Angle-dependence of the levitation force from a frustum-shaped magnet
and recessed superconducting bulk
Abstract
The widespread application of superconducting magnetic levitation
bearings is limited by their relatively low stiffness. Recently we
investigated a novel thrust bearing geometry comprised of a conical
frustum (or truncated cone) shaped permanent magnet levitating inside a
matching tapered hole machined into a high-temperature superconductor
bulk. This configuration was found to produce superior restoring forces
and stiffness compared to the conventional cylindrical magnet and
superconductor arrangement. Here, using H-formulation
finite-element simulations, we evaluate the angle-dependence of the
frustum on the levitation force. We find that the optimal angle is not
universal, but depends on the mode of displacement as well as the
frustum dimensions. Correlations with the incident magnetic flux are
identified for estimating the angle best suited to the operating regime
of the bearing.