Abstract
The pulse-tube cryocooler doesn't need moving parts in the expansion space and it is an advantage such as a low vibration and high reliability. On the other hand, in order that the pulse-tube cryocooler perform compression and expansion with a gas piston unlike other cryocoolers which have a solid piston, it is tended to influence the cryocooler performance by operating condition. When the low temperature part of the expander is in the top from the ambient temperature part, natural convection occurs by the influence of the gravity and a cooling capacity decreases greatly. We have developed the Stirling-type pulse-tube cryocooler ‘WE-SP2000’ with cooling capacity 4.6W at 77K for 200W input power for high-temperature superconductor devices and semiconductor sensors, but there have been demands a smaller size, a high efficiency and higher reliability and needed further improvement. This paper describes an examination that was done of the efficiency improvement due to the change in the pulse-tube size and 24% of a cooling capacity has improved as a result. Furthermore, the influence of the inclination exerted on the cooling capacity for differences in expander form was examined.
