Superconducting magnet coil system
A superconducting magnet coil system with high resistance to quench events includes a first coil portion ( 1 ) with a first superconducting material and a second coil portion ( 2 ) with a second superconducting material. The first superconducting material has a higher critical temperature than the second superconducting material. The first and the second coil portions are bridged by a common quench protection element ( 6 ) and together with the quench protection element form a first loop. The magnet coil system also includes a third coil portion ( 3 ) which is part of a second electrical loop with a second quench protection element ( 8, 8′, 8″ )as well as a heating element ( 9 ) which is supplied with a heating voltage in response to a quench of the third coil portion. Among the series connected coil portions ( 1, 2 ) only the second coil portion is in thermal contact with the first heating element ( 9 ).
1. A superconducting magnet coil system comprising:
a first electrical loop comprising:
a first main coil portion with a first conductor which comprises a first superconducting material,
a second main coil portion with a second conductor which comprises a second superconducting material, and
a first quench protection element bridging the first main coil portion and the second main coil portion,
wherein the first main coil portion and the second main coil portion are connected to one another in series such that in operation current flows through the first and second main coil portions in a single, same direction, and
a second electrical loop comprising a third main coil portion with a third conductor made of a third a superconducting material and a second quench protection element, and
a first heating element configured to be supplied with a heating voltage for reducing the current in the first electrical loop,
wherein the first superconducting material has a higher critical temperature than does the second superconducting material,
wherein the second electrical loop is connected in series to the first electrical loop, and
wherein the second main coil portion but not the first main coil portion is in thermal contact with the first heating element.
2. The superconducting magnet coil system according to claim 1 , wherein the first main coil portion has the highest critical temperature of main coil portions of the system.
3. The superconducting magnet coil system according to claim 1 , wherein the first superconducting material comprises a High Temperatures Superconductor (HTS) material.
4. The superconducting magnet coil system according to claim 1 , wherein the second superconducting material comprises a Low Temperatures Superconductor (LTS) material.
5. The superconducting magnet coil system according to claim 4 , wherein the LTS material comprises one of NbTi or Nb 3 Sn.
6. The superconducting magnet coil system according to claim 1 , wherein the second quench protection element bridges the third main coil portion.
7. The superconducting magnet coil system according to claim 1 , wherein the second quench protection element bridges a series connection which comprises the third main coil portion and a fourth main coil portion, wherein the fourth main coil portion comprises a fourth superconducting material, wherein the fourth superconducting material has a higher critical temperature than the third superconducting material.
8. The superconducting magnet coil system according to claim 7 , further comprising a second heating element configured to be supplied with a heating voltage for reducing the current in the second electrical loop, wherein the third main coil portion but not the fourth main coil portion is in thermal contact with the second heating element.
9. The superconducting magnet coil system according to claim 1 , wherein the second quench protection element serves as the first heating element.
10. The superconducting magnet coil system according to claim 1 , wherein the first heating element is connected in parallel to the second quench protection element.
11. The superconducting magnet coil system according to claim 1 , wherein the first main coil portion and the second main coil portion directly follow one another radially.
12. The superconducting magnet coil system according to claim 1 , further comprising a heating control device,
wherein the heating control device comprises a quench diagnosis element configured to monitor at least one of the first main coil portion or the second main coil portion,
wherein the heating control device is configured, in the event of a quench of the first main coil portion or the second main coil portion, to supply an additional heating element with voltage, wherein the second main coil portion but not the first main coil portion is in thermal contact with the additional heating element.
13. The superconducting magnet coil system according to claim 1 , wherein the first main coil portion, the second main coil portion, and the third main coil portion are radially nested in one another.
14. The superconducting magnet coil system according to claim 1 , wherein the first main coil portion is an innermost main coil portion of the magnet coil system.
15. The superconducting magnet coil system according to claim 1 , wherein the first heating element is arranged inside the second main coil portion at a location at which a maximum capacity of the second superconducting material is available during operation of the magnet coil system.
16. The superconducting magnet coil system according to claim 1 , wherein the superconducting magnet coil is configured as a superconducting Nuclear Magnetic Resonance (NMR) magnet coil system.
17. A method for operating a superconducting magnet coil system according to claim 1 , wherein, in the event of a quench of a main coil portion of the second electrical loop in the first electrical loop, the second main coil portion, but not the first main coil portion and the third main coil portion, is heated by the first heating element.