A.C. Losses in Superconducting Synchrotron Magnets

A.C. Losses of composite conductors and synchrotron magnets are given. A new equation based on a skin-effect assumption, is presented, which shows, that the generally accepted self field calculations yield too high values. Results from loss equations are compared to a few tests an small solenoids. Losses in superconducting coils, when exposed to time varying magnetic fields have several origins: Eddy current losses in the conductor matrix, self field, hysteretic and auxiliary losses in the superconducting coils and composite conductors, hysteretic and eddy current losses in the iron return path and eddy current losses in the metallic support structure, reinforcements and containers. As all losses including heat conduction and radiation have to be removed by the coolant, the major effort will be to limit these losses to manageable low values. Losses in superconductors and composits have been treated by Bean, Hancox, Wilson et al. and many others. Due to discrepancies between theory and experimental data specifically losses due to transport current (self field), the theory of loss generation is reexamined by Ries and Brechna. This paper summarizes the results of new investigations.