PARAMETRIC INVESTIGATION OF THE ROTAMAK DISCHARGE IN A 10-LITER SPHERICAL VESSEL

A new series of rotamak experiments conducted in a 10-litre spherical pyrex discharge vessel are described. This series of experiments uses a two-channel RF system (0.5 MHz, 40 ms pulse duration, 116 kW/channel ) capable of operating at much higher power levels than have previousl y been available. The properties of the rotamak discharge as a circuit element are presented together with detailed measurements of the plas ma/field configuration. Steady toroidal currents of up to 7 kA have be en driven with an RF power input of 180 kW. Electron densities and tem peratures of up to 6 x 10(19) M-3 and 11 eV have been obtained. A subs tantial fraction of the driven current has been tentatively identified as bootstrap current driven by the dynamo action of the radial plasma transport across the poloidal magnetic field.