Hydrogen retention and release in first-wall coatings for tokamaks

Abstract

The hydrogen retention and release of two first-wall coating materials, TiB 2 and B 4C, were measured. Hydrogen is released from TiB 2 at substantially lower temperatures or laser energy fluxes (pulsed annealing) than for B 4C. Hydrogen also diffuses to a much smaller extent into TiB 2 than into B 4C. On the basis of tritium inventory control, TiB 2 appears to be superior to B 4C.