Mechanical pumping at low temperature

Results are presented that were obtained at low temperatures (80 K and 25 K) with a molecular drag pump Holweck type (MDP) of 100 mm diameter and with few stages of a turbomolecular pump (TMP) running at the same temperatures. This novel concept consist of a mechanical pump able to run at low temperature (25 K). Since gas density varies inversely with temperature, this pump would deliver much higher mass flow rate than at room temperature for a given size. Advantages of this concept are order of magnitude reduction in size, weight, when compared to a conventional pump scaled to perform the same mass flow rate at room temperature. This pump would be a solution to allow continuously tritium extraction and minimize the mass inventory. (author) 4 refs.; 5 figs.; 2 tabs