afivo-streamer 1.1
1D/2D/3D streamer simulations with AMR
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By default, the "classical" fluid model is used, which is a drift-diffusion-reaction model with the local field approximation. The equations solved in this model are:
\[ \partial_t n_{e} + \nabla \cdot \boldsymbol{\Gamma}_e = S_\mathrm{chem} + S_\mathrm{ph}, \]
with the electron flux given by
\[ \boldsymbol{\Gamma}_e = -\mu_e \boldsymbol{E} n_e - D_e \nabla n_e. \]
In these equations, the symbols have the following meaning:
With the local field approximation (LFA), electron transport coefficients are assumed to depend on the local electric field strength. In the code, so-called reduced transport coefficients are used. For example, the input data for the electron mobility is a table with rows
\[\mathrm{E/N}, N \, \mu_e(\mathrm{E/N}),\]
where \(N\) is the gas number density and \(\mathrm{E/N}\) is the reduced electric field in Townsend. The code then interpolates this table (see Transport data interpolation) and multiplies with the inverse of \(N\) to obtain the actual electron mobility.
The equation for ions looks similar to that of electrons,
\[ \partial_t n_{j} + \nabla \cdot \boldsymbol{\Gamma}_j = S_\mathrm{chem} + S_\mathrm{ph}, \]
but there are a couple of differences:
input_data%mobile_ions
and input_data%ion_mobilities
, then the ion flux is computed as \(\boldsymbol{\Gamma}_j = \pm \mu_j \boldsymbol{E} n_e\), with the sign depending on the ion chargeNeutrals evolve only due to chemical reactions
\[ \partial_t n_{j} = S_\mathrm{chem}. \]
An experimental feature is the use of a fluid model with an energy equation. In this case, transport and reaction data is interpolated based on the local mean electron energy. The code can automatically convert input data to this format.
The use of a different models is controlled by the following code:
TODO