Microengineered Textured Armor for Plasma-Facing Components
With its low generation of radioactive waste, thermonuclear fusion is ideal for large-scale energy generation. Efforts are already in place to complete construction of the International Thermonuclear Experimental Reactor (ITER) with heavy U.S. participation. Practical demonstration of fusion technology is being pursued in the DEMO (European-led) and FNSF (U.S.-led) studies, and the development of advanced materials that can tolerate extreme plasma-generated heat flux is essential to their success. Application of nuclear fusion for cost-competitive energy generation cannot be realized until advanced plasma-facing materials and structures are developed. The specific problem addressed in this project was the mitigation of heat-induced failure, surface erosion, and surface blistering of tungsten-based plasma-facing components as a result of the interaction of tungsten with energetic helium and hydrogen isotopes. Ultramet, teaming with Digital Materials Solutions (DMS) and the University of California-San Diego (UCSD), proposed to demonstrate the initial feasibility of microengineered textured plasma-facing armor for tungsten-based components that is highly tolerant of thermomechanical stress relative to conventional smooth tungsten, and that can efficiently release implanted helium and deuterium ions without blistering. Specifically, structural open-cell tungsten foam (several millimeters thick) was diffusion bonded to the surface of tungsten, followed by chemical vapor deposition (CVD) of a high surface area textured tungsten coating throughout the foam ligament structure to volumetrically distribute incident radiation. The performance of Ultramet’s textured tungsten foam armor was evaluated through helium plasma testing at the UCSD PISCES facility and through modeling at DMS. Modeling and confirmatory test results showed that textured foam can withstand substantially greater helium fluence levels with reduced damage and possesses greater thermal stress resistance compared to smooth tungsten. The growth rate of tungsten “fuzz” was shown to be substantially lower for all textured foam armor specimens, while the net sputtering erosion was drastically reduced by a factor of 7. After continued optimization, it is anticipated that a divertor armor can be developed to substantially increase plasma-facing component lifetime. Divertor protection technology utilizing textured foams and coatings can be transferred to many other demanding applications such as cathodes used in spacecraft electric propulsion systems, which are subjected to extremely energetic plasma environments. Based on research performed by UCLA for the Air Force, fast-startup, high-current cathode technology utilizing Ultramet textured foams and coatings has the potential to provide more than an order of magnitude improvement in cathode lifetime and startup time for high-power, high-efficiency electric propulsion. The technology is also anticipated to find application in a variety of X-ray and high-energy laser applications.
- Research Organization:
- Ultramet (Pacoima, CA)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Contributing Organization:
- Digital Materials Solutions (DMS); University of California-San Diego (UCSD)
- DOE Contract Number:
- SC0017846
- OSTI ID:
- 1832491
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE-ULTRAMET-0017846-1; ULTRA-TR-18-16611
- Resource Relation:
- Related Information: Includes appendix comprising Digital Materials Solutions (DMS)' final report detailing the extensive thermomechanical and plasma damage modeling performed by DMS and the results of the helium plasma testing of Ultramet armor development specimens at the UCSD PISCES facility.
- Country of Publication:
- United States
- Language:
- English
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