binaryIonization

binaryIonization

Works with VSimPD and VSimPA licenses.

Models the electron-impact ionization of a kinetically neutral gas species. In the process, the incident electron is scattered and loses the energy of the secondary electron created.

The builtIn collisional ionization rate in Vorpal is [SVS82]:

\[C_i = A_{col} T^{1/2}\exp(-T_{col}/T) \left(1+0.1 T/T_{col} \right)^{-1}\]

where \(T=0.5mv^2\) is the temperature in K, with \(v\) the relative velocity of the two particles interacting. The coefficients \(A_{col}\) and \(T_{col}\) are calculated in [SVS82], and must be defined in the input file.

Note

This feature replaces the ionization feature, which was previously implemented in the Collision feature.

binaryIonization Parameters

crossSection (string, optional, default = builtIn)

Cross-section to be used in the interaction. Possible values are builtIn or functionDefined. See below for required parameters for each choice.

electrons (string)

Name of the impact electron species.

intElecMass (real, optional)

Mass of the interacting electron. Default value is the mass specified in the species block.

inSpecies (string)

Name of the background gas species to be ionized.

outSpecies (string)

Name of the ion species resulting from the ionization of inSpecies.

speciesName (string)

Name of the atomic element involved in the ionization process.

thresholdEnergy (real)

Ionization threshold energy used to calculate the energy of the secondary electron.

builtIn Parameters

Please see Types of collisions for the available builtIn gases.

The builtIn option is based on the data from [SVS82]. For Xe ionization, the cross-section data is based off [AMMS00].

If the builtIn cross-section type is used the following parameters must be set:

Acol (real)

Coefficient used in the calculation of the ionization rate. This parameter can be found in tables in the paper by [SVS82].

Tcol (real)

Coefficient used in the calculation of the ionization rate. This parameter can be found in tables in the paper by [SVS82].

functionDefined Parameters

If the functionDefined cross-section type is used, the following parameters must be set:

OAFunc (block, required)

An OAFunc block of name crossSectionFunc must be used inside the Interaction block. The OAFunc block allows the user to define its own cross-section for the interaction, either through a two-column data file or through an expression. The kinds of OAFunc available for this interaction are interpolatedFromFile, LXcatFile, or expression. The OAFunc must return the value of the cross-section in m².

Please see OAFunc Block for more information on the OAFunc block.

crossSectionVariable (string, optional, default = velocity)

Used in the case when an OAFunc function is given for the cross section to specify whether the parameter of the function is either the:

• Relative collision velocity magnitude of the incident particle in m^-1: crossSectionVariable = velocity

• Kinetic energy of the incident particle in eV: crossSectionVariable = energy

Example binaryIonization Block

<Interaction ionization>
  kind = binaryIonization
  electrons = electrons
  intElecMass = 9.1093896999999993e-31
  speciesName = oxygen
  inSpecies = oxygen0
  outSpecies= oxygen1
  crossSection = builtIn
  Acol = 0.000436
  Tcol = 1.58e5
</Interaction>