Due to the anisotropy of a tape-shaped HTS wire, the method to determine the operating current of an HTS magnet needs to be different from that of a LTS magnet. This paper presented estimation of the critical current of pancake windings excited by multiple power sources. Critical currents were determined by using field dependent -relation. A new method to define the magnetic field of the HTS wire has been proposed in this paper. Calculated critical currents of pancake windings were compared with measured ones of the HTS BSCCO magnet consisting of 10 pancake windings. Effects of multiple power excitation on the increment of the central magnetic field has been also described. Test results showed the estimated critical currents of pancake windings agreed well with that of measured ones and the central magnetic field was increased at multiple power excitation by 28.4% comparing with that of single power excitation.Index Terms--relation, HTS BSCCO magnet, multiple power excitation, pancake winding.

In the HTS magnet consisting of pancake windings, all pancake windings have been connected in series and excited by a single power source. Most of the pancake windings cannot conduct their critical current values at single power excitation. Current of each winding can be controlled separately to its critical current at multiple power excitation. This paper presents the excitation of an HTS YBCO magnet consisting of pancake windings by multiple power sources. To estimate the critical currents of the pancake windings more precisely, the magnetic field variation in the HTS wire was considered. Properties of multiple power excitation were measured by using the HTS YBCO magnet consisting of 8 pancake windings. Test results showed calculated currents agreed very well with measured ones and central magnetic field increased by multiple power excitation.Index Terms-Evolution strategy, HTS YBCO magnet, multiple power excitation, pancake winding, single power excitation.