Modeling of atmospheric-pressure anodic carbon arc producing carbon nanotubes

Global model of atmospheric-pressure anodic arc in helium is developed. This type of discharge is Currently used for efficient synthesis of various carbon nanostructures including carbon nanotubes. The model features include coupling between interelectrode plasma and electrodes, current continuity at electrodes, thermal regime of electrodes, and anode erosion. It is taken into account that arc radius increases linearly with the arc current according to experimental observation. Results indicate that substantial fraction of the current at the cathode is conducted by ions (0.7-0.9 of the total current). Calculated anode erosion rate and nonmonotonic voltage-current characteristic of the are predicted by the model are in agreement with experimental data. It is concluded that nonmonotonic behavior of the arc voltage can be only reproduced by considering experimentally observed dependence of the arc radius on arc current. (C) 2009 American Institute of Physics. [doi:10.1063/1.3262626]