Fully toroidal fluid model for low frequency modes in magnetized plasmas

A fully toroidal fluid model for the low frequency ion density response has been compared with the gyrokinetic response. In general a good agreement is obtained, particularly for unstable modes and modes propagating in the electron drift direction. In particular, good agreement for the stability threshold of ηi modes is obtained. The magnetic drift resonances are found to be destabilizing close to marginal stability. (authors)