ION-TEMPERATURE-GRADIENT-DRIVEN INSTABILITY AND ANOMALOUS ION HEATINGIN REVERSED-FIELD PINCHES

A possible mechanism is suggested for direct ion heating in reversed-f ield pinches (RFP). The ion temperature gradient mode induces collisio nless ion perpendicular viscosity which damps the velocity fluctuation s associated with resistive magnetohydrodynamic (MHD) mode activity. I t is found that the growth rate of the eta(i) instability is much larg er than that in a tokamak, because the effects of both bad magnetic cu rvature and negative compressibility are enhanced in a RFP configurati on. The anomalous perpendicular viscosity coefficient is estimated fro m the mixing length argument and the corresponding ion heating power d ue to viscous dissipation is found sufficient to balance the ion condu ctive losses.