Decay of Trapped Magnetic Field in Stacks of YBCO Coated Conductors Subjected to Traveling Magnetic Waves

High temperature superconducting stacks of tapes can also trap high magnetic fields which makes them a promising candidate for a multitude of electrical applications. In this paper, we aim to replace the traditional permanent magnet in linear synchronous motors by magnetized tape stacks. To study the characteristics of how traveling magnetic fields cause trapped fields to decay, stacked tape configurations comprised of two parallel columns were assembled, tested, and modeled computationally. The decay characteristics of the trapped magnetic field at different stator current amplitudes and different frequencies were measured by a homemade measurement system. A two-dimensional model including stator and stacks of YBCO coated conductors was constructed to investigate the related electromagnetic properties. The mechanisms linking the magnetic ac losses to the trapped magnetic field decay is discussed. Lastly, we present three effective methods to reduce trapped field decay which include: placing superconducting shielding layers at the sides; inserting Permalloy pieces in between; and increasing the number of stacked layers.