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    Doping-Induced Isotopic Mg11B2 Bulk Superconductor for Fusion Application
    (Mdpi, 2017) Cai, Qi; Guo, Qianying; Liu, Yongchang; Ma, Zongqing; Li, Huijun; Qiu, Wenbin; Patel, Dipak
    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 B-11 against fast neutron irradiation and its lower induced radioactivation properties, MgB2 superconductor with B-11 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 (MgB2)-B-11 bulk superconductor was synthesized from isotopic B-11 powder to enhance the high field properties. The critical current density was enhanced (10(3) Acm(-2) at 20 K and 5 T) over the entire field in contrast with the sample prepared from natural boron.
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    Fabrication, Transport Current Testing, and Finite Element Analysis of MgB2 Racetrack Coils
    (Springer, 2017) Kundu, Ananya; Patel, Dipak; Kumar, Nitish; Panchal, Arun G.; Qiu, Wenbin; Jie, Hyunseock; Ma, Zongqing
    This paper reports the fabrication, transport current testing, and finite element analysis of magnesium diboride (MgB2) racetrack coils made by a wind and react method at 4.2 K in self-field. This type of coil can be potentially appropriate for applications aimed at building block coils that can serve as wind turbine generator coils and correction coils for fusion magnets. We have fabricated racetrack coils using an in situ monofilament MgB2/Niobium/Monel wire; each coil had a wire length of 45 m and 80 turns. The best measured critical current of the coil was 134.9 A at 4.2 K and self-field of 0.55 T. In addition, the magnetic field and the Lorentz force contribution in the coil were estimated using finite element analysis.
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    A new approach to a superconducting joining process for carbon-doped MgB2 conductor
    (Iop Publishing Ltd, 2016) Patel, Dipak; Al Hossain, Md Shahriar; Maeda, Minoru; Shahabuddin, Mohammed; Yanmaz, Ekrem; Pradhan, Subrata; Tomsic, Mike
    We report a new approach to a superconducting joining process for unreacted in situ carbon (C)-doped magnesium diboride (MgB2) wires. To operate a magnetic resonance imaging (MRI) magnet in the persistent mode, the superconducting joints between two conductors are as critical as the other key components. In addition, a stable and reliable joining process enables the superconducting magnet to operate without an external power supply. However, joint results using unreacted in situ C-doped MgB2 wires, which are used for high-field operation, have been limited, and only very poor performance has been obtained. By controlling the pressure inside a joint part, in this study, we successfully obtained current carrying retention in the joint of up to 72% compared to wire without a joint. The closedcircuit resistance of our closed-loop coil was less than 1.8 x 10(-13) Omega at 16.7 +/- 4.7 K, as measured by the field-decay measurement method. These results indicate that MgB2 has a promising future in MRI application.
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    Superior transport Jc obtained in in-situ MgB2 wires by tailoring the starting materials and using a combined cold high pressure densification and hot isostatic pressure treatment
    (Pergamon-Elsevier Science Ltd, 2017) Jie, Hyunseock; Qiu, Wenbin; Billah, Motasim; Mustapic, Mislav; Patel, Dipak; Ma, Zongqing; Gajda, Daniel
    The best J(c) performance (8 x 10(4) A.cm(-2) at 10 T, 4.2 K) has been obtained in our work among all the in-situ powder -in-tube (PIT) MgB2 wires reported so far by tailoring their boron and magnesium precursors, as well as employing appropriate high pressure during the manufacturing process. Moreover, the second stage densification using the special HIP has been applied to commercial long-length wire. Our work suggests that the economical starting precursors and the combination of cold and hot densification techniques could represent a promising alternative for industrial and economical production of practical MgB2 wires with excellent J(c). (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.