Superconducting magnets with thermal radiation shields

A cylindrical superconducting magnet structure, comprising:

• a plurality of resin-impregnated, axially aligned annular coils of superconducting wire, each coil having an axis around which the coil is wound, and a radially outer surface and a radially inner surface;
• a tubular support structure at least partially surrounding the respective radially outer surfaces of said annular coils and having a larger diameter than said radially outer surfaces, each of said annular coils exhibiting a thermal resistance between the respective annular coil and the tubular support structure;
• a cooling arrangement in thermal communication with said tubular support structure that cools at least said tubular support structure to a cryogenic temperature;
• and
• a cryogenic radiation shield between the respective radially inner surfaces of the annular coil and the respective axes of the annular coils, said cryogenic radiation shield comprising a metal cylinder mechanically joined to the tubular support structure at a plurality of axial and circumferential intervals, and comprising a plurality of thermally linking structures that thermally link the metal cylinder to the tubular support, each of said thermally linking structures having a thermal resistance that produces a thermal resistance between the metal cylinder and the tubular support structure that is less than the respective thermal resistances between the annular coils and the tubular support structure.

A cylindrical superconducting magnet structure, comprising:

• a plurality of resin-impregnated, axially aligned annular coils of superconducting wire, each coil having an axis around which the coil is wound, and a radially outer surface and a radially inner surface;
• a tubular support structure at least partially surrounding the respective radially outer surfaces of said annular coils and having a larger diameter than said radially outer surfaces, each of said annular coils exhibiting a thermal resistance between the respective annular coil and the tubular support structure;
• a cooling arrangement in thermal communication with said tubular support structure that cools at least said tubular support structure to a cryogenic temperature;
• and
• a cryogenic radiation shield between the respective radially inner surfaces of the annular coil and the respective axes of the annular coils, said cryogenic radiation shield comprising a conformal layer of metal foil applied over the radially inner surface of each of said annular coils, and an electrically and thermally insulating layer interposed between each of said annular coils and said metal foil layer, and wherein said conformal layer of metal foil is also applied over axially facing surfaces of each of said annular coils, with said electrically and thermally insulating layer also interposed between each annular facing surface of each coil and said metal foil layer, with a thermal resistance between each metal foil layer and said tubular support structure being less than the thermal resistance between the respective annular coils and the tubular support structure.

A method of manufacturing a cylindrical superconducting magnet comprising a plurality of resin-impregnated, axially aligned annular coils of superconducting wire, each coil having an axis around which the coil is wound, and a radially outer surface and a radially inner surface, a tubular support structure at least partially surrounding the respective radially outer surfaces of said annular coils and having a larger diameter than said radially outer surfaces, each of said annular cods exhibiting a thermal resistance between the respective annular coil and the tubular support structure, a cooling arrangement in thermal communication with said tubular support structure that cools at least said tubular support structure to a cryogenic temperature, and a cryogenic radiation shield between the respective radially inner surfaces of the annular coil and the respective axes of the annular coils, said cryogenic radiation shield comprising a conformal layer of metal foil applied over the radially inner surface of each of said annular coils, and an electrically and thermally insulating layer interposed between each of said annular coils and said metal foil layer, and wherein said conformal layer of metal foil is also applied over axially facing surfaces of each of said annular coils, with said electrically and thermally insulating layer also interposed between each annular facing surface of each coil and said metal foil layer, with a thermal resistance between each metal foil layer and said tubular support structure being less than the thermal resistance between the respective annular coils and the tubular support structure, said method comprising:

• providing a mold for each of said coils, each mold comprising a journal surface and two annular retaining plates;
• positioning electrically conductive channel pieces, each having a limited azimuthal extent, inside each mold for each coil, so as to substantially cover interior surfaces of the mold formed by the journal surface and the annular retaining plates, said electrically conducted channel pieces forming said metal foil layers;
• providing a layer of porous electrically insulating material over the inner surfaces of the channel pieces for each coil;
• winding the respective coils into the porous electrically insulating material within the channel pieces;
• positioning a tubular support structure within the mold over the annular coils and thereby completing respective mold cavity for the respective annular coils;
• impregnating the respective annular coils and the associated electrically insulating layer with resin by filling the mold cavities with said resin and subsequently curing the resin;
• and
• removing the journal surface and the annular retaining plates, thereby releasing the cylindrical superconducting magnet from the mold.

A method of manufacturing a cylindrical superconducting magnet comprising a plurality of resin-impregnated, axially aligned annular coils of superconducting wire, each coil having an axis around which the coil is wound, and a radially outer surface and a radially inner surface, a tubular support structure at least partially surrounding the respective radially outer surfaces of said annular coils and having a larger diameter than said radially outer surfaces, each of said annular coils exhibiting a thermal resistance between the respective annular coil and the tubular support structure, a cooling arrangement in thermal communication with said tubular support structure that cools at least said tubular support structure to a cryogenic temperature, and a cryogenic radiation shield between the respective radially inner surfaces of the annular coil and the respective axes of the annular coils, said cryogenic radiation shield comprising a conformal layer of metal foil applied over the radially inner surface of each of said annular coils, and an electrically and thermally insulating layer interposed between each of said annular coils and said metal foil layer, and wherein said conformal layer of metal foil is also applied over axially facing surfaces of each of said annular coils, with said electrically and thermally insulating layer also interposed between each annular facing surface of each coil and said metal foil layer, with a thermal resistance between each metal foil layer and said tubular support structure being less than the thermal resistance between the respective annular coils and the tubular support structure, said method comprising:

• winding, impregnating with resin, and bonding the annular coils to the tubular support structure;
• applying an electrically isolating layer over the axial and radially inner surfaces of the annular coils;
• and
• affixing channel pieces over the electrically isolating layer to form said metal foil layer, and covering the axial and radially inner surfaces of the coils.