Observation of explosive collisionless reconnection in 3D nonlinear gyrofluid simulations

TL;DR

This paper demonstrates that in 3D gyrofluid simulations of high-temperature plasmas, collisionless reconnection can occur explosively with nonlinear growth rates significantly exceeding linear predictions, under strong guide fields.

Contribution

It introduces a 3D gyrofluid model to study collisionless reconnection, revealing explosive nonlinear growth rates in high-temperature plasma regimes with strong guide fields.

Findings

Nonlinear growth rates exceed linear rates by over an order of magnitude.

Reconnection occurs explosively in the small-Δ' regime.

Energy functional remains well conserved during nonlinear evolution.

Abstract

The nonlinear dynamics of collisionless reconnecting modes is investigated, in the framework of a three-dimensional gyrofluid model. This is the relevant regime of high-temperature plasmas, where reconnection is made possible by electron inertia and has higher growth rates than resistive reconnection. The presence of a strong guide field is assumed, in a background slab model, with Dirichlet boundary conditions in the direction of nonuniformity. Values of ion sound gyro-radius and electron collisionless skin depth much smaller than the current layer width are considered. Strong acceleration of growth is found at the onset to nonlinearity, while at all times the energy functional is well conserved. Nonlinear growth rates more than one order of magnitude higher than linear growth rates are observed when entering into the small-$\Delta'$ regime.