Formed Membrane Target Components for Inertial Confinement Fusion and Inertial Fusion Energy

72259-The future of inertial fusion energy depends upon the successful demonstration of ignition and gain. Ignition and other inertial confinement fusion experiments require thin, shaped membranes for target components. In most target concepts, the spherical fuel capsule is suspended in the middle of a cylindrical shell or hohlraum. The capsule must be accurately located within a few microns by the capsule support: two ultra-thin membranes that must possess high strength, high radiation resistance, and good cryogenic properties. While polyimide can meet all of the performance requirements, no methods are currently available for producing the complex shapes needed for these applications. This project will develop technology for forming polyimide films, 0.03-5.0 microns thick, into shapes needed for ignition targets and for a variety of inertial confinement fusion and inertial fusion energy applications. During Phase I, high-strength polyimide films were successfully formed into the hemispherical and conical shapes required for capsule supports for ignition and heavy ion fusion targets. Two processes, ultrathin pressure-forming and pressure-forming with reflow above the glass transition temperature, emerged as viable processes for achieving e a variety of forms in polyimide membranes. Complementary measurement techniques were developed to provide a predictive capability for determining the formed film thickness and strength. Phase II will extend the forming process in two ways: (1) to thinner films to optimize the capsule supports needed for ignition; and (2) to accommodate more shapes needed for other fusion science and energy applications. Formed membranes will be optimized for enhanced performance, and the precision assembly of ignition targets that incorporate the new capsule supports will be demonstrated. Commercial Applications and Other Benefits as described by awardee: The polyimide forming process should provide low cost target components for a variety of inertial fusion applications. In addition, shaped polyimide components may find use in other applications such as insulation in super conducting magnets, miniature pressure transducers or flexible electronics.