Secondary pulse tubes and regenerators for coupling to room temperature phase shifters in multistage pulse tube cryocoolers

Abstract

Pulse tube refrigeration or cooling systems are described which utilize a secondary regenerator or a secondary pulse tube. Use of such a secondary regenerator or pulse tube enables a commercially available pressure oscillator to be incorporated in the cooling system. The commercially available oscillator can be operated at room temperature or approximately so.

What is claimed is: 
     
         1 . A pulse tube cooling system comprising:
 at least one of (i) a cryocooler and (ii) a compressor, and a pulse tube in fluid communication with the at least one of (i) the cryocooler and (ii) the compressor, the pulse tube having a cold end and a warm end;   an ambient temperature phase shifter component; and   a secondary component selected from (i) a secondary regenerator and (ii) a secondary pulse tube, the secondary component in fluid communication with, and disposed between, the warm end of the pulse tube and the phase shifter component.   
     
     
         2 . The pulse tube cooling system of  claim 1  wherein the secondary component is a secondary regenerator. 
     
     
         3 . The pulse tube cooling system of  claim 1  wherein the secondary component is a secondary pulse tube. 
     
     
         4 . The pulse tube cooling system of  claim 1  wherein the phase shifter component is a pressure oscillator. 
     
     
         5 . The pulse tube cooling system of  claim 1  wherein the phase shifter component is an expander. 
     
     
         6 . The pulse tube cooling system of  claim 1  wherein the warm end of the pulse tube is at 30 K. 
     
     
         7 . The pulse tube cooling system of  claim 1  further comprising a working fluid in periodic communication with the pulse tube, the phase shifter component, and the secondary component. 
     
     
         8 . The pulse tube cooling system of  claim 1  wherein the working fluid is selected from the group consisting of  3 He and  4 He. 
     
     
         9 . The pulse tube cooling system of  claim 1  wherein the cold end of the pulse tube is at 4 K. 
     
     
         10 . A method for using a phase shifter at ambient temperature in a multistage pulse tube cooling system, the pulse tube cooling system including a compressor, a regenerator, a pulse tube having a cold end and a warm end, and the phase shifter, the method comprising:
 providing a secondary component selected from (i) a secondary regenerator and (ii) a secondary pulse tube;   establishing fluid communication between the secondary component and the warm end of the pulse tube;   whereby upon operation of the cooling system, the phase shifter is at ambient temperature.   
     
     
         11 . The method of  claim 10  wherein the warm end of the pulse tube is at 30 K.