Emergency run-down unit for superconducting magnets

1. An emergency run down unit for a superconductive magnet assembly said, the emergency run down unit comprising:

at least one electrical resistance associated with a coil of a superconductive magnet; and

a quench initiation device which provides electrical energy to said resistance;

wherein said quench initiation device comprises a generator for generating said electrical energy and an actuator for initiating a generation of said electrical energy; and

wherein said electrical energy is generated by a release of stored mechanical energy at the time of quenching of the coil.

2. An emergency run down unit according to claim 1 , wherein the generator comprises at least first and second components, arranged to generate electrical energy in response to at least a predetermined degree of relative movement between said components.

3. An emergency run down unit according to claim 2 , wherein one of said components comprises means for generating a static magnetic field, relative to which the other component is arranged to move whereby to generate said electrical energy.

4. An emergency run down unit according to claim 3 , wherein the means for generating a static magnetic field is the superconductive magnet assembly.

5. An emergency run down unit according to claim 3 , wherein said magnetic field is provided by a special-purpose, permanent magnet component.

6. An emergency run down unit according to any of claim 2 , wherein the relative movement between the first and second components is one of rotational and linear.

7. An emergency run down unit according to claim 6 , wherein the relative movement between the two components is enhanced by gearing.

8. An emergency run down unit according to claim 1 , wherein the generator is adapted to be reset after actuation, and thereafter re-used.

9. An emergency run down unit according to claim 1 , wherein the generator is replaceable and is adapted for single use.

10. An emergency run down unit according to claim 1 , wherein the generator comprises:

a generator component capable of generating electrical energy in response to mechanical stress; and

actuator means associated with said generator component and being actuatable between first and second operational relationships with the generator component; wherein

said actuator means is configured to subject said generator component to a varying degree of stress during a transition between said first and second relationships, thereby generating said electrical energy during said transition.

11. An emergency run down unit according to claim 10 , further comprising a frangible member which holds said actuator means in said first relationship while it is intact, and which permits said actuator means to assume said second relationship when fractured.

12. An emergency run down unit according to claim 11 , wherein the frangible means is adapted to be broken manually.

13. An emergency run down unit according to claim 11 , wherein said generator component is maintained in a pre-stressed condition by means of the frangible link, whereby fracture of the frangible link releases stress from said generator component.

14. An emergency run down unit according to 10 , wherein the generator component comprises a piezoelectric material.

15. An emergency run down unit according to claim 1 , wherein:

the electrical resistance is also arranged to receive electrical energy derived from one of mains electrical power and a battery: and

said generator of electrical energy is provided as a back-up system which is operable in the event of failure of the mains electrical power or battery.

16. An emergency run down unit according to claim 1 ,

further comprising visually perceptible means for rendering its actuation visually evident.

17. An emergency run down unit for a superconductive magnet assembly, said emergency run down unit comprising:

at least one coil of a superconductive magnet;

means for applying to said coil sufficient energy to quench the coil; and

actuation means for impinging upon the coil, on demand, to create an interaction sufficient to induce quenching;

wherein said actuation means comprises one of an externally-introduced object arranged to strike the coil, thereby to impart a mechanical impact, and a jet of gas at a temperature higher than the superconducting transition temperature of the material of the coil to be directed onto the coil.

18. An emergency run down unit according to claim 17 , further comprising visually perceptible means for rendering its actuation visually evident.

19. An emergency run down unit for a superconductive magnet assembly said, the emergency run down unit comprising:

at least one electrical resistance associated with a coil of a superconductive magnet; and

a quench initiation device which provides electrical energy to said resistance;

wherein said quench initiation device comprises a generator for generating said electrical energy and an actuator for initiating a generation of said electrical energy; and

wherein said electrical energy is generated using energy applied by muscular action by an operator at the time of quenching of the coil.

20. An emergency run down unit according to claim 19 , wherein the electrical energy is generated by manual operation of a rotor, thereby generating electrical energy.