Role of electron inertia and electron/ion finite Larmor radius effects in low-beta, magneto-Rayleigh-Taylor instability

TL;DR

This study investigates the impact of electron inertia and finite Larmor radius effects on the low-beta magneto-Rayleigh-Taylor instability using two-fluid models, revealing that FLR effects significantly influence nonlinear evolution and energy distribution.

Contribution

It extends previous MRT instability analyses by incorporating FLR effects through a 10-moment model and examines the role of electron inertia in nonlinear evolution.

Findings

FLR stabilization affects high-wavenumber mode energy.

Electron inertia has minimal impact in 5-moment model.

Lower ion-to-electron mass ratio increases FLR stabilization.

Abstract

The magneto-Rayleigh-Taylor (MRT) instability has been investigated in great detail in previous work using magnetohydrodynamic and kinetic models for low-beta plasmas. The work presented here extends previous studies of this instability to regimes where finite-Larmor-Radius (FLR) effects may be important. Comparisons of the MRT instability are made using a 5-moment and a 10-moment two-fluid model, the two fluids being ions and electrons. The 5-moment model includes Hall stabilization whereas the 10-moment model includes Hall and FLR stabilization. Results are presented for these two models using different electron mass to understand the role of electron inertia in the late-time nonlinear evolution of the MRT instability. For the 5-moment model, the late-time nonlinear MRT evolution does not significantly depend on the electron inertia. However, when FLR stabilization is important, the 10-moment results show that a lower ion-to-electron mass ratio (i.e. larger electron inertia) under-predicts the energy in high-wavenumber modes due to larger FLR stabilization.