Particle Tracing Module Updates

New Option for Friction Force Calculation in Weak Electric Field Limit

For users of the Particle Tracing Module, with COMSOL Multiphysics® version 6.2 it is now possible to accurately calculate the friction force for charged particles in the weak electric field limit. The weak electric field limit is reached when the ratio of the magnitude of the electric field to the background gas number density is small. In this scenario, the kinetic energy of charged particles is mostly thermal; that is, the thermal energy of charged particles is much greater than the energy acquired from the electric field between collisions of the particles and the background gas molecules. The Friction Force feature in the Charged Particle Tracing interface has a new option for calculating the friction force in the weak electric field limit using the Mason–Schamp equation.

The COMSOL Multiphysics UI showing the Model Builder with the Friction Force node highlighted, the corresponding Settings window, and an ion funnel model in the Graphics window.
Trajectories of positive ions in an electrodynamic ion funnel. The contour on the background shows the combined DC and AC potential in the funnel.