EXPERIMENTAL STUDY ON COOLING PERFORMANCE OF A COAXIAL PULSE TUBE CRYOCOOLER FOR A LIQUID XENON DETECTOR

An experimental study to improve the cooling power of a coaxial pulse tube cryocooler (PTC) has been carried out. The operating temperature was optimized for cooling liquid xenon at around 165-170K. The PTC has a coaxial configuration with a cylindrical regenerator inside, a hollow-walled cylindrical pulse tube. The cooling performance obtained was similar to 180-200 W at around 165 K, when operated with a 6-6.5 kW GM-type compressor. For the phase shift between pressure and flow, a simple-orifice scheme was used, which resulted in stable operation of a long-term physics experiment. PTCs have now been successfully applied in physics experiments such as MEG and XENON for many years. In order to study flow disturbance inside of a tube, thermometers were placed on an outer cylinder wall to monitor gas temperature inside of a tube. In the original scheme, there is a single gas exhaust line from the pulse tube to an orifice valve and buffer tank. In this study, an additional exhaust line was used to suppress the flow disturbance in such a pulse tube. Also, the cooling power dependence on the regenerator was experimentally studied by changing the mesh size and the length of the regenerator.