Molecular Dynamics Simulations of Diffusion in Atmospheric Pressure Plasmas *

Ion diffusion in the presence of other ions, electrons, and neutrals is important in regards to timescales for discharge evolution and for determining the fields which drive plasma chemistry.  We apply molecular dynamics simulations to show that strong Coulomb coupling can influence diffusion coefficients at atmospheric pressure plasma conditions. This is done by computing the radial distribution functions and interdiffusion coefficients over a range of conditions relevant to atmospheric pressure plasmas. The simulations applied a model plasma utilizing the Lennard-Jones potential for neutral-neutral interactions, the charge induced dipole potential for charge-neutral interactions, and Coulomb potential for charge-charge interactions.  Since existing kinetic theories are not valid at strong coupling conditions, the simulation results motivate that there is a need for generalized kinetic theories that accurately model charge particle transport in atmospheric pressure plasmas.