Cooling apparatus

Abstract

Cooling apparatus comprises a cooling system defining a closed path around which a coolant flows. The system includes a pump for causing coolant flow, a supply line extending from the pump to a cold location, positioned in a cryostat, in order to cool that location, and a return line extending from the cold location to the pump. The pump is located externally of the cryostat. A first heat exchanger is positioned within the cryostat and links the supply and return lines to allow heat exchange therebetween such that coolant flowing in the supply line is cooled by coolant flowing in the return line. A refrigerator is provided having a cooling stage within the cryostat and coupled to the supply line downstream of the first heat exchanger such that coolant reaching the first cooling stage has been precooled by the first heat exchanger.

1 . Cooling apparatus comprising a cooling system defining a closed path around which a coolant flows, the system including a pump for causing coolant flow, a supply line extending from the pump to a cold location, positioned in a cryostat, in order to cool that location, and a return line extending from the cold location to the pump, the pump being located externally of the cryostat; a first heat exchanger positioned within the cryostat and linking the supply and return lines to allow heat exchange therebetween such that coolant flowing in the supply line is cooled by coolant flowing in the return line; and a refrigerator having a cooling stage within the cryostat and coupled to the supply line downstream of the first heat exchanger such that coolant reaching the first cooling stage has been precooled by the first heat exchanger.  
   
   
       2 . Apparatus according to  claim 1 , wherein the cooling system includes a coolant containing vessel forming part of the supply line, the cooling stage of the refrigerator being located in the coolant containing vessel.  
   
   
       3 . Apparatus according to  claim 2 , wherein the coolant containing vessel is also connected to an auxiliary coolant containing vessel at the cold location whereby a portion of the coolant can flow from the coolant containing vessel to the auxiliary coolant containing vessel.  
   
   
       4 . Apparatus according to  claim 1 , wherein the cooling system includes a helium lambda-point refrigerator positioned at the cold location.  
   
   
       5 . Apparatus according to  claim 1 , further comprising a second heat exchanger, located within the cryostat, and linking the supply and return lines such that coolant flowing in the supply line is cooled by coolant flowing in the return line, the second heat exchanger being upstream of the first heat exchanger with respect to coolant flow direction along the supply line.  
   
   
       6 . Apparatus according to  claim 1 , wherein the refrigerator has an additional cooling stage, warmer than the one coolant stage, the additional cooling stage being located within the cryostat and being coupled to the supply line to cool the supply line at a location upstream of the first heat exchanger.  
   
   
       7 . Apparatus according to  claim 1 , wherein the refrigerator has an additional cooling stage, warmer than the one cooling stage, the additional cooling stage being located within the cryostat and being coupled to a shield of the cryostat so as to cool the shield.  
   
   
       8 . Apparatus according to  claim 6 , wherein the shield is coupled via a third heat exchanger to the supply line so that the additional cooling stage of the refrigerator cools both the shield and coolant in the supply line.  
   
   
       9 . Apparatus according to  claim 8 , wherein the second heat exchanger is located outside the shield.  
   
   
       10 . Apparatus according to  claim 7 , wherein the shield is also cooled by a second coolant contained within a second, coolant containing vessel attached to the shield.  
   
   
       11 . Apparatus according to  claim 1 , wherein the coolant in the cooling system comprises helium.  
   
   
       12 . Apparatus according to  claim 1 , wherein the refrigerator comprises a pulse tube cryocooler.  
   
   
       13 . Apparatus according to  claim 1 , wherein the refrigerator comprises a Stirling, Gifford-McMahon, Joule-Thomson or dilution refrigerator.  
   
   
       14 . Apparatus according to  claim 1 , wherein the one cooling stage of the refrigerator provides a temperature of about 4K.  
   
   
       15 . Apparatus according to  claim 6 , wherein the additional cooling stage of the refrigerator provides a temperature in the range 40-50K.  
   
   
       16 . Apparatus according to  claim 1 , further comprising a superconducting magnet located at the cold location.  
   
   
       17 . Apparatus according to  claim 16 , wherein the superconducting magnet defines a room temperature bore adapted to receive a sample.  
   
   
       18 . NMR or ICR apparatus including cooling apparatus according to  claim 17;  and a probe for insertion into the bore, the probe having means to support a sample.