CABLING OF THIN MgB[sub 2] STRANDS FOR HIGH-CURRENT CONDUCTORS WITH REDUCED AC LOSSES

Abstract

Since the discovery of superconductivity in MgB 2 many efforts have been undertaken to improve the current carrying capacity of mono-or multifilament MgB 2 conductors. However, even though MgB 2 conductors can be produced in geometries which easily allow twisting or cabling, the reduction of ac losses has often played a minor role, even though many technical superconductor applications like transformers, rotating machinery, and ramped magnets require conductors with low AC losses. In this paper we present short cables together with measured AC-losses applying a simple cabling technique. Coupling losses of the cables with strands having a single component stainless steel (SS) sheath are negligible. The lower apparent measured losses of cables with Nb/Cu/SS sheaths may be explained by magnetic shielding of the Nb layer and by a systematic problem of the magnetization method for samples containing diamagnetic and ferromagnetic components.