The defect detection in HTS films on third-harmonic voltage method using various inductive coils

Kim, S.B.

doi:10.1016/j.physc.2007.03.481

Cited by 22 publications

(9 citation statements)

References 6 publications

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“…However, the area of D c is not negligibly small as compared with that of the cross section of the film. These results imply that, although the SPM method is applicable to the crack identification, its resolution is not so desirable as that of the inductive method [6], [8]. In this sense, both methods should be combined to develop a high-speed and high-resolution method for identifying a crack.…”

Section: Crack Identificationmentioning

confidence: 99%

“…Since physical properties of HTS films are remarkably degraded by cracks, crack detection is essential in a production process of largesized HTS films. For this reason, two types of contactless and nondestructive methods have been applied to crack detection: permanent-magnet method [1]- [3] and inductive method [4]- [6]. Although both of them are originally powerful methods for measuring the critical current density j C in HTS films, they are extremely time-consuming.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of Permanent Magnet Method: Applicability to Crack Detection in High-Temperature Superconducting Film

2015

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Applicability of the scanning permanent-magnet (SPM) method to crack detection in a high-temperature superconducting film is assessed by means of the numerical simulation. As a measure of crack detection, a defect parameter is defined by using the electromagnetic force acting on the film. After the defect parameter is calculated along various scanning lines, the sensitivity and the resolution are determined numerically. The results of computations show that both the sensitivity and the resolution are hardly affected by the scanning speed. On the other hand, the resolution of the SPM method is much inferior to that of the inductive method. In this sense, the SPM method is a high-speed but low-resolution method for detecting cracks.

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Section: Crack Identificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Permanent Magnet Method: Applicability to Crack Detection in High-Temperature Superconducting Film

2015

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“…From their results, they derived a theoretical formula between j C and threshold current. In general, this method has been successfully employed as the measurement of the j C -distributions in the film and as the detection of the cracks [3].…”

Section: Introductionmentioning

confidence: 99%

High-speed method for analyzing shielding current density in HTS with cracks: implementation of H-matrix method to GMRES

Takayama

Kamitani

Saitoh

2016

JASSE

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Abstract. A high-speed analysis of a shielding current density in a high-temperature superconducting film containing cracks has been proposed. To this end, a numerical code has been developed for analyzing the shielding current density in an HTS film. In the code, the GMRES(k) with the H-matrix method has been implemented to solve a linear-system obtained by discretizing an initial-boundary-value problem of a nonlinear integro-differential equation with respect to time and space. The results of the computations show that, if the Jacobi scaling is not applied to the linear-system, the Newton method does not converge at a certain time step. Therefore, the Jacobi scaling is an necessary tool for analyzing the shielding current density. Furthermore, by using the GMRES(k) method with the H-matrix method as a linear-system solver, the time evolution of the shielding current can be analyzed with high speed. In conclusion, the speed of the GMRES(k) with H-matrix method is about 221.3 times as fast as that of the LU decomposition.

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“…From their results, they derived a theoretical formula between j C and I T . The inductive method has been successfully employed as the measurement of the j C -distributions and the detection of a crack [4]. The purpose of the present study is to develop a numerical code for analyzing the time evolution of the shielding current density in an HTS film containing a crack and to investigate the influence of a coil shape on the accuracy of the inductive method.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Contactless Methods for Measuring jC in High-Temperature Superconducting Film: Influence of Defect on Resolution and Accuracy

Takayama

Kamitani

Ikuno

et al. 2014

Plasma and Fusion Research

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The inductive method for measuring the critical current density in a high-temperature superconducting (HTS) film has been reproduced numerically. To this end, a numerical code has been developed for analyzing the time evolution of a shielding current density in an HTS film containing a crack. The of computational results show that the accuracy of the inductive method monotonously increases with the height of the coil. In addition, the accuracy is slightly improved by changing the inner radius of the coil, and there exists the optimum inner radius. Although the accuracy is degraded due to the crack, this result means that the inductive method can be applied to the crack detection. Consequently, the crack located near the film edge cannot be detected with high accuracy because the crack is treated the same as the film edge.

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The defect detection in HTS films on third-harmonic voltage method using various inductive coils

Cited by 22 publications

References 6 publications

Numerical Simulation of Permanent Magnet Method: Applicability to Crack Detection in High-Temperature Superconducting Film

Numerical Simulation of Permanent Magnet Method: Applicability to Crack Detection in High-Temperature Superconducting Film

High-speed method for analyzing shielding current density in HTS with cracks: implementation of <i>H</i>-matrix method to GMRES

Numerical Simulation of Contactless Methods for Measuring <i>j</i><sub>C </sub>in High-Temperature Superconducting Film: Influence of Defect on Resolution and Accuracy

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