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Isolation and Phase-Space Energization Analysis of Shock Ripple and Non-Adiabatic Electron Heating in Heliospheric Collisionless Shocks

Collin Brown; University of Iowa

Studying the generation of kinetic instabilities and their effect on the energization of ions and electrons in both perpendicular and quasi-perpendicular collisionless shocks provides insight into non-homogenous and non-linear plasmas and the connection between Earth’s bow shock and the solar wind. However, doing so is challenged by the strong spatial and temporal dependence of the system along with the limited measurements that can be made in situ. Thus, causally linking proposed mechanisms to observed phenomena in shocks and measuring their individual contribution to particle acceleration and heating has required advancements in methodology. Here, we present methods composed of two techniques to solve this issue. We use the ‘Instability Isolation Method’ which isolates instabilities in shocks as a linear superposition of the electric field and verifies the validity of the superposition. We use this with the Field-Particle Correlation Technique, a diagnostic that examines the transfer between the electric fields and particles in phase-space and generates signatures that provide both a quantitative and qualitative understanding of particle energization which can be identified using in situ measurements. We apply these techniques to study the connection between ions and shock ripple and the non-adiabatic heating of electrons. We study two simulations of supercritical collisionless shocks, a 3D3V hybrid simulation of an oblique (θ = 45°) shock with βi = βe = 1 and a 2D3V PIC simulation of a perpendicular shock with βi = βe = 0.125.