EFFECTS OF THERMAL SHUNT TO SUBSTRATE ON NORMAL ZONE PROPAGATION IN HIGH T(C) SUPERCONDUCTING THIN-FILMS

Normal zone propagation is examined in high T(c) superconducting (HTSC ) thin films grown on Al2O3 substrates. The transient heat equation is solved by a two-dimensional numerical model. In fact it appears that conventional analyses are inappropriate for this kind of HTSC system. The computational results indicate that the substrate, with its high v alue of thermal conductivity, is an efficient thermal shunt for the no rmal zone propagation in the thin film. This effect induces a signific ant increase in the quench velocity. Furthermore, the substrate is a g ood stabilizer: the minimum quench energy of the system is high for a current I far from the critical value I(c); in addition, the HTSC film is cooled efficiently. Thus the HTSC thin films deposited on a Al2O3 substrate are very stable against a pulsed disturbance or an accidenta l transition (I much less than I(c)).