility with nominal photon energy range covering almost 3 orders of magnitude: 250 eV - 25 keV. In this work we explore the possibility to extend the photon energy range of the facility up to 100 keV via combination of superconducting undulator technology, period doubling and harmonic lasing, thus allowing for excellent tunability. To this purpose, we propose a dedicated FEL line, discuss its overall concept and provide analytical and numerical estimations of its expected performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP061  
About • paper received ※ 20 August 2019       paper accepted ※ 25 August 2019       issue date ※ 05 November 2019  
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TUP064 Effect on FEL Gain Curve Using Phase Shifters FEL, electron, undulator, laser 203
 
  • M.H. Cho, H.-S. Kang, G. Kim, C.H. Shim, H. Yang
    PAL, Pohang, Republic of Korea
  
  Phase matching between FEL and electron beam should be precisely controlled for FEL amplification. Phase shifters located between undulators performs the phase matching. An electron beam can be controlled to be in the in- or out-phase by setting the phase shifters from the phase shifter scan. In this article, we show effects of FEL gain curve by setting the in- and out-phase of electron beam. We address reasons of the reduction of FEL intensity in the out-phase condition dividing the linear and saturation FEL amplification regimes. In the linear regime the gain curve is shifted, and in the saturation regime the electron loss occurs during the undulator tapering. Our results show agreements with experiments performed at PAL-XFEL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP064  
About • paper received ※ 21 August 2019       paper accepted ※ 28 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, electron, linac, 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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TUP074 FLASH Upgrade for Seeding FEL, laser, undulator, electron 226
 
  • V. Grattoni, S. Ackermann, B. Faatz, T. Lang, C. Lechner, M.M. Mohammad Kazemi, G. Paraskaki
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  An upgrade for FLASH, the SASE FEL in Hamburg, is planned after 2020 aiming at fulfilling user requirements like fully coherent, variable polarization, and multi-colour pulses. In this proceeding, we focus on the FLASH1 beamline that will be operated in seeded mode at a high repetition rate. In particular, we will present and discuss the proposed seeding schemes for delivering FEL radiation with wavelengths from 60 down to 4 nm  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP074  
About • paper received ※ 19 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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TUP077 Study of a Seeded Oscillator-Amplifier FEL laser, electron, FEL, free-electron-laser 234
 
  • G. Paraskaki, S. Ackermann, B. Faatz, V. Grattoni, C. Lechner, M. Mehrjoo
    DESY, Hamburg, Germany
  • G. Geloni, S. Serkez, T. Tanikawa
    EuXFEL, Schenefeld, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  In recent years, there is interest of the Free-Electron Laser (FEL) community in external-seeding techniques such as the Echo-Enabled Harmonic Generation (EEHG) and the High-Gain Harmonic Generation (HGHG). With these techniques, pulses of an improved temporal coherence are generated, but at the same time, they are limited by the repetition rates that seed lasers can currently offer with the required pulse energies. A big challenge is to combine the advantages of seeding schemes with high repetition rates. For this purpose, we study a combination of an oscillator-amplifier. The modulator in the oscillator is used at a long wavelength to modulate the electron beam and an amplifier is operated to extract the FEL radiation of the desired harmonic. This way we can use a seed laser of 10 Hz in a burst mode and a resonator to feedback the radiation at repetition rates of superconducting accelerators instead of using an external seed at these high-repetition rates. In this contribution, we present simulation results of a seeded oscillator-amplifier FEL in an HGHG scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP077  
About • paper received ※ 19 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
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TUP078 Impact of Electron Beam Energy Chirp on Seeded FELs electron, FEL, laser, timing 238
 
  • G. Paraskaki, S. Ackermann, B. Faatz, V. Grattoni, C. Lechner, J. Zemella
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  Seeded FELs enable the generation of fully coherent, transform-limited and high brightness FEL pulses, as the start-up process is driven by an external coherent light pulse. During the design process of such FELs, it is important to choose carefully the electron beam parameters to guarantee high performance. One of those parameters is the electron beam energy chirp. In this contribution, we show simulation results and we discuss how the electron beam energy chirp affects the final spectrum.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP078  
About • paper received ※ 16 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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TUP079 Status of the Hard X-Ray Self-Seeding Setup at the European XFEL FEL, undulator, electron, radiation 242
 
  • G. Geloni, S. Karabekyan, D. La Civita, L. Samoylova, S. Serkez, R. Shayduk, H. Sinn, V. Sleziona, M. Vannoni, M. Yakopov
    EuXFEL, Schenefeld, Germany
  • J.W.J. Anton, S.P. Kearney, D. Shu
    ANL, Lemont, Illinois, USA
  • V.D. Blank, S. Terentiev
    TISNCM, Troitsk, Russia
  • W. Decking, V. Kocharyan, S. Liu, E. Negodin, E. Saldin, T. Wohlenberg
    DESY, Hamburg, Germany
  • X. Dong
    European X-Ray Free-Electron Laser Facility GmbH, Schelefeld, Germany
  
  A Hard X-Ray Self-Seeding (HXRSS) setup will be soon commissioned at the European XFEL. It relies on a two-chicanes scheme to deal, in particular, with the high pulse repetition rate of the facility. In this contribution we review the physics choices made at the design stage and the expected performance of the setup. We will also focus on the description of the hardware installations made at the SASE2 line of the European XFEL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP079  
About • paper received ※ 27 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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TUP087 Start-to-end Simulations of the Reflection Hard X-Ray Self-Seeding at the SHINE Project FEL, undulator, photon, electron 254
 
  • T. Liu, X. Dong, C. Feng
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  
  The Shanghai high repetition rate XFEL and extreme light Facility (SHINE) project is designed to produce fully coherent X-ray photons covering the photon energy from 3 keV to 25 keV. We have reported our FEL proposal and schemes in the hard X-ray regime which is self-seeding based on the crystal monochromator previously. Comparing to the transmission self-seeding scheme, the reflection one has several advantages and might be the base proposal. Start-to-end (S2E) simulations from the beam generation by Astra, the linac accelerating by Elegant to the FEL simulation by Genesis are performed. In this manuscript, the FEL simulations based on the S2E beam will be presented mainly. The results demonstrate the feasibility of the reflection hard X-ray self-seeding at the SHINE project.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP087  
About • paper received ※ 20 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
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TUP090 Considerations on Implementing EEHG with a Strong Linear Chirp electron, laser, FEL, bunching 262
 
  • M.A. Pop, F. Curbis, W. Qin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  • F. Curbis, S. Werin
    SLF, Lund, Sweden
  • W. Qin
    Lund University, Lund, Sweden
  
  Funding: The work is supported by Knut and Alice Wallenberg foundation.
The Soft X-ray Laser (SXL) currently being studied at MAX IV Laboratory is envisioned to produce coherent radiation in the 1-5 nm wavelength range. In this contribution, we present the results of simulations aimed at adding to the SXL an Echo Enabled Harmonic Generation scheme, which has been shown to increase the coherence of FELs in the Soft X-ray regime. Our work puts special emphasis on accommodating the positive energy chirp of the electron bunch coming out of the MAX IV Linac and on generating sufficient bunching at the high harmonics necessary for covering the full wavelength range. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP090  
About • paper received ※ 20 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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TUP091 Start-to-End Simulation of the NSRRC Seeded VUV FEL FEL, laser, electron, undulator 266
 
  • S.Y. Teng
    NTHU, Hsinchu, Taiwan
  • C.H. Chen, W.K. Lau, A.P. Lee
    NSRRC, Hsinchu, Taiwan
  
  A free electron laser (FEL) driven by a high brightness electron linac system has been proposed to generate ultrashort intense coherent radiation in the vacuum ultraviolet region. It is a third harmonic high-gain high harmonic generation (HGHG) FEL for generation of VUV radiation with wavelength at 66.7 nm from a 20-mm period length helical undulator. A 200-nm seed laser is used for beam energy modulation in a 10-periods helical undulator of 24-mm period length. A small chicane is placed between the two undulators to optimize power growth in the radiator. In this study, we perform start-to-end simulation to foresee the operational performance of the test facility and preliminary results are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP091  
About • paper received ※ 20 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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WEP050 Status of Chirped Pulse Laser Shaping for the PITZ Photoinjector laser, electron, flattop, optics 437
 
  • C. Koschitzki, Y. Chen, J.D. Good, M. Groß, M. Krasilnikov, G. Loisch, R. Niemczyk, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • E. Khazanov, S. Mironov
    IAP/RAS, Nizhny Novgorod, Russia
  • T. Lang, L. Winkelmann
    DESY, Hamburg, Germany
  
  The beam emittance at FEL facilities like European XFEL and FLASH is dominated by the emittance sources in the electron injector. Shaping of the laser pulses that are employed to release electrons from the cathode of a photo injector, was shown in theory to allow improved beam emittance starting from the electron emission process. At the photo injector test facility at DESY in Zeuthen (PITZ) a laser system capable of controlling the temporal and spatial profile of laser pulses is being set up to demonstrate the predicted emittance reduction experimentally. The presentation will show its current capabilities to provide temporally and spatially shaped laser pulses from a pulse shaper operating at infrared (IR) wavelengths. Furthermore, results from a shape preserving conversion into fourth harmonic ultra-violet (UV), as needed for the photo emission process, will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP050  
About • paper received ※ 21 August 2019       paper accepted ※ 17 September 2019       issue date ※ 05 November 2019  
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WEP052 Simulation Studies on the Saturated Emission at PITZ laser, space-charge, gun, cathode 444
 
  • X. Li, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
  
  In this paper we report our consideration and simulation on the space charge dominated emission in the L-band photocathode RF gun at the Photo Injector Test facility at DESY in Zeuthen (PITZ). It has been found that the emission curve, which relates the extracted and accelerated bunch charge after the gun to the laser energy, doesn’t agree very well with Astra simulations when the emission is nearly or fully saturated. Previous studies with a core-halo model for a better fit of the experimentally measured laser transverse profile as well as with an improved transient emission model have resulted in a better agreement between experimental data and simulation. A 3D FFT space charge solver including mirror charge and binned energy/momentum has been built, which also allows more emission mechanisms to be included in the future. In this paper, the energy spread during emission was preliminarily analyzed. Experimentally measured emission curves were compared with simulation, showing the effect of the inhomogeneity of the laser on the emission and beam parameters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP052  
About • paper received ※ 20 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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WEP055 Multiphysics Analysis of a CW VHF Gun for European XFEL gun, cavity, FEL, vacuum 456
 
  • G. Shu, Y. Chen, S. Lal, H.J. Qian, H. Shaker, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  
  R&D for a possible future CW mode operation of European XFEL started after the successful commissioning of the pulse mode operation. For the CW electron source upgrade, a fully superconducting CW gun is under experimental development at DESY in Hamburg, and a normal conducting (NC) CW gun is under physics design at the Photo Injector Test facility at DESY in Zeuthen (PITZ) as a backup option. Based on the experience of the LBNL on a 187 MHz gun, the DESY 217 MHz gun increased the cathode gradient and RF power to 28 MV/m and 100 kW, respectively, to further improve the beam brightness. In this paper, the multiphysics analysis investigating the RF, thermal and mechanical properties of the 217 MHz NC CW gun are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP055  
About • paper received ※ 20 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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WEP070 Influence of Radiation Exposure on the FEL Performance at FLASH undulator, FEL, radiation, operation 488
 
  • B. Faatz, M. Tischer, P. Vagin
    DESY, Hamburg, Germany
  
  FLASH has been operated as user facility for about 14 years. In this time, the total charge accelerated and transported through the FLASH1 undulator is around 35 Coulomb. Based on detailed monitoring of the radiation loss and reference measurements on degradation of the magnetic field of the undulator, we have performed simulations to study the change in FEL performance and first comparison of the simulations with the changes we observe during operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP070  
About • paper received ※ 07 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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WEP072 Expected Radiation Properties of the Harmonic Afterburner at FLASH2 undulator, radiation, polarization, bunching 492
 
  • M. Mehrjoo, B. Faatz, G. Paraskaki, M. Tischer, P. Vagin
    DESY, Hamburg, Germany
  
  We discuss the afterburner option to upgrade the FLASH2 undulator line, at the FLASH facility in the Hamburg area, for delivering short wavelengths down to approximately 1.5 nm with variable polarization. This relatively straightforward upgrade enables us the study of the scientific cases in L- absorption edges of rare earth metals. The proposed afterburner setting with an energy upgrade to 1.35 GeV would potentially cover many of the community’s requests for the short wavelengths radiation and circular polarization. We also study the influence of reverse tapering on the radiation output. This contribution presents a series of simulations for the afterburner scheme and some of the technical choices made for implementation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP072  
About • paper received ※ 19 August 2019       paper accepted ※ 28 October 2019       issue date ※ 05 November 2019  
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WEP079 Effect of Heat Load on Cryo-Cooled Monochromators at the European X-Ray Free-Electron Laser: Simulations and First Experimental Observations FEL, experiment, electron, photon 502
 
  • I. Petrov, U. Boesenberg, M. Dommach, J. Eidam, J. Hallmann, K. Kazarian, C. Kim, W. Lu, A. Madsen, J. Möller, M. Reiser, L. Samoylova, R. Shayduk, H. Sinn, V. Sleziona, A. Zozulya
    EuXFEL, Schenefeld, Germany
  • J.W.J. Anton, S.P. Kearney, D. Shu
    ANL, Lemont, Illinois, USA
  • X. Dong
    SINAP, Shanghai, People’s Republic of China
  • X. Dong
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  
  European XFEL (EuXFEL) generates high-intensity ultra-short pulses at MHz repetition rate. At hard X-ray instruments, cryo-cooled silicon monochromators are used to reduce pulse bandwidth. Here, first experimental observations during commissioning of a cryo-cooled monochromator at Materials Imaging and Dynamics (MID) instrument are presented and compared with heat flow simulations. A thermal relaxation time is estimated and compared with arrival time interval between pulses. This provides the repetition rate tolerable for stable operation of monochromator.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP079  
About • paper received ※ 19 August 2019       paper accepted ※ 25 August 2019       issue date ※ 05 November 2019  
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THB02 Understanding 1D to 3D Coherent Synchrotron Radiation Effects radiation, emittance, electron, experiment 578
 
  • A.D. Brynes
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Collective effects such as coherent synchrotron radiation (CSR) can have a strong influence of the properties of an electron bunch with respect to the quality of the FEL light that it produces. In particular, CSR experienced by a bunch on a curved trajectory can increase the transverse emittance of a beam. In this contribution, we present an extension to the well-established 1D theory of CSR by accounting fully for the forces experienced in the entrance and exit transients of a bending magnet. A new module of the General Particle Tracer (GPT) tracking code was developed for this study, showing good agreement with theory. In addition to this analysis, we present experimental measurements of the emittance growth experienced in the FERMI bunch compressor chicane as a function of bunch length. When the bunch undergoes extreme compression, the 1D theory breaks down and is no longer valid. A comparison between the 1D theory, experimental measurements and a number of codes which simulate CSR differently are presented, showing better agreement when the transverse properties of the bunch are taken into account.  
slides icon Slides THB02 [3.591 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THB02  
About • paper received ※ 19 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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THP003 Arbitrary Order Perturbation Theory for a Time-Discrete Model of Micro-Bunching Driven by Longitudinal Space Charge bunching, space-charge, FEL, electron 596
 
  • Ph. Amstutz
    LBNL, Berkeley, California, USA
  • M. Vogt
    DESY, Hamburg, Germany
  
  A well established model for studying the micro-bunching instability driven by longitudinal space charge in ultra-relativistic bunches in FEL-like beamlines can be identified as a time-discrete Vlasov system with general drift maps and Poisson type collective kick maps. Here we present an arbitrary order perturbative approach for the general system and the complete all-orders solution for a special example. For this example we benchmark our theory against our Perron-Frobenius tree-code.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP003  
About • paper received ※ 20 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
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THP007 Frequency-Detuning Dependent Transient Coaxial RF Coupler Kick gun, cavity, focusing, electron 599
 
  • Y. Chen, J.D. Good, M. Groß, P.W. Huang, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
  • F. Brinker, W. Decking
    DESY, Hamburg, Germany
  
  We model and characterize a transverse kick which results from the coaxial RF coupler in the L-band RF gun at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). The RF pulse is typically 600 µs long and used to produce a train of up to 2700 electron bunches. The kick is transient and found to be dependent on the detuning of the resonance frequency of the gun cavity. The frequency detuning within the RF macro-pulse results in a variation in the kick strength along the pulse. This leads to a downstream orbit and size change of individual bunches within the train. Using 3D RF field distributions calculated at detuned frequencies of the cavity, particle tracking simulations are performed to simulate the transient kick onto the bunch train. Given a drift distance, the orbit and size change along a train of fixed length is estimated. Systematic measurements of the kick have meanwhile been carried out. The temperature of the cooling water for the gun is tuned allowing detailed characterization of the frequency detuning within the RF pulse, and thereby measurements of the kick under conditions of practical interest. Experimental findings and simulation results will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP007  
About • paper received ※ 13 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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THP009 Space Charge Field Beam Dynamics Simulations for the THz SASE FEL at PITZ undulator, radiation, space-charge, FEL 606
 
  • S.A. Schmid, H. De Gersem, E. Gjonaj
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Dohlus
    DESY, Hamburg, Germany
  • M. Krasilnikov
    DESY Zeuthen, Zeuthen, Germany
  
  Funding: This work is supported by the DFG in the framework of GRK 2128.
A proof-of-principle experiment on a THz SASE FEL is under consideration at the Photo Injector Test facility at DESY in Zeuthen (PITZ). One of its options assumes utilization of 4.0 nC bunches at 16.7 MeV [1]. In this operation mode, space charge interaction strongly influences the dynamics of the electron beam inside the undulator. In this contribution, we investigate the beam dynamics in the THz undulator of PITZ using a particle-particle interaction model based on a Lienard-Wiechert approach. We analyze the influence of retardation and radiation fields on the beam dynamics resulting in the microbunching effect. Furthermore, we compute the radiation field and estimate the radiation power at the exit of the undulator. The validity of the underlying numerical models is discussed.
[1] M. Krasilnikov et al., in Proc. ICAP’18, Key West, USA, paper TUPAF23, 2018
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP009  
About • paper received ※ 20 August 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, RF-structure, linac 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, linac, 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 icon 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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THP027 Simulation and Optimization of the Transport Beamline for the NovoFEL RF Gun gun, electron, solenoid, emittance 647
 
  • A.S. Matveev, I.V. Davidyuk, O.A. Shevchenko, V.G. Tcheskidov, N.A. Vinokurov, V. Volkov
    BINP SB RAS, Novosibirsk, Russia
  • I.V. Davidyuk, A.S. Matveev, N.A. Vinokurov
    NSU, Novosibirsk, Russia
  
  A new low-frequency CW RF gun was developed and tested at Budker Institute of Nuclear Physics recently. We plan to use it to upgrade the ERL of the Novosibirsk FEL facility. It will allow increasing the average beam current (due to higher beam repetition rate) and thus increasing the average radiation power. The transport beamline for the RF gun uses the ninety-degree achromatic bend. It is designed in a way that keeps an option to operate with the old electrostatic gun as well. Due to the low beam energy (290 keV) the beam dynamics is strongly influenced by space-charge forces. The paper describes results of simulation and optimization of the RF gun transport beamline. Space-charge forces were taken into account with the code ASTRA. Main sources of emittance degradation were considered in order to decrease their influence during the optimization. In addition, the RF gun output beam parameters were measured for various RF gun emission phases. These experiments were simulated and the results were compared. The resulting beam parameters meets requirements of the Novosibirsk FEL facility ERL.  
poster icon Poster THP027 [3.158 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP027  
About • paper received ※ 16 August 2019       paper accepted ※ 27 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, linac, gun, radiation 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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THP041 Interaction of Powerful Electro-Magnetic Fields With Bragg Reflectors laser, FEL, experiment, electron 673
 
  • I. Bahns, W. Hillert, P. Rauer, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • H. Sinn
    EuXFEL, Schenefeld, Germany
  
  Funding: supported by BMBF FKZ 05K16GU4
The interaction of an X-ray free electron laser (XFEL) with a Bragg Reflector can cause a change of the lattice constant, which has a direct influence on the stability of the reflection conditions [1] and can also excite modes of vibration [2]. The dynamical thermoelastic effects of the photon-matter-interaction are simulated with a finite-element-method (FEM) using the assumptions of continuums mechanics. To compare the simulation results with measured signals, a Michelson interferometer with ultrafast photodiodes (risetime <175ps, bandwith >2GHz) has been built up. To test the experimental setup in an in-house environment a pulsed UV laser is used to introduce a temporal displacement field in a silicon crystal created by about 0.26µJ of absorbed energy. The measured signal is in agreement with the FEM simulation and has shown that if averaging over thousands of pulses is applied a resolution <0.5pm is feasible. This makes this experimental setup useful to investigate the X-ray-matter-interaction of Bragg reflectors at modern X-ray facilities.
[1] S. Stoupin et al., Physical Review B 86.5 (2012): 054301.
[2] B. Yang, S. Wang and J. Wu, J. Synchrotron Rad. (2018) 25, 166-176. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP041  
About • paper received ※ 23 August 2019       paper accepted ※ 31 October 2019       issue date ※ 05 November 2019  
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THP044 The Simulation Study for Single and Multi Turn ERL Based EUV FEL electron, FEL, linac, 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 icon 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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THP054 Nanosecond Pulse Enhancement in Narrow Linewidth Cavity for Steady-State Microbunching cavity, laser, optics, impedance 697
 
  • Q.H. Zhou
    Southwest University of Science and Technology, Mianyang, Sichuan, People’s Republic of China
  
  Funding: The National Natural Science Foundation of China under Grant No.11875227.
In steady-state microbunching (SSMB), nanosecond laser pulse with megawatt average power is required. We build up a theoretic model to enhance such pulse in a narrow linewidth (e.g. kHz level) cavity for this demand, which shows that a mode-locked mechanism in frequency domain should be considered. Simulations indicate that such pulse can be enhanced sufficiently under this condition. And we also propose some experimental schematics to realize it. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP054  
About • paper received ※ 25 August 2019       paper accepted ※ 22 October 2019       issue date ※ 05 November 2019  
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THP055 A Storage Ring Design for Steady-State Microbunching to Generate Coherent EUV Light Source lattice, storage-ring, electron, radiation 700
 
  • Z. Pan, X.J. Deng, W.-H. Huang, T. Rui, C.-X. Tang, Y. Zhang
    TUB, Beijing, People’s Republic of China
  • A. Chao
    SLAC, Menlo Park, California, USA
  • W. Wan
    ShanghaiTech University, Shanghai, People’s Republic of China
  
  The proposal of Steady State Microbunching (SSMB) makes it available to generate high average power coherent radiation, especially has the potential to generate kW level of EUV source for lithography. In order to achieve and maintain SSMB, we propose several concepts. One is that a very short electron bunch below 100 nm is stored in the ring, inserting a strong focusing part to compress the bunch to ~3 nm, then radiating coherently, which is called longitudinal strong focusing (LSF) scheme. We have optimized the candidate lattice to achieve the very short electron bunch storage and microbunching for electron beam. The tracking results show the equilibrium length of the electron bunch is about 400 nm and no particles lose after 4.3 damping time while only single-particle effect is considered. More optimization and some new design based on the simulation results are still implementing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP055  
About • paper received ※ 19 August 2019       paper accepted ※ 26 August 2019       issue date ※ 05 November 2019  
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THP060 Development of RF-Undulators and Powering Sources for Compact Efficient Compton FEL-Scattrons undulator, electron, radiation, FEL 704
 
  • A.V. Savilov, E.D. Abubakirov, N.S. Ginzburg, S.V. Kuzikov, N.Yu. Peskov, A.A. Vikharev, V.Yu. Zaslavsky
    IAP/RAS, Nizhny Novgorod, Russia
  
  Conception of Compton-type FELs operating up to X-ray band is under development currently at IAP RAS (N.Novgorod). This concept is aimed at reducing energy of a driving relativistic electron beam and thereby increasing efficiency of the electron-wave interaction in FEL, as well as achieving relative compactness of the generator. The basis of this concept is RF-undulators of a new type - the so-called ’flying’ undulators. Results of current research of these RF-undulators, their simulations and ’cold’ tests in the Ka-band are presented. For powering RF-undulators spatially-extended narrow-band Cerenkov masers are developed in the specified frequency range. In order to achieve the required sub-gigawatt power level of the pumping wave in a strongly oversized oscillator, we exploit the original idea of using two-dimensional distributed feedback implemented in the 2D doubly-periodical slow-wave structures. The design parameters of Ka-band surface-wave oscillator intended for powering RF-undulators, results of its simulation and initial experimental studies are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP060  
About • paper received ※ 15 August 2019       paper accepted ※ 25 August 2019       issue date ※ 05 November 2019  
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THP065 Multi-Objective FEL Design Optimisation Using Genetic Algorithms FEL, brightness, framework, electron 711
 
  • D.J. Dunning, H.M. Castañeda Cortés, J.K. Jones, N. Thompson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.K. Jones, N. Thompson
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  Simulation studies were carried out to optimise the performance of various FEL designs, with examples including longitudinal current profile shaping for a seeded FEL, and selection of the chicane delays for the High-Brightness SASE technique. In these examples multi-objective genetic algorithms were applied to a single section of the overall facility simulation, i.e. the undulator, as is the common approach. Further studies are also reported in which a full start-to-end simulation chain was optimised, with the aim of delivering a more holistic facility design optimisation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP065  
About • paper received ※ 20 August 2019       paper accepted ※ 25 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, linac, 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. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP084  
About • paper received ※ 21 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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