Working with neutralGas Fluids and the gasKind Parameter

A Fluid block of kind=neutralGas provides a static background gas density. The block must also have the parameter gasKind and an InitialCondition of component 0 to give the gas density. The gasKind is required in all cases, otherwise an exception is thrown.

How this gasKind effects cross-section calculations depends on which interaction is being used. They are summarized in following:

impactElastic

If crossSection = builtIn, the only value of gasKind available is Xe. For all other gasKind, the cross-section is 0.

If crossSection = eedl, gasKind and the user supplied EEDL data file should match. If gasKind and EEDL data file do not match, Vorpal still runs, but the results are unphysical.

If crossSection = functionDefined, the user provides an OAFunc that defines the cross-section. In this case, gasKind does not set the mass, charge, ionization threshold, or other relevant properties, but it is still validated by the Composer. Thus, it must at least be set to a value that is normally accepted as a gasKind.

impactExcitation`

If crossSection = builtIn, the only value of gasKind available is Xe. For all other gasKind, cross-section is 0.

If crossSection = eedl, gasKind and the user supplied EEDL data file should match. If gasKind and EEDL data file do not match, Vorpal still runs, but the results are unphysical.

If crossSection = functionDefined, the user provides an OAFunc that defines the cross-section. In this case, gasKind does not set the mass, charge, ionization threshold, or other relevant properties, but it is still validated by the Composer. Thus, it must at least be set to a value that is normally accepted as a gasKind.

impactIonization

If crossSection = builtIn, available values for gasKind for electron impact are H2, He, CO2, O2, N2, Ar, Ne, Xe, XePlus and for proton impact are H, H2, He, CO2, CO, O2, N2.

If crossSection = eedl, gasKind and the user supplied EEDL data file should match. If gasKind and EEDL data file do not match, Vorpal still runs, but the results are unphysical.

If crossSection = functionDefined, the user provides an OAFunc that defines the cross-section. In this case, gasKind does not set the mass, charge, ionization threshold, or other relevant properties, but it is still validated by the Composer. Thus, it must at least be set to a value that is normally accepted as a gasKind.

impactIonCollisions

If crossSection = builtIn

If gasKind is Xe or Ar, cross-section is based on [MPL+02].

For all other gasKind, cross-section is based on [LS05].

If crossSection = functionDefined, the user provides an OAFunc that defines the cross-section. In this case, gasKind does not set the mass, charge, ionization threshold, or other relevant properties, but it is still validated by the Composer. Thus, it must at least be set to a value that is normally accepted as a gasKind.

No EEDL for ion.

negativeIonDetachment

If crossSection = builtIn, the only available gasKind are H, H2. All other gasKind leads to cross-section = 0.

If crossSection = functionDefined, the user provides an OAFunc that defines the cross-section. In this case, gasKind does not set the mass, charge, ionization threshold, or other relevant properties, but it is still validated by the Composer. Thus, it must at least be set to a value that is normally accepted as a gasKind.

electronAttachment

If crossSection = functionDefined, the user provides an OAFunc that defines the cross-section. In this case, gasKind does not set the mass, charge, ionization threshold, or other relevant properties, but it is still validated by the Composer. Thus, it must at least be set to a value that is normally accepted as a gasKind.

nullBgAbsorber

If stoppingPower = builtIn, rate values are obtained from TxPhysics. gasKind must be one of following, otherwise an exception is thrown: H, He, C, N, O, Na, Al, Si, P, Ar, Fe, Ni, Cu, Ge, Ag, Ba, Os, Pt, Au, Pb, U, Air, Water, Stainless.

nullFieldIonization

A neutralGas Fluid block provides a background gas density field. If crossSection = builtIn, the only available gasKind are H, He, Li, Na, Rb, and Cs. All other gasKind leads to cross-section = 0.