Current diffusion effects on the performance of large monolithic conductors

This paper describes a mathematical model developed to study the effects of slow current diffusion on the performance of large monolithic conductors. The model is based on the numerical solution of the coupled heat and magnetic flux (current) diffusion equations in a slab geometry. The model is used to calculate stability margins for large monoliths; relatively low margins are predicted. Normal zone propagation velocities are also calculated. It is shown that for large monolithic conductors, when current diffusion times are long, a propagating normal zone can be established even in a conductor designed under the traditional cryostability criterion. Examples are given to illustrate the fact that for large monoliths, cryostability must be assigned a new meaning (or lack of)