Engineered Ceramic Composite Insulators for High Field Magnet Applications

72330-High field magnets used in accelerators and fusion devices are subject to high mechanical loads at cryogenic temperatures. The end parts, pole pieces, spacers, and other insulator components must withstand these loads and be capable of surviving the high reaction temperatures of the superconducting coil. The currently used, coated metal parts are mechanically acceptable, but the fragile, insulating coating limits their reliability and increases magnet fabrication costs. This project will develop novel moldable ceramic insulators for use in accelerator and fusion magnets as end pieces, pole pieces, winding mandrels, spacers, and other components. Their electrical and mechanical strengths will be high, and their thermal properties will be tailored to meet the magnet specifications for niobium tin, niobium titanium, or even high temperature superconductor magnets. These ceramic insulators will withstand the high temperature heat treatments and will be radiation resistant. In Phase I, cast ceramic insulators were fabricated. It was shown that the shape and machining of the parts could be controlled to produce high quality components, and that the cryogenic thermal expansion could be tailored over a wide range. In Phase II, improved molding techniques will be developed using traditional molds and low-cost rapid prototyping techniques. Mechanical, thermal, and electrical performance will be measured at both room and cryogenic temperatures. Manufacturing and quality control methods will be developed. Commercial Applications and Other Benefits as described by awardee: The ceramic insulators should be more robust and reliable than current materials used in high field accelerator and fusion magnet systems. More robust insulators would lower magnet production costs, enabling future devices to be constructed within budgetary restrictions. Commercial magnets also could benefit from molded insulator components, increasing their reliability at lower cost.