Ion-beam system for tritium permeation experiments

An experimental facility has been developed to carry out permeation experiments for candidate first-wall materials subjected to high fluxes of energetic hydrogen isotope ions. The experimental facility consists of (a) an ion-beam system for production of intense, mass-analyzed ion beams with energies variable from 500 eV to 10 keV, (b) a target chamber system for directing an ion beam onto a heated target and for measuring various implantation-related experimental parameters, and (c) a downstream system for measuring the implanted gas which permeates the specimen. The target chamber and downstream system are equipped with diagnostic capabilities to permit simultaneous measurement of the permeation, reemission, and sputtering effects for target materials. Operational tests with the system have yielded hydrogen and deuterium ion-beam intensities from 0.4 x 1015 ions/cm2-s at 0.8 keV to greater than 3.0 x 1015 ions/cm2-s at 9.6 keV. Baseline pressures as low as 7 x 10-6 Pa, 0.7 x 10-6 Pa, and 3 x 10-6 Pa have been achieved in the accelerator, target chamber, and downstream systems, respectively. Target temperatures in excess of 5000C have been achieved with the target heater assembly. Experiments will be conducted to investigate reemission and permeation for various stainless steels and vanadium alloys implanted with deuterium ion beams. The facility will then be converted to tritium operation for engineering tests of first-wall structures