Particle-in-Cell Simulations of Collisionless Magnetic Reconnection with a Non-Uniform Guide Field

TL;DR

This study uses particle-in-cell simulations to explore collisionless magnetic reconnection starting from a nonlinear force-free equilibrium with a non-uniform guide field, revealing a transition from guide field to anti-parallel reconnection.

Contribution

It introduces the first simulation of collisionless reconnection from a nonlinear force-free Vlasov-Maxwell equilibrium with a non-uniform guide field, showing a transition in reconnection behavior.

Findings

Reconnection initially resembles guide field reconnection.

A gradual transition to anti-parallel reconnection occurs.

Comparison with other equilibrium simulations highlights the transition process.

Abstract

Results are presented of a first study of collisionless magnetic reconnection starting from a recently found exact nonlinear force-free Vlasov-Maxwell equilibrium. The initial state has a Harris sheet magnetic field profile in one direction and a non-uniform guide field in a second direction, resulting in a spatially constant magnetic field strength as well as a constant initial plasma density and plasma pressure. It is found that the reconnection process initially resembles guide field reconnection, but that a gradual transition to anti-parallel reconnection happens as the system evolves. The time evolution of a number of plasma parameters is investigated, and the results are compared with simulations starting from a Harris sheet equilibrium and a Harris sheet plus constant guide field equilibrium.