Instabilities due to Resistivity Gradients in a Low-Pressure Plasma

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Abstract
Instabilities due to resistivity gradients in a low‐pressure plasma are reconsidered using the electrostatic approximation. The fastest growth rate is proportional to η∥⅓, where η∥ is the resistivity component parallel to the magnetic field. Contrary to earlier belief, heat conductivity along the field lines does not reduce the growth rate appreciably for Stellarator type of data. This mode is strongly localized in a thin layer inside the plasma, and hence may not produce much anomalous diffusion. Comparison is made with the much slower Kadomtsev mode, proportional to η∥, which is not localized. The effects of finite Larmor radius and Hall current acting in the plane perpendicular to the magnetic field are deduced. The corresponding actions parallel to the magnetic field, which seems to be more important when the plasma pressure is not too low, is not considered.