Influence of twisting and bending on the J and n-value of multifilamentary MgB2 strands

Yang, Y.; Li, G.; Susner, Michael A.; Sumption, M.D.; Rindfleisch, M.; Tomsic, M.; Collings, E. W.

doi:10.1016/j.physc.2015.10.002

Cited by 11 publications

(8 citation statements)

References 26 publications

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“…Critical current degradation bellow 160 mm was measured for ex situ 19-filament Ni sheathed tape with one side Cu stabilization of total thickness 0.7 mm [12]. Comparable dependences were obtained for 7-filament wire of 0.6 mm in diameter with a NbTi barrier [22] and 30PIT with stainless steel, both made by the in situ PIT process.…”

Section: Resultsmentioning

confidence: 99%

Bending strain tolerance of MgB₂superconducting wires

Kòváč¹,

Hušek²,

Melíšek³

et al. 2016

Supercond. Sci. Technol.

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This work describes the strain tolerance of MgB2 superconductors subjected to variable bending stresses. Bending of MgB2 wire was done at room temperature in different modes: (i) direct bending of straight annealed samples to variable diameters and by (ii) indirect bending by straightening of bent and annealed samples. Ic–bending strain characteristics of samples made by in situ PIT and by the internal magnesium diffusion (IMD) process were measured at 4.2 K. The results show a good agreement between the direct and indirect bending mode, which allows easier estimation of limits important for the winding process of MgB2 superconductors with brittle filaments. A comparison of MgB2 wires made by in situ PIT and IMD processes showed improved strain tolerance for IMD due to better grain connectivity the low annealing temperature, which does not appear to reduce the mechanical strength of sheath material.

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Section: Resultsmentioning

confidence: 99%

Bending strain tolerance of MgB₂superconducting wires

Kòváč¹,

Hušek²,

Melíšek³

et al. 2016

Supercond. Sci. Technol.

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“…The allowable bending strain of the copper-sheathed monofilamentary PIT wire heat-treated at 800 °C and bent at room temperature was reported to be 0.45%. 21) A PIT wire is produced by filling a metal tube with a mixed powder of magnesium and boron or MgB 2 powder, drawing the tube,…”

Section: Discussionmentioning

confidence: 99%

“…The limit under which J c does not deteriorate is reported to be 0.45% in the case of the monofilamentary wire bent at room temperature. 21) Regarding the multifilamentary wire bent at room temperature, the allowable bending strain was reported to be 0.50%-0.60%. [22][23][24] In contrast, deterioration of J c due to bending of MgB 2 thin-film wires has not been reported, and at present, the reports on bending properties are limited to verifying changes in appearance (such as cracking) of such wires.…”

Section: Introductionmentioning

confidence: 99%

Flexural properties of a MgB₂ thin-film wire

Iwanaka

Kusunoki²,

Kotaki³

et al. 2023

Jpn. J. Appl. Phys.

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Aiming to understand the bending characteristics of MgB2 thin-film wire and utilize the wire in the design of superconducting magnets, we examined the degradation of critical current density Jc due to bending. Six short MgB2 thin-film wire with thickness of 1 µm, were prepared under a same deposition conditions. They were bent in different radius, and their Jc were compared. The allowable bending radius at which Jc does not degrades was 25.0 mm. As for MgB2 thin-film wires, thickening the film effectively increase engineering critical current density Je . On the basis of material mechanics, the allowable bending radius was estimated to be 25.5 mm when the film thickness increased to 10 µm. The allowable bending radius of the MgB2 thin-film wire is sufficiently smaller than the radius of a typical superconducting coil, so it is not considered to be a barrier to fabricating a coil with the wire.

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“…NIST has measured the axial tensile strain limit at 0.4% for HTR conductor. Also, measurements of permissible room temperature bending strain after reaction HT have been made by OSU [79]. …”

Section: Persistent Jointsmentioning

confidence: 99%

Conceptual designs of conduction cooled MgB₂ magnets for 1.5 and 3.0 T full body MRI systems

Baig

Amin

Deissler

et al. 2017

Supercond. Sci. Technol.

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Conceptual designs of 1.5 and 3.0 T full-body magnetic resonance imaging (MRI) magnets using conduction cooled MgB2 superconductor are presented. The sizes, locations, and number of turns in the eight coil bundles are determined using optimization methods that minimize the amount of superconducting wire and produce magnetic fields with an inhomogeneity of less than 10 ppm over a 45 cm diameter spherical volume. MgB2 superconducting wire is assessed in terms of the transport, thermal, and mechanical properties for these magnet designs. Careful calculations of the normal zone propagation velocity and minimum quench energies provide support for the necessity of active quench protection instead of passive protection for medium temperature superconductors such as MgB2. A new ‘active’ protection scheme for medium Tc based MRI magnets is presented and simulations demonstrate that the magnet can be protected. Recent progress on persistent joints for multifilamentary MgB2 wire is presented. Finite difference calculations of the quench propagation and temperature rise during a quench conclude that active intervention is needed to reduce the temperature rise in the coil bundles and prevent damage to the superconductor. Comprehensive multiphysics and multiscale analytical and finite element analysis of the mechanical stress and strain in the MgB2 wire and epoxy for these designs are presented for the first time. From mechanical and thermal analysis of our designs we conclude there would be no damage to such a magnet during the manufacturing or operating stages, and that the magnet would survive various quench scenarios. This comprehensive set of magnet design considerations and analyses demonstrate the overall viability of 1.5 and 3.0 T MgB2 magnet designs.

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Influence of twisting and bending on the J and n-value of multifilamentary MgB2 strands

Cited by 11 publications

References 26 publications

Bending strain tolerance of MgB₂superconducting wires

Bending strain tolerance of MgB₂superconducting wires

Flexural properties of a MgB₂ thin-film wire

Conceptual designs of conduction cooled MgB₂ magnets for 1.5 and 3.0 T full body MRI systems

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Influence of twisting and bending on the J and n-value of multifilamentary MgB2 strands

Cited by 11 publications

References 26 publications

Bending strain tolerance of MgB2superconducting wires

Bending strain tolerance of MgB2superconducting wires

Flexural properties of a MgB2 thin-film wire

Conceptual designs of conduction cooled MgB2 magnets for 1.5 and 3.0 T full body MRI systems

Contact Info

Product

Resources

About

Bending strain tolerance of MgB₂superconducting wires

Bending strain tolerance of MgB₂superconducting wires

Flexural properties of a MgB₂ thin-film wire

Conceptual designs of conduction cooled MgB₂ magnets for 1.5 and 3.0 T full body MRI systems