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In an ultrahigh sensitive NMR apparatus, a stability of a temperature of a very low temperature probe coil is improved. A low temperature probe of the high sensitive NMR apparatus is structured at a very low temperature by a cooling apparatus. A cooling medium at a room temperature (300 K) discharge

In an ultrahigh sensitive NMR apparatus, a stability of a temperature of a very low temperature probe coil is improved. A low temperature probe of the high sensitive NMR apparatus is structured at a very low temperature by a cooling apparatus. A cooling medium at a room temperature (300 K) discharged from a compressor is cooled down to 70K by a countercurrent heat exchanger, and is next cooled down to 4K or less by a series of second stages. Further, the cooling medium enters into a low temperature probe via a transfer tube, cools a probe coil to 5 to 10K by a heat exchanging portion, further cools a radiation shield to 40 to 60K, and makes a circuit via the countercurrent heat exchanger. A high temperature stability can be applied to a receiving probe coil in the low temperature probe by a cooling apparatus having a high temperature stability.

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The invention claimed is: 1. A low temperature probe having a transmitting coil and a receiving coil or a transmit/receive coil, and used in an NMR apparatus, comprising: an opposed heat exchanger cooling a cooling medium at a room temperature from a compressor to 70 K or less in one side; a coolin

The invention claimed is: 1. A low temperature probe having a transmitting coil and a receiving coil or a transmit/receive coil, and used in an NMR apparatus, comprising: an opposed heat exchanger cooling a cooling medium at a room temperature from a compressor to 70 K or less in one side; a cooling apparatus structured by connecting at least two refrigerating machines having two stages in series, and cooling the cooling medium from said opposed heat exchanger, said two cooling stages having a first cooling stage capable of cooling to 30 K or less and a second cooling stage capable of cooling to 4 K or less; a probe portion having a first heat exchanging portion executing a heat exchange between the cooling medium from said cooling apparatus and said receiving coil or said transmit/receive coil; a circulation structure circulating the cooling medium from said probe portion into the other side of said opposed heat exchanger; wherein said probe portion is provided with a second heat exchanging portion executing a heat exchange between the cooling medium from said first heat exchanging portion and a masking shield internally wrapping the cooling medium from said first heat exchanging portion and said receiving coil or said transmit/receive coil, and the cooling medium from said second heat exchanging portion is circulated into the other side of said opposed heat exchanger; and wherein a buffer tank having a larger capacity than the cooling medium flowing through said circulation structure is provided between an outlet of said compressor and an inlet of said opposed heat exchanger. 2. A low temperature probe for an NMR apparatus as claimed in claim 1, wherein said opposed heat exchanger and said cooling apparatus are arranged in a vacuum tank, an outward route and a homeward route of said first heat exchanger and said second heat exchanger are connected by a pair of cooling medium transport paths. 3. A nuclear magnetic resonance analysis apparatus comprising: a split type superconducting coil; and a probe for an NMR inserted to the split, wherein the low temperature probe used in the NMR apparatus as claimed in claim 2 is used in said NMR probe. 4. A low temperature probe for an NMR apparatus as claimed in claim 1, wherein a piping diameter is made narrower toward a rear stage in a piping between said compressor and said opposed heat exchanger, a piping in the vicinity of said first cooling medium stage, a piping between said second cooling medium stages and a piping after said cooling medium stage. 5. A low temperature probe for an NMR apparatus as claimed in claim 4, wherein the diameter of the piping between said second stages and after the piping is set about one third of the diameter of the piping in the vicinity of said first stage. 6. A nuclear magnetic resonance analysis apparatus comprising: a split type superconducting coil; and a probe for an NMR inserted to the split, wherein the low temperature probe used in the NMR apparatus as claimed in claim 5 is used in said NMR probe. 7. A nuclear magnetic resonance analysis apparatus comprising: a split type superconducting coil; and a probe for an NMR inserted to the split, wherein the low temperature probe used in the NMR apparatus as claimed in claim 4 is used in said NMR probe. 8. A nuclear magnetic resonance analysis apparatus comprising: a split type superconducting coil; and a probe for an NMR inserted to the split, wherein the low temperature probe used in the NMR apparatus as claimed in claim 1 is used in said NMR probe. 9. A low temperature probe having a transmitting coil and a receiving coil or a transmit/receive coil, and used in an NMR apparatus, comprising: an opposed heat exchanger cooling a cooling medium at a room temperature from a compressor to 70 K or less in one side; a cooling apparatus structured by connecting at least two refrigerating machines having two stages in series, and cooling the cooling medium from said opposed heat exchanger, said two cooling stages having a first cooling stage capable of cooling to 30 K or less and a second cooling stage capable of cooling to 4 K or less; a probe portion having a first heat exchanging portion executing a heat exchange between the cooling medium from said cooling apparatus and said receiving coil or said transmit/receive coil; and a circulation structure circulating the cooling medium from said probe portion into the other side of said opposed heat exchanger; wherein said probe portion is provided with a second heat exchanging portion executing a heat exchange between the cooling medium from said first heat exchanging portion and a masking shield internally wrapping the cooling medium from said first heat exchanging portion and said receiving coil or said transmit/receive coil, and the cooling medium from said second heat exchanging portion is circulated into the other side of said opposed heat exchanger; and wherein a piping diameter is made narrower toward a rear stage in a piping between said compressor and said opposed heat exchanger, a piping in the vicinity of said first cooling medium stage, a piping between said second cooling medium stages and a piping after said cooling medium stage. 10. A low temperature probe for an NMR apparatus as claimed in claim 9, wherein a buffer tank having a larger capacity than the cooling medium flowing through said circulation structure is provided between an outlet of said compressor and an inlet of said opposed heat exchanger. 11. A nuclear magnetic resonance analysis apparatus comprising: a split type superconducting coil; and a probe for an NMR inserted to the split, wherein the low temperature probe used in the NMR apparatus as claimed in claim 10 is used in said NMR probe. 12. A low temperature probe for an NMR apparatus as claimed in claim 10, wherein the diameter of the piping between said second stages and after the piping is set about one third of the diameter of the piping in the vicinity of said first stage. 13. A nuclear magnetic resonance analysis apparatus comprising: a split type superconducting coil; and a probe for an NMR inserted to the split, wherein the low temperature probe used in the NMR apparatus as claimed in claim 12 is used in said NMR probe. 14. A low temperature probe for an NMR apparatus as claimed in claim 9, wherein the diameter of the piping between said second stages and after the piping is set about one third of the diameter of the piping in the vicinity of said first stage. 15. A nuclear magnetic resonance analysis apparatus comprising: a split type superconducting coil; and a probe for an NMR inserted to the split, wherein the low temperature probe used in the NMR apparatus as claimed in claim 14 is used in said NMR probe. 16. A nuclear magnetic resonance analysis apparatus comprising: a split type superconducting coil; and a probe for an NMR inserted to the split, wherein the low temperature probe used in the NMR apparatus as claimed in claim 9 is used in said NMR probe. 17. A low temperature probe for an NMR apparatus as claimed in claim 9, wherein said opposed heat exchanger and said cooling apparatus are arranged in a vacuum tank, an outward route and a homeward route of said first heat exchanger and said second heat exchanger are connected by a pair of cooling medium transport paths.