Abstract: An expander for a concentric pulse tube cooler. The inventive expander includes a central pulse tube; a concentric insulation tube disposed around the central pulse tube, the insulation tube having a concentric chamber therein and the chamber being filled with an insulator and the insulator being atmospheric; and a regenerator disposed around the concentric insulation tube. In a particular implementation, the insulator tube includes a vent which allows the insulation chamber to communicate with the surrounding atmosphere. When used in space, the chamber is filled with a void and the insulator becomes a vacuum and provides effective insulation at cryogenic temperatures.

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.

Abstract: A pulse tube cooler comprising pulse tube, a regenerator concentrically disposed around the pulse tube, and a thermal insulator concentrically disposed between the pulse tube and the regenerator. More specifically, the concentric pulse tube cooler comprises a cold finger assembly disposed at a first end of the concentric pulse tube cooler, a heat exchanger assembly disposed at a second end of the concentric pulse tube cooler that is coupled to a a surge volume and that is coupled to a source of operating gas, and a pulse tube expander assembly slidably and sealably secured to the heat exchanger assembly. The pulse tube expander assembly comprises a central pulse tube, a thermal insulator concentrically disposed around the central pulse tube, and a regenerator concentrically disposed around the concentric insulation tube. The pulse tube expander assembly comprises a slidable axial seal for slidably and sealably securing the pulse tube expander assembly to the heat exchanger assembly.

Abstract: Uniform electrical heating of a circular, single crystal germanium window (18) uses its bulk resistance and pairs of electrodes (20) equally spaced about the window's periphery. The electrode pairs are sequentially switched at a rate high enough to avoid thermal switching transients.