Rinsable cold head for a cryo refrigerator using the pulse tube principle

Abstract

A cold head ( 20; 30 ) for a cryo refrigerator comprises at least one refrigerator tube ( 5 ), at least one pulse tube ( 6, 9 ), and one feed line ( 4 ) for feeding a working gas from a turning valve ( 3 ) of the cryo refrigerator to a warm end of the regenerator tube ( 5 ), wherein a cold end of the pulse tube ( 6, 9 ) is connected to a cold end of the regenerator tube ( 5 ) via a connecting line ( 7, 8 ), and wherein a buffer line ( 10, 11 ) extending to a buffer volume ( 14, 15 ) of the cryo refrigerator is provided at a warm end of the pulse tube ( 6, 9 ), is characterized in that a first reversing valve ( 21 ) is provided in the feed line ( 4 ), and a second reversing valve ( 23; 31, 32 ) is provided in the buffer line ( 10, 11 ), such that, in a rinsing state of the reversing valves ( 21, 23; 31, 32 ), the turning valve ( 3 ) and the buffer volume ( 14, 15 ) are separated from the regenerator tube ( 5 ) and from the pulse tube ( 6, 9 ), and the regenerator tube ( 5 ) and the pulse tube ( 6, 9 ) can be rinsed via the reversing valves ( 21, 23; 31, 32 ). The inventive cold head can be cleaned in the cold, installed state in the cryostat.

I claim: 
     
         1 . A cold head for a cryo refrigerator, the cold head comprising:
 at least one refrigerator tube, said refrigerator tube having a warm end and a cold end;   at least one pulse tube, said pulse tube having a warm end and a cold end;   a cryo refrigerator turning valve;   a feed line for feeding a working gas from said turning valve to said warm end of said refrigerator tube   a connecting line connecting said cold end of said pulse tube to said cold end of said refrigerator tube;   means defining a cryo refrigerator buffer volume;   a buffer line extending from said warm end of said pulse tube to said buffer volume;   a first reversing valve disposed in said feed line; and   a second reversing valve disposed in said buffer line, wherein, in a rinsing state of said first and said second reversing valves, said turning valve and said buffer volume are separated from said refrigerator tube and from said pulse tube, wherein said regenerator tube and said pulse tube can be rinsed via said first and said second reversing valves.   
     
     
         2 . The cold head of  claim 1 , wherein the cold head comprises a heating means or an electric heating means. 
     
     
         3 . The cold head of  claim 1 , wherein the cold head has two cooling stages. 
     
     
         4 . The cold head of  claim 1 , wherein at least one of said first and said second reversing valves opens into a pressure-relief valve. 
     
     
         5 . The cold head of  claim 4 , wherein said pressure-relief valve is adjusted to an average working pressure of the cryo refrigerator. 
     
     
         6 . A method for cleaning the cold head of  claim 1 , wherein, in a cold state of the cold head, the cold head is separated from other components of the cryo refrigerator and a rinsing gas flows through the cold head.