A novel mechanism for energy transfer from energetic particles to bulk ions via geodesic acoustic modes (GAMs) is presented. The mechanism involves the excitation of GAMs by energetic particles. The GAMs are damped on ions by the Landau damping, by which wave energy is given to bulk ions. This process of energy exchange is formulated within the framework of quasilinear theory. The rate of energy transfer from energetic particles to GAMs can be comparable to that of energy exchange to particles via collisions, if the E × B velocity of GAMs reaches the level of diamagnetic velocity. Under this circumstance, the partition of energy absorptions by bulk ions and electrons is substantially modified due to the selective ion heating by GAMs.
Zonal flows induced by symmetry breaking with existence of geodesic acoustic modes