Orientation effects on the magnetization of NbTi superconductors

Magnetization measurements in slowly varying fields have shown an anisotropy of pinning forces and of hysteretic losses for different angles α between conductor axis and magnetic field. With decreasing α the hysteretic losses are growing and catastrophic flux jumps appear depending on magnetic history. At intermediate angles alterations in shape of the magnetization curve are observed which may be due to flux lines inclined to the external field. Moreover, in twisted multifilamentary wires fast pulsed longitudinal fields influence the area of the magnetization curve as well as its shape and position.