THE RANGE OF GIANT FLUX INSTABILITIES IN THE H-T PLANE IN HARD SUPERCONDUCTORS - CALCULATIONS AND EXPERIMENT

We have studied magnetothermal instabilities, giant flux jumps, both t heoretically and experimentally. Magnetostriction and magnetization hy steresis loops with flux jumps were calculated over a wide range of ex perimental parameters employing two critical-state models: the Kim-And erson model and the exponential model. The influence of the magnetic h istory on the flux jumps' magnetostriction and magnetization were inve stigated for the LaSrCuO single crystal. The shape of the unstable reg ion of the critical state in the temperature-magnetic field plane was constructed from calculations and experimental results. In the Kim-And erson model H-T diagrams of flux instabilities agree well with experim ental results on HTSC single-crystal LaSrCuO and experimental results on LTSC niobium.