Structural Mechanics Exploration for Multicomponent Superconducting Solenoids by Hoop Strain Tests During Cooling and Excitation

The hoop stress/strain distribution is one of the key issues for construction of a high field, low temperature, and multicomponent superconducting solenoid magnet. Usually, the multicomponent solenoids belong to a multilayer composite structure, thus the change of hoop thermal strain during cooling is complex. On the other hand, the theory formula is widely used for the electromagnetic stress calculation of the coil, due to its simplicity. However, the assumption of this calculation makes it impossible to consider the effects of multifield, on stress of the coil. So, all kinds of stress/strain need be well explained by fine strain measurements. In this work, the mechanics characteristics of two multilayer coils in the multicomponent magnet, which were wound using NbTi/Cu and stainless steel wires, by hoop strain tests have been explored during cooling and excitation. According to the measurements of hoop strain, the structural mechanics of multicomponent superconducting solenoids were evaluated during the above two physical processes. The uniform of prestressing tension exerted during wounding can also be estimated by the recoverability of the solenoids using hoop stress measurements. The validness of the experimental methods was also confirmed by comparison with analysis results, which were obtained considering coupled and multilayer effect for the multicomponent superconducting coils. Moreover, the test method and numerical procedures for the hoop strain were also described and discussed.