Possibilities to increase the critical current of solenoids made of anisotropic HTS tapes

摘要

The results of the theoretical analysis of the influence of external magnetic field on the critical currents of cylindrical solenoids made of BSCCO tapes with the high anisotropy to I_C(B) characteristic at 77 K are presented. Critical current of such coils is determined especially by the radial component of the magnetic field close to the coil's flanges. In principle there are two ways how to increase the coil's critical current. First, applying the magnetic field parallel with the coil axis generated by the outer coil leads to decrease of the angle between the tape surface and the direction of the resulting magnetic field. However, the best results can be obtained using supplementary windings that are located close to the coil's flanges where rather the effect of the partial compensation of undesired radial component of the magnetic field is utilised. Depending on the coil's geometry, tape I,;(B) characteristic and its anisotropy, the increase in the coil's critical current higher than 50 % can be expected.