Ion temperature, heating and scaling relations at the Extrap-T1 reversed-field pinch

Investigations of the temperatures of the in situ impurity ions , , , and have been performed at the Extrap-T1 reversed-field pinch (RFP) via measurements of the Doppler broadening of emission lines in the near-UV wavelength region. Ion temperatures of the high ionization stages are found to be of the order of the electron temperature. This means that ion heating can be connected with RFP dynamo activity giving rise to the non-Spitzer part of the power input. Power input to the ions of the order of the non-Spitzer part of the total power input is required to explain the high ion temperatures. MHD effects could be responsible for this heating. We present scaling of the observed ion temperatures with plasma current , electron density , pinch parameter and magnetic fluctuations. We also present an empirical scaling law in which the ion temperature can be expressed as . Keeping constant, this gives a constant ion beta poloidal .