AC CURRENT DISTRIBUTION AND LOSSES IN MULTIFILAMENTARY SUPERCONDUCTORS EXPOSED TO LONGITUDINAL MAGNETIC-FIELD

The current distribution and also AC losses, in a multifilamentary sup erconductor carrying a transport current, are influenced by the self a nd the external magnetic field. By using the Maxwell equations, a mode l has been developed in order to calculate the temporal evolution of c urrent distribution in a single wire exposed or not to external magnet ic field. This model is based on the actual relationship of electrical field E with current density J and takes into account the twist pitch of the wire. AC losses are calculated by adding all local losses thro ugh the cross section. This paper presents calculations of the influen ce of the cable twist coupled with the longitudinal magnetic field, an d also gives some ideas how to decrease losses.