Fundamentals of Non-relativistic Collisionless Shock Physics: III. Quasi-Perpendicular Supercritical Shocks

TL;DR

This paper reviews the theory and simulations of quasi-perpendicular collisionless shocks, focusing on their structure, particle dynamics, instabilities, and non-stationary behavior, providing a comprehensive understanding of supercritical shock physics.

Contribution

It offers a detailed synthesis of theoretical frameworks and simulation results for quasi-perpendicular shocks, highlighting new insights into shock non-stationarity and particle acceleration mechanisms.

Findings

Shock non-stationarity due to nonlinear whistler variability

Ion and electron instabilities influence shock reformation

Potential for shock breaking under certain conditions

Abstract

The theory and simulations of quasi-perpendicular and strictly perpendicular collisionless shocks are reviewed. The text is structured into the following sections and subsections: 1. Setting the frame, where the quasi-perpendicular shock problem is formulated, reflected particle dynamics is described in theoretical terms, foot formation and foot ion acceleration discussed, and the shock potential explained. 2. Shock structure, 3. Ion dynamics, describing its role in shock reformation and the various ion-excited instabilities. 4. Electron dynamics, describing electron instabilities in the foot; 5. The problem of stationarity, posing the theoretical reasons for shocks being non-stationary, discussing nonlinear whistler mediated variability, two-stream and modified two-stream variability, formation of ripples in two-dimensions, 6. Summary and conclusions: The possibility of shock breaking.