Resonant Effects on the Low-Frequency Vlasov Stability of Axisymmetric Field-Reversed Configurations

We investigate the effect of particle resonances on low-frequency magnetohydrodynamic modes in field-reversed geometries, e.g., an ion ring. It is shown that, for sufficiently high field reversal, modes which are hydromagnetically stable can be driven unstable by ion resonances. The stabilizing effect of a toroidal magnetic field is discussed.