Low frequency electrostatic instabilities in a toroidal plasma with a hot ion beam

A kinetic and an unexpanded diamagnetic heat flow fluid model are used for investigating microinstabilities in a system with auxiliary heating. The hot particles supposed to originate from ion cyclotron resonance heating or from neutral beam injection are represented in the form of a hot Maxwellian distribution. It is found that a hot ion beam usually has only a slight stabilizing influence on the toroidal ηi mode but leads to a significant reduction of the ion heat flow. Also found is a new interchange instability which is driven by the steep density gradient of the beam. (author). Letter-to-the-editor. 16 refs, 6 figs