Low-Frequency Instability of Partially Ionized Plasma

The stability of a partially ionized plasma in a magnetic field is investigated. The electron and ion flow equations and continuity equations are used to describe low-frequency, macroscopic variations of plasma density and space potential. The solutions to the linearized forms of these equations consist of a set of eigenfunctions of perturbed density, and a complex frequency eigenvalue corresponding to each perturbed density eigenfunction. It is found that rotating ``flutelike'' density perturbations may grow when a steady radial electric field is present, either parallel or antiparallel to the unperturbed density gradient. The growth rate is proportional to a ``corrected'' electric field, which includes the time-invariant gradients of both density and space potential. The stabilizing effects of diffusion, parallel and perpendicular to the magnetic field, are considered.