Alfvén-wave ion heating in the reversed field pinch

Ion energies in reversed-field pinch plasmas are observed to be considerably higher than expected from ohmic heating and collisional transfer from electrons. Other mechanisms must be involved and seem to be related to tearing-mode fluctuations. Observations of ion heating and fluctuation spectra are reviewed here as well as various mechanisms proposed to be responsible for the ion heating. A mechanism is proposed, where induced currents due to rotating tearing-mode perturbations passing by irregularities in the wall structure excite plasma waves, which in turn are absorbed at the Alfven-wave resonance. The partition of energy between electrons and ions is discussed.