Turbulent magnetic diffusion and magnetic field reversal

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Abstract
The behavior of compressible plasmas caused by small fluctuations superimposed on slowly varying profiles is investigated self-consistently within the framework of resistive magnetohydrodynamics. The effect of the fluctuations is shown to be the generation of an additional ‘‘eddy’’ resistivity, and not of a dynamo. This effect, nevertheless, suffices to explain magnetic field reversal in pinches. The functional form of the turbulent resistivity is derived from the dynamics of the fluctuations, taken as a bath of local and global modes that are believed to be responsible for field reversal. It is shown that the fluctuations tend to flatten the pressure and parallel current profiles and thus produce plasmas near a ‘‘Taylor state.’’