Selective destabilization of ion cyclotron modes

Abstract
Observations of the current-driven electrostatic ion cyclotron instability, both at Te/Ti=1 and Te/Ti>>1, show that as the normalized wave number, kperpendicular to rho i is varied, different modes (m=1, 2, 3...) become successively the most unstable mode. The calculated values of kperpendicular to rho i at which the cross-over from one mode to the next occurs are in reasonable agreement with the observed values provided that the local density gradient is taken into account.