Quench characteristics of Bi-2223 coil at liquid helium temperature

The quench characteristics of Bi-2223 single and four double pancake coils operating at liquid helium temperature were investigated based on experiments and numerical simulations. Broad resistive transition was observed in the double pancake coils. The Bi-2223 double pancake coil operating at liquid helium showed a slow normal zone propagation velocity. The stability margin of the coil was confirmed to be high because of the low operating temperature and a good cooling condition. The quench characteristics of a four double pancake coil system was simulated by a numerical method. It is clear that the protection resistance has a great influence on the current decay, transient voltage and hot-spot temperature.