NMR probe having an inner quadrature detection coil combined with a spiral wound outer coil for irradiation

• US 6,876,200 B2
• Filed: 03/31/2003
• Issued: 04/05/2005
• Est. Priority Date: 03/31/2003
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Varian Incorporated (Agilent Technologies, Inc.)
• Inventors: Finnigan, James, Wong, Wai Ha, Anderson, Weston
• Primary Examiner(s): Shrivastav, Brij B.
• Application Number:
  US10/403,064
• Publication Number:
  US 20040189304A1
• Time in Patent Office: 736 Days
• Field of Search: 324/318, 324/319, 324/322, 600/410, 606/20
• US Class Current: 324/318
• CPC Class Codes: G01R 33/34023 Superconducting RF coils
• CPC Class Codes: G01R 33/34046 Volume type coils, e.g. bird-cage coils; Quadrature bird-cage coils; Circularly polarised coils

Abstract

A high resolution NMR probe having two or more resonators, an inner resonator which is closely coupled to a sample and is used to stimulate and receive a response from one nuclear species, and an outer resonator to induce transitions in another nuclear species, wherein the resonators may be provided with cooling capability and may be made of superconducting material, and wherein the inner resonator may be a saddle coil or a birdcage coil with capability of being tuned, and wherein the outer resonator may be one or more spiral wound saddle coil.

Claims

1. An NMR probe comprising:

a birdcage coil composed of susceptibility compensated material and comprising;

a non-conductive first cylinder;

a first conductive ring disposed inside said first conductive cylinder fitted on an end portion thereof;

a second conductive ring fitted external to said first non-conductive cylinder,

wherein

said first and second conductive rings and said non-conductive first cylinder form capacitance or inductance therebetween, and are mutually movable so as to selectively control a resonant frequency of said birdcage coil.

2. The NMR probe of claim 1, wherein said birdcage coil comprises a plurality of conductive parallel and axially extending legs connected to said first or second conductive ring.

3. The NMR probe of claim 1, wherein said birdcage coil comprises a plurality of conductive tapered legs extending from a said first or second conductive ring.

4. The NMR probe of claim 1,

further comprising a third conductive ring with a second non-conductive cylinder having fitted on an inside surface end portion thereof, said second non-conductive cylinder being fitted between said third and second conductive rings, wherein said second and third conductive rings and said first conductive ring are mutually movable therebetween so as to selectively control resonant frequency of said birdcage coil.

5. The NMR probe of claim 1, wherein said first cylinder comprises a birdcage coil having a plurality of tapered or parallel straight legs extending from said conductive ring.

6. The NMR probe of claim 4, further comprising at least one twisted saddle decoupling coil disposed on the outside surface of said second cylinder, which has inconsiderable mutual coupling to said birdcage coil.

7. The NMR probe of claim 1, wherein said first non-conductive cylinder further comprising a ring end portion and extending from said ring end portion two pairs of coils extending axially therefrom.

8. The NMR probe of claim 7, wherein said two pairs of coils are held by at least a pair of sapphire rods, and each coil of said two pairs of coils comprises at least one capacitance.

9. The NMR probe of claim 6, wherein said at least one decoupling coil is provided with signals from a first tuning circuit comprising a first capacitor connected in parallel to a first inductor and a second tuning circuit comprising a second capacitor serially connected to a second inductor, thereby to form a double tuned circuit.

10. The NMR probe of claim 1, wherein said birdcage coil is supplied with a low temperature environment.

11. The NMR probe of claim 6, wherein said at least one twisted saddle decoupling coil is subjected to low temperature environment.

12. The NMR probe of claim 7, wherein said two pairs of coils are subjected to a low temperature environment.

13. An RF resonator system, which irradiates and detects nuclear magnetic resonance signals, said system comprising:

an inner resonator composed of susceptibility compensated material which stimulate and detect said nuclear magnetic resonance signals from one nuclear species; and

at least one outer resonator composed of susceptibility compensated material, which irradiates of resonance of at least one other nuclear speciels, said outer resonator having the shape of one or more turn spiral wound coil which has substantially zero mutual coupling to said inner resonator.

14. The RF resonator system of claim 13, wherein said inner resonator comprises a birdcage coil.

15. The RF resonator system of claim 13, wherein said inner resonator comprises a Helmholz coil.

16. The RF resonator system of claim 13, wherein said inner resonator comprises a single saddle coil.

17. The RF resonator system of claim 13, wherein said inner resonator comprises a first saddle coil and a second saddle coil arranged at 90°

angle from said first saddle coil so as to enable quadrature detection.

18. The RF resonator system of claim 13, further comprising a receiver and wherein said inner resonator is inductively coupled to said receiver.

19. The RF resonator system of claim 13, further output amplifier, and wherein said spiral wound coil is inductively coupled to said RF output amplifier.

20. The RF resonator system of claim 13, wherein said inner resonator comprises a birdcage coil including at least a pair of conductive rings forming a capacitor and which is axially or circumferentially movable to selectively control resonant frequency of said birdcage coil.

21. The RF resonator system of claim 13, further comprising:

means for cryogenically cooling at least said inner resonator.

22. The RF resonator system of claim 21, wherein said inner resonator is made of a superconductive material.

23. An NMR system, which irradiates and detects nuclear magnetic resonance signals from a sample, said system comprising:

a resonator composed of susceptibility compensated material, which simulates and detects said nuclear magnetic resonance signal from at least one nuclear species, said resonator comprising a birdcage coil and conductive ring disposed inside or outside of said birdcage coil, said resonator having a capacitance formed by said conductive ring and said birdcage coil, said capacitance being changeable by mutual movement of said conductive ring and said birdcage coil to selectively control resonant frequency of said resonator; and

means for cooling at least said birdcage coil of said resonator.

24. The NMR system of claim 23, wherein said birdcage coil comprises a conductive ring and extending therefrom a plurality of parallel straight legs.

25. The NMR system of claim 23, wherein said birdcage coil comprises a plurality of conductive tapered legs extending from said conductive ring.