The Use of Very Thin TFMs in Electromechanical Devices

Abstract

The contribution offered by this paper is to point out the advantage gained by the use of ultra thin trapped field magnets (TFMs) in electromechanical devices. They closely match the torque and force generation capability of their thicker counterparts due to the small reluctance paths they present to the stator side of the magnetic circuit. These conclusions are based on recent experimental progress in the production of these thin TFMs which show they can support critical current densities in the range of 47 kA/cm 2 at 77 K. The results prove that the default electromechanical design objective of maximizing the TFM air gap magnetic field density should be reconsidered. Because of the reduction in the reluctance of the stator field path, substantial torques result even when the volume of superconducting material is vanishingly small. A second advantage is that the stator windings can more easily activate the rotor TFMs.