Cryopumping for fusion power applications

Programs are described which were undertaken to show the capability of pumping continuously at high speed the outflow of deuterium and helium from fusion reactors. A cryopump system was developed, fabricated and tested to demonstrate continuous deuterium pumping and to show the ease with which a cryopump can be regenerated automatically. A continuous duty cryopump system for fusion reactor application which maintains low gas inventory (most importantly tritium) can be projected from the test results. A development program for optimizing charcoal sorbents for cryopumping helium was undertaken in parallel. Systems comprising a preferred combination of charcoal sorbent and methods of charcoal attachment to the cryogenic substrate were produced. The attachment method had to be compatible with the fusion environment. A study, described here, valuated the effect of vacuum system contamination on helium pumping performance