SUPERCONDUCTING WIRES OR STRANDS

A Tokamak-type magnetic confinement reactor is a plant designed to produce electricity by thermonuclear fusion.
The DTT (Divertor Tokamak Test) facility is a research experimental facility to solve the problems related to the management of thermal energy produced in a nuclear fusion plant. A Tokamak has a magnetic system for the confinement, stabilization and control of plasma. The magnetic fields required are very high, therefore the magnets must be made with superconducting cables. Superconductors are, in fact, materials capable of carrying large electric currents without dissipation. In the following figure, the maincomponents of the magnetic system of DTT are shown. In particular, the Toroidal Field (TF) coils, the Poloidal Field (PF) coils and the Central Solenoid (CS) are highlighted.


The magnets are obtained by winding superconducting cables. The starting element of a superconducting cable is a superconducting wire, called strand, about 1 mm in diameter. 
A superconducting cable is obtained by cabling superconducting strands together with Copper wires to optimize the electrical stability. The as obtained rope is inserted in a stainless steel tube to form the cable (see figure below)