Resistive instability of a low-beta plasma cylinder without assumed mode localization

Resistive instabilities in a low-β incompressible cylindrical model are investigated in a weakly sheared magnetic field. No boundary layer assumptions are made. Previous analytic results are found to fail badly when resistivity becomes too large, causing peaking in the growth rate dependence upon resistivity, and when the resonant surface approaches the axis, causing stabilization. The m = 1 tearing mode is investigated and found to lack the cut-off of higher m numbers. Finite Larmor radius effects have expected stabilization properties, but produce a new, delocalized instability. (author)