Author: Neveu, N.R.
Paper Title Page
MOPA12 Commissioning of HOM Detectors in the First Cryomodule of the LCLS-II Linac 69
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • B.T. Jacobson, N.R. Neveu, J.P. Sikora
    SLAC, Menlo Park, California, USA
  Long-range wakefields (LRWs) may cause emittance dilution effects. LWRs are especially unwanted at facilities with low emittance beams like the LCLS-II at SLAC. Dipolar higher-order modes (HOMs) are a set of LRWs that are excited by off-axis beams. Two 4-channel HOM detectors were built to measure the beam-induced HOM signals for TESLA-type superconducting RF (SRF) cavities; they were tested at the Fermilab Accelerator Science and Technology (FAST) facility and are now installed at SLAC. The HOM detectors were designed to investigate LRW effects on the beam and to help with beam alignment. This paper presents preliminary results of HOM measurements at the first cryomodule (CM01) of the LCLS-II linac and describes the relevant hardware and setup of the experiment.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA12  
About • Received ※ 09 August 2022 — Accepted ※ 20 August 2022 — Issue date ※ 31 August 2022  
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Multiobjective Optimization of the LCLS-II Photoinjector  
  • N.R. Neveu
    SLAC, Menlo Park, California, USA
  • T.H. Chang, S.T.P. Hudson, J.M. Larson
    ANL, Lemont, Illinois, USA
  • P.L. Franz
    Stanford University, Stanford, California, USA
  Genetic algorithms and particle swarm optimization are currently the most widely used optimization algorithms in the accelerator physics community. These algorithms can take many evaluations to find optimal solutions for one machine prototype. In this work, the LCLS-II photoinjector is optimized with three optimization algorithms: a genetic algorithm, a surrogate based algorithm, and a multi-start scalarization method. All three algorithms were able to optimize the photoinjector, with various trade-offs for each method discussed here.  
slides icon Slides TUYE5 [3.919 MB]  
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Nonlinearly Shaped Pulses at LCLS-II  
  • N.R. Neveu, S. Carbajo, Y. Ding, J.P. Duris, R.A. Lemons, A. Marinelli, J. Tang
    SLAC, Menlo Park, California, USA
  Funding: DOE
With the goal of improving emittance and longitudinal phase space of the electron beam, we consider nonlinear shaping of the temporal laser profile at the cathode. The operational Ultraviolet (UV) optics installed at the LCLS and LCLS-II currently produce Gaussian shaped pulses. Our simulations show the potential to reduce emittance and increase peak brightness when comparing nonlinear UV laser shapes on the cathode to baseline Gaussian pulses at the cathode.
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