Modeling Nanoparticle Charge Distribution in the Afterglow of Non-Thermal Plasmas And Comparison With Measurements

A modeling approach to investigate the charge distribution of particles exiting flow-through non-thermal plasmas and the afterglow region is presented. Understanding the effect of plasma concentration, discharge parameters, plasma temperature, diffusivity of charged species, and reaction rate constants in the resulting particle charge distributions is critical to material synthesis and relevant applications. In this work, ion-flux coefficient models developed by analyzing particle-ion trajectories calculated using Langevin Dynamics based simulations are incorporated into species transport equations for ions, electrons, and charged particles in the afterglow. The developed collision rate models are validated by comparing particle charge predictions against measured values in stationary, non-thermal DC plasmas from past PK- 4 campaigns 1 , 2 . The atmospheric-pressure flow-through plasma experiments by Sharma et al. 3 to probe particle charge distributions are modeled using experimentally validated particle-ion collision rate constant models and the calculated charge fractions are compared with measurements. The comparisons reveal that the plasma concentration and gas temperature in the afterglow region critically influence the particle charge and the predictions are generally in qualitative agreement with the measurements 4 . Modeling assumptions and challenges will be highlighted.