Discharge cleaning on TFTR after boronization

Technical Report · Wed May 01 00:00:00 EDT 1991

DOI:https://doi.org/10.2172/5617720· OSTI ID:5617720

Mueller, D; Dylla, H F; LaMarche, P H; Bell, M G; Blanchard, W; Bush, C E; Gentile, C; Hawryluk, R J; HIll, K W; Janos, A C; Jobes, F C; Owens, D K; Pearson, G; Schivell, J; Ulrickson, M A; Vannoy, C; Wong, K L

At the beginning of the 1990 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 ({approximately}20 kA) Taylor Discharge Cleaning (TDC) pulses were required before high current ({approximately}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{degrees}C to 250{degrees}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 <5000. The number of aggressive PDC pulses required was approximately unchanged. 14 refs., 1 tab.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5617720
• Report Number(s): PPPL-2758; ON: DE91012310
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
LIMITERS
CLEANING
BORON
CARBON
COMPOSITE MATERIALS
FIRST WALL
GLOW DISCHARGES
HEATING
TFTR TOKAMAK
ELECTRIC DISCHARGES
ELEMENTS
MATERIALS
NONMETALS
SEMIMETALS
THERMONUCLEAR REACTOR WALLS
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
700209* - Fusion Power Plant Technology- Component Development &amp; Materials Testing