Swarm transport simulations track individual charged particles as they move through a neutral gas or liquid, predicting transport quantities such as drift velocities, ionisation coefficients and lifetimes. State of the art codes for both Monte Carlo simulation and Boltzmann equation solution of transport in gases have proven their high accuracy and are now as good as their inputs.
In contrast, liquids or even dense gases present many features that make the life of a theorist difficult: a) the e+ and e- is a “quasi-free” particle, as it is never far from any neutral particle; b) scattering from a single neutral is always “screened” by the surrounding neutrals; c) the medium has short-range but no long-range order, precluding a solid-state approach; d) the medium can respond to the e± giving rise to self-trapping.
I will overview the attempts co-workers and I have been making to explain and simulate these effects and point out where the main challenges remain.
Dr Danny Cocks started his research career in 2007 with a PhD at James Cook University in Townsville. He has jumped fields between diatomic collisions of He* in his PhD, to many-body simulations of ultracold atoms in optical lattices when at the Goethe University in Frankfurt, returning to Australia in 2013 to swarm transport physics. Danny came to the ANU as a DECRA Fellow in September 2017 to investigate solvation mechanisms of light particles in liquids.