Hydromagnetic Stability of Toroidal Equilibria with an Externally Imposed Rotational Transform

Abstract
A simple ``single‐term'' stability criterion is obtained for hydromagnetic equilibria with multipolar fields. It replaces an earlier criterion in which it is necessary to evaluate the ratio of two infinite determinants. It corresponds to the criterion recently developed for arbitrary equilibria by Mercier, Bineau, and ourselves but is tailored to a specific geometry.