Qeneration of liquid helium temperatures using a lead regenerator in a GM precooled pulse tube stage

摘要

This paper describes the coolingperformance of a pulse tube stage extending to roomtemperature which is precooled by a single-stage GMrefrigerator. With this system it was possible to reachliquid helium temperatures without using rare earthcompounds as regenerator material. Instead theregenerator was filled with conventional lead spheres.With the regenerator warm end being at a precoolingtemperature of about 31 K a minimum no-load temperaturenear 4.2 K at the cold end of the pulse tube wasachieved. This no-load temperature is considerablylower than what has been achieved before by two-stageregenerative refrigerators which. operate without rareearth material and attain typically no-loadtemperatures above 6 K when operated with lead in thecoldest regenerator section. In the presented hybridsystem a cooling power of 10 mW at 4.6 K, 100 mW at 6K and I W at 9.2 K was achieved using a 6 kW helium compressor.