HEC Pulse Tube Coaxial Cold Head Coolers

Presented at the 16th International Cryocooler Conference, held May 17-20, 2008 in Atlanta, Georgia.A large number of NGAS high efficiency coolers (HEC) have been manufactured for six different space payload designs using a linear configuration cold head that is integrally mounted to the compressor. One of the payloads has been in orbital operation since 2005 and a second since 2009. For some applications it may be desirable to have a different cold head mechanical and thermal interface in order to ease integration into the system. For that purpose we have developed both one and two stage HEC coolers that incorporate coaxial cold heads that are integrally mounted to the compressor. The single thermal and mechanical mounting interface of this integral configuration eases integration with a payload and reduces its complexity compared to a split cold head version that requires two warm interfaces rather than one. In this paper we present the measured performance of the single stage HEC coaxial cold head cooler in its integral configuration and compare its performance with the linear cold head version. We also present the measured performance of the parallel cold head two-stage version of the cooler designed for the simultaneous cooling of both focal planes at temperatures above 35 K and optics and filters at temperatures greater than 75K