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

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 paper, 1D particle-in-cell simulations with realistic proton-to-electron mass ratio are used to show that in cases with upstream electron temperature $T_e$ exceeding the ion temperature $T_i$, the magnitude of the fluctuations increases with the electron plasma-to-cyclotron frequency ratio ${\omega }_{pe}/{\Omega }_{ce}$, reaching realistic values at ${\omega }_{pe}/{\Omega }_{ce}\gtrsim 30$. The large-amplitude fluctuations in the simulations are shown to be associated with electrostatic solitary structures, such as ion phase-space holes. In the cases where upstream temperature ratio is reversed, the magnitude of the fluctuations remains small.

References in corpus (7)

• Energy transfer, pressure tensor and heating of kinetic plasma
• Electron Injection by Whistler Waves in Non-relativistic Shocks
• Electrostatic turbulence and Debye-scale structures in collisionless shocks
• Electrostatic solitary waves in the Earth's bow shock: nature, properties, lifetimes and origin
• Microinstabilities at perpendicular collisionless shocks: A comparison of full particle simulations with different ion to electron mass ratio
• A Field-Particle Correlation Analysis of a Perpendicular Magnetized Collisionless Shock
• Double layers in the Earth's bow shock