A.c. stability and a.c. loss in composite superconductors

Two methods of loss calculations are reviewed. The first method, for loss calculations in wires, uses a numerical solution of the Maxwell equations. The second method makes use of Kirchhoff's equations and is much better suited to cables, including braids. Both methods require a knowledge of the constitutive equations relating E and j or V and l in the composite conductor. Experimental results regarding the stability of large cables are presented and a way of improving the stability of a single strand is suggested.