Keyword: FEL
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MOPLR005 Design, Manufacturing and Installation of Two Dual-Feed Accelerating Structures for the FERMI Injector linac, cavity, accelerating-gradient, emittance 139
 
  • C. Serpico, A. Fabris, G. Penco, M. Svandrlik
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • B. Keune
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
 
  FERMI is a seeded Free Electron Laser (FEL) driven by a warm S-band Linac. In the injector region, two 3- meter long Forward Traveling Wave (FTW) accelerating structures, coming from the old Elettra injector, were installed. In order to improve the e-beam quality at higher bunch charge, it was decided to replace the existing ones with two dual-feed accelerating structures. Those structures have been designed and manufactured by RI Research Instruments GmbH and delivered to Elettra in July 2015. The following paper will report about the RF design and the manufacturing of the new structures. Details about the RF conditioning and the installation will also be illustrated.  
poster icon Poster MOPLR005 [1.100 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR005  
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MOPLR016 Status of the Injection System of the CLARA FEL Test Facility gun, cavity, solenoid, cathode 174
 
  • B.L. Militsyn, D. Angal-Kalinin, R.K. Buckley, R.J. Cash, J.A. Clarke, L.S. Cowie, B.D. Fell, P. Goudket, T.J. Jones, K.B. Marinov, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, T.C.Q. Noakes, B.J.A. Shepherd, R. Valizadeh, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • V.V. Paramonov
    RAS/INR, Moscow, Russia
 
  The 250 MeV CLARA FEL test facility is now under construction at Daresbury Laboratory. Electron beam for this facility is provided by two normal conducting S-band photocathode guns: a 10 Hz 2.5 cell gun earlier used as the injector for the VELA machine, and a 400 Hz 1.5 cell gun now under commissioning. At the initial stage of Phase I CLARA will operate with the 10 Hz gun and a 45 MeV 2 m long linac section working as a buncher and/or booster. The beam will be deflected into the existing VELA beamline with an S-bend and directed to the spectrometer line for analysing beam properties or into one of two VELA user areas. The 400 Hz gun will be installed in the VELA beamline for detailed high power RF and beam commissioning in the VELA beam diagnostics suite. As the 400 Hz gun is equipped with an interchangeable photocathode it is possible to investigate different metal photocathodes and select the one providing minimal beam emittance at highest quantum efficiency. A state of the art photocathode preparation system is under commissioning at Daresbury. After commissioning the 400 Hz gun will be installed to the CLARA beam line to deliver high energy, high repetition rate beams for the FEL facility, and the 10 Hz gun will be returned to the VELA beam line.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR016  
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TUOP01 Applying Transverse Gradient Undulators to Suppression of Microbunching Instability electron, linac, laser, simulation 380
 
  • D. Huang, H.X. Deng, C. Feng, D. Gu, Q. Gu, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
 
  Funding: Major State Basic Research Development Program of China (2011CB808300). National Natural Science Foundation of China (NSFC), grant No. 11275253.
The microbunching instability developed during the beam compression process in the linear accelerator (LIN-AC) of a free-electron laser (FEL) facility has always been a problem that degrades the lasing performance, and even no FEL is able to be produced if the beam quality is destroyed too much by the instability. A common way to suppress the microbunching instability is to introduce extra uncorrelated energy spread by the laser heater that heats the beam through the interaction between the electron and laser beam, as what has been successfully implemented in the Linac Coherent Light Source and Fermi@Elettra. In this paper, a simple and effective scheme is proposed to suppress the microbunching instability by adding two transverse gradient undulators (TGU) before and after the magnetic bunch compressor. The additional uncorrelated energy spread and the density mixing from the transverse spread brought up by the first TGU results in significant suppression of the instability. Meanwhile, the extra slice energy spread and the transverse emittance can also be effectively recovered by the second TGU. The magnitude of the suppression can be easily controlled by varying the strength of the magnetic fields of the TGUs. Theoretical analysis and numerical simulations demonstrate the capability of the proposed technique in the LINAC of an x-ray free-electron laser facility.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP01  
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TUPRC017 Field Flatness and Frequency Tuning of the CLARA High Repetition Rate Photoinjector cavity, cathode, coupling, gun 452
 
  • L.S. Cowie, P. Goudket, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • T.J. Jones
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • B. Keune
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
 
  The High Repetition Rate Photoinjector, designed for the CLARA FEL at Daresbury Laboratory, was tuned at the manufacturers for both field flatness and frequency. Due to the high average power in the cavity of 6.8 kW the cavity requires significant cooling, achieved by water channels in the cavity body. These channels prohibit the use of tuning studs to tune the cavity. The cavity was tuned by taking pre-braze clamped low power RF measurements and using the data to trim the cavity cells to the optimum length for both field flatness and frequency. The optimum field flatness is 100% and the design frequency is 2998.5 MHz. Both cells were trimmed in 3 stages, resulting in a post-braze frequency of 2998.51 MHz and field flatness of 98%.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC017  
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TH3A03 The VELA and CLARA Test Facilities at Daresbury Laboratory electron, gun, cavity, laser 734
 
  • P.A. McIntosh, D. Angal-Kalinin, J.A. Clarke, L.S. Cowie, B.D. Fell, S.P. Jamison, B.L. Militsyn, Y.M. Saveliev, D.J. Scott, N. Thompson, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A. Gleeson, T.J. Jones
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
 
  The Versatile Electron Linear Accelerator (VELA) provides enabling infrastructures targeted at the development and testing of novel and compact accelerator technologies, specifically through partnership with academia and industry, aimed at addressing applications in medicine, health, security, energy and industrial processing. The facility is now fully commissioned and is taking advantage of the variable electron beam parameters to demonstrate new techniques/processes or otherwise develop new technologies for future commercial realization. Examples of which include; electron diffraction and new cargo scanning processes. The Compact Linear Accelerator for Research and Applications (CLARA) will be a novel FEL test facility, focused on the generation of ultra-short photon pulses with extreme levels of stability and synchronization. The principal aim is to experimentally demonstrate that sub-cooperation length pulse generation with FELs is viable, and to compare the various schemes being championed. The results will translate directly to existing and future X-ray FELs, enabling attosecond pulse generation. Both the VELA and CLARA facilities are co-located at Daresbury Laboratory and provide the UK with a unique platform for scientific and commercial R&D using ultra-short pulse, high precision electron and photon beams.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH3A03  
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FR2A01 Status of the PAL-XFEL undulator, linac, cavity, gun 1042
 
  • H.-S. Kang, D.E. Kim, K.W. Kim, I.S. Ko, T.-Y. Koo, H.-S. Lee, K.-H. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The construction of the PAL-XFEL was completed at the end of 2015 and the FEL commissioning started from the beginning of 2016. The commissioning aims for the lasing of 0.5 nm FEL in the first campaign by July 2016, and for the lasing of 0.1 nm hard X-ray FEL in the second campaign by December 2016. The commissioning results of the 0.5 nm FEL lasing will be presented.  
slides icon Slides FR2A01 [92.474 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-FR2A01  
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