Quantitative imaging of carbon dimer precursor for nanomaterial synthesis in the carbon arc

Delineating the dominant processes responsible for nanomaterial synthesis in a plasmaenvironment requires measurements of the precursor species contributing to the growth ofnanostructures. We performed comprehensive measurements of spatial and temporal profiles ofcarbon dimers in sub-atmospheric-pressure carbon arc by laser-induced fluorescence.Measured spatial profiles of carbon dimers coincide with the growth region of carbon nanotubes (Fang et al2016 Carbon 107 273-80) and vary depending on the arc operation mode, which is determinedby the discharge current and the ablation rate of the graphite anode. The carbon dimer density profileexhibits large spatial and time variations due to motion of the arc core. A comparison of theexperimental data with the 2D simulation results of self-consistent arc modeling shows a goodagreement. The model predicts well the main processes determining spatial profiles of carbondimers.