Experimental investigation of a neon cryogenic capillary pumped loop

This paper describes the first known demonstration of a cryogenic capillary pumped loop (CCPL) using neon as the working fluid. One obvious application for a neon CCPL is in thermally coupling redundant 35 K cryocoolers to a long-wave TR sensor operating at 40 K without the need for additional flexible links and with negligible (off-cooler) parasitic penalties. The test hardware utilized in this investigation is the 3rd-generation CCPL which was developed by Cullimore and Ring Technologies and Swales Aerospace under NASA/GSFC SBIR funding. Since neon melts at 24.5 K, boils at 27 K, and is a gas above 44.5 K, the practical operating range for a neon CCPL is 30-40 K. The specific demonstrations described herein include several start-ups from a supercritical state without the aid of a cooled shroud, power cycling from 0.1-3.5 W, long-term operation, and start-up/operation under 1.0 cm of adverse evaporator elevation. This paper describes the test set-up, analysis, and results associated with this first neon CCPL