Visualization of the Field Penetration at the Shielding Current Break and Its Restoration in the Pulse Magnetized YBCO Ring

The Hall scanning method was used to measure the distribution of the trapped magnetic field above the melt grown high temperature superconducting (YBCO) ring at various modes of the pulsed field magnetization. The scan detects the ring’s sector with a small trapped magnetic field after pulse with a short duration (14 ms) of sufficient amplitude (μ0На > 0.86 T). The residual field in the entire ring hole is also very low. Under these conditions of magnetization, the screening current is observed to break down in a certain region of the ring. This sector of the current break (SCB) arises as the result of the local overheating and the destruction of superconductivity. But in the rest (larger) part of the ring, the trapped magnetic field is significant since high current densities remain due to its weak heating. If descending time of the magnetizing field is increased from 7 ms to sufficiently large values > 100 ms, then the SCB has time to cool and the irregularity of the trapped magnetic field in the SCB disappears.