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

Abstract

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. 38 refs., 6 figs.

Authors:
Publication Date:
Research Org.:
Princeton Univ., NJ (USA). Plasma Physics Lab.
OSTI Identifier:
5723021
Report Number(s):
PPPL-2642; CONF-8904230-4
ON: DE89016954
DOE Contract Number:  
AC02-76CH03073
Resource Type:
Conference
Resource Relation:
Conference: AVS topical conference on surface conditioning of vacuum systems, Los Angeles, CA, USA, 3-7 Apr 1989; Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; FIRST WALL; GLOW DISCHARGES; GRAPHITE; HELIUM; HYDROGEN ISOTOPES; IMPURITIES; PRESSURE VESSELS; TFTR TOKAMAK; CARBON; CONTAINERS; ELECTRIC DISCHARGES; ELEMENTAL MINERALS; ELEMENTS; FLUIDS; GASES; ISOTOPES; MINERALS; NONMETALS; RARE GASES; THERMONUCLEAR REACTOR WALLS; THERMONUCLEAR REACTORS; TOKAMAK TYPE REACTORS; 700209* - Fusion Power Plant Technology- Component Development & Materials Testing

Citation Formats

Dylla, H F. A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning. United States: N. p., 1989. Web.
Dylla, H F. A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning. United States.
Dylla, H F. 1989. "A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning". United States. https://www.osti.gov/servlets/purl/5723021.
@article{osti_5723021,
title = {A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning},
author = {Dylla, H F},
abstractNote = {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. 38 refs., 6 figs.},
doi = {},
url = {https://www.osti.gov/biblio/5723021}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 1989},
month = {Fri Sep 01 00:00:00 EDT 1989}
}

Conference:
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