Review and perspectives of helicon waves and negative ion studies in the basic plasma physics device RAID

The Resonant Antenna Ion Device (RAID) is a basic plasma physics device located at the SPC-EPFL in Lausanne. In RAID, a novel radio frequency helicon plasma source, based on a resonant network antenna delivering up to 10 kW power at 13.56 MHz, is presently under study as a negative ion source for neutral beam applications for fusion. RAID is equipped with an extensive set of diagnostics, including laser photo detachment, cavity ring down spectroscopy and optical emission spectroscopy for negative ion characterization, movable Langmuir probes and interferometry for plasma profiles, as well as magnetic probes for helicon wave studies. We review recent advances in the understanding of helicon wave physics and negative hydrogen/deuterium production by volumetric processes and outline future research towards the use of resonant antennas for neutral beams.