Interactions of Bulk-Boronized Graphites with Deuterium Plasmas in the Pisces-B Facility
- 1 July 1991
- journal article
- research article
- Published by Taylor & Francis in Fusion Technology
- Vol. 19 (4), 2059-2069
- https://doi.org/10.13182/fst91-a29340
Abstract
Newly developed bulk-boronized graphites and boronized carbon-carbon composites, with a total boron concentration ranging from 3 to 30 wt%, have been bombarded with steady-state deuterium plasmas at temperatures between 200 and 1600°C in the PISCES-B facility. The erosion yield of bulk-boronized graphite is smaller than that of pyrolytic graphite by a factor of 2 to 3 in regimes of chemical sputtering, physical sputtering, and radiation-enhanced sublimation (RES). Plasma bombardment at elevated temperatures does not noticeably alter the near-surface composition of bulk-boronized graphite. A chemical pinning effect of boron on the migration of interstitial carbon atoms is the key to the reduction of erosion due to RES. Post-bombardment thermal desorption spectroscopy indicates that bulk boronization enhances recombinative desorption of deuterium. The enhanced deuterium desorption is responsible for the suppressed chemical sputtering. Deuterium retention in bulk-boronized graphite at temperatures from room temperature to 800°C has been measured, and it is maximized at temperatures around 300°C. The maximized deuterium retention increases by a factor of 2 as the boron concentration changes from 0 to 90%.Keywords
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