THE RFX GLOW DISCHARGE CLEANING SYSTEM

The internal wall of the RFX toroidal vacuum vessel, whose total surface is approximately 36 m 2 , is completely covered by 2016 graphite tiles. The cleaning and conditioning of the RFX first wall, that is crucial to obtain good plasma heating and confinement performances, is obtained by means of baking up to 350 °C, Pulse Discharge Cleaning (PDC) and Glow Discharge Cleaning (GDC). A general description of the GDC system and the technical characteristics of its components are reported in the paper. Four vertical antennae, equispaced around the torus, can be located at the center of the vessel cross-section and are fed by DC current (up to 10 A) and by radiofrequency at 4 MHz (up to 1 kW). The paper also describes methods and results of the final tests on the system and the main characteristics of the first glow discharges obtained so far.