Study on the impedance characteristics of a high-capacity pulse tube cryocooler

Abstract

Stirling-type pulse tube cryocoolers are used in many applications such as military facilities, aerospace devices and superconductive systems. A major problem in improving its energy conversion efficiency is how to achieve a better impedance matching. In this study, a pulse tube cryocooler is investigated based on the impedance analyses. A group of impedance maps is proposed to analyze the energy conversion performance of the compressor. The velocity map, the efficiency map, the acoustic power map and the phase angle map are provided under the total equivalent impedance. These maps offer a visualized guidance of the maximum performance a compressor could reach and in which direction to optimize. Experiments on a high capacity pulse tube cryocooler are conducted to verify the theoretical analyses. The results show that it is of great help in using the proposed maps to analyze and improve the energy conversion performance of the cryocooler. A cooling capacity of 300W@80K is finally achieved. The study clearly reveals the influence of the impedance on the energy conversion efficiency and it is quite useful in improving the performance of the pulse tube cryocooler.