Review for the Heat Transfer Between Liquid Helium and Metal Sinters
Abstract
Ultra-low temperature refers to the temperature below 1K and is now a widely used temperature range in frontier physics. Kapitza resistance, the inverse of thermal boundary conductance of interfacial thermal conductance, increases in a cubic order with the temperature dropping at several milliKelvins, which detracts ultra-low temperature refrigeration. As Kapitza resistance is inversely proportional to heat transfer surface area, the sintered silver heat exchanger with a high specific surface area is the key module in the high-performance dilution refrigerator. However, the experiment data of Kapitza resistance of metal sinters is different from the theoretical estimate, so the mechanism within such a system is worth studying. We reviewed the sintering processes of different metallic powder materials generally used in dilution refrigerators and emphasized the importance of pore space size for heat transfer between sinter and liquid helium. The analysis of the theory of Kapitza resistance of liquid helium and sintered metal powder is also reviewed. Further, the measurement and latest results of multiple research are collected here.