Keyword: wakefield
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TUPP041 Observations of Long-Range and Short-Range Wakefield Effects on Electron-Beam Dynamics in TESLA-type Superconducting RF Cavities cavity, HOM, FEL, detector 428
  • A.H. Lumpkin, N. Eddy, D.R. Edstrom, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The Fermilab Accelerator Science and Technology (FAST) facility has a unique configuration of a photocathode rf gun beam injecting two TESLA-type single cavities (CC1 and CC2) in series prior to the cryomodule. Beam propagation off axis in these cavities can result in both long-range and short-range transverse wakefields which can lead to emittance dilution within the macropulses and micropulses, respectively. Two configurations of a Hamamatsu C5680 streak camera viewing a downstream OTR screen were utilized to track centroid shifts during the macropulse (framing mode) for the long-range case and during the micropulse for the short-range case (~10-micron spatial resolution and 2-ps temporal resolution). Steering off axis before CC1, resulted in a 100-kHz bunch centroid oscillation within the macropulse that was detected by the downstream rf BPMs and the streak camera*. At 500 pC/b, 50b, and 4-mrad off-axis vertical steering into CC2, we observed an ~ 100-micron head-tail centroid shift in the streak camera image y(t) profiles which we attributed to a short-range wakefield effect. Additional results for kick-angle compensations and model results will be presented.
*A.H. Lumpkin et al., Phys. Rev. Accel. and Beams 21,064401 (2018).
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About • paper received ※ 10 September 2019       paper accepted ※ 11 September 2019       issue date ※ 10 November 2019  
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WEPP018 THz Generation by Optical Rectification for a Novel Shot to Shot Synchronization System Between Electron Bunches and Femtosecond Laser Pulses in a Plasma Wakefield Accelerator laser, plasma, electron, optics 555
  • S. Mattiello, A. Penirschke
    THM, Friedberg, Germany
  • H. Schlarb
    DESY, Hamburg, Germany
  Funding: The work of S. Mattiello is supported by the German Federal Ministry of Education and Research (BMBF) within the Project ¿ MAKE-PWA.
We investigate the influence of the optical properties and of the theoretical description of the THz generation on the conversion efficiency of the generation of short THz pulses. The application is a feedback-system for SINBAD with a time resolution of less than 1 fs for the synchronization of the electron bunch and of the plasma wake field in a laser driven plasma particle accelerator*. Here stable THz pulses are generated by optical rectification of a fraction of the plasma generating high energy laser pulses in a nonlinear lithium niobate crystal. Then the generated THz pulses will energy modulate the electron bunches shot to shot before the plasma to achieve the required time resolution. In this contribution we compare different approximations for the modeling of the generation dynamics using second order or first order equations as well as considering pump depletion effects. Additionally, the dependence of the efficiency of the THz generation on the choice of the dielectric function has been investigated.
*The feedback system will be tested at the Accelerator R&D facility SINBAD (Short Innovative Bunches and Accelerators at DESY).
DOI • reference for this paper ※  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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