Reducing cross-field demagnetization of superconducting stacks by soldering in pairs

Superconducting stacks can be used as strong permanent magnets in several applications. One of their uses is to build light and compact superconducting motors for aviation, where these magnets can be used in the rotor, but they can demagnetize quickly in the presence of cross fields. In this article, we propose a new configuration of soldered stacks face-to-face, which can be constructed by relatively simple joining techniques. Based on numerical modeling of the cross-field demagnetization of stacks of two and 16 tapes, we show that such a sample can withstand around twice as high ripple field amplitudes than isolated stacks. This is due to the increase in the parallel penetration field by around a factor 2. For cross-field amplitudes below this value, a soldered stack can retain higher permanent magnetization than isolated stacks. This method of reducing cross-field demagnetization does not decrease the power or torque rating of a motor, compared to other strategies like the increase in the gap between rotor and stator.