Abnormal quench process with very fast elongation of normal zone in multi-strand superconducting cables

An abnormal quench process with apparent high propagation velocity of the normal zone, ·fast quench', was studied in relation to electromagnetic and thermal couplings among strands for multi-strand superconducting cables. The quench process was numerically evaluated by simultaneous equations of heat balance and equivalent electrical circuit of the multi-strand cables. Experimental results are well explained by the numerical simulation concerning threshold current of the fast quench for a two-strand cable. The quench process of a six-strand cable was also calculated numerically and the relation between the fast quench and current commutation among strands is discussed.