First Plasmas and Initial Characterization with the RISE and SupRISE Test Devices for the DIII-D Neutral Beam System Upgrade

As part of the recent initiative to develop inductively coupled plasma (ICP) ion sources for the DIII-D neutral beam injection system, two ICP test devices have been constructed at DIII-D to tackle several engineering challenges and optimize design parameters for the prototype that will be installed in the near-future. A small-scale device called RISE (Radiofrequency Ion Source Experiment) has been retrofitted with additional plasma diagnostics and RF power handling capabilities to investigate various Faraday grid geometries and run comparative studies with the LUPIN ion source developed by our partners at NC State. In parallel, a full-scale test device called SupRISE (Superior Radiofrequency Ion Source Experiment) aims to determine the optimal RF frequency and ICP chamber dimensions for high power coupling as well as explore high voltage isolation capabilities for DIII-D facility integration. Both test devices are also being used to characterize a 50 kW solid state RF generator manufactured by Aethera Technologies^TM. SupRISE couples 50 kW of RF power (between 4 – 8 MHz) through a ~70 x 30 x 30 cm quartz vessel to achieve a plasma density of ~10¹⁸ m^-3 with a 10s ON, 3.5m OFF duty cycle. Results from initial experiments on plasmas generated with RISE and SupRISE will be presented.

This work is supported by the US DOE under DE-SC0024523 and DE-FC02-04ER54698.