The Effect of Trapped Particles on Gradient Drift Instabilities in Finite Pressure Plasma with a Longitudinally Nonuniform Magnetic Field

摘要

Gradient drift instabilities are considered on the basis of local dispersion relation developed for the case of longitudinally nonuniform magnetic field. Such a field allows simulating the effect of trapped particles in tokamak geometry separately from other effects. Completely electromagnetic approach is developed to take into account finite pressure. Trapped particles and magnetic field non-uniformity are taken into account by the frequency of the magnetic drift of the particle. Modes propagating perpendicularly to the magnetic field lines are typical from the viewpoint of effect of trapped electrons. In finite pressure plasma (ratio of the plasma pressure to the magnetic pressure P ～ 0.1), growth rate decrease is significant, as compared with electrostatic limit (β → 0).