Study of a liquid helium jet pump for circulating refrigeration systems

A basic diagram of the refrigeration system, in which liquid helium is circulated by means of a jet pump, is described. The equations have been derived to design jet devices which operate with liquid helium.In the experimental setup with a jet pump the flow rate of liquid was 5 to 10 times larger than that of compressed gas in a direct stream of the refrigerator. After pumping the pressure was equal to (0.15–0.40) × 10⁵Nm^?2. A circulating stream of liquid helium at supercritical pressure, due to the heat load corresponding to the refrigerator capacity, was heated to 0.15–0.25 K.The results of our studies permit one to determine circulation loop parameters and main geometric dimensions of the jet pump.