Proceedings of the 14th International Cryocooler Conference: Ravex

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Free Third-Stage Cooling for a Two-Stage 4 K Pulse Tube Cryocooler

A. Ravex¹, T. Trollier¹, J. Tanchon¹, T. Prouvé²
¹Air Liquide, Sassenage, France, ²CNRS, Grenoble, France

Abstract

The helium enthalpy variation with temperature and pressure in the operating range of 4K cryocoolers is by far different from an ideal gas. The real gas behavior leads to large irreversibility in the regenerator operation. It is theoretically possible to reduce these losses and recover some â€œfreeâ€? cooling power by implementing heat intercepts in the regenerator. We have experimentally confirmed this opportunity with a commercial 4 K pulse tube. Several hundred mW of â€œfreeâ€? cooling power in the temperature range of 6 K to 20 K has been obtained without any degradation in the initial cooling power at 4 K. The experimental set up is described and preliminary experimental results are presented and discussed.