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Nuclear—Foaming at the heat

An ORNL-developed graphite foam, which could be used in plasma-facing components in fusion reactors, performed well during testing at the Wendelstein 7-X stellarator in Germany. Credit: Max Planck Institute of Plasma Physics

Scientists have tested a novel heat-shielding graphite foam, originally created at Oak Ridge National Laboratory, at Germany’s Wendlestein 7-X stellarator with promising results for use in plasma-facing components of fusion reactors. The lightweight foam—developed in the 1990s and used by NASA for space applications and at the Large Hadron Collider—provides excellent thermal conductivity at low temperatures and equally impressive thermal insulation at high temperatures. ORNL scientists added a tungsten coating that tailors the foam conductivity and improves the integrity when facing potential fusion plasma temperatures near 100 million degrees Kelvin. “The foam components have all the hallmarks of an engineered materials system,” ORNL’s Dennis Youchison said. “It’s easy to fabricate, inexpensive, reliable and compatible with the plasma. If you’re looking down the road to commercial fusion power, advanced materials like these are needed.” The team is planning additional high heat-flux testing and tokamak plasma exposures.