Author: Bruhwiler, D.L.
Paper Title Page
WEPAF03
Magnetized Electron Cooling Simulations for JLEIC  
 
  • I.V. Pogorelov, D.T. Abell, D.L. Bruhwiler, J.A. Carlsson, Y.I. Eidelman, C.C. Hall, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  • J. Gerity, P.M. McIntyre
    Texas A&M University, College Station, USA
  • H. Zhang, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: This work is supported by the U.S. DOE Office of Science, Office of Nuclear Physics, under Award Number DE-SC0015212.
Relativistic magnetized electron cooling in untested parameter regimes is essential to achieve the ion luminosity requirements of proposed electron-ion collider (EIC) designs. Therefore, accurate calculations of magnetized dynamic friction are required, with the ability to include all relevant physics that might increase the cooling time, including space charge forces, field errors and complicated phase space distributions of imperfectly magnetized electron beams. We present simulations relevant to the JLEIC design, using the BETACOOL and JSPEC codes. We also present recent work on Warp simulations of the electron beam through the solenoid field. Space charge neutralization is provided by impact ionization of a background hydrogen gas. For optimal cooling it is essential that space charge be sufficiently neutralized. We also present recent work on a new analytic treatment of momentum transfer from a single magnetized electron to a drifting ion, and its use for calculations of dynamic friction.
 
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WEPLG03 Theoretical and Computational Modeling of a Plasma Wakefield BBU Instability 341
 
  • S.D. Webb, D.L. Bruhwiler, N.M. Cook
    RadiaSoft LLC, Boulder, Colorado, USA
  • A.V. Burov, V.A. Lebedev, S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
 
  Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics, under contract number DE-SC0018718.
Plasma wakefield accelerators achieve accelerating gradients on the order of the wave-breaking limit, m c2 kp/e, so that higher accelerating gradients correspond to shorter plasma wavelengths. Small-scale accelerating structures, such as plasma and dielectric wakefields, are susceptible to the beam break-up instability (BBU), which can be understood from the Panofsky-Wenzel theorem: if the fundamental accelerating mode scales as b-1 for a structure radius b, then the dipole mode must scale as b-3, meaning that high accelerating gradients necessarily come with strong dipole wake fields. Because of this relationship, any plasma-accelerator-based future collider will require detailed study of the trade-offs between extracting the maximum energy from the driver and mitigating the beam break-up instability. Recent theoretical work* predicts the tradeoff between the witness bunch stability and the amount of energy that can be extracted from the drive bunch, a so-called efficiency-instability relation . We will discuss the beam break-up instability and the efficiency-instability relation and the theoretical assumptions made in reaching this conclusion. We will also present preliminary particle-in-cell simulations of a beam-driven plasma wakefield accelerator used to test the domain of validity for the assumptions made in this model.
* V. Lebedev, A. Burov, and S. Nagaitsev, "Efficiency versus
instability in plasma accelerators", Phys. Rev. Acc. Beams 20, 121301
(2017).
 
slides icon Slides WEPLG03 [2.234 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG03  
About • paper received ※ 01 November 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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