Abstract
To investigate how to reach 4K by the pulse tube and the best multiple staging configuration for the pulse tube, the experiments have been done on the several type single stage pulse tube refrigerators coupled with a G-M cryocooler. The minimum temperature at the cold end of the pulse tube obtained by this unit was 3.5K when the hot end of pulse tube was located at room temperature. The hot end of final stage regenerator was precooled at around 15K to 20K. The optimum operating condition was both at mean pressure around 1.0 to 1.5MPa and with frequency about 1 to 2Hz. Heat flow and loss analysis related to phase shift effect, as well as arrangement of the multi-stage pulse tube refrigerator to reach 4K are briefly discussed.
