Argon Microdischarge

This example is based on a ZDPlasKin example of an argon microdischarge at atmospheric pressure (Pancheshnyi et al., 2008). The model includes five species: Ar, Ar, Ar, Ar, and electrons. The number density versus time is shown in the plot below, with ZDPlasKin's results for comparison.

The reactions are included in the input file as shown below:


[ChemicalReactions]
  [./ScalarNetwork]
    species = 'e Ar* Ar+ Ar Ar2+'
    reaction_coefficient_format = 'rate'
    file_location = 'Example3'

    # These are parameters required equation-based rate coefficients
    equation_constants = 'Tgas J pi'
    equation_values = '300 2.405 3.141'
    equation_variables = 'Te'
    rate_provider_var = 'reduced_field'
    sampling_variable = 'reduced_field'


    reactions = 'e + Ar -> e + e + Ar+          : EEDF
                 e + Ar -> Ar* + e              : EEDF
                 e + Ar* -> Ar + e              : EEDF
                 e + Ar* -> Ar+ + e + e         : EEDF
                 Ar2+ + e -> Ar* + Ar           : {8.5e-7*((Te/1.5)*11600/300.0)^(-0.67)}
                 Ar2+ + Ar -> Ar+ + Ar + Ar     : {(6.06e-6/Tgas)*exp(-15130.0/Tgas)}
                 Ar* + Ar* -> Ar2+ + e          : 6.0e-10
                 Ar+ + e + e -> Ar + e          : {8.75e-27*((Te/1.5)^(-4.5))}
                 Ar* + Ar + Ar -> Ar + Ar + Ar  : 1.399e-32
                 Ar+ + Ar + Ar -> Ar2+ + Ar     : {2.25e-31*(Tgas/300.0)^(-0.4)}
                 e -> W                         : {1.52*(760/100)*(Tgas/273.16)*(Te/1.5)*((J/0.4)^2 + (pi/0.4)^2)}
                 Ar+ -> W                       : {1.52*(760/100)*(Tgas/273.16)*(Te/1.5)*((J/0.4)^2 + (pi/0.4)^2)}
                 Ar2+ -> W                      : {1.52*(760/100)*(Tgas/273.16)*(Te/1.5)*((J/0.4)^2 + (pi/0.4)^2)}'
  [../]
[]

Rate coefficients are separated from the reaction notation by a colon character. If a rate coefficient is enclosed in brackets, it will be added as a parsed function. (Note that this may incur a slight performance penalty, but the benefit is that any functional form may be included.) Variables that are added as constants inside the function must be noted with the equation_values parameter, and the values assigned with equation_values. Any nonlinear or auxiliary variables must be specified with the equation_constants parameter.

Argon species and electrons versus time. Solid lines are computed by CRANE, dotted lines by ZDPlasKin.

commentnote:Plot Differences

The profiles are not identical. The main difference between ZDPlasKin and CRANE is that a Boltzmann solver is not dynamically coupled to CRANE, but BOLSIG+ is coupled and run with ZDPlasKin. Instead, electron-impact rate coefficients are tabulated prior to runtime.

References

  1. Sergey Pancheshnyi, Benjamin Eismann, Gerjan Hagelaar, and Leanne Pitchford. ZDPlasKin: a new tool for plasmachemical simulations. In The Eleventh International Symposium on High Pressure, Low Temperature Plasma Chemistry (HAKONE XI). Oleron Island, France, September 2008.[BibTeX]