Simulation studies of the collisionless tearing instabilities

Abstract

Collisionless tearing instabilities and the consequent enhanced transport are investigated theoretically and also numerically, using a two-and-one-half-dimensional particle simulation code in a slab geometry. The effects of electrostatic fields on the instability are also considered. The initial current is found to diffuse along the perturbed magnetic field lines, the observed diffusion along the perturbed magnetic field lines, the observed diffusion coefficient being in good agreement with the theoretical prediction. The growth of the instability is observed to divide into three phases; a linearly unstable phase, a quasi-stable phase, and a nonlinear phase similar to the Rutherford phase. Electrostatic effects have a tendency to enhance the tearing mode growth rate. In multi-mode tearing, a coalescence of magnetic island is observed.