Investigating the flux jump behaviour during single waveform control pulsed field magnetization of GdBaCuO superconducting bulk

Abstract

We aimed to improve the trapped magnetic flux density obtained with a waveform control pulsed field magnetization (WCPM) by using a negative feedback control of the magnetic flux density on the growth sector boundary of a GdBaCuO superconducting bulk sample. The WCPM method with negative feedback control has previously shown that it could help increase the trapped magnetic flux density, compared to conventional passive pulsed flux magnetization, if the magnetic field penetrates the bulk centre substantially using a flux jump. The flux jump sometimes greatly changes the magnetic and thermal state of the bulk, which limits the maximum trapped magnetic field. The active control method of the applied magnetic field helps to overcome this limit if the control conditions are appropriate. While searching for the ideal control conditions of the WCPM, the magnetization characteristics have been investigated. We found that the flux jump, which assists the flux in penetrating the centre of the bulk, can be “slowed down” thanks to the negative-feedback WCPM. This operation helped to decrease the heat generated by the moving flux inside the bulk and reduced the temperature rise, which contributed to the increase of the trapped magnetic flux density.