Massachusetts Institute of Technology

Alexander Zhukovsky

John E Williams

Alexey L Radovinsky

Yukikazu Iwasa

Valery Fishman

Emanual Bobrov

Ronald DeRocher

Ronald De Rocher

A system and method to connect a cryocooler (refrigerator) to a superconducting magnet or cooled object allows for replacement without the need to break the cryostat vacuum or the need to warm up the superconducting magnet or other cooled object. A pneumatic or other type of actuator establishes a thermo-mechanical coupling. The mechanical closing forces are directed perpendicular (cross-axially) to the cryocooler axis and are not applied to the thin wall cryocooler body or to the thin cryostat walls or to the cooled object or to its shield. It is also possible that some of the compressive force be transferred to the cryocooler body. In that case, the extensions are designed so that the forces transferred to the cryocooler thermal stages do not exceed allowable stresses in the cryocooler stage. Additionally the device provides the possibility of easy inspection and cleaning of the thermal contacting surfaces of the cryostat cold and intermediate stations from the bonded chips of compressible gasket after the cryocooler retraction.

Cryogenic vacuum break thermal coupler with cross-axial actuation

A novel thermal coupler apparatus and method to couple a cryocooler or another cooling device to a superconducting magnet or cooled object allows for replacement without a need to break the cryostat vacuum or to warm up the superconducting magnet or other cooled object. A method uses a pneumatic actuator for coupling, and a retractable mechanical actuator for uncoupling. Mechanical closing forces are balanced between the intermediate temperature and low temperature cooling surfaces and do not transfer to the cooled object. The pneumatic actuator provides permanent control under mechanical closing forces in the thermal coupling.

Cryogenic vacuum break thermal coupler

A superconducting joint includes a niobium-tin superconducting composite member, a niobium-tin superconducting wire diffusion bonded to the superconducting composite, a spacer diffusion bonded to the superconducting wire, a support diffusion bonded to the spacer and a superconducting member in electrical contact with the superconducting composite. According to the method of the invention, a wire comprising unreacted niobium and tin is machined to form a tapered end having a first tapered surface exposing the wire interior and an opposing surface. A complementary spacer having the taper substantially similar to that of the wire is assembled with the wire so that the tapered wire and the tapered spacer in surface contact with one another such that the spacer occupies the area of the wire removed by machining and the exposed tapered surface remains still exposed. The wire/spacer assembly are positioned between a support plate and a composite member comprising unreacted niobium and tin such that the spacer is in surface contact with the support plate and the wire is in surface contact with the composite member thereby forming an assembled joint. Transverse pressure is applied to the assembled joint and the assembled joint is heated to form a superconducting phase and to diffusion bond the component elements of the assembled joint to one another. Lastly, a superconducting member is brought into electrical contact with an exposed face of the superconducting composite member.

Method of producing a superconducting joint with niobium-tin

A superconducting coil is mounted on a permanent non-magnetic coil form by first winding an unreacted wire onto a temporary coil form made of refractory materials which can be assembled and disassembled, reacting the wound unreacted wire at high temperatures to form a superconducting coil. The temporary coil form is disassembled and the superconducting coil is transferred to a permanent coil form made of a non-magnetic material. The temporary coil form includes a bore tube and an end flange made of a refractory material and a terminal flange made of a non-magnetic refractory material. The terminal flange is removably secured to the bore tube. The end flange is positioned next to the other end of the bore tube and held in position against the tube by means of an end plate. A terminal plate is removably positioned adjacent to the bore tube. The assembly is held together by means of an axial force on the terminal and end plates. The superconductor wire can be wound around the outer surface of the bore tube to form a superconducting coil.

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Brighton, MA, United States of America

Alexander Zhukovsky