Evaluation of Coupling Currents in MgB₂ Wire Under Rotating Magnetic Field Using Numerical Analysis

This paper reports numerical analysis results of AC losses when a rotating magnetic field is applied to a MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wire. The losses include coupling losses, hysteresis losses, and eddy current losses. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H-ϕ</i> formulation is used for the finite element analysis for the loss analysis of the electromagnetic phenomena in the MgB2 wire. And the losses are calculated when the contact resistivity and contact length between MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wires are changed. The given rotational frequencies are 25 Hz and 50 Hz, and the flux density amplitude of the applied magnetic field is 0.01 T. As a result, it is shown that the coupling losses are inversely proportional to the contact resistance. And it is also found that the coupling losses are proportional to the square of the contact length. These tendencies can be explained by the theoretical formula for coupling losses.