Strong Coulomb coupling influences ion and neutral temperatures in atmospheric pressure plasmas

Molecular dynamics simulations are used to model ion and neutral temperature evolution in partially-ionized atmospheric pressure plasma at different ionization fractions. Results show that ion-ion interactions are strongly coupled at ionization fractions as low as 10(-5) and that the temperature evolution is influenced by effects associated with the strong coupling. Specifically, disorder-induced heating is found to rapidly heat ions on a timescale of the ion plasma period (similar to 10 s ps) after an ionization pulse. This is followed by the collisional relaxation of ions and neutrals, which cools ions and heats neutrals on a longer (similar to ns) timescale. Slight heating then occurs over a much longer (similar to 100 s ns) timescale due to ion-neutral three-body recombination. An analytic model of the temperature evolution is developed that agrees with the simulation results. A conclusion is that strong coupling effects are important in atmospheric pressure plasmas.

Automated summary

This study uses molecular dynamics simulations to investigate the temperature evolution of ion and neutral particles in partially-ionized atmospheric pressure plasma. The results reveal that ion-ion interactions are strongly coupled even at very low ionization fractions, and the temperature evolution is influenced by these strong coupling effects.