Electromagnetic modeling of the jacket in cable-in-conduit conductors

Most magnets designed for thermonuclear fusion experiments rely on the cable-in-conduit conductor technology. These cables are made of several hundreds or thousands of multifilamentary superconducting strands. The strands are refrigerated by a flow of liquid helium in forced convection through a conduit, usually made of aluminum or stainless steel. The complexity of the manufacturing techniques makes it very difficult to perform direct voltage measurements inside the jacket of these cables. Voltage taps are usually placed on the jacket outer surface, deriving relevant information about the inner cable electrical characteristics. In the present study, an electromagnetic model is presented that allows us to take into account the presence of the jacket and its interactions with the superconducting cable. Some unexpected qualitative behaviors of the voltage signals detected on the jacket, whose interpretation is currently under debate in the scientific community, are reproduced by the model.