Numerical modeling of linear drift-tearing mode stability

Abstract

Numerical modeling results of the linear drift tearing modes are presented. The present model is based on the two-fluids equations, and the perturbed bootstrap current is also included. The electron temperature and the density perturbations are self-consistently calculated by solving the two-dimensional transport equations. It is found that, with the inclusion of the electron perpendicular heat transport, which is neglected in the previous theory, the behavior of the drift tearing mode becomes significantly different, and a new type of tearing mode instability appears. This mode is driven unstable by a sufficiently large electron temperature gradient in a certain range of the electron diamagnetic drift frequency ω*e. The stability of the drift tearing mode is found to be mainly determined by ω*e. The parallel ion flow driven by the parallel pressure gradient is found to be stabilizing for the drift tearing modes, while the perturbed bootstrap current is destabilizing for large or small ω*e but can be stabilizing for a certain range of ω*e.