Electrostatic drift modes with stochastic particle diffusion

The effect of stochastic particle diffusion on the collisionless universal mode in slab geometry is considered. Cross-field particle diffusion is assumed to be caused by a model static magnetic field turbulence. The resultant eigenmode equation is an integral equation for the perturbed electrostatic potential, which is solved numerically. As stochastic particle diffusion is gradually turned on, its effect on the usual drift branch is found to be stabilizing. At the same time, however, there appears a new, stochasticity-induced mode which, under certain circumstances, may become unstable