R&amp;D Project on HTS Magnets for Ultrahigh-Field MRI Systems

Tosaka, Taizo; Miyazaki, Hiroshi; Iwai, Sadanori; Otani, Yasumi; Takahashi, Masahiko; Tasaki, Kenji; Nomura, Shunji; Kurusu, Tsutomu; Ueda, Hiroshi; Noguchi, So; Ishiyama, Atsushi; Urayama, Shin‐ichi; Fukuyama, Hidenao

doi:10.1109/tasc.2016.2535863

Cited by 45 publications

(15 citation statements)

References 9 publications

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“…The magnetic field components of 6 T and 3 T are applied in the radial and axial directions. Such a combination of the field components is evidenced, for instance, at the end turns of a high-field MRI magnet [2].…”

Section: A Simulation Methodsmentioning

confidence: 93%

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Simulation of Screening Current Reduction Effect in REBCO Coils by External AC Magnetic Field

Noguchi

Čingoski

2017

IEEE Trans. Appl. Supercond.

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Section: A Simulation Methodsmentioning

confidence: 93%

“…high-temperature superconducting (HTS) tapes are used to develop ultra-high-field NMR and MRI magnets, e.g., 1.3-GHz NMR [1] and 9.4-T MRI [2]. These HTS applications have two critical problems.…”

Section: Introduction Econd-generationmentioning

confidence: 99%

Simulation of Screening Current Reduction Effect in REBCO Coils by External AC Magnetic Field

Noguchi

Čingoski

2017

IEEE Trans. Appl. Supercond.

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“…So far, a few screening current simulation methods have been proposed, which include: (1) an axisymmetric finite element method (Axi-FEM) [23,24]; (2) a finite element method with a thin film approximation technique (FEM+TFA) [15,25,26,27,28]; (3) a simple equivalent circuit (SEC) model [29]; and (4) an advanced partial element equivalent circuit (A-PEEC) model which is shown for an SC simulation in this paper.…”

Section: Introductionmentioning

confidence: 99%

A newly developed screening current simulation method for REBCO pancake coils based on extension of PEEC model

Noguchi¹,

Hahn²

2022

Supercond. Sci. Technol.

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Since the screening current (SC) in rare earth-barium-copper-oxide (REBCO) coated conductor (CC) generates an undesired magnetic ﬁeld, it must be accurately estimated, especially for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR). Moreover, in recent years, it was pointed out that the screening current enhanced the stress/strain in REBCO CC, when an REBCO magnet was operated as an insert under an ultrahigh magnetic ﬁeld. The previously reported SC simulation methods may be roughly categorized into ﬁnite element method (FEM) and equivalent circuit method. The FEM-based method often adopted an axisymmetric model or a thin ﬁlm approximation model, while the circuit-based are the simple equivalent circuit model and the network equivalent circuit model, so-called the partial element equivalent circuit model. The latter is newly proposed in this paper. Features of those SC simulation models are brieﬂy compared to each other in this paper. Each SC simulation models have pros & cons. We have to adequately chose an SC simulation model depending on a purpose. In addition, we propose a new developed SC simulation model, named the advanced partial element equivalent circuit (A-PEEC) model. It is extendable to an SC simulation of no-insulation REBCO pancake coils. To simulate the SC of a simple coil model and the LBC3 magnet, we investigated the screening current distribution maps, and the simulated screening current-induced ﬁelds were compared with the measurements. We have conﬁrmed the validity of the newly proposed A-PEEC model.

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“…This may represent the first use of an HTS magnet for a large-scale national accelerator facility. In fact, applications of HTS magnet are rapidly expanding beyond laboratory magnets to fusion [9][10][11] , high energy physics [12][13][14][15] , biochemistry [16][17][18][19][20][21] , biomedical diagnosis [22][23][24][25][26][27] , renewable energy [28][29][30][31] , electric propulsion [32][33][34][35] and more [36][37][38][39][40][41] .…”

Section: Introductionmentioning

confidence: 99%

“Thermal Eraser” to Mitigate Screening Current by Optimal Control on Spatial Temperature Distribution in a High Temperature Superconductor Magnet

Bang¹,

Kim²,

Lee³

et al. 2021

Preprint

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The so-called “screening current” in high temperature superconductor (HTS) is a well-known phenomenon that has detrimental effects on performance of an HTS magnet. To date, many research efforts have been devoted to suppressing screening current in an HTS magnet. Here we report a customized electric-heater, named “Thermal Eraser”, to mitigate the screening current. The key idea is to optimally control spatial temperature distribution in an HTS magnet using the customized heater and the consequent temperature-dependent local critical current of HTS wires of the magnet. To validate the idea, a Thermal Eraser was designed, constructed, and installed in an actual single-pancake HTS coil. And the Thermal Eraser plus test coil system was operated at temperatures ranging 7-40 K in our in-house conduction-cooling cryogenic facility. The feasibility of the Thermal Eraser was demonstrated in terms of two aspects: 1) creation of the designated spatial temperature distribution within the HTS test coil as designed; and 2) quantitative evaluation of its effectiveness to mitigate screening current using both experimental and numerical results. We confirmed that the screening current induced field in the test coil was reduced by 0.6 mT after activation of the Thermal Eraser, which implies 60% reduction of screening current in the HTS test coil. The results demonstrate that the Thermal Eraser is a viable option to effectively reduce the screening current in an HTS magnet.

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R&D Project on HTS Magnets for Ultrahigh-Field MRI Systems

Cited by 45 publications

References 9 publications

Simulation of Screening Current Reduction Effect in REBCO Coils by External AC Magnetic Field

Simulation of Screening Current Reduction Effect in REBCO Coils by External AC Magnetic Field

A newly developed screening current simulation method for REBCO pancake coils based on extension of PEEC model

“Thermal Eraser” to Mitigate Screening Current by Optimal Control on Spatial Temperature Distribution in a High Temperature Superconductor Magnet

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