Heat propagation and stability in a small high T-c superconductor coil

Using a Bi-based small high T-c superconductor (HTSC) coil, we have studied its stability against a local disturbance and current-induced quench in th e helium gas cooling condition. While the stability margin of HTSC coil aga inst a local disturbance was very large, quench current was limited by a ca tastrophic temperature rise which originated from the nonlinear characteris tic of the Joule heating. The crucial parameter for the quench becomes the nonlinear resistance in HTSC as a function of temperature and transport cur rent. It has been shown that the dynamic characteristics of the quench can be described quantitatively by the simplified one-dimensional heat balance equation. (C) 1998 Elsevier Science B.V. All rights reserved.