Formation of different arc-anode attachment modes and their effect on temperature fluctuation for carbon nanomaterial production in DC arc discharge

Diffuse and multiple arc-anode attachment modes were observed when using DC arc discharge to prepare carbon nanomaterials. The effects of arc current and electrode gap distance on the formation of different attachment modes were investigated. The formation of different attachment modes is explained by the competition of the cathode jet and the anode jet. During the arc discharge, the surface temperature of the carbon electrode was measured by two-colour pyrometry combined with a high-speed camera employing appropriate band-pass filters. The relationship between the arc-anode attachment mode and the temperature fluctuation of the electrode surface was investigated. Due to the unbalanced Lorenz force, the rotation of arc spot was severe in diffuse arc-anode attachment mode, which led to relatively large temperature fluctuations on the anode surface, resulting in low purity of synthesised multi-wall carbon nanotubes on the anode deposit. (C) 2017 Elsevier Ltd. All rights reserved.