A Monte Carlo modelling study of the electrons in the microdischarges in plasma addressed liquid crystal displays

Fluid models for gas discharges are based on restrictive assumptions for the electron-energy distribution function (EEDF). In this work we investigate the validity and consequences of these assumptions for discharges occurring in plasma addressed liquid crystal (PALC) displays. For this purpose we have developed a Monte Carlo model for electrons, which we compare to a fluid model. A direct current (DC) discharge and afterglow in the PALC geometry are considered, with helium as a discharge gas. In the discharge, the EEDF calculated with the Monte Carlo model displays several non-equilibrium phenomena, such as peaks of fast electrons that have undergone none or only a few collisions, and the absence of a high-energy tail. Although these features are not incorporated in the fluid model, both models lead to virtually the same electron density profile. However, the ionization rate obtained with the Monte Carlo model is spread out over a larger region than the ionization rate in the fluid model. The Monte Carlo calculations reveal that the electrons in the afterglow have a highly non-equilibrium nature, and require a special treatment in the fluid model.