Keyword: linac
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MOA02 First Lasing of the Third Stage of Novosibirsk FEL FEL, undulator, radiation, electron 1
 
  • O.A. Shevchenko, V.S. Arbuzov, K.N. Chernov, I.V. Davidyuk, E.N. Dementyev, B.A. Dovzhenko, Ya.V. Getmanov, B.A. Knyazev, E.I. Kolobanov, A.A. Kondakov, V.R. Kozak, E.V. Kozyrev, V.V. Kubarev, G.N. Kulipanov, E.A. Kuper, I.V. Kuptsov, G.Y. Kurkin, L.E. Medvedev, S.V. Motygin, V.N. Osipov, V.K. Ovchar, V.M. Petrov, A.M. Pilan, V.M. Popik, V.V. Repkov, T.V. Salikova, M.A. Scheglov, I.K. Sedlyarov, G.V. Serdobintsev, S.S. Serednyakov, A.N. Skrinsky, S.V. Tararyshkin, V.G. Tcheskidov, A.G. Tribendis, N. Vinokurov, P. Vobly
    BINP SB RAS, Novosibirsk, Russia
  
  Novosibirsk FEL facility is based on the first in the world multi-turn energy recovery linac (ERL). It comprises three FELs (stages). FELs on the first and the second tracks were commissioned in 2004 and 2009 respectively and operate for users now. The third stage FEL is installed on the fourth track of the ERL. It includes three undulator sections and 40-meters-long optical cavity. The design tuning range of this FEL is from 5 to 20 microns and the design average power at bunch repetition rate 3.74 MHz is about 1 kW. Recent results of the third stage FEL commissioning are reported.  
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MOC04 Operating of SXFEL in a Single Stage High Gain Harmonic Generation Scheme laser, bunching, FEL, electron 29
 
  • G.L. Wang, D.X. Dai, G.R. Wu, X.M. Yang, W.Q. Zhang
    DICP, Dalian, People's Republic of China
  
  The beam energy spread at the entrance of undulator system is of paramount importance for efficient density modulation in high-gain seeded free-electron lasers (FELs). In this paper, the dependencies of high harmonic bunching efficiency in the high-gain harmonic generation (HGHG) schemes on the electron energy spread distribution are studied. Theoretical investigations and multi-dimensional numerical simulations are applied to the cases of uniform and saddle beam energy distributions and compared to a traditional Gaussian distribution. It shows that the uniform and saddle electron energy distributions significantly enhance the performance of HGHG-FELs. A numerical example demonstrates that, with the saddle distribution of sliced beam energy spread controlled by a laser heater, the 30th harmonic radiation can be directly generated by a single-stage seeding scheme for a soft x-ray FEL facility.  
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MOP010 Linac Design of the IR-FEL Project in CHINA electron, FEL, gun, beam-transport 46
 
  • Z.G. He, Q.K. Jia, L. Wang, W. Xu, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  We are building an infrared free-electron laser (IR-FEL) facility that will operate from 5 um to 200 um. This FEL source is drived by a linac, which is composed of a triode electron gun, a subharmonic prebuncher, a buncher, two accelerators, and a beam transport line. The linac is required to operate from 15 to 60 MeV at 1 nC charge, while delivering a transverse rms emittance of smaller than 30 mm-mrad in a 5 ps rms length, smaller than 240 keV rms energy spread bunch at the Far-infrared and Mid-infrared undulators. In this article, the preliminary Linac design studies are described.  
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MOP017 Beam Commissioning Plan for the SwissFEL Hard-X-Ray Facility undulator, electron, FEL, operation 69
 
  • T. Schietinger
    PSI, Villigen PSI, Switzerland
  
  The SwissFEL facility currently being assembled at the Paul Scherrer Institute is designed to provide FEL radiation in the photon wavelength range between 0.1 and 7 nm. The commissioning of the first phase, comprising the electron injector, the main electron linear accelerator and the first undulator line, named Aramis and dedicated to the production of hard X-rays, is planned for the years 2016 and 2017. We present an overview of the beam commissioning plan elaborated in accordance with the installation schedule to bring into operation the various subsystems and establish beam parameters compatible with first pilot user experiments in late 2017.  
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MOP024 Status, Plans and Recent Results from the APEX Project at LBNL gun, cathode, cavity, electron 81
 
  • F. Sannibale, K.M. Baptiste, C.W. Cork, S. De Santis, M.R. Dickinson, L.R. Doolittle, J.A. Doyle, J. Feng, D. Filippetto, G.L. Harris, G. Huang, R. Huang, M.J. Johnson, M.S. Jones, T.D. Kramasz, S. Kwiatkowski, D. Leitner, R.E. Lellinger, C.E. Mitchell, V. Moroz, W.E. Norum, H.A. Padmore, G.J. Portmann, H.J. Qian, J.W. Staples, D. L. Syversrud, M. Vinco, S.P. Virostek, R.P. Wells, M.S. Zolotorev
    LBNL, Berkeley, California, USA
  • R. Huang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is dedicated to the demonstration of the capability of an electron injector based on the VHF-gun, the new concept RF gun developed at LBNL, of delivering the beam quality required by MHz-class repetition rate X-Ray free electron lasers. Project status, plans, and recent results are presented. 		 
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MOP034 Beam Optics Measurements at FERMI by using Wire-Scanner optics, emittance, quadrupole, FEL 101
 
  • G. Penco, A. Abrami, I. Cudin, S. Di Mitri, M. Ferianis, E. Ferrari, G. Gaio, L. Giannessi, S. Grulja, R. Sauro, L. Sturari
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • E. Ferrari
    Università degli Studi di Trieste, Trieste, Italy
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • G.L. Orlandi, C. Ozkan Loch
    PSI, Villigen PSI, Switzerland
  
  Measuring and controlling the electron beam optics is an important ingredient to guarantee high performance of a free-electron laser. In the FERMI linac, the Twiss parameters and the transverse emittances are routinely measured by detecting the beam spot size as a function of a scanning quadrupole placed upstream (i.e. quadrupole scan method). The beam spot size is usually measured with an OTR screen that unfortunately suffers from coherent optical transition radiation (C-OTR) that introduces spurious light and corrupts the image. Moreover, the beam size at the end of the FERMI linac is focused to a few tens of microns and this makes it difficult to precisely measure it with the OTR system, which has an estimated resolution of 20um. For this reason, a wire-scanner system has been installed at the end of the linac just in the waist of the optics channel. The wire-scanner is a SwissFEL prototype installed in FERMI in order to study the hardware and beam loss monitor performances at the GeV energy scale. The beam optics measurements performed with the wire-scanner is here presented, and the obtained results are more in agreement with the theoretical expectations. A more reliable beam optics estimation at the end of the linac has allowed to better match it to the nominal lattice and transport it up to the undulator chain, providing important benefits to the FEL performance.  
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MOP044 A Laser Heater for CLARA laser, electron, FEL, undulator 129
 
  • S. Spampinati
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • B.D. Muratori, N. Thompson, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  CLARA is a new FEL test facility, being developed at STFC Daresbury Laboratory in UK, based on a high brightness electron linac. The electron beam of CLARA can potentially be affected by the longitudinal microbunching instability leading to a degradation of the beam quality. The inclusion of a laser heater in the linac design can allow control of the microbunching instability, the study of microbunching and deliberate increase of the final energy spread to study energy spread requirements of the FEL schemes tested at CLARA. We present the initial design and layout of the laser heater system for CLARA and its expected performance.  
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MOP052 Linear Vlasov Solver For Microbunching Gain Estimation with Inclusion of CSR, LSC, And Linac Geometric Impedances impedance, simulation, dipole, electron 147
 
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • D. Douglas, R. Li, C. Tennant
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
As is known, microbunching instability (MBI) has been one of the most challenging issues in designs of magnetic chicanes for short-wavelength free-electron lasers or linear colliders, as well as those of transport lines for recirculating or energy recovery linac machines. To more accurately quantify MBI in a single-pass system, we further extend and continue to increase the capabilities of our previously developed linear Vlasov solver [1] to incorporate more relevant impedance models into the code, including transient and steady-state free-space and/or shielding CSR impedances, the LSC and linac geometric impedances with extension of the existing formulation to include beam acceleration [2]. Then, we directly solve the linearized Vlasov equation numerically for microbunching gain amplification factor. In this study we apply this code to a beamline lattice of transport arc [3] following an upstream linac section. The resultant gain functions and spectra are presented here, and some results are compared with particle tracking simulation by ELEGANT [4]. We also discuss some underlying physics with inclusion of these collective effects and the limitation of the existing formulation. It is anticipated that this more thorough analysis can further improve the understanding of MBI mechanisms and shed light on how to suppress or compensate MBI effects in lattice designs.
[1] C. -Y. Tsai et al., FEL'14 (THP022), IPAC'15 (MOPMA028) and ERL2015 (TUICLH2034)
[2] M. Venturini, Phys. Rev. ST Accel. Beams 10, 104401 (2007)
[3] D. Douglas et al., arXiv: 1403.2318v1 [physics.acc-ph]
[4] M. Borland, APS Light Source Note LS-287 (2000) 		 
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MOP053 Intra-Beam Scattering in High Brightness Electron Linacs electron, emittance, brightness, quadrupole 153
 
  • S. Di Mitri
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  Intra-beam scattering (IBS) of a high brightness electron beam in a linac has been studied* analytically, and the expectations found to be in reasonable agreement with particle tracking results from the Elegant code. It comes out that, under standard conditions for a linac driving a free electron laser, IBS plays no significant role in the development of microbunching instability. A partial damping of the instability is envisaged, however, when IBS is enhanced either with dedicated magnetic insertions, or in the presence of an electron beam charge density at least 4 times larger than that produced by present photo-injectors.
* S. Di Mitri, Phys. Rev. Special Topics Accel. Beams, 17, 074401 (2014).
 		 
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MOP055 The Effect of Wakefields on the FEL Performance emittance, wakefield, FEL, undulator 161
 
  • A. Novokhatski, F.-J. Decker, Y. Nosochkov, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  
  Funding: This work was supported by Department of Energy Contract No. DOE-AC03-76SF00515.
If a beam travels near collimator jaws or other discontinuities of the beam pipe, it gets the energy loss and the transverse kick due to the back reaction of the beam field diffracted on the collimator's jaws. The wake field effect from collimators may not only bring an additional energy jitter and change the trajectory of the beam, but may also lead to degradation of the performance of Free Electron Laser (FEL) It may be possible due to the special character of the wake fields: the response reaction depends on the longitudinal position of the particles in the bunch. We describe a model of the wake field radiation, simulation results and comparison with measurements. 		 
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MOP057 Front End Simulations and Design for the CLARA FEL Test Facility laser, emittance, gun, simulation 171
 
  • J.W. McKenzie, A.D. Brynes, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  We present the design and simulations of the Front End for CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. This is based around an S-band RF photocathode gun. Initially this will be the 2.5 cell gun, currently used on VELA facility at Daresbury, which is limited to 10 Hz repetition rate. Later, this will be up-graded to a 1.5 cell gun, currently under development, which will allow repetition rates of up to 400 Hz to be reached. The beam will be accelerated up to 50 MeV with a booster linac which will be operated in both bunching and boosting modes for different operating regimes of CLARA. Simulations are presented for a currently achieved performance of the RF system and drive laser with optimisation of the laser pulse lengths for various operational modes of CLARA.  
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MOP062 Technology Maturation for the MaRIE 1.0 X-FEL emittance, FEL, simulation, laser 181
 
  • J.W. Lewellen, K. Bishofberger, B.E. Carlsten, L.D. Duffy, F.L. Krawczyk, Q.R. Marksteiner, D.C. Nguyen, S.J. Russell, R.L. Sheffield, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
  
  Funding: This research was funded by the Matter-Radiation Interactions in Extremes program at Los Alamos National Laboratory, under contract DE-AC52-06NA25396.
Los Alamos National Laboratory is proposing a high-energy XFEL, named MaRIE*, to meet its mission needs. MaRIE will be required to generate coherent 42+ keV photons, and, due to space constraints at the LANSCE accelerator complex at Los Alamos, MaRIE's design electron beam energy is 12 GeV. This combination places significant restrictions upon the MaRIE electron beam parameters, in particular the transverse emittance and energy spread at the undulator entrance. We are developing approaches to meet these requirements, but these often require solutions extending beyond the current state-of-the-art in X-FEL design. To reduce overall project risk, therefore, we have identified a number of key experimental and modeling / simulation efforts intended to address both the areas of greatest uncertainty in the preliminary MaRIE design, and the areas of largest known risk. This paper describes the general requirements for the MaRIE X-FEL, our current areas of greatest concern with the preliminary design concept, and our corresponding Technology Maturation Plan (TMP).
* MaRIE website: http://www.lanl.gov/science-innovation/science-facilities/marie/index.php 		 
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MOP081 Generating a Single-Spike SASE Pulse in the Soft X-Ray Regime by Velocity Bunching FEL, radiation, electron, undulator 233
 
  • J. Lee, B.H. Oh, M. Yoon
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  
  A bright ultrashort X-ray pulse emerges as a valuable tool for many fields of research nowadays. The single-spike operation of X-ray FEL is one way of making a bright ultrashort X-ray pulse. It requires extreme bunching and a magnetic chicane is a conventional compressor. In a low charge range, a magnetic chicane can be replaced by the velocity bunching technique. In this paper, we present the result of particle tracking simulation generating a single-spike soft X-ray SASE pulse without a magnetic chicane. We also investigate the error effects and show that this scheme is feasible under current technology.  
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MOP082 New Soft X-Ray Undulator Line Using 10 GeV Electron Beam in PAL-XFEL undulator, photon, electron, simulation 237
 
  • C.H. Shim, I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • Y.W. Parc
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  PAL-XFEL is designed to have five undulator lines and only two undulator lines, the HXR undulator line with 10 GeV electron beam and the SXR undulator line with 3.15 GeV electron beam, will be installed during phase I. A photon beam energy from 0.28 to 1.24 keV will be provided at the SXR undulator line and different range from 2 to 20 keV will be supplied at the HXR undulator line. According to existing schedule, however, photon beam energy from 1.24 to 2 keV won't be provided in PAL-XFEL. In this research, new soft X-ray undulator line for PAL-XFEL using 10 GeV electron beam in main linac is proposed to cover the vacant photon energy. Four candidates are evaluated by estimating and comparing FEL performances using Ming Xie's formula.  
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TUC01 The Microbunching Instability and LCLS-II Lattice Design simulation, laser, bunching, FEL 308
 
  • M. Venturini
    LBNL, Berkeley, California, USA
  
  The microbunching instability is a pervasive occurrence when high brightness electron beams are accelerated and transported through dispersive sections like bunch-compression chicanes or distributions beamlines. If uncontrolled the instability can severely compromise the performance of x-ray FELs, where beam high brightness is crucial. In this talk we discuss how consideration of the microbunching instability is informing the LCLS-II design and determining the specifications for the laser heater and transport lines. We also review some of the expected and not so-expected phenomena that we have encountered while carrying out high-resolution macroparticle simulations of the instability and the analytical models we have developed to interpret the numerical results.  
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TUP010 Recent Progress in Upgrade of the High-Intensity THz-FEL at Osaka University FEL, electron, klystron, operation 354
 
  • G. Isoyama, M. Fujimoto, S. Funakoshi, K. Furukawa, A. Irizawa, R. Kato, K. Kawase, A. Tokuchi, R. Tsutsumi, M. Yaguchi
    ISIR, Osaka, Japan
  
  We are upgrading the THz-FEL at Osaka University for its applications to high intensity THz sciences, which originally generated the high intensity FEL with the macropulse energy up to 3.7 mJ and the micropulse energy up to ~10 uJ at a wavelength around 70 um. To increase the micropulse energy, charge in electron bunches is increased four time higher and the bunch intervals are expanded four times longer to maintain the average current in the linac unchanged. In the new operation mode, the macropulse energy increases up to 26 mJ and the micropulse energy to ~0.2 mJ, which is 20 times higher than the energy previously obtained in the conventional mode. We have developed a solid-state switch for the klystron modulator to highly stabilize the klystron voltage, so that the output power of the FEL becomes stable. We are conducting basic studies on FEL for further improvement of its performance, including measurement of power evolution from start-up to saturation, time structures of FEL micropulses measured with a Michelson interferometer, and time structures of macropulses measured with a Schottky diode detector. We will report results of these studies on the THz-FEL at Osaka University.  
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TUP013 The X-Band FEL Collaboration FEL, undulator, electron, emittance 368
 
  • J. Pfingstner, E. Adli
    University of Oslo, Oslo, Norway
  • A.A. Aksoy, O. Yavaş
    Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
  • D. Angal-Kalinin, J.A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • C.J. Bocchetta, A.I. Wawrzyniak
    Solaris, Kraków, Poland
  • M.J. Boland, T.K. Charles, R.T. Dowd, G. LeBlanc, Y.E. Tan, K.P. Wootton, D. Zhu
    SLSA, Clayton, Australia
  • G. Burt
    Lancaster University, Lancaster, United Kingdom
  • N. Catalán Lasheras, A. Grudiev, A. Latina, D. Schulte, S. Stapnes, I. Syratchev, W. Wuensch
    CERN, Geneva, Switzerland
  • A. Charitonidis
    NTUA, Athens, Greece
  • G. D'Auria, S. Di Mitri, C. Serpico
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • T.J.C. Ekelöf, M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  • W. Fang, Q. Gu
    SINAP, Shanghai, People's Republic of China
  • E.N. Gazis
    National Technical University of Athens, Athens, Greece
  • X.J.A. Janssen
    VDL ETG, Eindhoven, The Netherlands
  • Z. Nergiz
    Nigde University, Nigde, Turkey
  
  The X-band FEL collaboration is currently designing an X-ray free-electron laser based on X-band acceleration technology. Due to the higher accelerating gradients achievable with X-band technology, a X-band normal conducting linac can be shorter and therefore potentially cost efficient than what is achievable with lower frequency structures. This cost reduction of future FEL facilities addresses the growing demand of the user community for coherent X-rays. The X-band FEL collaboration consists of 12 institutes and universities that jointly work on the preparation of design reports for the specific FEL projects. In this paper, we report on the on-going activities, the basic parameter choice, and the integrated simulation results. We also outline the interest of the X-band FEL collaboration to use the electron linac CALIFES at CERN to test FEL concepts and technologies relevant for the X-band FEL collaboration.  
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TUP014 Beam Commissioning and Initial Measurements on the MAX IV 3 GeV Linac gun, storage-ring, sextupole, electron 375
 
  • S. Thorin, J. Andersson, F. Curbis, M. Eriksson, L. Isaksson, O. Karlberg, D. Kumbaro, F. Lindau, E. Mansten, D.F. Olsson, S. Werin
    MAX-lab, Lund, Sweden
  
  The linear accelerator at the MAX IV facility in Lund, Sweden, was constructed for injection and top up of the two storage rings and as a high brightness driver for the Short Pulse Facility. It is also prepared to be used as an injector for a possible future Free Electron Laser. Installation of the linac was completed and beam commissioning started in the early fall of 2014. In this paper we present the progress during the first phase of commissioning along with results from initial measurements of optics, emittance, beam energy and charge.  
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TUP026 Measurment Uncertainties in Gas-Based Monitors for High Repetition Rate X-Ray FEL Operations FEL, undulator, simulation, detector 417
 
  • Y. Feng, M.L. Campell, J. Krzywinski, E. Ortiz, T.O. Raubenheimer, M. Rowen, D.W. Schafer
    SLAC, Menlo Park, California, USA
  
  Funding: Portions of this research were carried out at the LCLS at the SLAC National Accelerator Laboratory. LCLS is an User Facility operated for the US DOE Office of Science by Stanford University.
Thermodynamic simulations using a finite difference method were carried out to investigate the measurement uncertainties in gas-based X-ray FEL diagnostic monitors under high repetition rate operations such as planned for the future LCLS-II soft and hard X-ray FEL's. For monitors using relatively high gas pressures for obtaining sufficient signals, the absorbed thermal power becomes non-negligible as repetition rate increases while keeping pulse energy constant. The fluctuations in the absorbed power were shown to induce significant measurements uncertainties, especially in the single-pulse mode. The magnitude of this thermal effect depends nonlinearly on the absorbed power and can be minimized by using a more efficient detection scheme in which the gas pressure can be set sufficiently low 		 
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TUP029 Single Picosecond THz Pulse Extraction from the FEL Macropulse using a Laser Activating Semiconductor Reflective Switch FEL, laser, radiation, extraction 430
 
  • K. Kawase, M. Fujimoto, K. Furukawa, A. Irizawa, G. Isoyama, R. Kato, K. Kubo
    ISIR, Osaka, Japan
  
  The THz-FEL at the Institute of Scientific and Industrial Research, Osaka University can generate high-intensity THz pulses or FEL macropulses, which comprise approximately 100 micropulses at 37 ns intervals in the 27 MHz mode or 400 micropulses at 9.2 ns intervals in the 108 MHz mode. The maximum macropulse energy in the 27 MHz mode reaches 26 mJ at a frequency of 4.5 THz and the micropulse energy is estimated to be 0.2 mJ. To open new areas of studies with high intensity THz radiation for user experiments, we are developing a single pulse extraction system from the pulse train using a laser activating semiconductor reflective switch. We have succeeded in extracting a single THz pulse, duration of which is estimated to be less than 20 ps, from the FEL macropulse using a gallium arsenide wafer for the switch. We will report on the THz pulse extraction system and its performance.  
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TUP036 Initial Commissioning Results of the MAX IV Injector gun, laser, emittance, cathode 448
 
  • J. Andersson, F. Curbis, M. Eriksson, D. Kumbaro, F. Lindau, E. Mansten, D.F. Olsson, S. Thorin, S. Werin
    MAX-lab, Lund, Sweden
  
  The MAX IV facility in Lund, Sweden is currently under commissioning. In the MAX IV injector there are two guns, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. The commissioning of the injector and the LINAC has been ongoing for the last year and ring commissioning is due to start shortly. In this paper we will present the results from beam performance experiments for the injector at the current stage of commissioning.  
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TUP066 Benchmark of ELEGANT and IMPACT space-charge, wakefield, optics, undulator 505
 
  • L. Wang, P. Emma, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  The beam dynamics codes ELEGANT and IMAPCT have many users. We use these two codes for the design of LCLSII. Both codes use a 1D model for the coherent synchrotron radiation (CSR) in bend magnets. In addition, IMPACT has a 3D space-charge model, while ELEGANT uses a 1D model. To compare the two codes, especially the space-charge effects, we systematically benchmark the two codes with different physics aspects: wakefields, CSR and space-charge forces.  
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TUP067 Effect of Hot Ions in LCLC-II ion, electron, simulation, vacuum 508
 
  • L. Wang, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  
  The ions in a linac, such as ERL, draw more attention recently. LCLSII has a long linac with 1MHz repetition rate. The ions, in general, are not deeply trapped due to the long bunch spacing. The effect of ion thermal energy becomes important in this regime. The beam dynamics with ions are studied numerically. There is a linear growth in amplitude, but not exponential growth as traditional fast ion instability. This instability set a maximum bunch-train length to limit the beam amplitude to fractional beam σ. Theoretical works are also done to compare the simulations. We also extend our works to different regimes where the motions of ions from stable to unstable.  
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TUP070 Energy Jitter Minimization at LCLS timing, experiment, operation, simulation 523
 
  • L. Wang, A.L. Benwell, A. Brachmann, W.S. Colocho, F.-J. Decker, Z. Huang, T.J. Maxwell, T. Tao, J.L. Turner
    SLAC, Menlo Park, California, USA
  
  The energy jitters of the electron beam can affects the FEL in self-seeded modes if the jitter is large compared to the FEL parameter. We work in multiple ways to reduce the jitters, including hardware improvement, optimization linac set-up. This paper discusses the optimization of linac set-up. The solutions always suggest that we can largely reduce the energy jitter from a weak compression at BC1 and a stronger compression at BC2. Meanwhile a low beam energy at BC2 also reduce the energy jitter, which is confirmed by the experiment. The results can be explained by a simple model. Experimental results are also presented, demonstrating better than 20% and 40% relative energy jitter reduction for 13.6 and 4 GeV linac operation, respectively.  
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TUP071 A FAST Particle Tracking Code wakefield, collective-effects, bunching, space-charge 530
 
  • L. Wang
    SLAC, Menlo Park, California, USA
  
  This paper presents a fast particle tracking (FPT) code for linac beam dynamics. It includes wake fields, coherent synchrotron radiation (CSR) and longitudinal space charge. We systematically benchmark the FPT with ELEGANT with different physics aspects: pure optics, wakefields, CSR and space-charge forces  
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WEA03 SwissFEL Status Report undulator, FEL, vacuum, electron 567
 
  • R. Ganter
    PSI, Villigen PSI, Switzerland
  
  SwissFEL is a 5.8 GeV linac which sends electron bunches at 100 Hz into a 60 m long in-vacuum undulator line to produce hard X-rays between 0.1 nm and 0.7 nm. The SwissFEL accelerator design is based on a low emittance beam with tight tolerances on RF stability. The first lasing of SwissFEL is planned for early 2017 and two end-stations should then be brought into operation in the same year. The delivery of the SwissFEL building to PSI is planned for fall this year, but some rooms are already completed and currently in use for components assembly. The production of the C-band RF accelerating structures has now reach the nominal rate of 5 structures/month. Two different RF solid state modulator prototypes could demonstrate jitter lower than 20 ppm but stability and reliability tests are still going on. The undulators assembly and measurement sequence have started and 13 undulators are planned to be ready in the tunnel by October 2016. Large series of components like magnets, vacuum systems and mechanical supports are already in house and under assembly. Photonics components for two beamlines and two end stations are ordered and planned to be ready for 2017.  
slides icon Slides WEA03 [36.505 MB]  
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WEP005 Laser Heater Transverse Shaping to Improve Microbunching Suppresion for X-ray FELs laser, electron, FEL, undulator 602
 
  • S. Li
    Stanford University, Stanford, California, USA
  • A.R. Fry, S. Gilevich, Z. Huang, A. Marinelli, D.F. Ratner, J. Robinson
    SLAC, Menlo Park, California, USA
  
  In X-ray free electron lasers (FELs), a small amount of initial density or energy modulation in the electron beam will be amplified through acceleration and bunch compression process. The undesired microbunching on the electron bunch will increase slice energy spread and degrade the FEL performance. The Linac Coherent Light Source (LCLS) laser heater (LH) system was installed to increase the uncorrelated energy spread in the electron beam in order to suppress the microbunching instability. The distribution of the induced energy spread depends strongly on the transverse profile of the heater laser and has a large effect on the microbunching suppression. In this paper we discuss strategies to shape the laser profile in order to obtain better suppression of microbunching. We present analysis to achieve the Gaussian-like energy spread using a Laguerre-Gaussian laser mode and study the efficiency and alignment tolerance for implementation.  
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WEP014 LCLS-II: Status of the CW X-ray FEL Upgrade to the LCLS Facility undulator, FEL, gun, electron 618
 
  • T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by Department of Energy contract DE-AC02-76SF00515
The LCLS-II is a CW X-ray FEL based on a 4 GeV superconducting RF linac that will upgrade the LCLS facility at the SLAC National Accelerator Laboratory. The upgrade is being constructed by a collaboration including ANL, Cornell, Fermilab, JLab, LBNL, and SLAC. This talk will describe the status of the LCLS-II project as well as the major technical issues and R&D to address them.
Presented on behalf of the LCLS-II collaboration 		 
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WEP022 Photon Energies beyond the Selenium K-Edge at LCLS FEL, photon, electron, operation 630
 
  • F.-J. Decker, W.S. Colocho, Y. Ding, R.H. Iverson, H. Loos, J. Sheppard, H. Smith, J.L. Turner
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) was designed for a photon energies of 830 eV to 8.3 keV. This range was widened and up to 11.2 keV photons were already delivered for users. The Selenium K-edge at 12.6578 keV is very interesting since Selenium can replace Sulfur in biological structures and then that structure could be precisely measured. To reach this the electron energy would need to be raised by about 6% which initially didn't seem possible. The trick is to change the final compression scheme from a high correlated energy spread and moderate R56 in the compression chicane to moderate energy spread and high R56. The same bunch length can be achieved and RF energy is freed up, so the overall beam energy can be raised. Photons up to an energy of 12.82 keV (1.3% above the K-edge) with a pulse intensity of 0.93 mJ were achieved. The photon energy spread with this setup is wider at around 40-50 eV FWHM, since less correlated energy spread is left after the compression. 		 
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WEP038 Production Status of Accelerator Components network, status, LLRF, vacuum 658
 
  • N. Shigeoka, M. Kimura, S. Miura, K. Okihira
    MHI, Hiroshima, Japan
  
  Mitsubishi Heavy Industries, LTD. (MHI) has been delivered various kind of accelerator components to multiple FEL facilities. Recently we completed production of S-band accelerating structures for PAL-XFEL. Currently we are manufacturing C-band waveguide network for SwissFEL. Production status and result of above-mentioned products will be presented in the presentation.  
poster icon Poster WEP038 [2.189 MB]  
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WEP042 Commissioning and First Performance of the LINAC-based Injector Applied in the HUST THz-FEL FEL, target, gun, beam-diagnostic 662
 
  • T. Hu, Q.S. Chen, J. Li, B. Qin, P. Tan, Y.Q. Xiong
    HUST, Wuhan, People's Republic of China
  • L. Cao, W. Chen
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
  • Y.J. Pei, Zh. X. Tang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The construction of a compact high-power THz source based on the free electron laser(FEL), which is constructed in HUST, is undergoing. Before the end of 2014, we have installed most of the key components, completed conditioning of the LINAC-based FEL injector, and performed first beam experiment. During last 5 months, we have established a high efficient beam diagnostic system with a reliable online monitor platform and precise data processing methods. At present, longitudinal properties such as the micro-pulse width and the energy spread are kept to a reasonable level, while transverse emittance compensation by adjusting focusing parameters is still undergoing. In this paper, we will give the summary on the commissioning schedule, detailed commissioning plan, the development of the commissioning and first performance of the LINAC, etc.  
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WEP045 Study on Beam Modulation Technique using a Masked Chicane at FAST (Fermilab Accelerator Science and Technology) Facility simulation, bunching, dipole, space-charge 665
 
  • Y.-M. Shin, D.R. Broemmelsiek, D.J. Crawford, A.H. Lumpkin
    Fermilab, Batavia, Illinois, USA
  • A.T. Green
    Northern Illinois Univerity, Dekalb, Illinois, USA
  
  Funding: This work was supported by the DOE contract No. DEAC02-07CH11359 to the Fermi Research Alliance LLC.
Longitudinal density modulations on electron beams can improve machine performance of beam-driven accelerators and FELs with resonance beam-wave coupling. The sub-ps beam modulation has been studied with a masked chicane by the analytic model and simulations with the beam parameters of the Advanced Superconducting Test Accelerator (ASTA) in Fermilab. With the chicane design parameters (bending angle of 18 degree, bending radius of 0.95 m and R56 ~ - 0.19 m) and a nominal beam of 3-ps bunch length, the analytic model showed that a slit-mask with slit period 900 microns and aperture width 300 microns generates about 100 microns modulation periodicity with 2.4% correlated energy spread. With the designed slit mask and a 3- ps bunch, particle-in-cell simulations (CST-PS), including nonlinear energy distributions, space charge force, and coherent synchrotron radiation (CSR) effect, also result in ~ 100 microns of longitudinal modulation. The beam modulation has been extensively examined with three different beam conditions, 2.25 ps (0.25 nC), 3.25 ps (1 nC), and 4.75 ps (3.2 nC), by extended 3D tracking simulations (Elegant). The modulated bunch generation will be tested by a slit-mask installed at the chicane of the ASTA 50-MeV-injector beamline for beam-driven acceleration experiments. 		 
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WEP061 Numerical and Experimental Studies on Electron Beam Properties from Asymmetric RF-gun gun, electron, simulation, emittance 698
 
  • S. Rimjaem, N. Chaisueb, J. Saisut, C. Thongbai, W. Thongpakdi
    Chiang Mai University, Chiang Mai, Thailand
  • N. Kangrang
    FNRF, Chiang Mai, Thailand
  • E. Kongmon, K. Kosaentor, P. Wichaisirimongkol
    IST, Chiang Mai, Thailand
  
  Funding: This work has been supported by the CMU Junior Research Fellowship Program, and the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University.
The electron linear accelerator at the Plasma and Beam Physics Research Facility (PBP-CMU Linac), Chiang Mai University, Thailand, is used to produce femtosecond electron bunches for generation of THz radiation. The main components of the PBP-CMU Linac are a thermionic RF electron gun, an alpha magnet, a travelling wave linac structure, quadrupole lens, steering magnets, and various diagnostic components. The RF-gun consists of a 1.6 S-band standing wave structure and a side-coupling cavity. The 2856 MHz RF wave is transmitted from the klystron to the gun through a rectangular waveguide input-port. Both the RF input-port and the side-coupling cavity cause an asymmetric electromagnetic field distribution inside the gun. The electron beam from the RF-gun has asymmetric transverse shape with an emittance value, which is higher than the beam from the symmetric fields. The problems are increased when the beam is transported from the gun through the whole accelerator system. Beam dynamic simulations are performed to investigate the effect of the asymmetric fields on the electron properties by using the codes PARMELA and ELEGANT. An integrated electron beam diagnostic station to measure the beam properties will be installed in the system to investigate these effects. Results from numerical and experimental studies are reported in this contribution. 		 
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WEP062 Study on Undulator Radiation from Femtosecond Electron Bunches undulator, electron, radiation, brightness 702
 
  • N. Chaisueb, S. Rimjaem
    Chiang Mai University, Chiang Mai, Thailand
  
  Funding: This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Faculty of science, Chiang Mai University, and SAST Scholarship.
Linac based terahertz (THz) source at the Plasma and Beam Physics (PBP) Research Facility, Chiang Mai University, consists of a thermionic RF electron gun, an alpha magnet for magnetic bunch compressor, a travelling wave S-band accelerating structure for post acceleration, and various beam diagnostic instruments. The PBP-CMU linac can produce relativistic femtosecond electron bunches, which are used to generate coherent THz radiation via transition radiation technique. To increase the radiation intensity, an electromagnetic undulator will be added in the beam transport line. The designed electromagnetic undulator has 40.5 periods with a period length of 56 mm and a pole gap of 15 mm. Numerical calculation result shows that the brightness of the undulator radiation, which is produced from electron bunches with an energy of 10 MeV, a peak current of 300 A, and an effective bunch length of 120 fs, is about 10 thousand times higher than the brightness of the transition radiation. This study investigates the dependence of the electron beam energy, electron bunch charge, and electron bunch length on the coherent undulator radiation by using the PARMELA code. The numerical simulation and procedure to generate the undulator radiation in the terahertz regime by using femtosecond electron bunches produced at the PBP research facility is reported and discussed in this contribution.
The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Material Science and the Graduate School, Chiang Mai University. 		 
poster icon Poster WEP062 [8.172 MB]  
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WEP070 Start-to-End Simulation of the LCLS-II Beam Delivery System with Real Number of Electrons FEL, emittance, electron, simulation 714
 
  • J. Qiang, C.E. Mitchell, C. F. Papadopoulos, M. Venturini
    LBNL, Berkeley, California, USA
  • Y. Ding, P. Emma, Z. Huang, G. Marcus, Y. Nosochkov, T.O. Raubenheimer, L. Wang, M. Woodley
    SLAC, Menlo Park, California, USA
  
  The LCLS-II as a next generation high repetition rate FEL based X-ray light source will enable significant scientific discoveries. In this paper, we report on the progress in the design of the accelerator beam delivery system through start-to-end simulations. We will present simulation results for three cases, 20 pC, 100 pC and 300 pC that are transported through the hard X-ray line and the soft X-ray line for FEL radiation.  
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