Construction of a Dilution Refrigerator for Low Temperature Microgravity Experiments and Novel Phenomena of Solid 4He under Microgravity

Abstract

A compact dilution refrigerator which can be boarded on the jet plane (MU-300) was constructed for the purpose of studying solid 4He physics under zero gravity. It was demonstrated that the fridge could cool down to 140 mK on the plane and the lowest temperature was not affected by the parabolic flight. We successfully cooled solid 4He down to the same temperature, and were able to perform the observation of the crystal growth of solid 4He under zero gravity. The detailed description of the construction is presented and an interesting melting and growth of c-facet of 4He at 140 mK under zero gravity is reported.