Ultrahigh Heat Flux Plasma-Facing Components for Magnetic Fusion Energy, Phase II

The potential economic, environmental, and strategic benefits associated with the development of magnetic fusion energy are enormous. However, fusion technology cannot be realized without the development of advanced materials that allow operation under the high heat flux and radiation conditions necessary for maintaining burning plasmas. This project will develop and demonstrate innovative materials and components to allow extended steady-state operation of fusion devices at heat flux levels greater than 15 MW/m, with brief, more intense pulses of energy deposition during plasma disruptions. Chemical vapor deposition/infiltration will be used to produce refractory materials and structures for this application that cannot be fabricated by conventional processing techniques. In Phase I, preliminary design work was performed on an innovative, ultrahigh-heat-flux plasma-facing component composed of a thin tungsten shell integrally bonded to an open-cell tungsten foam core. Tungsten-foam/tungsten-shell heat exchangers were fabricated using chemical vapor deposition. High-heat-flux testing demonstrated an outstanding heat flux capability of 22.4 MW/m at 4 MPa pressure and 27 g/s of helium flow, a world-class heat flux for a helium-cooled refractory device. In Phase II, ultrahigh-heat-flux capabilities (>20 MW/m ) will be achieved by further optimizing the plasma-facing component design; size scalability of a unique modular channel concept operating at very low pressure drop will be demonstrated; and high-heat-flux capability limits will be established through an expanded matrix of tests. Commercial Applications and other Benefits as described by the awardee: Heat exchangers with high-heat-flux capability and low-coolant pressure drop are critical for efficient heat transfer in nuclear power generation plants (fission and fusion), which remain the only practical alternative to fossil fuel energy sources. Other areas of commercial application are high-Mach combined-cycle propulsion and airframe systems. In addition, the automotive industry is turning to the use of refractory materials for high-efficiency, low-heat-rejection engines and exhaust systems, which have the potential to significantly reduce fuel consumption and unwanted emissions.