Toward Optimization of Multi-Pulse, Pulsed Field Magnetization of Bulk High-Temperature Superconductors
Pulsed field magnetization (PFM) is the most practical method for magnetizing bulk superconducting materials as trapped field magnets, but the record trapped field achieved by PFM to date is still significantly less than the true trapped field capability of these materials. In this paper, a flexible numerical modeling technique based on the finite element method is used to provide a comprehensive and realistic picture of multi-pulse PFM, which has been shown to be effective in increasing the trapped field/flux over a single pulse. First, the maximum trapped field capability of a representative sample is determined using two types of numerical model simulating field-cooling and zero-field-cooling magnetization. Next, various sets of magnetic field pulses are applied to the bulk to analyze multi-pulse PFM. An increase in the trapped field can be achieved after a second pulse and to do so an increased amplitude of applied field is required to maximize the trapped field fully. The numerical analysis shows that this occurs in subsequent pulses because it is more difficult for the magnetic flux to penetrate the sample and there is a lower temperature rise.