Abstract View
The Study of Inelastic Collisions in Electrical Mobility by Coupling MD to Kinetic Theory Physical Gas Modelling
CARLOS LARRIBA-ANDALUZ, Viraj Gandhi, IUPUI
Abstract Number: 127
Working Group: Aerosol Physics
Abstract
One of the least understood problems when trying to calculate electrical mobility in polyatomic ions and charged nanoparticles is the understanding of how the size, mass and structure of the gas and ion affect the momentum transfer. This effect is known to be manifested differently for different gases. For example, He gas tends to have collisions that are more specular and elastic. However, air or N2 tend towards more diffusive and inelastic collisions. While the diffuse vs. elastic nature of the gas collisions can be attributed in part to the potential interaction (4-6-12), the elastic vs. inelastic condition is not that well understood. The reason has to do with the fact that not only the strength of the field must be taken into account, but also the energy transferred into the internal degrees of freedom of the molecule itself.
In this work, we couple the solution of the Boltzmann equation to the ion velocity distribution in a gas environment in the free molecular regime with a Molecular Dynamics simulation in order to study the effect that different gases and ions have on the elastic vs. inelastic nature of the interaction. By considering the two-temperature theory, an effective temperature may also be used to describe how this effect changes at different temperatures and fields. This is the first time that this coupling has been accomplished to this degree of detail, and it can be the basis to better understand nucleation, coagulation, collision induced dissociation, and mobility and diffusion of ions.