AC losses in Bi-2223 tapes and in the 1-kA transmission line model.

We present here results of our study of the 5-m-long AC transmission tine model with 1 kA current capability at 77 K. Primary attention was paid to the current characteristics and AC losses in individual tapes and in the core of the cable. The losses were measured as a function of AC magnetic field amplitude in various orientations of magnetic field with respect to the plane of the tape and filaments. Hysteresis losses were. close to the losses in the AC regime, meaning that eddy current losses in tapes may be neglected when compared with hysteresis losses. We designed and constructed a 5-m-long model of the AC transmission line using multi filamentary Bi-2223 tapes. The current core of the model contains 120 tapes for the forward line and 120 tapes for the backward line. The AC losses in the current core were substantially greater than those seen in the individual tapes. The reason for this is related to a complex magnetic field distribution inside the current core