Design considerations and experimental results for MRI systems using HTS magnets

Parkinson, Ben

doi:10.1088/0953-2048/30/1/014009

Cited by 52 publications

(30 citation statements)

References 53 publications

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“…Research Institute [104]; neither coupling current nor screening current have prevented the operation. A Bi2223 tape is qualitatively similar to a non-twisted soldered stack of REBCO tapes, in the sense that both are composed of parallel (non-transposed) superconducting paths in good electrical contact (metal matrix); also the size of the cross section is comparable.…”

Section: Non-twisted Soldered Stack (Rebco)mentioning

confidence: 99%

A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors

Uglietti

2019

Supercond. Sci. Technol.

179

123

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High Temperature Superconducting (HTS) materials have the potential to generate magnetic field beyond the level obtainable with Low Temperature Superconducting (LTS). This review reports the past and present R&D on HTS cables and conductors for high field tokamaks, accelerator dipoles and large solenoids. Among the HTS wires and tapes available commercially, coated conductor tapes are the most appealing because of the outstanding critical strength and large improvement margin. Limitations are the weakness against peeling and shearing and the short piece length. The prices for technical superconductors are reviewed because they play an important role in large projects; moreover the perspective of industrial production of HTS wires and tapes is discussed considering the historical development of the LTS wire market. Various designs have been proposed for HTS cables and conductors: some are better suited for soft materials, while others can exploit the anisotropy of coated conductors (by aligning the tape with the field), providing the highest current density. The last decade has seen an increase in the size and complexity of the prototypes; however some peculiar features of HTS, such as high stability margin and high mechanical limits, have not yet been fully incorporated in the designs: for example the transposition requirements for HTS have not yet been studied in detail. Several facts indicate that tapes (even if anisotropic) can be used for manufacturing cables and magnets of any size and have advantages with respect to round wires.

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Section: Non-twisted Soldered Stack (Rebco)mentioning

confidence: 99%

A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors

Uglietti

2019

Supercond. Sci. Technol.

179

123

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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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“…In the case of current flow this is particularly valuable, as localised faults in the HTS winding can be avoided, with current instead flowing into and through adjacent turns. This avoids the potentially destructive quench events that commonly threaten insulated (INS) HTS coils [8,9,14]. From a macroscopic viewpoint, the extra current paths can be considered as a resistance in parallel with the inductance of the coil.…”

Section: Introductionmentioning

confidence: 99%

Finite-element modelling of no-insulation HTS coils using rotated anisotropic resistivity

Mataira¹,

Ainslie²,

Badcock³

et al. 2020

Supercond. Sci. Technol.

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The no-insulation (NI) winding method is an effective technique for winding coils from high-T c superconductors (HTS). NI coils are electrically and thermally robust due to their ability to radially bypass current away from the fragile superconducting path when necessary. This avoids stored magnetic energy being entirely discharged on local defects in the HTS tape. However, the increased degrees of freedom for the current distribution makes finite-element modelling of these coils a complicated and multi-level problem. Here we present and validate a 2D axially symmetric model of an NI (or partially insulated) coil that captures all the inherent electromagnetic properties of these coils, including axial vs radial current flow and critical current suppression, and also reproduces the well-known charging and discharging characteristics. The model is validated against previously reported discharge measurements, and is shown to produce results consistent with the expected equivalent-circuit behaviour. Only by solving the NI coil problem with both axial and radial fidelity can the interplay of critical current anisotropy and turn-to-turn current be properly accounted for. The reported FE model will now enable coil designers to simulate key complex behaviours observed in NI coils, such as shielding currents, magnetic field inhomogeneity and remnant field effects.

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Design considerations and experimental results for MRI systems using HTS magnets

Cited by 52 publications

References 53 publications

A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors

A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors

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

Finite-element modelling of no-insulation HTS coils using rotated anisotropic resistivity

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