Current-Sheet Equilibria with Crescent Distributions: Structure, Evolution, and Wave-Particle Interactions

Abstract:

A general class of quasineutral kinetic current-sheet equilibria have been developed and used to initialize PIC simulations in order to study their stability and role in generating waves. These equilibria can be designed to incorporate agyrotropic features in the electron distribution such as the crescents observed by MMS in association with magnetic reconnection. Here we focus on electron-scale current sheets, but the method can be used to study ion-scale phenomena as well. Both symmetric and asymmetric current sheets can be modeled using this technique. 2D simulations in different planes highlight different instability mechanisms in the inhomogeneous environment of the current sheet such as tearing, kinking, and whistler-mode generation. These 2D simulations will be supplemented by lower-resolution 3D simulations to study the interaction between the different instabilities. Visualization of the electron distributions and their evolution—including tracing the orbits of individual particles—will be used to illustrate the role of wave-particle interactions.