Helium-3 Pulse Tube Cryocooler

Abstract

A three-stage pulse tube refrigerator has been developed for the purpose of reaching temperatures as low as 1.5 K using ³He as the working medium. This work is a continuation of the research on a three-stage pulse tube refrigerator started in 1999 at Eindhoven University of Technology; during that effort a minimum average temperature of 1.78 K was achieved. The size of the three-stage refrigerator is small, compared to other sub-4K pulse tube cryocoolers, in order to have a small amount of ³He gas in the system. The regenerator plays an important role in the performance of the refrigerator. The regenerator was designed to be very flexible in order to be able to test different compositions of materials and their influence on the performance of the cooler. In this contribution we report on the progress in the development of the three-stage pulse tube cryocooler. We also describe our future plans, in which we intend to combine the ³He pulse tube refrigerator with a superfluid vortex cooler in order to achieve temperatures below 0.7 K.