Hysteresis losses in hollow superconducting filaments and in multifilament systems

The magnetization of hollow superconducting filaments in a perpendicular applied field is calculated numerically using a mathematical model. With this model the hysteresis losses over a closed cycle of the applied field, as well as the instantaneous power dissipation in the filament, can be calculated. Theoretical results are compared with data from experiments using wire with hollow Nb3Sn filaments. Demagnetization effects caused by the influence of the field of one filament on another are studied and, finally, bridging between neighouring filaments and its influence on the effective filament diameter and the hysteresis losses are discussed