Quench protection for persistant superconducting magnets for magnetic resonance imaging
AssigneeGeneral Electric Company
InventorsXianrui Huang, Phillip William Eckels
Life of this patent
Estimating the term…
Abstract
A quench protection circuit for the series connected but spatially separated magnet coils of a superconducting magnet utilizes a parallel circuit of multiple heaters and reverse connected diodes shunting portions of the series connected magnets coils with the heaters physically positioned in thermal contact with other coils in the series circuit to thermally transfer a heat quenching action in any coil to all coils, along with a shunting current through the diodes to shunt peak currents upon coil quenching to avoid undesired spot temperature rise and enable controlled quenching of the entire magnet upon quenching of any coil.
Claims16
A superconducting main magnet coil quench protection for a magnetic resonance imager magnet assembly comprising:
- a cryogen pressure vessel surrounding a central imaging bore;
- a plurality of spatially separated superconducting main magnet coil portions connected in series forming a main coil series circuit in said cryogen vessel and surrounding said imaging bore to provide a magnetic field in said imaging bore;
- a liquid cryogen in said cryogen vessel which produces cryogen gas in cooling said coil portions to superconducting temperatures;
- a first temperature limiting circuit electrically connected in parallel with each main magnet coil portion to limit the temperature rise of each of said magnet coil portions upon the start of quenching of superconducting operation of any one of said magnet coil portions;
- each of said first temperature limiting circuits including a quench heater circuit with a plurality of quench heaters connected in parallel for all of the parallel quench heaters to be simultaneously energized upon quenching action of the main magnet coil portion they are in parallel with;
- and
- different of said parallel quench heaters of each temperature limiting circuit positioned in thermal contact with different of said separated main magnet coil portions being protected to raise the temperature of all of said separated main magnet coil portions being protected and to simultaneously begin quenching the superconducting operation of all of such different main magnet coil portions upon the quenching action of said one or more main magnet coil portions through the simultaneous heating of all of said main magnet coil portions upon quenching of any of said main magnet coil portions;
- the number of said quench heaters connected across each of said separated main magnet coil portions being at least equal to the number of said main magnet coil portions being protected;
- said main coil series circuit distributing the energy and heat within said magnetic field upon said start of quenching of said any one of said main magnet coil portions to avoid the development of a hot spot in said any one of said main magnet coil portions.
A superconducting main magnet coil quench protection for a magnetic resonance imager magnet assembly comprising:
- a cryogen pressure vessel surrounding a central imaging bore;
- a main magnet coil quench protection circuit including:
- a plurality of spatially separated superconducting main magnet coil portions connected in series in said cryogen vessel forming a main magnet series coil circuit and surrounding said imaging bore to provide a magnetic field in said imaging bore;
- a plurality of heater circuits each connected across a portion of said main magnet series coil circuit;
- each of said heater circuits including a plurality of heaters in parallel;
- a heater from said plurality of heaters in each heater circuit positioned in thermal contact with the other coil portions of said main magnet series coil circuit;
- the number of said heaters connected in parallel with each of said separated main magnet coil portions being at least equal to the number of said main magnet coil portions being protected;
- all of the heaters in one of said heater circuits heating upon current flow there through upon quenching of the coil portion shunted by said one of said heater circuits;
- providing simultaneous heating and quenching action of all said main magnet coil portions upon current flow through any heater circuit upon quenching of the coil portion it shunts.
Dependencies are inferred from the claim text.