Experimental investigation of the connecting tube effect on a step displacer type two stage pulse tube refrigerator

Using the step displacer in two stage pulse tube refrigerator has already been proved as a sufficient way to improve the efficiency. In this article, an experimental setup has been manufactured. A no-load temperature of 16.9 K is achieved with a step displacer type gas-coupled pulse tube refrigerator filled with stainless steel mesh. The influence of the connecting tube between pulse tube hot end and displacer on the performance of the refrigerator is investigated. The experimental results show that the phase shifting ability can be adjusted by the connecting tube. The performance of the refrigerator can be optimized by this method. For different rod diameters, there is an optimum connecting tube ratio to get the lowest temperature.