MHD DIFFUSION IN SYSTEMS WITH J.B=0 AND J ALONG AN IGNORABLE COORDINATE

Using a model based on simple resistive MHD equations, where thermal conductivity, radiation losses and inertial effects are neglected, it is shown that for systems with j.B = 0 and j along an ignorable coordinate, plasma evolution can be described through the evolution of some proper parameter. This is possible thanks to the fact that an initial uniform temperature profile remains uniform during diffusion. A subtle balance between plasma flow and ohmic dissipation is responsible for the temperature uniformity. An example of application, for the special case of an elliptical plasma column in an external quadrupole magnetic field, is shown.59124334433