Source location of quenches in SSC dipole magnets

Superconducting-to-normal transitions in two 16.6-m-long superconducting dipole magnets for the Superconducting Supercollider (SSC) were monitored with six axially-distributed acoustic emission (AE) sensors. The origin of each quench was determined by examination of AE data captured at quench. In one magnet, these data showed that the first few quenches started from various locations along the magnet while most later quenches started from the feed end. In the second magnet, most of the spontaneous quenches started near the feed end of the magnet. By supplementing AE data captured at quench with AE attenuation data taken at room temperature, it was determined that, of these, more than half started in the region within 25 cm of the feed end. The results are in general agreement with temperature and pressure post-quench histories.