Simulation Analysis of the Neutral and Charged Intermediate Species Produced in the Triboplasma Using the PIC/MCC Method

Triboplasma should be one of the main causes of the tribochemical reactions. In this report the distributions and intensities of the neutral and charged radicals produced in the triboplasma generated in the rear gap of the sliding contact has been analyzed using the PIC/MCC simulation method for the tribosystem of a diamond pin with a tip radius of 300 μm sliding on a sapphire disk in ambient air. Side distribution images of three kinds of neutral radicals of N, O and O1D and an anion radical O− were analyzed. They coincided well the experimentally observed side image of the triboplasma. Further, the maximum densities and the total numbers of the intermediate particles were calculated for the neutral radicals of N, O and O1D and the charged particles of e−, O−, N2+ and O2+. They showed that both the maximum densities and the total numbers of the neutral particles of N, O and O1D are much higher than those of the charged particles of e−, N2+, O2+ and O−. The latter intensities of the charged particles were even negligibly small compared to those of neutral particles. This means that most of the particles exist in the triboplasma are neutral radicals such as N, O and O1D. This concludes that the tribochemical reactions due to triboplasma are caused mainly through the active intermediates of the neutral radicals.