New Highly Radiation-Resistant Insulation Process for High Field Accelerator Magnets

78092S High performance, wind-before-react magnet insulation systems, which enable the use of thinner insulation for close packing of the conductor and can withstand high radiation loads, are needed for future accelerator magnets such as the Large Hadron Collider project. However, the most radiation-resistant ceramic insulation systems currently available for use as wind-and-react insulation have been developed in tape form, which causes increased thickness buildup within the insulation layer. This limitation forces the designer to choose between lower radiation performance or less conductor, leading to lower field magnets. Braided ceramic-based prepreg insulation, stable at the superconductor processing temperatures, would eliminate this problem. Therefore, this project will develop an entirely new insulation process, in which a ceramic fiber is braided directly onto the superconducting cable and then pre-impregnated with a ceramic matrix, forming a radiation resistant insulation capable of being co-processed with Nb3Sn superconductor. When combined with an organic cyanate ester resin, this insulation system would result the most radiation resistant insulating materials currently available in a form that would allow a very thin insulation layer and enable close conductor packing. Phase I will develop and evaluate a pre-impregnated ceramic sleeve braided directly onto the superconductor, forming a high strength ceramic insulation. Along with the braiding process, a ceramic sizing will be developed that can be applied to the ceramic fiber thereby eliminating the organic sizing that must be burned off during the superconductor heat treatment. A process to enable the pre-impregnation of a ceramic matrix onto the braided superconductor will also be developed. The ceramic insulation, combined with a cyanate ester resin, will be evaluated for use and compatibility in high field accelerator magnets through the fabrication and mechanical testing of conductor/insulation stack specimens. Commercial Applications and Other Benefits as described by the awardee: The high temperature stability and radiation resistance of a thin ceramic insulation should eliminate complex coil fabrication steps, thus lowering fabrication costs and allowing higher operating fields. Applications such as high field magnets, fusion magnets, and medical Magnetic Resonance Imaging instruments would become more viable with improved magnet processing, higher strength, and improved reliability. Higher efficiency transformers that are resistant to heat damage would also become viable.