LXCat is an open‐access platform (http://www.lxcat.net) for curating data needed for modeling the electron and ion components of technological plasmas. The data types presently supported on LXCat are scattering cross sections and swarm/transport parameters, ion‐neutral interaction potentials, and optical oscillator strengths. Twenty‐four databases contributed by different groups around the world can be accessed on LXCat. New contributors are welcome; the database contributors retain ownership and are responsible for the contents and maintenance of the individual databases. This article summarizes the present status of the project.

High power microwave breakdown at atmospheric pressure leads to the formation of filamentary plasma arrays that propagate toward the source. A two-dimensional model coupling Maxwell equations with plasma fluid equations is used to describe the formation of patterns under conditions similar to recent experiments and for a wave electric field perpendicular to the simulation domain or in the simulation domain. The calculated patterns are in excellent qualitative agreement with the experiments, with good quantitative agreement of the propagation speed of the filaments. The propagation of the plasma filaments is due to the combination of diffusion and ionization. Emphasis is put on the fact that free electron diffusion (and not ambipolar diffusion) associated with ionization is responsible for the propagation of the front.

During microwave breakdown at atmospheric pressure, a sharp plasma front forms and propagates toward the microwave source at high velocities. Experiments show that the plasma front may exhibit a complex dynamical structure or pattern composed of plasma filaments aligned with the wave electric field and apparently moving toward the source. In this paper, we present a model of the pattern formation and propagation under conditions close to recent experiments. Maxwell’s equations are solved together with plasma fluid equations in two dimensions to describe the space and time evolution of the wave field and plasma density. The simulation results are in excellent agreement with the experimental observations. The model provides a physical interpretation of the pattern formation and dynamics in terms of ionization-diffusion and absorption-reflection mechanisms. The simulations allow a good qualitative and quantitative understanding of different features such as plasma front velocity, spacing between filaments, maximum plasma density in the filaments, and influence of the discharge parameters on the development of well-defined filamentary plasma arrays or more diffuse plasma fronts.