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Development of the Miniature Pulse Tube Cryocooler

Fuji Electric has developed a pulse tube cryocooler (PTC) with in‐line configuration with a cooling capacity of 3 W at 70 K and requiring 100 W of electrical input power. The emphasis has been on compactness, lightweight, high performance and low cost. In particular, the dimensions of the PTC have been reduced to a width of 190 mm and a height of 300 mm. Presently, we are developing a U‐shaped PTC based on the technology of the in‐line PTC. The advantage of the U‐shaped PTC is that the cold head is located at the end for easy accessing. The key issue for developing the U‐shaped PTC is the design of the flow straightener at the cold head. As a first step in the development we visualized the inside of the pulse tube by using particle image velocimetry (PIV). The design of the flow straightener is based on the visualization results. Preliminary tests indicated that the cooling performance of the U‐shaped PTC is 2 W at 70 K while requiring 51 W PV power. We will present the test results on the U‐shaped PTC as...