Optimal pulse tube volume design in GM-type pulse tube refrigerator

For given compression work, a GM-type pulse tube refrigerator can be designed to operate with large pressure swing and small shuttle mass (small pulse tube volume) or with small pressure swing and large shuttle mass (large pulse tube volume). In this paper, the refrigeration performance analysis is carried out by quantitatively evaluating the concurrent pressure swing and the shuttle mass in the pulse tube. The analysis result of the GM-type pulse tube refrigerator shows that the design of large pressure swing and small shuttle mass is a preferable one. In a practical case, however, a helium compressor has a certain limit in differential pressure between supply and return and, accordingly, the achievable pressure swing in GM-type pulse tube refrigerator is also limited. From this limit-point of the differential pressure, the volume reduction of the pulse tube does not lead to the intensification of the differential pressure any further. The refrigerator performance begins to decrease beyond this point. The differential pressure limit-point, as a consequence, is considered as the optimal design point.