Modelling gas plasma interactions in driven systems

We explore numerically the impact of collisions in gas plasma systems and possible ways to exploit plasma chemistry in different experimental contexts. \textbf{Electron Avalanches}: We investigate the early stages of the initiation of a high pressure discharge paying particular attention to the production of excited neutral species. This highly non-equilibrium initiation is a Townsend-like avalanche created by electron impact ionisation and occurs on a sub-nanosecond timescale. Understanding this stage of the discharge could identify a technique for the non-steady production of metastables for high-activation energy chemistry without full plasma ignition. \textbf{Electronegative Instabilities}: Instabilities manifesting as variations in light emission and number density have been reported in electronegative discharges. Here electron attachment and detachment drives a radiative instability in a pre-formed RF discharge. We propose a simple model that captures the physics behind the experimental phenomena.