Electromagnetic Response of a Superconducting Wire of Finite Length in aPerpendicular Applied AC Magnetic Field

摘要

The electromagnetic response of a finite, circular, composite superconducting,twisted, multifilamentary wire (with wire axis parallel to the cylindrical z axis) is determined in a perpendicular applied AC magnetic field. The stationary electric field, the current distribution and the coupling losses are calculated. The complete problem is nonlinear due to saturation effects in the superconducting filaments. This nonlinearity is removed making use of a linear surface current. Therefore, the analysis is only valid for small saturated regions. Earlier literature considers a hollow wire represented by a current sheet. The presented analysis considers a massive wire. The coupling loss formulae derived by both methods show great resemblance: the dependence with respect to the finite length of the wire is identical. The dependence with respect to the wire radius is, however, different. Furthermore, it is shown that, considering the electric field and resulting coupling losses, the infinite length problem can be identified with the z invariant problem. This is not the case with the current profiles: they are only identical when averaged quantities over an integer number of twist lengths are considered.