User:Timgenuity/Cable-in-conduit conductor

A cable-in-conduit conductor (CICC) is a type of jacketed electrical cable used produce low-temperature superconducting magnets. The unique construction of a CICC enables the use of liquid helium to cool the wires to superconducting temperatures, while achieving other requirements of superconducting magnetic coils. CICC's consist of superconducting wires twisted into strands and bundled into a cable which is jacketed by a non-superconducting material.

Preparation
The preparation of a cable-in-conduit conductor begins with the production of superconducting wires, strands, bundles, and finally cables. By combining different numbers of wires in the strands, strands in the bundles, and bundles in the cables, and by controlling the twist geometry, unique configurations can be achieved that optimize the electrical performance of the cable and the ability to cool the wires.

After the cable has been formed it is jacketed. The jacket is often formed by coextrusion and consists of a non-superconducting material such as stainless steel or aluminum. During coextrusion the jacket must only loosely pack the cable to allow the flow of liquid helium around the wires. The jacket must be designed to withstand the hydraulic pressures necessary to achieve this flow, and to achieve other requirements of superconducting magnetic coils such as withstanding magnetic pressure and Lorentz forces. Rectangular cross sections are most often used to allow very tight packing of the CICC into the coil.

After being jacketed, the cable is cleaned and wound with fiberglass tape for insulation.The cable is finally wound onto a large spool. In order to achieve superconducting properties, the cable must undergo a heat treatment to form the superconducting compound, such as Niobium-titanium. This process is necessary because superconducting wires are formed only with elemental precursors to the superconducting compound to maximize ductility in the wire which is necessary for processing.

Usage
Cable-in-conduit conductors are used when superconducting magnets require fast ramp-rates and/or must achieve very high magnetic fields such as in particle accelerators and stellarators.