Magnetothermal instabilities in cylindrical melt-textured Y-Ba-Cu-O

The magnetothermal flux jump instabilities of the critical state in cylindrical melt-textured Y-Ba-Cu-O samples are investigated during the magnetization process. The flux jumps result in a drastic reduction of the magnetization accompanied by a strong heating of the sample. We determine the first flux jump field as function of the parameters, which influence the stability, such as the heat transfer coefficient between the surface of the sample and the surrounding, the sweep rate of the external field and the temperature of the sample. The comparison of the thermal and magnetic diffusivity of the melt-textured material indicates isothermal behavior of the flux jump scenario, supporting a dynamic stability criterion.