A slow-wave heating experiment on RFC-XX using an array of phased antennas

Experimental data for ion cyclotron resonance heating in RFC-XX machine in IPP-Nagoya are presented. The achieved ion temperature is as high as 100 eV at n=1013 cm-3 and 1 keV at n=1012 cm-3. The ion energy confinement becomes worse by the application of a longer pulse, which is found to be due to the enhanced charge-exchange loss and/or electron drag. Axially and azimuthally arrayed antennas are used in the heating, and the importance of the phasing is demonstrated. A simple model of the multiple-antenna problem is also given and used to interpret the experimental data. (author)