Interface Characterization for Superconducting Magnets

The nature of the resin used in the impregnation of superconducting magnets plays a crucial role on the magnet's performance. The interfacial region between magnet constituents has been postulated as the potential region for training origin. Its characterization and analysis are therefore crucial to understand the phenomena involved in magnet training. In this paper, we focus on the development of an experimental method for the characterization of the interfacial bond strength between individual constituents normally found in superconducting magnets. The sample preparation developed for this method as well as the required hardware for testing are presented and discussed. The initial studies focus on a copper strand and different resins normally used in superconducting magnets, such as CTD-101 K, NHMFL Mix61, paraffin wax and Stycast 2850. The initial results are reported and discussed for experiments at room temperature and 77 K, analyzed based on a shear stress failure criteria, and demonstrating the low energy dissipation of the paraffin wax system that might explain the performance improvement of superconducting magnets based on this resin in terms of training.