Effect of Quench Time Lag on the Succeeding Quench in the Parallel Mechanical PCS Circuit

摘要

This paper describes quench time lag property of NbTi mechanical persistent current switch (PCS) investigated by using ramp current waveforms with various sweep rates up to 10~4 A/s. Quench of the mechanical PCS is generated when the current reaches a critical value I_(TO) with a rate slower than 1 A/s. On the other hand, the quench occurs beyond I_(TO) with a time delay T_D when the current changes more rapidly. The quench time lag T_D results in the quench occurrence with a quench current I_Q which is higher than the static critical current I_(TO). T_D decreases and a resultant I_Q increases with an increase in the current sweep rate. From the computing simulation on the quench with ramp current, it can be confirmed that T_D corresponds to a time to raise the contact bridge temperature up to the critical temperature T_C due to flux flow loss.