Anomalous Ion Heating in Very LowqaDischarges of the SINP Tokamak

Abstract

Impurity ion temperatures and their rate of rise were anomalously high ( ${T}_{i}>{T}_{e}$) in the SINP tokamak having a high current density in a low toroidal magnetic field ( ${q}_{a}\ensuremath{\approx}1.5$). The dynamo effect, which is believed to explain the anomaly in such discharges of reversed-field pinch or ultralow ${q}_{a}$ discharges of other tokamaks cannot account for our heating results. Large fluctuations in ${n}_{e}$, the potential and the magnetic field of frequency ( $\ensuremath{\omega}/2\ensuremath{\pi}\ensuremath{\sim}40--50\mathrm{kHz}$) which appeared during the ion heating indicate large amplitude drift-Alfv\'en waves existed in the plasma and caused the anomalous heating by fast stochastic processes.