Initial stage of fiber-form nanostructure growth on refractory metal surfaces with helium plasma irradiation

Abstract

The initial stage of fiber-form nanostructure growth on tungsten and molybdenum surfaces with helium plasma irradiation is investigated by a technique that allows time evolution of nanostructure growth to its spatial variation. The pitting of the original base surface resulting from successive hole formation is clearly demonstrated. The surface fine-grained miniatuarization proceeds with increasing hole area. Then, loop-like nano-scale structures appear with some coherency, which are thought to be precursors of fiber-form tendrils. Loop raptures and branching out are considered as possible candidates of the initial stage of nano-fiber growth. © 2014 The Japan Society of Plasma Science and Nuclear Fusion Research.