Destabilization and Quasilinear Evolution of the Ion Flute Mode

The regions of instability of the ion flute mode are investigated for a low -β plasma in axisymmetric multipoles. A stability criterion is given including the effects of (1) finite Debye length, (2) small temperature anisotropy, and (3) small temperature gradient. Using quasilinear theory the growth of a spectrum of waves is shown to produce a stabilizing anisotropy. The level of density fluctuations in the saturated state is given for plasmas close to marginal stability.