AC losses in prototype conductors for the NET toroidal field coils

With the numerical model current distribution in superconductors can be determined as function of the applied field for superconductors of arbitrary shape, such as hollow filaments, multifilament systems or filaments which are connected by superconducting bridges. A definition of the effective filament diameter is proposed. Knowing the current distribution in a superconductor, quantities such as the hysteresis losses and instantaneous heat dissipation can be determined. The heat dissipation has been calculated for a model coil, which is ramped up to 93% of its critical current and subsequently ramped down to the same current in opposite direction. It is shown that filaments in outer parts of the magnet are not fully saturated during most of the ramp. To assume that all filaments are penetrated would lead to overestimation of the power dissipation. (author). 83 refs., 109 figs., 27 tabs