Patent ID: 8408014

Claim:
A pulse tube cooler comprising: a compressor; a regenerator having a first end and a second end, wherein the regenerator is in fluid communication with the compressor at the first end; a pulse tube having a cold end and a hot end, wherein the pulse tube is in fluid communication with the regenerator at the cold end; a reservoir, wherein the reservoir is in fluid communication with the pulse tube at the hot end of the pulse tube; a working fluid positioned within the regenerator, the pulse tube, and the reservoir; and a variable phase control device positioned in a fluid path between the hot end of the pulse tube and the reservoir, the pulse tube cooler having a thermodynamic cycle defined by the flow of working fluid into and out of the regenerator, pulse tube and reservoir; and a control circuit in communication with the variable phase control device, wherein the control circuit is programmed to vary a characteristic of the variable phase control device based on the position of the pulse tube cooler in its thermodynamic cycle.