Insulation of Coated Conductors for High Field Magnet Applications

Lü, Jun; Kandel, Hom; Han, Ke; Sheppard, W. R.; McRae, D. M.; Voran, A. J.; Pickard, K. W.; Goddard, R. E.; Viouchkov, Y.; Weijers, H.W.; Markiewicz, W.D.

doi:10.1109/tasc.2011.2177230

Cited by 15 publications

(10 citation statements)

References 11 publications

(11 reference statements)

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“…However, combining steel co-wind with placing the turn insulation on the steel appears to be a practical approach. UV cured epoxy and sol-gel ceramics have been successfully applied to steel co-wind strip [9]. Sol-gel has advantages in reduced thickness and increased thermal conductivity.…”

Section: B Turn Insulationmentioning

confidence: 99%

Design of a Superconducting 32 T Magnet With REBCO High Field Coils

Markiewicz

Larbalestier

Weijers

et al. 2012

IEEE Trans. Appl. Supercond.

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187

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The design and fabrication of a 32 T, 32 mm cold bore superconducting magnet with high field REBCO inner coils is underway at the NHMFL. In support of the design, conductor characterization measurements have been made including critical current as a function of field, field orientation, temperature, and strain on conductors and joints. Various conductor and turn insulation systems were examined. The selected coil fabrication method for the 32 T magnet is pancake wind, dry wind coils with sol-gel insulation on a stainless steel co-wind. Quench protection of the REBCO coils by distributed heaters is under development. Small REBCO coils have been made and tested in a 20 T background field to demonstrate performance of the technology. The design of the 32 T magnet is described, including coil configuration and conductor lengths, fraction of critical current, selection of conductor copper content for protection, and stress in the windings.Index Terms-High field superconducting magnets, insulation, quench protection, REBCO.

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Section: B Turn Insulationmentioning

confidence: 99%

Design of a Superconducting 32 T Magnet With REBCO High Field Coils

Markiewicz

Larbalestier

Weijers

et al. 2012

IEEE Trans. Appl. Supercond.

Self Cite

187

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“…In this work, we mainly focus our attention on the REBCO pancake coils co-wound with insulated stainless-steel tapes and REBCO conductors [36]. It is noteworthy that the steel co-wind not only achieves turn insulation but also increases the mechanical strength of the whole winding.…”

Section: Geometrical Descriptionmentioning

confidence: 99%

Numerical analysis of the electromechanical behavior of high-field REBCO coils in all-superconducting magnets

Niu

Xia

Yong

2021

Supercond. Sci. Technol.

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Despite the excellent improvements in high fields resulting from the adoption of REBa2Cu3O x (REBCO)-coated conductors (CCs), the resulting stress and strain due to winding tension, cooling stress, and the screening-current-induced Lorentz force may lead to severe plastic deformation and degradation of superconductivity. Therefore, it is essential to understand the comprehensive electromechanical behavior and deformation mechanism of high-field REBCO magnets. In this paper, multistep finite element analysis is designed to simulate the electromechanical behavior of REBCO coils after the winding, coolingdown, and charging processes. All major constituent materials including the mandrel, CCs, cowinding reinforcement, and over-banding are considered in the mechanical models to emulate contact–separation behavior between them. In addition to contact nonlinearity, an intrinsic elastoplastic property is introduced to predict the plastic deformation observed in experiments. To reveal the screening-current effect, the distributions of the screening current and the magnetic field are analyzed by solving the T-A formulation of Maxwell’s equations using a homogeneous technique. Then, with the electromagnetic load acting as a body force, the electromagnetic stress and strain are computed and experimentally validated for a pancake coil, including the transport current and external field. Finally, the electromechanical behavior under a Lorentz load is investigated by considering the accumulation of stress and strain due to winding tension and cooling down. The simulation results reveal that the winding tension and thermal stress affect the final stressstates in the fully charged state and therefore the electromechanical properties. Both plastic deformation and possible degradation are more likely to occur in the outermost tape of several pancakes due to the influence of screening-current-induced stress and strain. In addition, this work further analyzes the effect of the current sweep reversal method, which could be favorable in reducing the screening-current-induced high stress and strain in the steady state.

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“…The solution tested here is a co-wound high strength/high resistivity tape. This solution is particularly appealing applications where the mechanical stress is very large, like high field (or high flux) solenoids, where such tape is already used both as mechanical reinforcement and insulation [20].…”

Section: Conclusion and Prospectmentioning

confidence: 99%

Transient voltages and energy balance in REBCO insulated magnet: experimental and numerical studies

Vialle

Badel

Rozier

et al. 2021

Supercond. Sci. Technol.

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Different means are investigated today to protect a REBCO coil against local thermal runaway, what is commonly called a "Quench". Metal Insulated Coil or No-Insulated coil have been successfully introduced. However, these protections method may show other issues and are limited in terms of dynamics, making them impractical for fast applications. We successfully tested early detection of dissipative voltage followed by current dumping as a method to protect REBCO insulated test coils, even with engineering current density in the kA/mm2 range. Pick up coils can be used to compensate inductive coil voltage. In previous works we highlighted the presence of transient voltage due to the hysteretic current distribution in REBCO tape width, which can complicate the detection. We then developed a numerical electromagnetic model that reproduce the transient behaviour of REBCO coils. Here we study a small REBCO coil instrumented with three different pick-up coils, including a co-wound pick-up whose coupling is close to perfect. The post processing and analysis of the simulation results makes it possible to identify in the transient coil voltage the contribution due to transient losses and coil inductance variation. The resulting evaluation of the REBCO coil inductance and its variations is validated by analysis of the pick-up coil signals. From a practical point of view, this work shows the possibility to have very sensitive early detection of thermal runaway if the threshold is adjusted based on the expected coil compensated voltage drift. The interest of using isolated high-strength co-wound reinforcement tape as pick-up coil is also highlighted.

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Insulation of Coated Conductors for High Field Magnet Applications

Cited by 15 publications

References 11 publications

Design of a Superconducting 32 T Magnet With REBCO High Field Coils

Design of a Superconducting 32 T Magnet With REBCO High Field Coils

Numerical analysis of the electromechanical behavior of high-field REBCO coils in all-superconducting magnets

Transient voltages and energy balance in REBCO insulated magnet: experimental and numerical studies

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