Stepwise Flux Density Amplification of Coil Stacked by HTS Plates with Different Diameter Holes

High temperature superconducting (HTS) magnet is promising in many applications due to its advantages of high upper magnetic field at low temperature compared with conventional magnet. In this paper, a RE-Ba-Cu-O (REBCO, RE is rare earth) plate consisting of several holes with different diameters made from the second-generation high temperature superconducting (2G HTS) tape is proposed. An exciting coil with iron core is located in one hole with the biggest diameter and then excites the HTS coil by the field cooling (FC) method. Based on the law of flux conservation, the principle of excitation and multistage magnetic field generation of HTS ring is presented. Numerical analyses by finite element method (FEM) are performed to verify the feasibility of the HTS magnet at 77 K. The results show that the permanent magnet model can be excited to generate a stepwise amplified magnetic field by the FC method and has the ability of long-term stable operation with persistent current mode (PCM), which can possibly be extended to practical HTS permanent magnets stacked by REBCO plates with multi- holes and magnetic fields.