Isotope effects in hydrogen retention of graphite and beryllium irradiated simultaneously with dual H+ and D+ beams

The concentration profiles of H and D retained in graphite at temperatures from room temperature to 900 K and beryllium at room temperature by simultaneous dual H+ and D+ ion implantation have been measured by means of an elastic recoil detection (ERD) technique. It has been found that as the fluence increases, the concentrations of H and D retained in graphite and beryllium increase at the same rate in the beginning of the implantation and hereafter that of H saturates faster than that of D. The concentration ratios of D to H retained in graphite and beryllium n(T)(D)/n(T)(H), at steady state were determined to be 1.8 +/- 0.2 and 1.25 +/- 0.2, respectively. The steady state values of n(T)(D)/n(T)(H) for graphite at room and high temperatures and beryllium at room temperature have been also calculated to be 1.5 +/- 0.2, 1.5 +/- 0.2 and 1.3 +/- 0.2, respectively, by solving a set of mass balance equations for H and D under simultaneous H+ and D+ ion implantation. The experimental and theoretical values are compared and discussed.