Development of MgB2 superconducting wire for the low activation superconducting magnet system operated around core D-T plasma

Hishinuma, Yoshimitsu; Kikuchi, A.; Shimada, Yusuke; Kashiwai, Taro; Hata, Satoshi; Yamada, S.; Muroga, T.; Sagara, A.

doi:10.1016/j.fusengdes.2015.05.005

Cited by 20 publications

(10 citation statements)

References 7 publications

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“…According to previous work78, this lower J c is a result of the increased amount of non-reactive precursor, which decreases the superconducting fraction. On the other hand, inter-grain connectivity is considered another crucial factor in the current-carrying capability of Mg 11 B 2 superconducting wires91011.…”

mentioning

confidence: 60%

“…For reference purposes, transport J c data of for the multi-filament Mg 11 B 2 /Ta/Cu wire reported by Hishinuma7 is also plotted in the figure. It should be noted that our best monofilament Mg 11 B 2 wire shows comparable transport J c performance to the multifilament wire fabricated by the National Institute for Fusion Science (NIFS)7. This result is considered as a big breakthrough, and it strongly supports the feasibility of replacing commercial NbTi by high-performance Mg 11 B 2 wires in highly radioactive fusion reactors.…”

Section: Resultsmentioning

confidence: 99%

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Improvement in the transport critical current density and microstructure of isotopic Mg11B2 monofilament wires by optimizing the sintering temperature

Qiu

Jie

Patel

et al. 2016

Sci Rep

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Superconducting wires are widely used in fabricating magnetic coils in fusion reactors. In consideration of the stability of 11B against neutron irradiation and lower induced radio-activation properties, MgB2 superconductor with 11B serving as boron source is an alternative candidate to be used in fusion reactor with severe irradiation environment. In present work, a batch of monofilament isotopic Mg11B2 wires with amorphous 11B powder as precursor were fabricated using powder-in-tube (PIT) process at different sintering temperature, and the evolution of their microstructure and corresponding superconducting properties was systemically investigated. Accordingly, the best transport critical current density (Jc) = 2 × 104 A/cm2 was obtained at 4.2 K and 5 T, which is even comparable to multi-filament Mg11B2 isotope wires reported in other work. Surprisingly, transport Jc vanished in our wire which was heat-treated at excessively high temperature (800 °C). Combined with microstructure observation, it was found that lots of big interconnected microcracks and voids that can isolate the MgB2 grains formed in this whole sample, resulting in significant deterioration in inter-grain connectivity. The results can be a constructive guide in fabricating Mg11B2 wires to be used as magnet coils in fusion reactor systems such as ITER-type tokamak magnet.

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mentioning

confidence: 60%

Section: Resultsmentioning

confidence: 99%

Improvement in the transport critical current density and microstructure of isotopic Mg11B2 monofilament wires by optimizing the sintering temperature

Qiu

Jie

Patel

et al. 2016

Sci Rep

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“…For long-term and steady-state operation of the D-T plasma fusion reactors, it is desirable that the superconducting magnet elements have low neutron activation. 4,5 The Nb-based superconductors, however, require a very long period for the radioactivity to decay and to cool down after neutron irradiation. 6 Thus, this creates an additional problem for the maintenance and treatment of the radioactive wastes.…”

Section: Introductionmentioning

confidence: 99%

“…6 On the other hand, MgB 2 -based superconductors have a short decay time and are known as one of the most low activation superconducting materials. 7 Furthermore, MgB 2 superconductors have a higher operating temperature compared to the Nb-based superconductors. 8 For the purpose of using MgB 2 -based superconducting magnets in the fusion reactor, it is necessary to consider the properties of the boron precursor carefully, especially the nuclear properties.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of isotopic boron (¹¹B) for the fabrication of low activation Mg¹¹B₂ superconductor for next generation fusion magnets

et al. 2020

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In this study, we analyze the properties of boron isotope (11B)‐rich powders from three different sources, that is, American, Cambridge, and Pavezyum, to fabricate the bulk Mg11B2 superconductors and evaluate their superconducting properties. While 11B‐rich powder is an essential precursor to fabricate Mg11B2 superconductors for fusion magnet applications, the properties of the 11B powder turned out to be critical to determine the quality of the final superconducting product. Therefore, appropriate control of processing conditions is needed to comply with the requirements of the nuclear fusion application. Analysis of the B isotope ratio by accelerator mass spectroscopy and neutron transmission revealed that all three types of powder are enriched with 11B to better than 99 at % quality. In addition, Pavezyum's 11B shows the lowest crystallinity and smallest crystalline domain size as evidenced by the high‐resolution X‐ray diffractometer and scanning electron microscopy. The chemical states of the boron isotope investigated with near edge X‐ray absorption fine structure spectroscopy and X‐ray photoemission spectroscopy also reveals that Pavezyum boron has amorphous structure. Mg11B2 bulks and multi‐filamentary (12‐filament) wires have been manufactured, sintered at different temperatures and characterized via the transport critical current density. The wire with Pavezyum 11B shows three times higher current carrying capacity at a particular magnetic field compared to the wire using Cambridge 11B and hence, Pavezyum 11B boron has the potential for manufacturing fusion grade Mg11B2 based magnets. The results of this study demonstrated that Boron powders with higher purity, smaller grain size and lower crystallinity are critical for improving the superconducting and electronic properties of Mg11B2 samples fabricated from the powder. Thus, the low‐neutron‐activation Mg11B2 is possibly an affordable and technically viable candidate to replace NbTi superconductors in the low field poloidal field and correction coils for the next‐generation fusion reactors.

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“…Additionally, because of the reaction 10 B + n → 7 Li + He (gas) under the heavy irradiation condition, 10 B can no longer guarantee the stability of the MgB 2 superconducting magnet. 10 B isotope is transformed to 7 Li and He by the neutron irradiation, while 11 B isotope is stable against the neutron irradiation without nuclear transformation and can reduce nuclear heating from 2.58 to 0.13 W/cm 3 [22].…”

Section: Introductionmentioning

confidence: 99%

Doping-Induced Isotopic Mg11B2 Bulk Superconductor for Fusion Application

et al. 2017

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Superconducting wires are widely used for fabricating magnetic coils in fusion reactors. Superconducting magnet system represents a key determinant of the thermal efficiency and the construction/operating costs of such a reactor. In consideration of the stability of 11 B against fast neutron irradiation and its lower induced radioactivation properties, MgB 2 superconductor with 11 B serving as the boron source is an alternative candidate for use in fusion reactors with a severe high neutron flux environment. In the present work, the glycine-doped Mg 11 B 2 bulk superconductor was synthesized from isotopic 11 B powder to enhance the high field properties. The critical current density was enhanced (10 3 A·cm −2 at 20 K and 5 T) over the entire field in contrast with the sample prepared from natural boron.

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Development of MgB2 superconducting wire for the low activation superconducting magnet system operated around core D-T plasma

Cited by 20 publications

References 7 publications

Improvement in the transport critical current density and microstructure of isotopic Mg11B2 monofilament wires by optimizing the sintering temperature

Improvement in the transport critical current density and microstructure of isotopic Mg11B2 monofilament wires by optimizing the sintering temperature

Evaluation of isotopic boron (¹¹B) for the fabrication of low activation Mg¹¹B₂ superconductor for next generation fusion magnets

Doping-Induced Isotopic Mg11B2 Bulk Superconductor for Fusion Application

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Development of MgB2 superconducting wire for the low activation superconducting magnet system operated around core D-T plasma

Cited by 20 publications

References 7 publications

Improvement in the transport critical current density and microstructure of isotopic Mg11B2 monofilament wires by optimizing the sintering temperature

Improvement in the transport critical current density and microstructure of isotopic Mg11B2 monofilament wires by optimizing the sintering temperature

Evaluation of isotopic boron (11B) for the fabrication of low activation Mg11B2 superconductor for next generation fusion magnets

Doping-Induced Isotopic Mg11B2 Bulk Superconductor for Fusion Application

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Evaluation of isotopic boron (¹¹B) for the fabrication of low activation Mg¹¹B₂ superconductor for next generation fusion magnets