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The discovery of superconductivity in magnesium diboride ($\text{Mg}\text{B}_{{\text{2}}}$) in 2001 generated significant interest due to its relatively high critical temperature and cost-effectiveness. While $\text{Mg}\text{B}_{{\text{2}}}$ has shown promise in direct current (DC) applications, its utilization in alternating current (AC) devices is hindered by dissipative phenomena. Consequently, research and development efforts have been devoted to understanding the factors influencing losses in $\text{Mg}\text{B}_{{\text{2}}}$ conductors and exploring novel designs aimed at reducing AC losses. This study presents an efficient computational tool based on a three-dimensional integral formulation of Maxwell's equations, enabling the calculation of losses in multi-filamentary $\text{Mg}\text{B}_{{\text{2}}}$ wires. By employing numerical simulations under various operating conditions and comparing the results with existing analytical formulæ, the study primarily focuses on simplified scenarios. Essential design criteria are identified, providing insights on how to effectively minimize coupling losses for specific operating conditions.

Nowadays, ex-situ Powder-In-Tube (PIT) MgB2 multifilamentary wires are commercially available in long length and can reach self-field critical current (Ic) values above 1000 A at 20 K; moreover, thanks to its high critical temperature Tc (38 K) such wires are good candidates for cryogen-free applications and devices required for the future. In the past, MRI system has already profited from these advantages and turned out to a series production of open MRI systems. Recently, this type of conductor has been chosen in the European project SCARLET for demonstrating the feasibility of a 500 MW DC monopolar cable system transferring 20 kA at 25 kV and, at the same time, distributes LH2. In addition, MgB2 is the most lightweight superconductor among the realm of practical superconductors, thus to be also suitable for aircraft components. In this work, the current state-of-the-art of the commercial ex-situ PIT MgB2 wires at ASG superconductors is reported and perspectives and challenges for their improvements over the next years is discussed.