Interface Control as a Means of Reducing Training in High Energy Physics Magnets

Superconducting magnets are critical components in particle accelerators and are used to generate and sustain the large magnetic fields needed for DOE’s High Energy Physics programs. Superconducting magnets are also commonly used in medical imaging, spectroscopy, and fusion energy applications. Current state-of-the-art Nb3Sn magnets suffer from long training cycles before stable magnet performance can be realized. The primary objective of the Phase I work is to address the interfaces within the cable and insulation system. The interaction between these systems appears to be the leading cause of magnet training and therefore the main limit in achieving ultimate magnet performance. We plan to address means of controlling the behavior at these interfaces to reduce the potential for magnet quench. Composite Technology Development, Inc. (CTD) will evaluate approaches to interfaces, primarily between the superconducting cable and insulation and between the insulation and the mandrel as they pertain to magnet training. Resin modifications such as adhesion promotors or surface energy reducing modifiers will be evaluated as will mandrel surface treatments such as mold releases. Treatments to the mandrel may be especially challenging since they must survive the Nb3Sn heat treatment process, whereas resin modifications do not have that restriction. These approaches will be evaluated through a testing program including conventional mechanical tests as well as “stack” testing that is more representative of magnet behavior. This program provides a generalized approach to reducing training of superconducting magnets through improvements by reducing the impacts of insulation cracking in the winding. This approach is also expected to benefit next-generation, higher field superconducting magnets, based on newer high temperature superconductors (HTS). Other industries and product areas that will benefit from the proposed technology include the aerospace industry (e.g., satellites, space-based antenna systems) and advanced electronics.