Author: Vafaei-Najafabadi, N.
Paper Title Page
Beam Induced Ionization Injection of Shaped Electron Bunches  
  • N. Vafaei-Najafabadi, L.D. Amorim
    Stony Brook University, Stony Brook, USA
  Funding: Simulations were conducted on NERSC facility, operated under Contract No. DE-AC02-5CH11231, and of SEAWULF at Stony Brook University.
Particle-driven Plasma Wakefield Accelerators (PWFAs) are promising candidates for future free electron laser and collider applications. In PWFAs, energy is transferred from a relativistic drive beam to a trailing bunch in a plasma wake. One of the challenges of PWFAs is reducing energy spread of the beam from typically few percent to the required 0.1% range. This can be accomplished by generating a trailing bunch with a trapezoidal density profile, which will allow the PWFA to operate in the beam-loading regime, therefore circumventing the energy-spread growth of the trailing beam during acceleration. In this work we show how the Beam Induced Ionization Injection (BIII) technique can produce a trailing bunch of electrons with a trapezoidal shape suitable for beam-loading. In BIII, the trailing beam is created by ionization injection of an impurity due to the increased field of the beam during betatron oscillations. By tailoring the longitudinal profile of the impurity, we can shape the injected trailing electron bunch to reach the beam-loading regime. We will present results of numerical simulations done to model BIII shaped beams with the Particle In Cell code OSIRIS*.
* R. A. Fonseca et al., Lect. Notes Comput. Sci. 2331, 342 (2002).
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WEPLO05 Developing Criteria for Laser Transverse Instability in LWFA Simulations 855
SUPLE07   use link to see paper's listing under its alternate paper code  
  • Y. Yan, L.D. Amorim, P. Iapozzuto, V. Litvinenko, N. Vafaei-Najafabadi
    Stony Brook University, Stony Brook, USA
  • M. Babzien, M.G. Fedurin, Y.C. Jing, K. Kusche, M.A. Palmer, I. Pogorelsky, M.N. Polyanskiy
    BNL, Upton, New York, USA
  • M. Downer, J.R. Welch, R. Zgadzaj
    The University of Texas at Austin, Austin, Texas, USA
  • C. Joshi, W.B. Mori
    UCLA, Los Angeles, California, USA
  • P. Kumar, V. Samulyak
    SBU, Stony Brook, USA
  Funding: We acknowledge resources of NERSC facility, operated under Contract No. DE-AC02-5CH11231, and of SEAWULF at Stony Brook University as well as funding from SBU-BNL Seed Grants.
Laser-driven plasma wakefield acceleration (LWFA) is considered as a potential technology for future colliders and light sources. To make the best use of a laser’s power, the laser is expected to maintain a stable propagation. A transverse instability is observed in our previous simulations when a long, intense CO2 laser propagates inside a plasma*. This unstable motion is accompanied by strong transverse diffraction of the laser power and results in the disruption of the ion channel typically used for radiation generation**. We investigated the hosing-like instability using the Particle-in-Cell code OSIRIS*** by modeling the laser portion where this instability is seeded and then evolves. In this proceeding, a criteria will be described that allows for the characterization of the temporal and spatial evolution of this instability.
*J. Yan, et al. , AAC, IEEE, 2018.
** L. Nemos et al., PPCF, 58(3), 2016.
***R. A. Fonseca et al., Lecture Notes Computation Science (2331) 342, 2002.
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About • paper received ※ 16 September 2019       paper accepted ※ 04 December 2019       issue date ※ 08 October 2019  
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