Impact of cold finger geometry on low temperature pulse tube cooler performances

Abstract Our developments in pulse tube technology are focused on low-temperature pulse tube cryocoolers, specifically building on the cold tip architecture of the PT15K cooler previously developed by ALAT/TCBV/CEA. While the original pulse tube cooler was designed to operate around 15 K, the current objective is to lower its operating temperature to achieve significant cooling power around 8 K or lower. Different steps have been outlined to decrease the working temperature while keeping a reasonable level of heat flux at interfaces, leading to a better overall thermodynamic efficiency. The impact of the cold finger’s diameter as well as its length have been studied, although the latter will not be discussed here. In this context, four pulse tubes coolers have been designed and tested in collaboration with the French Space Agency (CNES). All these preliminary results were obtained using a standard stainless steel mesh regenerator. In the future, tests will be conducted with a regenerator featuring a specific heat anomaly to improve performances at low temperatures.