Arc tracks on nanostructured surfaces after microbreakdowns

19th Conference on Plasma Surface Interactions

Sinelnikov, D.^1 ; Bulgadaryan, D.^1 ; Hwangbo, D.^2 ; Kajita, S.^3 ; Kolodko, D.^1 ; Kurnaev, V.^1 ; Ohno, N.^2

National Research, Nuclear University, MEPhI (Moscow Engineering Physics Institute), 31 Kashirskoe highway, Moscow

115409, Russia^1

Graduate School of Engineering, Nagoya University, Nagoya

464-0803, Japan^2

Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya

464-8603, Japan^3

关键词: Arc ignition;    Breakdown currents;    Helium plasmas;    Low current arc;    Metallic surface;    Nanostructured surface;    Thermonuclear device;    Unipolar arcs;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/748/1/012012/pdf
DOI  :  10.1088/1742-6596/748/1/012012

来源: IOP

【 摘 要 】

Studying of initial steps of unipolar arc ignition process is important for reduction of probability of arcing between the plasma and the wall in thermonuclear devices. Tungsten nano-fuzz surface formed by helium plasma irradiation at high fluences and temperatures is a perfect material for arc ignition. Snowflake-like craters were detected on the fuzzy surfaces after short micro-breakdowns. Such sort of craters have not been observed before on any other metallic surfaces. These specific traces are formed due to unique properties of the fuzz structure. The nano-fuzz could be easily melted and vaporized by micro-breakdown current, due to its porosity and bad thermal conductivity, and formation of low conducting metallic vapour under the cathode spot causes discharge movement to the nearest place. Thus, even low current arc can easily move and leave traces, which could be easily observed by a secondary electron microscope.