HTS Superferric Conformal AC Transmission Line

A conceptual design is presented for a REBCO-based superferric conformal AC transmission line. AC losses in REBCO tape are driven by transverse magnetic field <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{B}_ \bot }$</tex-math></inline-formula> at the tape surface, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\tilde{q}}_{AC}} \propto B_ \bot ^3$</tex-math></inline-formula> . A simple dipole transmission line consists of two REBCO tapes supported in parallel within a dielectric structure. Ferromagnetic laminated steel bars flanking the edges of the tapes minimize this transverse field by serving as magnetic flux diverters. This reduces the expected AC losses within the transmission line. The distribution of currents, fields, and AC losses were simulated in COMSOL using 2D H-ф formulation for transport and hysteresis losses and 3D frequency-domain for the eddy currents of the laminated poles. At a benchmark current of 1500 A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> per phase, the dipole-mode line sees losses of ∼45 mW/m per phase, compared to ∼100 mW/m per phase in a coaxial line of similar bravery. An improved design is also presented (∼12 mW/m). The total width of REBCO used is reduced by around a factor of five.