Some considerations on large-sized catalytic pumps for nuclear fusion apparatus

Studies have been made of the problems encountered in the development of a large-sized catalytic pump for the pumping of hydrogen in nuclear fusion apparatus. An experimental pump having a speed of about 5000 liter/sec is assumed to use at partial pressures between 10-7 and 10-5Torr. The influence of water vapor on the atomization of hydrogen at the rhenium filament is one of the problems, and is discussed from the structural point of view. The lifetime of the cuprous oxide layer is another important problem. A convenient method of oxidation of copper plates by atomic oxygen produced at an incandescent rhenium filament is proposed for the generation and regeneration of the oxide. The optimum temperatures of the cuprous oxide layer are also determined for the rapid desorption of water vapor from the oxide and for the effective reaction with hydrogen atoms. (auth.)