NMR spectrometer with refrigerator cooling

摘要

An NMR spectrometer comprising an NMR magnet system ( 27 ) disposed in a helium tank of a cryostat and an NMR probe head ( 11 ) disposed in a room temperature bore of the cryostat, which contains a cooled RF resonator ( 9 ) for receiving NMR signals from a sample to be investigated, and a cooled pre-amplifier ( 10 ), wherein the NMR probe head ( 11 ) is cooled by a common multi-stage compressor-operated refrigerator ( 2 ), wherein the refrigerator ( 2 ) comprises a cold head and several heat exchangers ( 5, 6 ) at different temperature levels, wherein the refrigerator ( 2 ) is disposed at a spatial separation from the cryostat in a separate, evacuated and thermally insulated housing ( 1 ) and wherein at least one cooling circuit with cooling lines, which are thermally insulated by a transfer line ( 13, 14 ) is disposed between the housing ( 1 ) containing the heat exchangers ( 5, 6 ) and the NMR probe head ( 11 ), is characterized in that additional cooling lines to an LN₂ tank ( 18 ) or radiation shield ( 21 ) disposed in the cryostat and surrounding the helium tank are provided, and the refrigerator ( 2 ) also cools the LN₂ tank ( 18 ) or the radiation shield ( 21 ). The inventive NMR spectrometer comprises a simple and inexpensive device for matching the holding time of LN₂ to that of LHe through cooling the LN₂ tank using the refrigerator provided for cooling the NMR probe head and without great expense.