Tearing mode analysis in electron magnetohydrodynamics with pressure gradient

Abstract

A two-dimensional three-component (2D/3C) electron magnetohydrodynamic (EMHD) model is implemented to investigate the linear behavior of collisionless tearing modes in slab geometry. Owing to nonuniformity of thermal pressure and plasma density, the electron diamagnetic drift and Biermann battery effects are involved. The linear structures, growth rate, and real frequency are analyzed with a thin current sheet in the electron inertia scale. The ratio of the electron current to the total current in equilibrium can notably promote the growth of the tearing mode in EMHD. More numerical results then show that the effect of the pressure gradient on the tearing mode is dependent on the plasma beta, stabilizing the mode in a low enough beta limit but destabilizing it with the higher beta. The frequency of the mode caused by the pressure gradient is found to be increasing with it. The Biermann battery effect slightly stabilizes the tearing mode in low beta plasma but is indicated to be significant in much higher beta conditions.