| 摘要 |
PROBLEM TO BE SOLVED: To obtain higher NMR sensitivity for an NMR probe, by realizing higher freezing efficiency and stably maintaining the RF coil over a long period. SOLUTION: The NMR probe is constituted of a GM/JT refrigerator unit 39, a probe head 41 in which an RF coil 27 as a cooled body is contained, and an insulation pipe 40 connecting the two, and a first JT valve 4 of the refrigerator unit 39 is arranged adjacent to a GM refrigerator 18 for pre-cooling in the unit 39. A second JT valve 5 is attached upstream of the RF coil 27 of the probe head 41. The expansion pressure of the first JT valve 4 is set at super-critical pressure or higher, and the coolant is made super-critical pressure helium so that pressure loss in the insulation pipe 40 is reduced and gas/liquid separation in the insulation pipe 40 is prevented. Furthermore, the expansion pressure of the second JT valve 5 is set below the super-critical pressure and helium mist of the gas-liquid mixture is generated so that the latent heat of the mist is utilized, to cool the RF coil 27 as the cooled body, to 4 to 5 Kelvin. COPYRIGHT: (C)2005,JPO&NCIPI
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