Measurement of Retained Hydrogen by Laser Thermal Desorption for Carbon Exposed to sub-EV Atomic Deuterium

摘要

Retention levels for sub-eV D exp 0 atoms in single crystal and pyrolytic graphite were measured using a newly-developed Laser Thermal Desorption (LTD) technique. Retention levels for single crystals were approx. 3 x 10 exp 13 D exp 0 /cm exp 2 for incident fluences of approx. 10 exp 19 D exp 0 /cm exp 2 . This is about two orders of magnitude lower than D exp 0 retention in pyrolytic graphite, and correlates very well with the differences in effective surface areas. The D( exp 3 He,p) exp 4 H/sub e/ Nuclear Reaction Analysis (NRA) was used to confirm retention levels as measured by the LTD technique. A further finding was the influence of a small layer of evaporated tungsten on the sample surface. Such W impurity resulted in an increase of D exp 0 retention of up to a factor of ten. (ERA citation 09:034953)