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Washington, DC, United States

Gillman E.D.,National Research Council Postdoctoral Associate | Amatucci W.E.,National Research Council Postdoctoral Associate
Physics of Plasmas | Year: 2014

These experiments utilize a linear hollow cathode to create a dense, rectangular plasma sheet to simulate the plasma layer surrounding vehicles traveling at hypersonic velocities within the Earth's atmosphere. Injection of fine dielectric microparticles significantly reduces the electron density and therefore lowers the electron plasma frequency by binding a significant portion of the bulk free electrons to the relatively massive microparticles. Measurements show that microwave transmission through this previously overly dense, impenetrable plasma layer increases with the injection of alumina microparticles approximately 60 μm in diameter. This method of electron depletion is a potential means of mitigating the radio communications blackout experienced by hypersonic vehicles. © 2014 U.S. Government. Source

Love O.,National Research Council Postdoctoral Associate | Kidwell D.A.,U.S. Navy | Epshteyn A.,U.S. Navy
Materials Research Society Symposium Proceedings | Year: 2013

Few techniques are available to systematically synthesize and characterize metal particles below 1nm in size. We build nanoparticles in an atomically defined manner through the use of a high-fidelity molecular container we call an atomic metron, which is used to select and count the metallic ions that will make up the resultant nanoparticle. After a defined number of ions are selected, the metron may be spatially isolated and the metallic ions reduced to an isolated nanoparticle. Each step in the process is characterized via analytical methods. AFM is used to demonstrate the formation of sub-nanometer particles. The counting of atoms, isolation, and formation of nanoparticles, shows high potential for easy synthesis of sub-nanometer particles with fine control over the number of atoms in each particle. © 2013 Materials Research Society. Source

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