50-80 K pulse tube cryocooler development

A strong effort is being made world wide in developing miniature cryocoolers for multi-year space missions. These cryocoolers must satisfy strong requirements among which reliability, minimal exported vibration and efficient thermal performance are: the most critical. Many cryocooler designs are under development. These designs include Stirling, Sorption and particularly Pulse Tube coolers. While this last technology is not new, major improvements have been made recently that promise significant benefits. Pulse tube coolers are very similar to Stirling coolers but they do not require any moving displacer in the cold finger and consequently no motorization, no synchronisation electronics, no bearings and clearance seals. This is very interesting in terms of mechanical simplicity, reliability, reduction of induced vibrations and electromagnetic noises. Performances comparable with those of Stirling coolers are achievable in terms of size, weight, cooling power, cooling temperature and efficiency. In the framework of an ESA contract we are developing for space purposes a pulse tube cryocooler associated with a diaphragm springs oscillator. An improved version of the oscillator has been developed by the Rutherford Appleton Laboratory. Preliminary prototypes of the pulse tube cooler have been designed and manufactured, and are presently being characterised.