Assembly for thermal insulation of a magnet in a magnetic resonance apparatus

1. An assembly for thermally insulating a superconducting magnet, comprising:

a container having a container interior in which a superconducting magnet is contained;

said container comprising thermal insulation that thermally insulates said container interior from an exterior of said container;

a cooling unit that is removably mountable to said exterior of said container;

said container having an opening bearing that places said cooling unit, when present, in communication with said container interior to cool said superconducting magnet in said container interior by operation of said cooling unit; and

a cap having a cap interior having a size and dimensions allowing said cooling unit, when present, to be accommodated inside said cap, and a seal between said cap and said exterior of said container that reversibly seals said cap to said exterior of said container, and said cap having a cap exterior exposed to ambient air, and said cap comprising thermal insulation that thermally insulates said interior of said cap from said exterior of said cap in order to prevent formation of thermal bridges between said cap interior and said ambient air.

2. An assembly as claimed in claim 1 wherein said cap is placed on said exterior of said container, over said opening, without said cooling unit situated inside said cap.

3. An assembly as claimed in claim 1 wherein said cap is placed on said exterior of said container, over said opening, with said cooling unit situated inside said cap.

4. An assembly as claimed in claim 1 wherein said seal comprises a sealing surface at a bottom of said cap, and a sealing surface on said exterior of said container surrounding said opening, and an intermediate seal situated between said sealing surface of said cap and said sealing surface of said container.

5. An assembly as claimed in claim 1 comprising a cooling system disposed in said container interior, said cooling system comprising a venting conduit that proceeds through said opening bearing, with a pressure valve situated in said venting conduit.

6. An assembly as claimed in claim 5 wherein said venting conduit opens into a space enclosed between said cap and said container.

7. An assembly as claimed in claim 6 wherein said cooling system produces gaseous coolant during operation of said cooling system, and wherein said gaseous coolant is discharged through said venting conduit, at a first flow rate, into said space, and wherein said seal comprises a first sealing surface formed by a bottom edge of said cap, a second sealing surface on said exterior of said container, opposite said first sealing surface, a seal element between said first and second sealing surfaces, and an adjustable attachment that attaches said cap to said exterior of said container and applies a selective adjustable compression to said seal element, thereby producing an exit path that allows said gaseous coolant to exit from said space, through said seal element, at a second flow rate that is less than said first flow rate and that is dependent on a degree of said compression of said seal element.

8. An assembly as claimed in claim 5 wherein said venting conduit comprises a conduit open that is opened to the environment at said exterior of said protective cap and said exterior of said container.

9. An assembly as claimed in claim 8 wherein said venting conduit has an external length, and comprises a path for said gaseous coolant flowing through said venting conduit that is longer than said external length.

10. An assembly as claimed in claim 8 wherein said venting conduit consists of a material having a thermal conductivity that is equal to or less than the thermal conductivity of aluminum.

11. An assembly as claimed in claim 9 wherein said space is evacuated, forming a vacuum therein.

12. An assembly as claimed in claim 1 wherein said thermal insulation of said cap comprises a vacuum insulation.

13. An assembly as claimed in claim 1 wherein said thermal insulation of said cap is a multi-layered insulating foil.

14. An assembly as claimed in claim 7 wherein said first sealing surface is a flange forming said bottom edge of said cap, and wherein said adjustable attachment comprises a plurality of threaded bolts projecting from said exterior of said container through respective holes in said flange, each of said bolts having a nut threaded thereon that is rotatable in order to selectively adjust said compression.