Microinstability and Shear Stabilization of a Low-β, Rotating, Resistive Plasma

A magnetoplasma in a radial electric field Er suffers from a gravitational instability driven by the centrifugal force. By using only fluid equations, the theory of Rosenbluth, Krall, and Rostoker was extended to finite k∥ and finite resistivity. The theory of resistive drift modes in cylindrical geometry is included as the limit Er → 0. The shear stabilization was computed, and it was found that the drift modes are not localized by shear unless ion Landau damping is taken into account. A stabilization criterion was obtained which is much more severe than those found previously and which is almost impossible to fulfill experimentally. However, it is the modes with short radial wavelength which are most difficult to stabilize, and these may not be harmful to plasma confinement. The role of the Coriolis force and the importance of these instabilities to experiments in cesium plasmas, stellarators, rotating plasmas, and beam-plasma discharges are also pointed out. This theory is particularly germane to cesium plasmas, in which it is shown that Er cannot be ignored.