Patent ID: 7430872
Filing Date: 2008-10-07
Classification: F25B,F25D,G01R,H01F

Abstract:
1. An NMR apparatus for analysis of a sample, the apparatus comprising: a cryostat having an outer shell, a room temperature bore, a helium tank, and a neck tube, said neck tube having an upper end connected to said outer shell and a lower end connected to said helium tank, wherein said neck tube and said helium tank delimit a helium space; a superconducting magnet coil system disposed in said helium tank; an NMR probe head disposed in said room temperature bore, said probe head having a cooled RF resonator for receiving NMR signals from the sample; a common, multi-stage, compressor-operated refrigerator having a cold head, wherein said cold head is disposed in said neck tube; and at least one cooling circuit having thermally insulated transfer lines, said cooling circuit extending between said helium space and said NMR probe head to cool said probe head and said RF resonator using cold helium gas from said helium space, said cooling circuit having a feed line extending from said helium space to said probe head within said transfer line, a return line extending from said probe head to said helium space within said transfer line, and a pump disposed within said return line, said feed line having an end opening disposed at a first vertical position within said neck tube, said return line having an end opening disposed at a second vertical position within said neck tube which is higher than said first vertical position, wherein helium gas is transported from said pump to exit from said end opening of said return tube and pass downwardly along said refrigerator within said helium space, wherein cold helium gas enters from said helium space into said end opening of said feed line to pass through said feed line to said probe head, and warmed helium gas passes from said probe head to said pump via said return line.