Friday, 2D-14, 5:20-5:30

Nondestructive Characterization of Critical Current Distribution Across the Width of Coated Conductor Tapes

Koichi Nakao

Takato Machi, Seiji Adachi, Keiichi Tanabe

Superconductivity Research Laboratory, ISTEC
10-13. Shinonome 1-chome, Koto-ku, Tokyo 135-0062, Japan
tel: 81-3-3536-5707, fax: 81-3-3536-5705, e-mail: nakao@istec.or.jp

The technology for producing long coated conductors have made a remarkable progress recently and its practical application is the next target. For the ac applications, superconductors must be thin enough to reduce the ac loss. The natural solution is the multi-filamentary structure realized by slicing or scribing wide tapes. Although the current-carrying capacity of many coated conductors with a width of 5-10 mm is enough for many applications as a whole, the homogeneity within the tape is not always perfect in many cases. If there is a substantial inhomogeneity in the critical current value across the width of the tape, slicing or scribing it into filaments may seriously degrade the final performance of the multi-filamentary conductor. Therefore, a technique is desirable for an efficient and nondestructive characterization of the critical current distribution across the width.

In the present work, we propose a simple procedure to characterize the homogeneity across the width based on a Hall sensor array measurement. In our scheme, the distribution of the critical current density is assumed to be expressed as a parabolic function of the lateral coordinate. The function has three parameters, j_c, s and p, which represent the total critical current, the slope and the parabolicity, respectively. These parameters are deduced in the spirit of the least square fitting based on the data from the Hall sensor array measurement using a commercial system (Tapestar, Theva). Once the distributions of these parameters along the length are known, the current carrying capacity after the slicing or scribing treatment can be predicted within the parabolic approximation.

This work was supported by the New Energy and Industrial Technology Development Organization (NEDO).

Download Extended Abstract

Back to the Friday Schedule.