Method and dilution refrigerator for cooling at temperatures below 1K.

摘要

The dilution refrigerator operates by sucking a 4He-rich mixture from a tank (1) and returning it to the tank through a superleak (11). Thereby the 3He is separated and returned to the 3He-rich content of the tank (1). By this cycling process, a drop in temperature is obtained at the exit of the superleak (11) and through re-mixing of the 3He with the 4He. Cycling of the liquid 3He-4He mixture is performed by a bellows pump (9) maintained in a container (16) at a temperature below 2K and by specially designed valves (4, 6, 10) comprising a steel ball as a plug and a gold ring as the valve seat.