NSTX Filament Preionization and Glow Discharge Cleaning Systems
H.W. Kugel, W. Blanchard, G. D'Amico, R. Gernhardt, T. Provost
Date of PPPL Report: November 1999
Presented at: The 18th IEEE/NPSS (Institute for Electrical and Electronics Engineers/Nuclear and Plasma Science Society) Symposium on Fusion Engineering (SOFE) which was held in Albuquerque, NM,on October 25-29, 1999.
Initial NSTX GDC experiments were performed with one moveable anode and a biased filament preionization system that allowed D2 and He Glow Discharge breakdowns at the actual operating pressure, voltage and current. The biased filament system was also operated continuously during ohmic operations, and used to reduce volt-sec consumption for February 1999 plasma discharges up to 280 KA. An upgraded system has been installed with 2 fixed wall anodes and 3 biased filaments; 2 on the mid-plane and one in the divertor region; all separately controllable remotely using a PLC system. Recent applications include assisting in preionization for 800 KA plasma discharges.