A sub-Kelvin superfluid pulse tube refrigerator driven by paramagnetic fountain effect pump

• A new type of sub-Kelvin superfluid Stirling refrigerator is proposed.
• The SJTR is capable of providing cooling below 1 K with no moving parts.
• Analysis has shown that the SJTR will have a mass of approximately 5 kg.
• The refrigerator could provide continuous distributed cooling at 200 mK.

A novel sub-Kelvin refrigeration cycle is introduced in this work. The magnetically driven superfluid pulse tube refrigerator (MSPTR) could provide cooling at temperatures below 200 mK while rejecting heat at 1.6 K and contains no moving mechanical parts. The MSPTR cycle has an advantage over other types of sub-Kelvin cooling in that it can provide distributed cooling. Additionally the MSPTR unlike the dilution refrigerator will be able to function in microgravity without any modification. This work includes a description of the MSPTR cycle and a summary of preliminary design calculations including results used to size components and predict cooling performance.