Abstract
The energy counting rate of acoustic emission (AE) has been measured as a function of energizing current for several dry wound superconducting solenoid in order to pursue the frictional motion of the conductor during the energization. A simple theory based on the frictional motion predicts that the AE rate increases monotonically with increasing current. This has been confirmed by the experiment for some test coils. Some practical magnets, however, exhibit different behaviors, depending on the type of winding: layer winding and pancake winding. For the layer wound coils, the AE rate has a peak in the high current region when the current is increased. For the pancake wound coils, the AE rate has a peak in the low current region. These behaviors are also discussed on the basis of the conductor motion.
