EFFECTS OF TRANSVERSE HEAT-TRANSFER ON NORMAL ZONE PROPAGATION IN METAL-CLAD HIGH-TEMPERATURE SUPERCONDUCTOR COIL TAPE

The effects of transverse heat transfer on the dynamic evolution of the normal zone in a composite tape made of YBCO superconductor with silver cladding as stabilizer are examined numerically. The numerical model solves the conjugate two-dimensional transient heat equation coupled with current sharing between clearly segregated superconductor and stabilizer. Heat removal in the transverse direction is characterized by a heat conductance imposed on the stabilizer's outer surface. The computational results indicate that the present tape configuration is intrinsically much more stable against a pulse disturbance that its counterparts with volume-averaged material properties and treated one-dimensionally. Conventional one-dimensional analyses for magnet stability have been demonstrated to be too conservative in many respects. The normal zone propagation characteristics and the detailed distribution of heat generation in the composite depend strongly on both the transverse heat transfer and the magnitude of operating current. Ohmic heating in the stabilizer can be very significant, especially for cases with low heat conductance and/or large operating current.