Plasma and Fusion Research
Volume 10, 3405023 (2015)
Regular Articles
- 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
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
Full Text
References
- [1] Y. Yoshida, M. Uesaka and K. Miya, IEEE. Trans. Magn. 30, 3503 (1994).
- [2] A. Kamitani, T. Takayama and S. Ikuno, IEEE Trans. Magn. 47, 1138 (2011).
- [3] A. Kamitani, T. Takayama and S. Ikuno, IEEE Trans. Magn. 49, 1877 (2013).
- [4] A. Kamitani, T. Takayama, S. Ikuno and H. Nakamura, Plasma Fusion Res. 9, 3405085 (2014).
- [5] W.H. Press, S.A. Teukolsky, W.T. Vetterling and B.P. Flannery, Numerical Recipes in Fortran 77 (Cambridge Univ. Press, New York, 1992) p.708.
- [6] K. Hattori, A. Saito, Y. Takano, T. Suzuki, H. Yamada, T. Takayama, A. Kamitani and S. Ohshima, Physica C 471, 1033 (2011).
- [7] R. Brambilla, F. Grilli and L. Martini, IEEE Trans. Appl. Supercond. 22, 8401006 (2012).
- [8] A. Kameni, M. Boubekeur, L. Alloui, F. Bouillault, J. Lambretchs and C. Geuzaine, IEEE. Trans. Magn. 50, 7009204 (2014).
This paper may be cited as follows:
Atsushi KAMITANI, Teruou TAKAYAMA, Ayumu SAITOH and Hiroaki NAKAMURA, Plasma Fusion Res. 10, 3405023 (2015).