Condensation of light gases with large cryopumps

In contact with the Design Team of the Joint European Torus (JET) project accompanying research and development regarding the operation of large cryopumps has been performed. The design of a bath-type cryopump with a condensation surface A = 2000 cm2 and a pumping speed s = 20 000 l/s for hydrogen is described. For investigations with this pump methods for measuring the temperature distribution at the condensation surface, the pumping speed and the thickness of the growing condensate have been developed and are described in detail. The performance data of the cryopump as well as results of measurements of the pumping speed for hydrogen and deuterium, the vapour pressure of these gases, the obtainable final pressure and instabilities of the condensed gas layers are given. The final chapter deals with the available knowledge on cryosorption of hydrogen, deuterium and helium based on a literature survey. (orig.)