Patent ID: 7915893
Filing Date: 2011-03-29
Classification: G01R

Abstract:
1. An NMR MAS probe for NMR investigations of a sample inside a rotor near room temperature in a magnet having static field B o greater than 4T, said probe comprising a hermetically sealed spinner assembly comprising concentric thin-walled ceramic stator tubes that are supplied with gas through hermetically sealed metallic bearing and drive gas lines and exhausted through a first hermetically sealed curved, rotor-loading exhaust tube at the upper end and a second hermetically sealed exhaust tube at the lower end, a vacuum zone external to said spinner assembly, a duct suitable for evacuation of said vacuum zone to a pressure less than 50 mTorr by external pumping means, a thin-walled ceramic coilform surrounding said spinner assembly and substantially thermally isolated therefrom, a thermally conductive first rf sample coil supported on said ceramic coilform, a thermally conductive second-stage cold plate inside said vacuum zone, said vacuum zone further characterized as containing a plurality of additional high voltage rf reactive elements in addition to said sample coil, at least one of said additional reactive elements providing thermal contact between said sample coil and said second-stage cold plate, a tuning zone near room temperature and separated from said vacuum zone by a gas-sealing barrier, rf feed-through elements through said gas-sealing barrier, a cooled radiation shield, said vacuum zone further characterized as enclosing warm metallic components having emissivity less than 0.2, first-stage cooling means for cooling said radiation shield to a temperature below 150 K, second-stage cooling means for cooling said cold plate to a temperature below 40 K.