Wall conditioning for performance improvement in the divertor reversed field pinch TPE-2M

A divertor reversed field pinch machine, TPE-2M (R/r=0.87 m/0.28 m), has been operated at AIST. The wall conditioning is one of key issues for the divertor study in this unique machine. Boronization on the shell inner surface (plasma-facing wall), titanium gettering on the vacuum wall and divertor plate surfaces and pulsed gas injection with glow-discharge pre-ionization are developed and applied successfully. They are indispensable to the analysis of divertor plasma behaviors and to the improved plasma operation