High density plasma generation by RF ohmic discharge in toroidal divertor simulator NAGDIS-T

A new toroidal divertor plasma simulator, NAGDIS-T (NAGoya DIvertor plasma Simulator with Toroidal magnetic configuration) has been constructed, in which the toroidal plasma is generated by RF Joule and/or DC discharge. In order to obtain high density deuterium plasmas relevant to divertor conditions in fusion devices, the optimum condition of RF ohmic discharge was investigated by varying gas pressure, driving frequency and RF transformer turn ratio. The experimental result was compared with the simple numerical modeling.