Particle Simulation of Finite Beta Interchange Modes in a Sheared Magnetic Field

Particle simulations of ideal and resistive interchange modes driven by density gradient and magnetic field curvature in finite beta plasmas and sheared slab geometry have been performed. A 2-1/2D bounded magneto -inductive guiding center electron particle code, which accurately follows the perturbed magnetic field in the shear Alfven limits has been implemented and used. To simulate effective collisions between electrons and ions in the guiding center electron plasma, an accurate algorithm for the Lorentz collision operator has been constructed and used for resistive interchange modes. With the particle code, linear and quasilinear behaviors of interchange modes in finite beta plasmas have been investigated along with their electrostatic limit as a reference for both collisionless and collisional regimes. Analytical estimates from quasilinear theory are also in agreement with the measured electrostatic potential and radial magnetic field fluctuation levels at saturation. Nonlinear features of particle simulations include mode condensation in wave number space at saturation in electrostatic collisional plasmas and a significant amount of parallel ion temperature profile modification associated with quasilinear density profile modification in finite beta collisional plasmas.