Doping-Induced Isotopic Mg11B2 Bulk Superconductor for Fusion Application

Abstract

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.

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

“…Therefore, the powder P with the smallest particle size and lower crystallinity was selected in order to improve the reaction rate and reduce the sintering temperature for the complete formation of Mg 11 B 2 . 46 The XRD analysis in Figure 5A shows that the main phase was Mg 11 B 2 , while MgO was also present as a second phase impurity in both bulk samples sintered at 700 and 800°C. Mg 11 B 2 bulk samples fabricated from 11 B (P) sintered at two temperatures 700 and 800°C were used for the characterization of superconducting properties.…”

“…Mg 11 B 2 samples fabricated with powders C and A with strong evidence of crystallinity and plate‐shaped large particle size resulted in resistive behavior even sintered at 700 and 800°C [not shown here]. Therefore, the powder P with the smallest particle size and lower crystallinity was selected in order to improve the reaction rate and reduce the sintering temperature for the complete formation of Mg 11 B 2 46 . The XRD analysis in Figure 5A shows that the main phase was Mg 11 B 2 , while MgO was also present as a second phase impurity in both bulk samples sintered at 700 and 800°C.…”