STABILITY AND AC LOSS OF SUPERCONDUCTING CABLES - ANALYSIS OF CURRENT IMBALANCE AND INTER-STRAND COUPLING LOSSES

The current imbalance and the inter-strand coupling losses are studied for the 3x3-twisted superconducting cables exposed to the temporally-changing external magnetic field or carrying the temporally-changing transport current, The current distribution is calculated based on electrical circuit models. When the cable length is not the common multiple of the twist pitches of the first-stage and second-stage cablings, the current imbalance among strands appears in the cables made with insulated strands. When the insulation of strand is removed, the transverse current flows across the contact resistance between strands. This results in a local current imbalance among strands and an additional inter-strand coupling loss.