THE EFFECT OF ELECTROMAGNETIC AND MECHANICAL STRESSES ON CRITICAL-CURRENT OF NB3SN CABLE DEVELOPED FOR SUPERCONDUCTING GENERATOR

A Nb3Sn superconducting cable for use as the field winding conductor o f a superconducting generator was developed with the in-situ process. A magnetic field of up to 7T, and a transverse compressive mechanical force of up to 29.4MPa were applied to the conductor, and the critical current and strain of the cable were measured. A cyclic compressive m echanical force was also applied in order to simulate DSS operation of tile generator for up to 30 years. Over 10,000 loading cycles, the cr itical current showed no degradation and was constant. By changing the magnetic field direction while maintaining the current direction, bot h compressive and tensile electromagnetic stresses were applied to the cable, and the critical currents were measured under both conditions. The critical current under compressive stress was smaller than that u nder tensile stress. Thus, it became apparent that electromagnetic str ain must be considered when measuring the critical current of large cu rrent capacity Nb3Sn superconducting cables.