NONLINEAR THERMAL RELAXATION WAVES IN HIGH-TC SUPERCONDUCTORS CARRYING CURRENT

In addition to the conventional wave of normal zone propagation, two new types of nonlinear heat waves have been predicted theoretically in high T(c) nitrogen-cooled superconductors under current and the conditions under which they occur are described. These waves are characterized by a concurrent relaxation of the electric fields and hence they define the stability of high T(c) superconductors. Within the scope of a phenomenological approach, the relationship between transport current and the velocity of transient boiling region boundary motion has been derived from the non-stationary heat transfer equation. The effect of the temperature dependence of the ceramic's resistivity on normal zone dynamics has also been analysed.