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

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