Micro-Instabilities in Magnetically Confined, Inhomogeneous Plasma

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Abstract
Plasma with a density gradient supported in a strong, nearly uniform magnetic field is liable to resistive, gravitationally (g‐) driven instability and short‐wave drift instability. Waves associated with both propagate almost perpendicular to the field lines. Only a low g, and low density plasma are considered, for which these flutelike perturbations remain quasi‐electrostatic, so that dispersion relations are readily found. When the magnetic‐field lines are sheared the localized perturbations which arise are treated by a phase‐integral approximation and growth rates appear as eigenvalues of certain standard equations. The ions are treated throughout by the Vlasov equation so that fine‐scale features such as finite ion Larmor radius ai and Hall current are correctly included. The results for the resistive, gravitational instability are compared with those based on fluid equations and are valid if the perturbation is not localized within ai.