Numerical and experimental investigation of AC losses in MgB2 wires

The efficacy of MgB2-based cables for DC power transmission applications is well-established due to several advantageous properties such as the natural abundance and cost-effectiveness of precursor powders and the innate compatibility with liquid hydrogen, which has a boiling point of 20 K. Notably, MgB2 has a critical temperature T-c of 39 K. However, transitioning this technology to alternating current (AC) applications, like electric motors or AC power transmission, poses challenges primarily due to the material's susceptibility to AC losses when subjected to alternating fields. Therefore, it is crucial to conduct a thorough investigation into the dissipative phenomena affecting MgB2 wires under AC conditions to develop design strategies for optimizing these wires for such applications. A detailed study involving both numerical simulations and experimental analyses has been conducted to understand the complex electrodynamics of MgB2 wires under sinusoidal time-varying external field conditions. Remarkably, a comprehensive numerical model has been developed, incorporating all dissipative contributions in a multifilamentary wire in a single numerical tool. This model also includes the ferromagnetic loss contributions due to the presence of ferromagnetic materials like Nickel and Monel in the stabilizing matrix. The monolithic nature of this model allows for a general treatment of AC losses in multifilamentary wires, accounting for the influence of ferromagnetic materials within the stabilizing matrix.