[en] In this paper a novel concept of a mechanical pump able to run at low temperatures (80-25 K) is presented. Since gas density varies inversely with temperature, a pump delivers much higher mass flow rate at low temperature than at room temperature for a given size. Advantages of this concept are reduction in size and weight, when compared with a conventional pump scaled for the same mass flow rate at room temperature. The inlet gas temperature is set in order to avoid condensation on the rotor blades and surroundings. A temperature gradient between the different pumping stages allows optimization of the exhaust pressure. This pump should be a solution for continuous tritium extraction and minimization of the mass inventory for fusion tokamaks fuel cycle control