The introduction of a magnetic limiter is proposed for stabilization of MHD interchange modes in the central cell of a tandem mirror. The magnetic limiter creates a ring null in the magnetic field, and electrons which enter the null can stream azimuthally and thereby 'short-circuit' m = 1 fluctuations. This disallows a rigid m = 1 response and introduces finite Larmor radius stabilization effects in much the same way as they appear for higher azimuthal modes. Some pressure gradient can be maintained on the separatrix flux surface by locating the null on a local magnetic maximum. This scheme introduces the possibility of a fully axisymmetric tandem mirror.
Wall stabilization of high-beta anisotropic plasmas in an axisymmetric mirror trap