Author: Tom Wijnands, Sam Borkent
Based on 'Numerical modelling of the plasma plume propagation and oxidation during pulsed laser deposition of complex oxide thin films', 2020, by T. Wijnands, E.P. Houwman, G. Koster, G. Rijnders, and M. Huijben.
The original script by Tom Wijnands modeled the propagation of a PLD plasma plume in 2D as result of ablation of a single crystal TiO2 target; initial ablation is not included. Rewritten and extended by Sam Borkent to improve usability and performance and to support targets of any composition containing species of any mass.
- The laser spot is assumed to be square, resulting in a circular plasma cross-section.
- The background gas starts out with zero velocity. The room temperature velocity is around 400 m/s, which is two orders smaller than the plasma particle velocities (~10^4 m/s). The particles in the background gas do not have a preferential direction, so their net velocity is zero.
- All collisions are head-on: collisions at random angles in all directions cancel.
- There is no net exchange of particles between angular bins: the number of particles entering and leaving each angular bin each time step is similar.
- Collisions of species with the same mass are neglected, as for completely elastic collisions they would interchange velocities, resulting in no net change of density.
- Particles are assumed static if their velocity is lower than the velocity required to travel one radial bin in one time step.
- Oxidation only occurs with the background gas, not with plasma particles. In non-oxygen background gasses the material oxidizes at the substrate surface solely from oxygen originating from the target.
- A sole particle can only undergo one collision per time step, which is valid for sufficient resolution if collisions between plasma particles are neglected.
- Background gas particles can have possess every velocity and can be modeled similar to plasma species.
- Double matrices are used for all data instead of structs, which improves performance and makes it easier to acces specific data.
- The code was written to be general purpose, so it works for any material, instead of only for TiO2.
- Adjusted collision rate calculation, and included a velocity weight term, so collisions with slower moving particles are more likely than collisions with faster moving particles.
- Implemented multiple initial velocity distributions, including a Maxwell- Boltzmann distribution, which is more physically accurate than a Gaussian distribution.
Follow MATLAB style guidelines v1.3
- bg : Background
- bin : Computational bin with similar position and velocity
- n : Number of particles/bins
- velo : Velocity
- uc : Unit cell