Magnitude of Short-Wavelength Electric Field Fluctuations in Simulations of Collisionless Plasma Shocks

ORAL

Abstract

Large-amplitude electrostatic fluctuations are routinely observed by spacecraft upon traversal of collisionless shocks in the heliosphere. Kinetic simulations of shocks have struggled to reproduce the amplitude of such fluctuations, complicating efforts to understand their influence on energy dissipation and shock structure. In this contribution, 1D particle-in-cell simulations with realistic proton-to-electron mass ratio are used to show that in cases with upstream electron temperature exceeding the ion temperature , the magnitude of the fluctuations increases with the ratio ωpe/Ωce of electron plasma-to-cyclotron frequency ratio, reaching realistic values at ωpe/Ωce=32 for the cases considered. The large-amplitude fluctuations are shown to be associated with ion phase-space holes. In the cases where upstream temperature ratio is reversed, the magnitude of the fluctuations remains small.

*Authors acknowledge fruitful discussions with the members of the International Team project "Collisionless Shock as a Self-Regulatory System" at the International Space Science Institute (ISSI) in Bern, as well as support by ISSI. This work was partially supported by NASA grant 80NSSC21K1680 and by NSF grant 2010144. Computational resources were provided by the the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center and by Texas Advanced Computing Center (TACC) at the University of Texas at Austin. Access to TACC resources was provided by Frontera Pathways allocation PHY23034. Supporting simulations were also performed using resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231 using NERSC award FES-ERCAP0024215. Some of the work was supported by the Geospace Environment Modeling (GEM) Focus Group entitled, "Particle Heating and Thermalization in Collisionless Shocks in the Magnetospheric multiscale mission (MMS) Era," led by L.B. Wilson III.

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Presenters

  • Vadim S Roytershteyn

    • Space Science Institute

Authors

  • Vadim S Roytershteyn

    • Space Science Institute

  • Lynn B Wilson

    • NASA Goddard Space Flight Center

  • Li-Jen Chen

    • NASA/GSFC

  • Michael Gedalin

    • Ben-Gurion University of the Negev, Beer-Sheva

  • Nikolai V Pogorelov

    • University of Alabama, Huntersville