Influence of Gyration Radius and Collisions on Hydromagnetic Stability

Publisher Website
Google Scholar
Abstract
The stability of low-pressure equilibrium configurations is analyzed considering regimes where the effects of ion Larmor radius and collisions are important. The theory is based on the asymptotic solution of moment equations derived from the Fokker-Planck equation. Purely growing interchange modes are found with growth rates proportional to η∥/a2, where η∥ is the longitudinal electrical resistivity and a the ion gyro-radius. The class of modes of this type which are not localized and a new class, of electrostatic and localized modes, are shown to have the same growth rates. Nonlocalized tearing-type modes are found to be overstable and have growth rates proportional to η∥/a⅔. When the ion gyro-radius effects are relatively large, the presence of a resistivity gradient in the equilibrium is shown not to modify tearing modes nor introduce new localized modes because of thermal conductivity along the magnetic field. For all the instabilities mentioned the width of the region where collisional effects are important is dependent on the ion gyro-radius but not on transport coefficients.

This publication has 13 references indexed in Scilit: