A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning

Conference · Mon Feb 05 00:00:00 EST 1990 · AIP Conference Proceedings (American Institute of Physics); (USA)

OSTI ID:6702368

Dylla, H F ^[1]

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1. Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (USA)

Hydrogen- and deuterium-fueled glow discharges are used for the initial conditioning of magnetic fusion device vacuum vessels following evacuation from atmospheric pressure. Hydrogenic glow discharge conditioning (GDC) significantly reduces the near-surface concentration of simple adsorbates such as H{sub 2}O, CO, and CH{sub 4}, and lowers ion-induced desorption coefficients by typically three orders of magnitude. The time evolution of the residual gas production observed during hydrogen-glow discharge conditioning of the carbon first-wall structure of the TFTR device is similar to the time evolution observed during hydrogen GDC of the initial first-wall configuration in TFTR, which was primarily stainless steel. Recently, helium GDC has been investigated for several wall-conditioning tasks on a number of tokamaks including TFTR. Helium GDC shows negligible impurity removal with stainless steel walls. For impurity conditioning with carbon walls, helium GDC shows significant desorption of H{sub 2}O, CO, and CO{sub 2}; however, the total desorption yield is limited to the monolayer range. In addition, helium GDC can be used to displace hydrogen isotopes from the near-surface region of carbon first-walls in order to lower hydrogenic retention and recycling.

• DOE Contract Number: AC02-76CH03073
• OSTI ID: 6702368
• Report Number(s): CONF-8904230-; CODEN: APCPC; TRN: 90-025328
• Journal Information: AIP Conference Proceedings (American Institute of Physics); (USA), Vol. 199:1; Conference: AVS topical conference on surface conditioning of vacuum systems, Los Angeles, CA (USA), 3-5 Apr 1989; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
FIRST WALL
SURFACE CLEANING
TFTR TOKAMAK
CARBON
DESORPTION
DEUTERIUM
GLOW DISCHARGES
HYDROGEN
STAINLESS STEELS
VACUUM SYSTEMS
ALLOYS
CLEANING
ELECTRIC DISCHARGES
ELEMENTS
HIGH ALLOY STEELS
HYDROGEN ISOTOPES
IRON ALLOYS
IRON BASE ALLOYS
ISOTOPES
LIGHT NUCLEI
NONMETALS
NUCLEI
ODD-ODD NUCLEI
STABLE ISOTOPES
STEELS
SURFACE FINISHING
THERMONUCLEAR REACTOR WALLS
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
700201* - Fusion Power Plant Technology- Blanket Engineering