Alternating current loss in a cylinder with power-law current-voltage characteristic

Abstract

The transport ac loss Q in a superconducting cylinder of radius a with a power-law current-voltage characteristic E=Ec∣J∕Jc∣n as a function of current amplitude Im is numerically calculated for a set of given values of a,Jc, and frequency f at n=5, 10, 20, and 30. After deriving a scaling law and defining a critical frequency fc, the results can be converted and interpolated to those for any values of a, Jc, f, and 5⩽n⩽30. The “power-law” Q(Im) at f=fc is a better alternative of the critical-state Q(Im), used not only for describing the features of Q(Im,f) of high-temperature superconductors but also for planning Q measurements and their interpretation.

Transport ac loss in a rectangular thin strip with power-law E(J) relation

“…1(a) that the scaling law derived in [20] for a cylinder is valid also for the strip. This law for the strip is stated as follows.…”

“…We see that q decreases with increasing f. Critical frequency f c ¼ 3:46 Hz is calculated from n ¼ 17 and I c ¼ 149 A using Eq. (15) of [20], and used for converting qði m Þ in Fig. 4(a) to q à ði à m Þ, which is shown in Fig.…”

“…In Appendix A, the derivations and discussions on the scaling law presented in [20] for a cylinder will be improved with important corrections. This is necessary since it is still difficult for us to completely derive the same scaling law for a thin strip.…”

“…(4) have been calculated by Chen and Gu [20,21], using a numerical technique proposed by Brandt and developed for the transport case by Rhyner and Yazawa et al [22,23]. A scaling law has been derived in terms of vector potential, so that for any given value of n, the qði m Þ function calculated at fixed I c and f may be used for any http Physica C 508 (2015) [12][13][14][15][16] Contents lists available at ScienceDirect Physica C j o u r n a l h o m e p a g e : w w w .…”

“…Improvements to [20] and physical meaning of E e It is necessary to improve the derivations carried out in [20] by adding a missing term E e =E c . The improved writing is as follows.…”