Phase Space Energization of Ions in Oblique Shocks

TL;DR

This paper uses the field-particle correlation technique to analyze ion energization in phase space within oblique collisionless shocks, revealing distinct energized ion populations and extending the method to complex 3D shock simulations.

Contribution

It demonstrates the application of the FPC technique to characterize ion energization in oblique shocks, including complex 3D dynamics, enhancing analysis capabilities for realistic plasma environments.

Findings

Identified phase space signatures of reflected ions in shocks.

Extended FPC analysis to 3D shock simulations with ripple.

Validated FPC utility for diverse shock conditions.

Abstract

Examining energization of kinetic plasmas in phase space is a growing topic of interest, owing to the wealth of data in phase space compared to traditional bulk energization diagnostics. Via the field-particle correlation (FPC) technique and using multiple means of numerically integrating the plasma kinetic equation, we have studied the energization of ions in phase space within oblique collisionless shocks. The perspective afforded to us with this analysis in phase space allows us to characterize distinct populations of energized ions. In particular, we focus on ions which reflect multiple times off the shock front through shock-drift acceleration, and how to distinguish these different reflected populations in phase space using the FPC technique. We further extend our analysis to simulations of three-dimensional shocks undergoing more complicated dynamics, such as shock ripple, to demonstrate the ability to recover the phase space signatures of this energization process in a more general system. This work thus extends previous applications of the FPC technique to more realistic collisionless shock environments, providing stronger evidence of the technique's utility for simulation, laboratory, and spacecraft analysis.