Statistical estimation of quench characteristics of quadrupole magnets

Quench tests of 9 quadrupole magnets for the TRISTAN accelerator were performed at the National Laboratory for High Energy Physics (KEK). Those magnets, with same specifications, had different training characteristics. Each magnet has 4 coils of the same winding configuration connected in series, and, in total, quench behaviors of 36 coils of the same configuration were obtained. Quenches were considered to be caused by conductor motions. In the paper, we explain the training behavior of the coils based an our previously derived theory which statistically estimates the expected number of quenches for the magnet current to reach a certain value. The theoretically estimated results are compared with the experimental results and the validity of our theory is discussed. It is also shown that the theory is useful for designing stable and high-current density magnets.