Author: Filippetto, D.
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MOPRI053 High Repetition Rate Ultrafast Electron Diffraction at LBNL 724
 
  • D. Filippetto, M. Mellado Munoz, H.J. Qian, F. Sannibale, W. Wan, R.P. Wells, M.S. Zolotorev
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231"
Here we propose to use the APEX photo-gun as novel source for time-resolved electron diffraction studies. The electron source has been designed, built and successfully tested at LBNL. It combines a high accelerating field needed for bright beams, MeV electron energy essential for time resolution in gas-phase experiments and studies of bulk processes, together with continuous (CW) operations. Ultra-short electron pulses can be delivered with a maximum repetition rate of 186 MHz, enabling new science to be studied. We report the design of a dedicated electron diffraction beamline that fits in the space constraints of the APEX tunnel. Simulations of beam properties have been carried out with a genetic optimizer, showing 100 fs time resolution. Beam jitters in energy, time and position are currently being characterized, and a mitigation strategy via fast feedback loops is discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI053  
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MOPRI054 Status of the APEX Project at LBNL 727
 
  • F. Sannibale, K.M. Baptiste, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, D. Filippetto, G.L. Harris, G. Huang, H. Huang, R. Huang, T.D. Kramasz, S. Kwiatkowski, R.E. Lellinger, V. Moroz, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, J.W. Staples, 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), consists in the development of an injector designed to demonstrate the capability of the VHF gun, a normal conducting 186 MHz RF gun operating in CW mode, to deliver the brightness required by X-ray FEL applications at MHz repetition rate. APEX is organized in 3 main phases where different aspects of the required performance are gradually demonstrated. The status and future plans for the project are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI054  
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MOPRI055 APEX Present Experimental Results 730
 
  • D. Filippetto, C.W. Cork, S. De Santis, L.R. Doolittle, G. Huang, R. Huang, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, F. Sannibale, J.W. Staples, R.P. Wells
    LBNL, Berkeley, California, USA
  • J. Yang
    TUB, Beijing, 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 APEX electron source at LBNL combines high-repetition-rate and high beam brightness typical of photo-guns, delivering low emittance electron pulses at MHz frequency. Proving the high beam quality of the beam is an essential step for the success of the experiment. It would enable high repetition rate operations for brightness-hungry applications such as X-Ray FELs, and MHz ultrafast electron diffraction. A full 6D characterization of the beam phase space at the gun beam energy (750 keV) is foreseen in the first phase of the project. Diagnostics for low and high current measurements have been installed and tested, measuring the performances of different cathode materials in a RF environment with mA average current. A double-slit system allows the characterization of beam emittance at high charge and full current (mA). An rf deflecting cavity and a high precision spectrometer allow the characterization of the longitudinal phase space. Here we present the latest results at low and high repetition rate, discussing the tools and techniques used.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI055  
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WEPRO015 RF Injector Beam Dynamics Optimization for LCLS-II 1974
 
  • C. F. Papadopoulos, D. Filippetto, F. Sannibale
    LBNL, Berkeley, California, USA
  • P. Emma, T.O. Raubenheimer, J.F. Schmerge, L. Wang, F. Zhou
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported in part by the Work supported, in part, by the LCLS-II Project and by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
LCLS-II is a proposal for a high repetition rate (>1 MHz) FEL, based on a CW, superconducting linac. The LCLS-II injector is being optimized by a collaboration from Cornell University, Fermilab, LBNL, and SLAC. There are a number of different possible technical choices for the injector including an rf gun or a high voltage DC gun. In this paper we present the status of the simulations for the injector optimization for an rf gun choice for LCLS-II. A multiobjective genetic optimizer is implemented for this reason, and optimized solutions for different bunch charges, corresponding to different operating modes, are presented. These operating points are also the initial part of the start-to-end simulations for LCLS-II. Finally, we discuss the trade-offs between compression and brightness conservation in the low energy (<100 MeV) part of the accelerator, as well as the status of sensitivity studies.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO015  
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THPRI066 Design of a 1.3 GHz Two-cell Buncher for APEX 3924
 
  • H.J. Qian, K.M. Baptiste, J.A. Doyle, D. Filippetto, S. Kwiatkowski, C. F. Papadopoulos, D. Patino, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The design of a 1.3 GHz buncher cavity for the APEX project, a MHz repetition rate high-brightness photoinjector, is presented. The buncher cavity operates at 240 kV in CW mode, and it compresses the 750 keV beam from APEX gun through ballistic compression. Compared with a single cell design, a two-cell cavity doubles the shunt impedance to 7.8 MΩ, which greatly relaxes the requirements for both RF amplifier and cavity cooling. Coupler design, multipacting analysis, HOM analysis and thermal analysis will be presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI066  
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