Influence of anode surface temperature in a continuously-fed arc discharge depositing carbon nanotubes

Mass production of carbon nanotubes (CNTs) by a cost effective process is still a challenge for further research and application of CNTs. The group has focussed on the deposition of CNTs on a continuously-fed carbon substrate via arc discharge at atmospheric pressure. This process produces MWNTs using carbon from the substrate. The method differs in other respects from the conventional batch arc discharge method by using lower currents (< 20 A) and larger inter-electrode gaps. To help define the local conditions of nanotube growth, the substrate surface temperature (T_s) was measured by optical pyrometry. Here, it was reported the influence of inter-electrode gap, substrate velocity and arc current on this temperature. It was found that carbon nanotube growth is favourable over a certain temperature range and retention time in the arc. To further understand the effect of arc parameters, a computer simulation to model the arc plasma was used. Computational fluid dynamic (CFD) software, Comsol Multiphysics, was used to simulate the temperature distribution and flow properties of the arc plasma. It was found necessary to include dusty plasma conductivity near to the electrodes to adequately represent observed arc behaviour.