Helium irradiation effects for deuterium retention in boron coating films

TDS analyses have been performed in order to examine helium irradiation effects for deuterium retention in boron coating films prepared by PACVD. It is clarified that the deuterium retention is reduced due to the irradiation prior to deuterium. There is no correlation between the retention variations of deuterium and helium, and thus the helium occupation seems hardly to contribute to the reduction. The third peaks in the TDS spectra shift on the high temperature side with the irradiation fluence. It is presumed that helium irradiation forms certain layers by knocking on boron atoms, in which deuterium retention is partly restricted, and trapped deuterium needs higher energy for the desorption.