Abstract: A pulse tube expander includes a regenerator, a pulse tube, a porous plug phase shifter, and a surge tank, in series gaseous communication with each other. The porous plug phase shifter is made of a porous material such as a sintered mass or a packed solid bed of distinct, free-flowing bodies. The porous plug phase shifter introduces a phase shift between the pressure wave and the mass flow rate in the pulse tube expander. The porous plug phase shifter is resistant to clogging due to contamination that may be present in the system.

Abstract: A hybrid two-stage cryocooler includes a first-stage Stirling expander having a first-stage interface and a Stirling expander outlet, a thermal-energy storage device in thermal communication with first-stage interface, and a second-stage pulse tube expander with a pulse tube inlet. A gas flow path extends between the Stirling expander outlet and the pulse tube inlet, and a heat exchanger is in thermal contact with the gas flow path. The relative cooling power of the first and second stages may be controlled to increase the cooling power of the second stage relative to the first stage in response to an increased heat load to the second stage. The thermal-energy storage device acts as a thermal buffer during this period, and is later cooled when the relative cooling power is adjusted to increase the cooling power of the first stage.

Abstract: A hybrid two stage expander having a first stage Stirling expander coupled to a second stage pulse tube expander. Both stages are pneumatically driven by a common reciprocating compressor in a typical application. The first stage Stirling expander provides high thermodynamic efficiency which removes a majority of the heat load from gas within the cryocooler. The second stage pulse tube expander provides additional refrigeration capacity and improved power efficiency with little additional manufacturing complexity since it has no moving parts.

Abstract: A cooling system utilizes a pulse-tube expander having a hollow pulse tube and three hollow regenerator tubes that lie parallel to and laterally displaced from the pulse tube, and are arranged in triangular fashion about the pulse tube. A cold end of each of the regenerator tubes is in gas pressure communication with a cold end of the pulse tube. Pulsing gas pressure is supplied to a warm end of each of the regenerator tubes, and a surge volume communicates with a warm end of the pulse tube. A heat sink is provided at the warm end of the regenerator tubes and the pulse tube to remove heat therefrom and from the pulsing gas. Heat is extracted from a heat load at the cold end of the regenerator tubes and the pulse tube.