Hysteretic ac loss of polygonally arranged superconducting strips carrying ac transport current

The hysteretic ac loss of a current-carrying conductor in which multiple superconducting strips are polygonally arranged around a cylindrical former is theoretically investigated as a model of superconducting cables. Using the critical state model, we analytically derive the ac loss $Q_n$ of a total of $n$ strips. The normalized loss $Q_n/Q_1$ is determined by the number of strips $n$ and the ratio of the strip width $2w$ to the diameter $2R$ of the cylindrical former. When $n>> 1$ and $w/R<< 1$, the behavior of $Q_n$ is similar to that of an infinite array of coplanar strips.