Keyword: cavity
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MOD06 Matter-Radiation Interactions in Extremes (MaRIE) Project Overview ion, photon, FEL, electron 24
 
  • R.L. Sheffield, C.W. Barnes, J.P. Tapia
    LANL, Los Alamos, New Mexico, USA
 
  The National Nuclear Security Administration (NNSA) requires the ability to understand and test how material structures, defects and interfaces determine performance in extreme environments. The MaRIE Project will provide the science ability for control of materials and their production for vital national security missions. To meet the mission requirements, MaRIE must be an x-ray source that has high brilliance and with very flexible and fast pulses to observe phenomena at shock-relevant time scales, and with high enough energy to study high-Z materials. This talk will cover the rationale for the machine requirements, a pre-conceptual reference design that can meet those requirements, and preliminary research needed to address the critical high risk technologies.  
slides icon Slides MOD06 [3.461 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOD06  
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MOP051 Polish In-Kind Contribution to European XFEL: Status in Summer 2017 ion, FEL, HOM, linac 166
 
  • J.A. Lorkiewicz, K. Chmielewski, Z. Gołębiewski, W.C. Grabowski, K. Kosinski, K. Kostrzewa, P. Krawczyk, I.M. Kudla, P. Markowski, K. Meissner, E.P. Plawski, M. Sitek, J. Szewiński, M. Wojciechowski, Z. Wojciechowski, G. Wrochna
    NCBJ, Świerk/Otwock, Poland
  • J. Świerbleski, M. Duda, M. Jezabek, K. Kasprzak, A. Kotarba, K. Krzysik, M. Stodulski, M. Wiencek
    IFJ-PAN, Kraków, Poland
  • P.B. Borowiec
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
  • M. Chorowski, P. Duda, A. Iluk, K. Malcher, J. Polinski, E. Rusinski
    WRUT, Wrocław, Poland
  • J. Fydrych
    ESS, Lund, Sweden
  • J. Glowinkowski, M. Winkowski, P. Wlk
    Wroclaw Technology Park, Wroclaw, Poland
  • P. Grzegory, G. Michalski
    Kriosystem, Wroclaw, Poland
  • J.K. Sekutowicz
    DESY, Hamburg, Germany
 
  In the years 2010-2017, some of the Polish research institutes took responsibility of production and delivery of certain components or test procedures for the EU-XFEL sc linear electron accelerator and elements of slow control systems for the first six XFEL experimental instruments. The presentation summarizes the output of the work on design and manufacturing of cryogenic transfer lines for supercritical helium transport and two vertical cryostats for low-power acceptance tests of sc cavities. The cryogenic installations were prepared by Wroclaw University of Science and Technology and its subcontractors. A team of Institute of Nuclear Physics in Cracow was in charge of preparation and performance of acceptance tests for XFEL sc cavities, accelerator modules and sc magnets. Two teams of National Centre for Nuclear Research (NCBJ)in Świerk were involved in the project. One of them was responsible for design, manufacturing, testing and delivery of 1648 high-order mode couplers, 824 pick-up antennae and 108 beam-line absobers. The other NCBJ group was obliged to deliver 200 modules containing programmable logic controller terminals to be used at the ends of SASE x-ray beam lines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP051  
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MOP059 Synchronized Mid-Infrared Pulses at the Fritz Haber Institute IR-FEL ion, FEL, electron, laser 188
 
  • R. Kiessling, S. Gewinner, A. Paarmann, W. Schöllkopf, M. Wolf
    FHI, Berlin, Germany
 
  The combined application of FEL radiation and femtosecond table-top lasers for two-color spectroscopy demands an accurate pulse synchronization. In order to employ the Infared FEL at the Fritz Haber Institute for non-linear and time-resolved experiments, an RF-over-fiber-based timing system has been established. Using a balanced optical cross-correlation scheme, we determined an FEL micro-pulse timing jitter of 100-200 fs (rms). The long-term timing drift was found to be well correlated to the energy fluctuations of the accelerated electron bunches. By means of the jitter-corrected cross-correlation signal, we directly measure the FEL pulse shape at different cavity detunings. For large cavity detuning, narrowband IR radiation (~ 0.3 % FWHM) can be generated and utilized for high-resolution non-linear spectroscopy. On the other hand, sub-picosecond pulses are provided at small detuning, which are well-suited for time-resolved measurements. At intermediate detuning values, we observe the build-up and dynamics of multipulses that result in the well-known limit-cycle power oscillations.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP059  
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MOP061 X-ray Regenerative Amplifier Free-Electron Laser Concepts for LCLS-II ion, FEL, electron, simulation 192
 
  • G. Marcus, Y. Ding, J.P. Duris, Y. Feng, Z. Huang, J. Krzywinski, T.J. Maxwell, D.F. Ratner, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • K.-J. Kim, R.R. Lindberg, Yu. Shvyd'ko
    ANL, Argonne, Illinois, USA
  • D.C. Nguyen
    LANL, Los Alamos, New Mexico, USA
 
  High-brightness electron beams that will drive the next generation of high-repetition rate X-ray FELs allow for the possibility of optical cavity-based feedback. One such cavity-based FEL concept is the Regenerative Amplifier Free-Electron Laser (RAFEL). This paper examines the design and performance of possible RAFEL configurations for LCLS-II. The results are primarily based on high-fidelity numerical particle simulations that show the production of high brightness, high average power, fully coherent, and stable X-ray pulses at LCLS-II using both the fundamental and harmonic FEL interactions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP061  
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TUP002 Numerical Studies on RF-Induced Trajectory Variations at the European XFEL ion, FEL, electron, alignment 251
 
  • T. Hellert, B. Beutner, W. Decking, N. Walker
    DESY, Hamburg, Germany
 
  At the European X-Ray Free-Electron Laser, superconducting TESLA-type cavities are used for acceleration of the driving electron bunches. Due to the high achievable duty cycle, a long radio frequency (RF) pulse structure can be provided, which allows to operate the machine with long bunch trains. The designated pointing stability of the FEL radiation places stringent restrictions on the acceptable trajectory variations of individual electron bunches. Therefore a transverse intra-bunch-train feedback system (IBFB) is located upstream of the undulator section. However, intra-bunch-train variations of RF parameters and misalignment of RF structures induce significant trajectory variations that may exceed the capability of the IBFB. In this paper we give an estimate of the expected RF-induced intra-bunch-train trajectory variations for different machine realizations and investigate methods for their limitation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP002  
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TUP016 Beam-Dynamics Analysis of Long-Range Wakefield Effects on the SCRF Cavities at the Fast Facility ion, wakefield, HOM, simulation 280
 
  • Y.-M. Shin
    Northern Illinois University, DeKalb, Illinois, USA
  • K. Bishofberger, B.E. Carlsten, F.L. Krawczyk
    LANL, Los Alamos, New Mexico, USA
  • A.H. Lumpkin, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by the subcontract (contract No: G2A62653) of LANL-LDRD program and DOE contract No. DEAC02-07CH11359 to the Fermi Research Alliance LLC.
Long-range wakefields in superconducting RF (SCRF) cavities create complicated effects on beam dynamics in SCRF-based FEL beamlines. The driving bunch excites effectively an infinite number of structure modes (including HOMs) which oscillate within the SCRF cavity. Couplers with loads are used to damp the HOMs. However, these HOMs can persist for long periods of time in superconducting structures, which leads to long-range wakefields. Clear understanding of the long-range wakefield effects is a critical element for risk mitigation of future SCRF accelerators such as XFEL at DESY, LCLS-II XFEL, and MaRIE XFEL. We are currently developing numerical tools for simulating long-range wakefields in SCRF accelerators and plan to experimentally verify the tools by measuring these wakefields at the Fermilab Accelerator Science and Technology (FAST) facility. This paper previews the experimental conditions at the FAST 50 MeV beamline based on the simulation results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP016  
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TUP034 Novel Aspects of Beam Dynamics in CeC SRF Gun and SRF Accelerator ion, gun, electron, simulation 313
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • T. Hayes, Y.C. Jing, D. Kayran, V. Litvinenko, G. Narayan, I. Pinayev, F. Severino, K.S. Smith, G. Wang
    BNL, Upton, Long Island, New York, USA
  • K. Mihara
    Stony Brook University, Stony Brook, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
 
  Funding: DoE NP office, grant DE-FOA-0000632, NSF grant PHY-1415252.
A 15 MeV CW SRF accelerator had been commissioned at Brookhaven National Laboratory to test the coherent electron cooling concept. The accelerator consists of an SRF 113-MHz photoemission gun, two 500 MHz bunching cavities and a 704-MHz 5-cell SRF linac. In this paper we describe our experience with this system with focus on unusual phenomena, such as multipacting in the SRF gun. We also discuss issues of wakefields in the CeC accelerator.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP034  
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TUP069 Simulating Beam Dynamics in Coherent Electron-Cooling Accelerator with WARP ion, electron, experiment, simulation 374
 
  • K. Shih
    SBU, Stony Brook, New York, USA
  • Y.C. Jing, V. Litvinenko, I. Pinayev, G. Wang
    BNL, Upton, Long Island, New York, USA
  • K. Mihara
    Stony Brook University, Stony Brook, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
 
  Funding: DoE NP office, grant DE-FOA-0000632, NSF grant PHY-1415252.
Coherent Electron Cooling (CeC) is a novel cooling technique based on amplification of interaction between hadrons and electron by an FEL. If proven, this CeC could bring a revolution in hadron and electron-hadron colliders. A dedicated CeC proof-of-principle experiment is under way at RHIC collider (BNL) using a sophisticated SRF accelerator for generating and accelerating electron beam. This paper is dedicated to studies of beam dynamics in the CeC accelerator and specifically to emittance preservation in its ballistic compressions section. Two 500-MHz RF cavities are used for generating the necessary energy chirp leading in 1.56-MeV, 0.5-nsec-long electron bunched to compress them to 25-psec duration downstream. During the commissioning of the CeC accelerator we noticed that beam emittance can be strongly degraded when electron beam passes these 500 MHz RF cavities off-axis. We used a full 3D PIC code Wrap to simulate effect of the off-axis beam propagation through these
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP069  
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WEP005 Coaxial Coupler RF Kick in the PITZ RF Gun ion, gun, simulation, electron 422
 
  • Y. Chen, P. Boonpornprasert, J.D. Good, H. Huck, I.I. Isaev, M. Krasilnikov, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • W. Ackermann, H. De Gersem
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Dohlus
    DESY, Hamburg, Germany
  • Q.T. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  We investigate a transverse RF kick induced by the transition between rectangular waveguide and coaxial line of the RF coupler in the 1.6-cell L-band normal conducting (NC) RF gun at the Photo Injector Test Facility at DESY, Zeuthen site (PITZ). A three-dimensional electromagnetic simulation shows the disturbed RF field distributions in the fundamental accelerating mode. Based on the 3D RF field map, an electron beam based characterization and quantification of the coaxial coupler RF kick in the PITZ gun is simulated. Preliminary results of the investigations are presented.  
poster icon Poster WEP005 [1.345 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP005  
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WEP009 A Cryocooled Normal-Conducting and Superconducting Hybrid CW Photoinjector ion, gun, SRF, cathode 436
 
  • H.J. Qian, M. Krasilnikov, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
 
  Continuous wave (CW) photoinjectors have seen great progress in the last decades, such as DC gun, SRF gun and normal conducting VHF-band RF gun. New developments of CW guns are aiming higher acceleration gradient and beam energy for higher-beam brightness. One of the technical challenges for CW SRF guns is the compatibility of normal-conducting high QE cathodes and superconducting cavity. In this paper, a high gradient cryocooled CW normal-conducting gun is proposed to house the high QE cathode, and a SRF cavity nearby gives further energy acceleration. Preliminary ASTRA simulations of such a hybrid photoinjector are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP009  
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WEP012 A 2.45 GHz Photoinjector Gun for an FEL Driven by Laser Wakefield Accelerated Beam ion, laser, klystron, cathode 444
 
  • S.V. Kuzikov, S.A. Bogdanov, E. Gacheva, E.V. Ilyakov, D.S. Makarov, S. Mironov, A. Poteomkin, A. Shkaev, A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
 
  Funding: This work was supported by the Russian Scientific Foundation (grant #16-19-10448).
The photoinjector of short electron bunches is a key element of investigations aimed on particle acceleration by pulses of the subpetawatt laser PEARL (10 J, 50-70 fs). The projected parameters of the photoinjector are an electron energy level of 5 MeV, a charge > 0.1 nC, a bunch length of about 3 mm, a transversal emittance no worse than 1 mm*mrad, and an energy spread no more than ~0.1%. The photoinjector is based on klystron KIU-111 at frequency 2.45 GHz, produced by company Toriy (output power ~ 5 MW, pulse length ~ 7 mcs, efficiency ~ 44%, power gain ~ 50 dB). It is proposed to use this klystron in order to feed the accelerating resonator of the classical design consisted of 1.5 cells in which the photocathode is inserted. On a base of third harmonics of a Ti:Sa laser, we plan to produce picosecond pulses of no less than 100 mcJ in energy. The photocathode is planned to be made of CVD diamond film which is not critical to vacuum degree and surface contamination, has high QE, a long lifetime, and is capable of being used with cheap, long wavelength optical lasers.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP012  
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WEP021 Preliminary Results of the Dark Current Modelling for the Polfel Superconducting Lead Photocathode ion, cathode, gun, electron 463
 
  • K. Szymczyk, J.A. Lorkiewicz, R. Nietubyć
    NCBJ, Świerk/Otwock, Poland
  • J.K. Sekutowicz
    DESY, Hamburg, Germany
 
  Preparation for the construction of Polish Free Electron Laser (POLFEL) will begin shortly at National Centre for Nuclear Research (NCBJ) in Warsaw. POLFEL is planned as a fourth-generation light source driven by a superconducting (sc) electron accelerator. The concept includes an all-superconducting injector with a thin-film lead sc photocathode, dedicated to continuous wave or long-pulse linac operation. One of the issues which emerges in connection with operation of high-gradient electron guns furnished with dismountable photocathode plugs is the dark current emitted from the cathode surface inhomogeneities. The dark current usually degrades accelerator performance. The purpose of this paper is to present preliminary investigation results of the dark current generation in the electron gun with a thin lead layer deposited on a niobium plug. Specific features of geometric configuration like rounded plug edges, a gap between the plug and the back gun wall as well as cathode surface roughness have been taken into account for the electron field emission and RF field calculations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP021  
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WEP024 Design and Research of a Micro-Pulse Electron Gun ion, electron, gun, high-voltage 466
 
  • D.Y. Yang, B.T. Li, X.Y. Lu, W.W. Tan, L. Xiao, Y. Yang, Z.Q. Yang, J. Zhao
    PKU, Beijing, People's Republic of China
  • K. Zhou
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
 
  Micro-pulse electron gun (MPG) is a novel electron source which can produce narrow-pulse, high-repetition rate electron current. Theoretical and experiment work have been done to study physical properties and steady operating conditions of MPG. Proof-of-principle work has been finished and the next work is to research the parameters of the MPG electron beam and master the MPG work property deeply. Thus, a high voltage accelerating platform which can supply 100 kV direct voltage was designed. Furthermore, electromagnetic and mechanism designs were operated to adapt the high voltage platform and measure beam parameters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP024  
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WEP034 Diagnostics Upgrades for Investigations of HOM Effects in TESLA-type SCRF Cavities ion, HOM, detector, electron 492
 
  • A.H. Lumpkin, N. Eddy, D.R. Edstrom, P.S. Prieto, J. Ruan, Y.-M. Shin, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • B.E. Carlsten
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Work at FNAL supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. DoE. Work at LANL supported by U.S. DoE through the LANL/LDRD Program.
We describe the upgrades to diagnostic capabilities on the Fermilab Accelerator Science and Technology (FAST) electron linear accelerator that will allow investigations of the effects of high-order modes (HOMs) in SCRF cavities on macropulse-average beam quality. We focus here on the dipole modes in the first pass-band generally observed in the 1.6-1.9 GHz regime in TESLA-type SCRF cavities due to uniform transverse beam offsets of the electron beam. Such cavities are the basis of the accelerator for the European XFEL and the proposed MaRIE XFEL facility. Initial HOM data indicate that the mode intensities oscillate for about 10 microseconds after the micropulse enters the cavity, resulting in centroid shifts throughout the train. This results in a blurring of the averaged beam image size. The upgrades will include optimizing the HOM detectors' bandpass filters and adding a 1.3-GHz notch filter, converting the BPM electronics to bunch-by-bunch processing, and using the C5680 streak camera in a framing mode for bunch-by-bunch spatial information at the <20-micron level. The preliminary HOM detector data, prototype BPM test data, and first framing camera OTR data will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP034  
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