Investigation on the minimum full penetration field and trapped field during the pulsed field magnetization of bulk high-temperature superconductors with giant flux leaps

In this paper, we have investigated the effects of the time constant of the external pulsed field on the minimum full penetration field (MFPF) and the trapped field (TF) and the influence of the thermomagnetic instability during the pulsed field magnetization (PFM) of the bulk high temperature superconductor (HTS) with the giant flux leaps (GFLs) using numerical simulations based on H-formulation. The MFPF is the minimum of the peaks of the external pulsed field that allows the flux to penetrate completely to the bulk’s center. In the PFM process of the bulk HTSs with a low (or normal) critical current density (Jc) limit, the MFPF remains unchanged for time constants longer than 1.5 ms. The MFPF decreases with a decrease in the time constant, and the TF remains approximately constant for the full range of the time constant for each of the three different Jc limits considered, provided the GFLs occur within the interior of the bulk HTS. For the case of the very high Jc (“Ultra-high Jc”), the MFPF increases when the time constant is shortened below 1.5 ms. The TF increases significantly when the Jc is increased. The GFLs are accompanied by the instantaneous appearances of hot spots above the critical temperature during the PFM.