We are often asked by potential customers, where the electron Monte Carlo approach implemented in HPEM and accessible via QVT gives an advantage in modelling plasma? Why not just use a fluid model alone?
| Fluid Model | Monte Carlo | |
|---|---|---|
| Electron Temperature | Calculated by the electron energy balance equation implying Maxwellian EEDFs | Obtained from the spatially resolved EEDFs. Accounts for non-Maxwellian EEDFs |
| Electron Impact Rates | Rates are calculated from EEDFs obtained from a global Boltzmann – Solver. Local rates are assigned according to the local electron temperature. This does somewhat account for non-Maxwellian EEDFs, however, the influence of, for example, high energy electrons in the bulk created by sheath interactions are not covered. | Rates are calculated from the spatially resolved EEDFs. This does take non-local effects such as high energy electrons created in the sheath region penetrating into the plasma bulk into account. |
| Transport Parameters | The diffusion coefficient and mobility are calculated using the local electron temperature and corresponding collision frequency from global EEDF | The diffusion coefficient and mobility are calculated using the electron temperature and collision frequency obtained from the spatially resolved EEDFs |
| Conclusion | The fluid model has only limited abilities to take non-local effects and non-Maxwellian effects into account. An example is high energy electrons created in the sheath region travelling into the bulk as they are observed in low pressure CCPs. | All parameters used in the fluid model are directly derived from the actual, spatially derived EEDFs taking non-local effects and non-Maxwellian EEDFs fully into account. |