MAS NMR probe head arrangement with replaceable stator

Patent metadata

Field	Value
Publication number	US-10649047-B2
Application number	US-201816194900-A
Country	US
Kind code	B2
Filing date	Nov 19, 2018
Priority date	Nov 20, 2017
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

An MAS NMR probe head arrangement has a stator ( 2 ) aligned along an axis of rotation (RA) to support a rotor ( 1 ), a stator mount ( 32 ), and a RF coil arrangement ( 21 ) to emit/receive RF pulses into/from the measurement substance ( 40 ) in the rotor. The stator mount has a stator bearing ( 41 ) into which the stator can be axially inserted and extracted. The stator, when inserted, passes through the RF coil arrangement ( 21 ), and can be fed through the RF coil arrangement ( 21 ). A mechanism fixes the stator axially in the stator bearing ( 41 ) when inserted. This arrangement enhances both ease of assembly and maintenance of the arrangement.

First claim

What is claimed is:

1. A magic angle spinning (MAS) nuclear magnetic resonance (NMR) probe head arrangement, comprising:
a stator aligned along an axis of rotation and configured to support a rotor holding a measurement substance,
a stator mount,
a radio frequency (RF) coil arrangement configured to emit RF pulses into the measurement substance held in the rotor and/or to receive RF signals from the measurement substance held in the rotor, and
a mechanism,
wherein the stator comprises a first bearing base, a sleeve element, and a second bearing base, wherein the sleeve element connects the first bearing base and the second bearing base to each other axially as a unit, wherein the first bearing base is configured as a first pneumatic bearing and the second bearing base is configured as a second pneumatic bearing,
wherein the second bearing base has a greatest external diameter AD 2 ,
wherein the sleeve element has a frontal section which adjoins the second bearing base axially and has a greatest external diameter ADV,
wherein the RF coil arrangement has a least inner diameter IDS,
wherein: AD 2 <IDS and ADV<IDS,
wherein the stator mount is formed with a stator bearing configured for axial insertion and axial extraction of the stator as the unit into and from the stator mount,
wherein the stator is configured to pass through the RF coil arrangement for axial insertion into and axial extraction from the stator mount, and
wherein the mechanism is configured to fix the stator axially in the stator bearing when the stator is inserted into the stator mount.

2. The probe head arrangement according to claim 1 , wherein the first bearing base and/or the sleeve element has a greatest external diameter AD 1 in the region of the first bearing base, and
wherein: AD 1 >IDS.

3. The probe head arrangement according to claim 1 , wherein the stator mount has a first seal with which the first bearing base and/or the sleeve element is/are sealed in a gas-tight manner against the stator mount in the region of the first bearing base.

4. The probe head arrangement according to claim 1 , wherein the stator mount has a second seal with which the second bearing base and/or the sleeve element is/are sealed in a gas-tight manner against the stator mount in the region of the second bearing base.

5. The probe head arrangement according to claim 1 , wherein the sleeve element is gas-tight.

6. The probe head arrangement according to claim 1 and configured to form, when the stator is inserted, a gas-tight space which is bounded by the sleeve element, and in which the RF coil arrangement is arranged.

7. The probe head arrangement according to claim 6 , wherein the gas-tight space is evacuated.

8. The probe head arrangement according to claim 6 , wherein the RF coil arrangement in the gas-tight space is cooled to a cryogenic temperature T.

9. The probe head arrangement according to claim 8 , wherein T≤40 K.

10. The probe head arrangement according to claim 6 , wherein a space surrounding the rotor is cooled to a cryogenic temperature T R .

11. The probe head arrangement according to claim 10 , wherein the space surrounding the rotor within the stator is cooled to a cryogenic temperature T R , where T R ≤40 K.

12. The probe head arrangement according to claim 1 , wherein the mechanism configured to fix the stator in the stator bearing when inserted comprises a movable or detachable retaining part which axially engages behind the stator in a retaining position.

13. The probe head arrangement according to claim 12 , wherein the movable or detachable retaining part is configured to engage on the stator in the region of the first bearing base.

14. The probe head arrangement according to claim 1 , wherein the mechanism configured to fix the stator axially in the stator bearing when the stator is inserted into the stator mount comprises at least one stationary retaining part, and wherein the stationary retaining part is configured with an elastic element which, when the stator is inserted into the stator mount, presses against the stator in the radial direction.

15. The probe head arrangement according to claim 14 , wherein the mechanism configured to fix the stator axially in the stator bearing when the stator is inserted into the stator mount comprises at least one further stationary retaining part, and wherein the two stationary retaining parts are each configured as sealing rings.

16. The probe head arrangement according to claim 1 , where the stator mount forms an axial stop which defines a maximum axial insertion position of the stator in the stator mount.

17. The probe head arrangement according to claim 16 , wherein the axial stop cooperates with a shoulder of the stator formed by the first bearing base or the sleeve element in a region surrounding the first bearing base.

18. The probe head arrangement according to claim 1 , wherein:
the first pneumatic bearing and the second pneumatic bearing are configured to radially support the rotor in the stator, and
the rotor, when inserted into the stator, forms a first bearing surface at a radius R 1 in the region of the first pneumatic bearing on a circular-cylindrical section of the rotor, and forms a second bearing surface at a radius R 2 in the region of the second pneumatic bearing.

19. The probe head arrangement according to claim 1 , further comprising a third pneumatic bearing disposed in one of the bearing bases and configured to hold the rotor axially in the stator.

20. The probe head arrangement according to claim 19 , wherein the third pneumatic bearing is disposed in the second bearing base, and the rotor has a third bearing surface oriented perpendicular to the axis of rotation.

21. The probe head arrangement according to claim 19 , further comprising a counter bearing in another of the bearing bases and constructed to hold the rotor arranged in the stator axially.

22. A method for measuring a measurement substance, comprising:
providing a probe head arrangement according to claim 1 ,
arranging a rotor in the stator, inserting and fixing the stator into the stator bearing, and
rotating the rotor about the axis of rotation at a frequency of at least 1 kHz.

Assignees

• Bruker Biospin Ag
• Bruker Switzerland Ag

Inventors

• Freytag Nicolas
• KUEHLER Fabian
• Osen David

Classifications

• G01R33/34092

  RF coils specially adapted for NMR spectrometers · CPC title

• G01R33/307 Primary

  specially adapted for moving the sample relative to the MR system, e.g. spinning mechanisms, flow cells or means for positioning the sample inside a spectrometer · CPC title

• G01R33/3403

  Means for cooling of the RF coils, e.g. a refrigerator or a cooling vessel specially adapted for housing an RF coil · CPC title