- Yevgeny Raitses, Princeton Plasma Physics Laboratory, Princeton, New Jersey
This work reviews experimental and theoretical studies of arc-based synthesis of carbon and boron nitride nanomaterials conducted at the PPPL LPN. Applying a set of the developed in situ diagnostics of plasma and nanoparticles, our synthesis experiments revealed that the atmospheric pressure DC arc forms a highly inhomogeneous plasma consisting of distinguishable regions with different dominant species, including ions, atoms, molecules and clusters, and nanoparticles. Experimental and modeling results demonstrate that different steps of the synthesis process, including generation of a feedstock of atomic and molecular species and ions, formation of larger molecules and clusters, growth of nanotubes, and agglomeration of nanoparticles in large particles and bundles occur in these different regions of the arc discharge. For example, the synthesis feedstock of atomic species is formed in the hot arc core where the plasma is at thermal equilibrium, while the formation of molecular species, nucleation and growth of nanotubes occur in colder nonequilibrium plasma of the arc periphery. Charging of nanoparticles, polarization in electric field and arc instabilities were shown to affect the growth of nanotubes. In order to facilitate experimental validation of predicted growth mechanisms of nanotubes in high pressure plasma environments we proposed a controllable synthesis experiment which will be discussed in this talk.