A NEW MINI PULSE TUBE WITH A HEAT INTERCEPTOR

An experimental study of a coaxial mini Pulse Tube Cryocooler is presented. First various rejection temperatures for the pulse tube warm end and the compressor foot have been investigated. It is shown that the rejection temperature at the warm side of the Pulse Tube is a key parameter and that the heat sink of the cooler can be located only at this point. Heat repartition between the pulse tube and the compressor as a function of the rejection temperatures is discussed. The coaxial mini pulse tube cooler has been equipped with a heat interceptor in order to take advantage of passive intermediate free cooling available for some space missions. The heat interceptor is a simple copper collar mounted on the half warm side of the regenerator tube. It is shown that this concept allows boosting the cryocooler performances with a small associated passive radiator thermally linked to the interceptor. As an example, a 0.05 m2 radiator allows to increase the cooling power at 80 K from 0.9 W to 1.6 W. Performances obtained for different heat interceptor positions are presented and discussed. An optimum position of the heat interceptor is found in the warm half part of the cold fmger.