[Table of Contents]

Plasma and Fusion Research

Volume 10, 3405023 (2015)

Regular Articles

High-Speed Algorithm for Shielding Current Analysis in HTS Film with Cracks
Atsushi KAMITANI, Teruou TAKAYAMA, Ayumu SAITOH1) and Hiroaki NAKAMURA2)
Yamagata University, 4-3-16 Johnan, Yonezawa, Yamagata 992-8510, Japan
1)
University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan
2)
National Institute of Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
(Received 23 November 2014 / Accepted 17 February 2015 / Published 19 March 2015)

Abstract

A fast and stable method is proposed for calculating the time-varying shielding current density in a high-temperature superconducting (HTS) film containing cracks. If an initial-boundary-value problem of the shielding current density is formulated by the T-method, integral forms of Faraday's law on crack surfaces are also imposed as boundary conditions. As a result of the spatial discretization of the initial-boundary-value problem, semi-explicit differential algebraic equations (DAEs) are obtained. Although the DAEs can be solved with standard ordinary-differential-equation (ODE) solvers, much CPU time is required for their numerical solution. In order to shorten the CPU time, the following high-speed algorithm is proposed: the block LU decomposition is incorporated into function evaluations in ODE solvers. A numerical code is developed on the basis of the proposed algorithm and detectability of cracks by the scanning permanent-magnet method is numerically investigated. The results of computations show that, when multiple cracks is contained in an HTS film, resolution of the scanning permanent-magnet method will be degraded remarkably.

Keywords

block LU decomposition, critical current density, high-temperature superconductor, integrodifferential equation, surface crack

DOI: 10.1585/pfr.10.3405023

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This paper may be cited as follows:

Atsushi KAMITANI, Teruou TAKAYAMA, Ayumu SAITOH and Hiroaki NAKAMURA, Plasma Fusion Res. 10, 3405023 (2015).