Ion-acoustic shocks with reflected ions: modeling and PIC simulations

TL;DR

This paper models ion-acoustic collisionless shocks using 1D kinetic simulations, focusing on reflected ions' role in shock dissipation and implications for particle acceleration in space plasmas.

Contribution

It provides a detailed kinetic simulation analysis of ion-acoustic shocks emphasizing reflected ions, a key aspect previously less understood.

Findings

Reflected ions significantly contribute to shock dissipation.

Shock structure depends on reflection efficiency and particle velocity distribution.

Applications to space and astrophysical particle acceleration are discussed.

Abstract

Non-relativistic collisionless shock waves are widespread in space and astrophysical plasmas and are known as efficient particle accelerators. However, our understanding of collisionless shocks, including their structure and the mechanisms whereby they accelerate particles remains incomplete. We present here the results of numerical modeling of an ion-acoustic collisionless shock based on one-dimensional (1D) kinetic approximation both for electrons and ions with a real mass ratio. Special emphasis is made on the shock-reflected ions as the main driver of shock dissipation. The reflection efficiency, velocity distribution of reflected particles and the shock electrostatic structure are studied in terms of the shock parameters. Applications to particle acceleration in geophysical and astrophysical shocks are discussed.