REDUCTION OF LOW-FREQUENCY AC LOSSES IN COAXIAL CABLES OF TYPE-II SUPERCONDUCTORS BY A STEADY BIAS CURRENT

Hysteresis losses, W-ac, in the core of a monolithic coaxial cable car rying an alternating current of fixed amplitude I-ac are predicted to trace a valley as a steady bias current I-bias is superimposed on I-ac , when (a) the critical current density j(c) diminishes with increasin g magnetic field H, and/or (b) a Meissner current IM or a surface barr ier current Is, opposing flux entry play a role. The predicted I-bias, I-min, where the valley minimum occurs and the value of W-ac at the mi nima are displayed for various I-M greater than or equal to O and I(SB )greater than or equal to 0 when j(c) = alpha (Bean) and j(c) = alpha/ H (Kim approximation). (C) 1996 American Institute of Physics.