Suppression of the tearing mode by energetic ions

Abstract
The effect of an energetic ion population on the nonlinear stability of a tearing mode of single helicity is determined using kinetic theory. A dynamical equation is derived for the magnetic-island width. It is shown that the island growth can be suppressed in a tokamak when the energetic ion-density profile peaks just outside the rational surface. Effects due to resistive interchanges and bootstrap currents are included in the model.