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Radiation enhanced sublimation of graphite due to fast neutron irradiation

Authors
Journal
Journal of Nuclear Materials
0022-3115
Publisher
Elsevier
Publication Date
Volume
228
Issue
1
Identifiers
DOI: 10.1016/0022-3115(95)00190-5

Abstract

Abstract Erosion of graphite by radiation enhanced sublimation due to neutron bombardment with an energy spectrum such as expected in a fusion reactor is estimated theoretically. Carbon atoms released from their lattice sites in collision cascades initiated by the neutron bombardment are able to diffuse to the graphite surfaces and sublime thermally. The production rate of interstitial carbon atoms is calculated from neutron irradiation damage theory. The calculations result in radiation enhanced sublimation yields of several 10 −4 C/n in the 400 to 1800 K temperature range. The yields are about one or two orders of magnitude larger than the forward physical sputtering yield of neutrons due to collision cascades in the near surface layer. Concerning the erosion of graphite at the vessel walls and the impurity introduction into the plasma in fusion research, both physical sputtering and radiation enhanced sublimation due to fast neutron irradiation are nearly three orders of magnitude smaller than ion and charge exchange neutral atom sputtering.

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