Asymptotic boundary conditions for open boundaries of axisymmetric magnetostatic finite-element models

Asymptotic boundary conditions (ABCs) are derived for open boundaries of axisymmetric magnetostatic finite-element models. Two formulations are considered, namely, for the magnetic vector potential A (r, z) and for the modified vector potential Φ=rA. The boundary conditions work for an arbitrary shape of the finite-element region. Explicit expressions are given for the coefficients of the boundary matrices. Numerical results obtained for a simple structure are compared with the analytical solution