Discharge cleaning on Tokamak Fusion Test Reactor after boronization
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey (USA)
- CEBAF Center, 12000 Jefferson Ave., Newport News, Virginia (USA)
At the beginning of the 1990 Tokamak Fusion Test Reactor (TFTR) experimental run, after replacement of POCO-AXF-5Q graphite tiles on the midplane of the bumper limiter by carbon fiber composite (CFC) tiles and prior to any pulse discharge cleaning (PDC), boronization was performed. Boronization is the deposition of a layer of boron and carbon on the vacuum vessel inner surface by a glow discharge in a diborane, methane, and helium mixture. The amount of discharge cleaning required after boronization was substantially reduced compared to that which was needed after previous openings when boronization was not done. Previously, after a major shutdown, about 10{sup 5} low current ({similar to}20 kA) Taylor discharge cleaning (TDC) pulses were required before high current ({similar to}400 kA) aggressive pulse discharge cleaning (PDC) pulses could be performed successfully. Aggressive PDC is used to heat the limiters from the vessel bakeout temperature of 150 to 250 {degree}C for a period of several hours. Heating the limiters is important to increase the rate at which water is removed from the carbon limiter tiles. After boronization, the number of required TDC pulses was reduced to {lt}5000. The number of aggressive PDC pulses required was approximately unchanged.
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 5147885
- Journal Information:
- Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States), Journal Name: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States) Vol. 9:5; ISSN 0734-2101; ISSN JVTAD
- Country of Publication:
- United States
- Language:
- English
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Discharge cleaning on TFTR after boronization
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