Plasma surface interaction experimental facility (PISCES) for materials and edge physics studies

PISCES is a laboratory research facility at UCLA for the study of plasma material interactions in continuous operation at particle and heat fluxes expected in advanced fusion experiments and in reactors. The PISCES plasma has parameters similar to the edge plasma in tokamaks and the halo plasma in tandem mirrors. The 10 cm diameter plasma is generated by a reflex arc discharge from a large area La-Mo disc cathode. The plasma from this H, D, or He discharge transports along the 2-4 kG magnetic field to produce a high density (1013 cm-3), low energy (< 10 eV) plasma. Alternatively, the ions can be extracted and accelerated along the magnetic field by a very low energy acceleration-deceleration system to produce a plasma with 50 - 500 eV ion energy and a density of about 1012 cm-3. Differential pumping in the baffled chamber and plasma pumping during operation maintain the neutral pressure at about 10-4 Torr in the target region. Initial operation has produced continuous cold hydrogen plasmas for hours at a time with densities in excess of 1013 cm-3. The three major foci of PISCES experimental work include: materials and coatings behavior under continuous plasma bombardment to high fluence; plasma and neutral gas effects important in the vicinity of the plasma interface with in-vessel components and the gas ducting and pumping systems; and the development, testing, and calibration of gas ducting and pumping systems; and the development, testing, and calibration of diagnostics to be used in long pulse plasma material interaction programs on confinement experiments. The continuous, controllable operation and moderately high heat fluxes (50 - 125 W/cm2) possible in PISCES permit high fluence investigations on edge plasma physics and materials interactions. Initial plasma operation, experimental investigations, and the capabilities of PISCES will be discussed. (orig.)