# MPZ Study Detail

The quench simulation study went into the MPZ determination, Many program runs changing initial normal zone (INZ) were proceded.
 first trial second trial Next step is finding the MPZ. At first, the current was fixed at 150A and the 6K normal zone is set. How does the normal zone increase or decrease as time goes on is the expected simulation result. The first result seems to be in too large normal zone range. The normal zone decreases in the beginning but eventually propagates in all cases. Then, the current was fixed at 66A in the second trial. It goes down when initial normal zone (INZ) is small. The scanned range of INZ was too low this time. The propagation of the normal zone was not seen. Intermediate range where normal zone neither increase nor decrease is larger than expected. By these trial, it is certain that there is a critical length of initial normal zone (INZ) where the quench glows above it and shrinks below it. RRR=100 and I=132A RRR=100 and I=105A RR=100 and I=79.2A RRR=100 and I=72.6A Finally, the MPZ determination is successful. For the case RRR=100 and I=132A, the MPZ is determined as 1.1 mm. The MPZ should be the function of the current. The MPZ changed to 1.7mm for current 105A. MPZ increases as the current goes down as expected. The behavior of the model is quite reasonable. At current 79.2A, more detailed behavior of the normal zone is observed. In this case The MPZ is 2.8mm The MPZ is 3.6mm at current 72.6A in the same manner. RR=50 and I=72.6A RRR=50 and I=79.2A RR=50 and I=66A The MPZ becomes 1.15mm at the same current of 72.6A when the RRR of the copper goes down to 50. The current change affects to the MPZ. The MPZ of the RRR=50 conductor is 0.95mm at Current 79.2A The MPZ of the RRR=50 conductor is 1.35mm at Current 66A Some more data wa taken in the same way. Summarizing the above analysis, The Current dependence of MPZ is obtaind as shown in the graph. The RRR=100 conductor becomes cryostable at 63A. The dotted line is for the case RRR=50.