ALFVEN-WAVE ION HEATING IN THE REVERSED-FIELD PINCH

Ion energies in reversed-field pinch plasmas are observed to be consid erably higher than expected from ohmic heating and collisional transfe r from electrons. Other mechanisms must be involved and seem to be rel ated to tearing-mode fluctuations. Observations of ion heating and flu ctuation spectra are reviewed here as well as various mechanisms propo sed to be responsible for the ion heating. A mechanism is proposed, wh ere induced currents due to relating tearing-mode perturbations passin g by irregularities in the wall structure excite plasma waves, which i n turn are absorbed at the Alfven-wave resonance. The partition of ene rgy between electrons and ions is discussed.