Massachusetts Institute of Technology

John E Williams

Alexander Zhukovsky

Yukikazu Iwasa

Ronald DeRocher

Ronald De Rocher

Emanual Bobrov

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.

Removable coil form for superconducting nmr magnets and a method for its

Superconducting joint with niobium-tin

An electrical resistance device which comprises a resistance element and a superconducting gate element electrically connected in series therewith. The normal state resistance of the superconducting gate element is substantially greater than the resistance of the resistance element. A plurality of such devices can be used with the windings of a superconducting magnet, for example, to protect the windings thereof if the temperature of a particular winding region rises rapidly (the winding region quenches) due to operational instabilities, for example. At a quench the voltage at the winding region being quenched is applied to all the other devices at the other windings to generate heat at such devices in response to a relatively small voltage increase at the initially quenched region. Each of the other winding regions is thereby quenched and the gate elements thereof are triggered into their normal resistive states so that the current in the devices is reduced to a safe level.

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Wayland, MA, United States of America

John E Williams