Regenerator for cryocooler with helium as working gas, a method for producing such a regenerator and a cryocooler with such a regenerator

摘要

Periodically operated cryocooler, such. B. Stirling, Gifford-McMahon and pulse tube cooler are operated regeneratorisch. Ie. one uses the heat capacity of a material to store the cold or to cool the hot gas entering the expansion chamber. A problem here is that at temperatures in the range 2K to 20K, the heat capacity of almost all materials decreases sharply. Thus it is very difficult to find materials that have a sufficiently high heat capacity in this area. Helium is often used as a working gas in cryogenic coolers. Helium has a comparatively high heat capacity in the temperature range from 2K to 20K, equal to the heat capacity of rare earth compounds in this temperature range. Therefore, helium is used as a regenerator material. The regenerator consists in the simplest case of a hollow cell with heat-conducting cell walls. The cavity is filled with helium and is connected via a pressure equalization opening with the outside of the cell. The working gas, usually also helium, flows around the can-shaped cell, whereby heat transfer takes place via the cell walls between the working gas helium outside the cavity and the helium inside the cavity. The size of the cell (s) in relation to the size of the flow channel of the working gas is chosen so that set the desired pressure differences at the lowest possible dead volume between the high pressure side and the low pressure side of the regenerator. The cell walls of the cell have a very small wall thickness, so that the desired heat exchange can take place.