Abstract: A first radial bearing includes nozzles in the stator at a radius r1 and a bearing surface on a circular section of the rotor at a radius R1. A second radial bearing includes nozzles in the stator at a radius r2 and a bearing surface on the rotor at a radius R2. An axial bearing includes a nozzle in the stator and a bearing surface on an axial end of the rotor, which runs orthogonally to the rotation axis and has an outer radius R3. The second radial bearing is formed on an end section of the rotor, which has a smaller radius than or a radius that decreases away from the circular section, so that R2<R1 and r2<r1. The third bearing surface is formed on an end of the end section facing away from the circular section, so that R3?R2.

Abstract: A method for operating an NMR probehead (10) with an MAS stator (11) receiving a circular-cylindrical hollow MAS rotor (13) with an outer jacket. The MAS rotor is mounted on pressurized gas in a measuring position within the MAS stator via a gas supply device with a bearing nozzle (12?) and rotates about the cylinder axis of the MAS rotor at a rotation frequency f?30 kHz. During a measurement, a temperature control gas is blown by a temperature control nozzle (12) onto the outer jacket of the rotor at an angle ?<90° with respect to the longitudinal axis of the cylinder-symmetrical rotor. The flow speed of the temperature control gas corresponds in the nozzle cross section to at least half the circumferential speed of the outer jacket of the rotating rotor and to at most the speed of sound in the temperature control gas.

Abstract: A first radial bearing includes nozzles in the stator at a radius r1 and a bearing surface on a circular section of the rotor at a radius R1. A second radial bearing includes nozzles in the stator at a radius r2 and a bearing surface on the rotor at a radius R2. An axial bearing includes a nozzle in the stator and a bearing surface on an axial end of the rotor, which runs orthogonally to the rotation axis and has an outer radius R3. The second radial bearing is formed on an end section of the rotor, which has a smaller radius than or a radius that decreases away from the circular section, so that R2<R1 and r2<r1. The third bearing surface is formed on an end of the end section facing away from the circular section, so that R3?R2.

Abstract: A method for operating an NMR probehead (10) with an MAS stator (11) receiving a circular-cylindrical hollow MAS rotor (13) with an outer jacket. The MAS rotor is mounted on pressurized gas in a measuring position within the MAS stator via a gas supply device with a bearing nozzle (12?) and rotates about the cylinder axis of the MAS rotor at a rotation frequency f?30 kHz. During a measurement, a temperature control gas is blown by a temperature control nozzle (12) onto the outer jacket of the rotor at an angle ?<90° with respect to the longitudinal axis of the cylinder-symmetrical rotor. The flow speed of the temperature control gas corresponds in the nozzle cross section to at least half the circumferential speed of the outer jacket of the rotating rotor and to at most the speed of sound in the temperature control gas.

Abstract: A cooling device for generating a cold gas flow comprising a gas source and at least one first heat exchanger (4) having a connection (14b) on the input side and a connection (15b) on the output side being cooled using a cold source (10), is characterized in that the cooling device comprises at least one second heat exchanger (5) having a connection (14a) on the input side and a connection (15a) on the output side, wherein the first heat exchanger (4) and the second heat exchanger (5) are disposed in an evacuated container (11) and operate in parallel, the first heat exchanger (4) and the second heat exchanger (5) being connected, via their connections (15a, 15b) on the output side, to a common output line (8) into which they alternately supply the cleaned gas flow. The inventive cooling device may be operated with conventional gases for a long time period without any disturbances.