Experiments and Simulation of Electromagnetic Properties in an HTS Knitted Tape Stack

High power density superconducting motors require magnets with high and uniform magnetic flux density as poles. HTS taped stacks have uniform superconducting current distribution properties, better thermal conductivity, and preferable mechanical properties. They are considered as feasible allocations to the superconducting machine. In order to explore the factors that affect the trapped field homogeneity of taped stacks, the trapped field of an HTS knitted tape stack under field cooling magnetization has been investigated by experiments and simulation in this paper. The relationships between the trapped field and the induced current distribution, the magnetization field distribution, and the demagnetization rate have been studied experimentally. Due to the uniqueness of the sample, the relationship between layers and the trapped field of taped stack has been investigated by simulation, which was promoted by using the E-J constitutive law together with a T-A formulation to calculate the electromagnetic properties of the taped stack in a three-dimensional stack model. Results show that the flow of induced current in the taped stack does not form a current circle but stay in the induction region. The shape of the trapped field of the tapped stack is influenced by the magnetization field to some extent. Increasing the number of layers and decreasing the rate of demagnetization are beneficial to increasing the trapped field of taped stacks, but they do not play a decisive role in building the shape of the trapped field in taped stacks.