Polarization insert for a cryogenic refrigerator

Abstract

A method includes pneumatically expelling a sample of magnetically polarized material along a pneumatic flow path from a cryogenic environment.

What is claimed is: 
     
         1 . A polarization insert for use in a refrigerator, comprising a pneumatic flow path that pneumatically expels a sample of magnetically polarized material from a cryogenic environment. 
     
     
         2 . The polarization insert of  claim 1 , wherein the pneumatic flow path comprises:
 a pneumatic port that is connected to and provides a gas flow path with a gas tube having a gas tube distal end, where the gas tube comprises a plurality of gas tube heat exchangers adjacent to the gas tube to cool gas within the gas tube; and   a sample port that is connected to and provides a flow path with an ejection tube, where the ejection tube is substantially parallel with the gas tube and has an ejection tube distal end connected to the gas tube distal end via a coupling that forms a gas flow path between the gas tube and the ejection tube, where the coupling includes a base surface having a metallic heat exchanger.   
     
     
         3 . The polarization insert of  claim 3 , where the polarization insert is substantially U-shaped as formed by the gas tube, the coupling and the ejection tube. 
     
     
         4 . The polarization insert of  claim 3 , where a pulse of pressurized gas applied to the pneumatic port provides a motive force that flows through the gas tube and is coupled to the ejection tube via the coupling to discharge the sample of magnetically polarized material located within the ejection tube at the ejection tube distal end from the sample port. 
     
     
         5 . The polarization insert of  claim 1 , where the source of the motive pneumatic force is helium gas. 
     
     
         6 . The polarization insert of  claim 1 , where the cryogenic environment is produced using the dilution refrigerator. 
     
     
         7 . The polarization insert of  claim 3 , where a superconducting magnet is used to maintain a large magnetic field on the sample. 
     
     
         8 . The polarization insert of  claim 1 , where a magnetic field is maintained on the sample during expulsion. 
     
     
         9 . The polarization insert of  claim 4 , where the sample contains at least one methyl rotor group. 
     
     
         10 . The polarization insert of  claim 10 , where the sample contains MR active nuclei such as 1H, 13C, 15N, 129Xe, 31P. 
     
     
         11 . The polarization insert of  claim 4 , where the speed of expulsion is in excess of 1 msec. 
     
     
         12 . The polarization insert of  claim 1 , where the temperature of the sample is less than about 20 K during expulsion. 
     
     
         13 . The polarization insert of  claim 1 , where the sample of magnetically polarized material is a liquid at room temperature and is expelled from the polarization insert in the frozen state. 
     
     
         14 . The polarization insert of  claim 1 , wherein the pneumatic flow path comprises:
 a pneumatic port that is connected to and provides a gas flow path with a gas tube having a gas tube distal end, where the gas tube comprises a plurality of gas tube heat exchangers in-line with the gas tube to cool gas within the gas tube; and   a sample port that is connected to and provides a flow path with an ejection tube, where the ejection tube has an ejection tube distal end connected to the gas tube distal end via a coupling that forms a gas flow path between the gas tube and the ejection tube.   
     
     
         15 . The polarization insert of  claim 14 , wherein the coupler comprises:
 a metallic heat exchanger;   a heating element that applies heat to a metallic coupler surface; and   a thermometer that provides a signal indicative of temperature at the metallic coupler surface.   
     
     
         16 . A cryogenic refrigerator polarization insert, comprising
 a pneumatic port that is connected to and provides a gas flow path with a gas tube having a gas tube distal end, where the gas tube comprises a plurality of gas tube heat exchangers in-line with the gas tube to cool gas within the gas tube; and   a sample port that is connected to and provides a flow path with an ejection tube, where the ejection tube is substantially parallel with the gas tube and has an ejection tube distal end connected to the gas tube distal end, via a coupling that forms a gas flow path between the gas tube and the ejection tube,   where the gas tube and the ejection tube form a pneumatic flow path that pneumatically expels a sample of magnetically polarized material from an ejection tube proximal end in response to pressurized gas being applied to a proximal end of the gas tube.   
     
     
         17 . A dilution refrigerator polarization insert, comprising
 a pneumatic port configured and arranged to provide a gas flow path with a gas tube having a gas tube distal end, where the gas tube comprises a plurality of gas tube heat exchangers in-line with the gas tube to cool gas within the gas tube; and   a sample port that is connected to and provides the gas flow path with an ejection tube, where the ejection tube has an ejection tube distal end connected to the gas tube distal end via a coupling in the gas flow path between the gas tube and the ejection tube,   where a sample of magnetically polarized material is expelled from an ejection tube proximal end in response to pressurized gas being applied to the pneumatic port.   
     
     
         18 . A method comprising:
 pneumatically expelling a sample of magnetically polarized material along a pneumatic flow path from a cryogenic environment.   
     
     
         19 . The method of  claim 18 , further comprising:
 actively cooling the pneumatic flow path.