RxnProcess

RxnProcess Block

The RxnProcess block sets the reactants and products for a particular reaction. The reactants and products can be any combination of Fluids or Kinetically Modeled Particle Species. Each reactant and product to be used in a RxnProcess must have a corresponding Reactant block. The actual reactant and product names referenced in the RxnProcess block should be the names of the corresponding Reactant blocks that point to the species/fluids.

This block points to a RxnPhysics Block which will determine the physics of the reaction, i.e., whether the interaction is an ionization, scattering, dissociation, or an other type of process. See RxnProductGenerator for a list of supported processes.

Note

For some processes, the order that the reactants and products are written in the Reactants and Products lists below is important. Check the documentation for the ProductGenerator to determine whether the reactants and products need to be written in a particular order.

RxnProcess Attributes

kind (string, required)

The kind will always be collisionProcess for physical reactions. The other option is weightManager` for splitting/combining macroparticles (see weightManager).

reactants (list of strings, required)

A list, enclosed by square brackets, of the names of the reacting species Reactants. Can be any fluid or kinetically modeled species, and must have a corresponding Reactant block. Order is important for some reactions. Find the reaction types in RxnProductGenerator for information on ordering.

products (list of strings, required)

A list, enclosed by square brackets, of the names of the product species Reactants. Can be any fluid or kinetically modeled species, and must have a corresponding Reactant block. Order is important for some reactions. Find the reaction in RxnProductGenerator for information on ordering.

rxnPhysics (string, required)

This string points to a name of a RxnPhysics Block. The RxnPhysics block determines the physics properties of the RxnProcess.

rxnFrequencyField (string, optional)

The rxnFrequencyField can be provided so that a frequency diagnostic is recorded for the reaction. This can be time averaged using the rxnFrequencyPeriod attribute (discussed below). The units are reactions per cubic meter per second, and are recorded with spatial resolution the same as the grid.

rxnFrequencyPeriod (int, optional)

Specify the number of stepsfor time averaging of the reaction frequency diagnostic. The default is 1, meaning no averaging. As the field is only dumped on the dumpPeriod of the simulation, if you use the default you will see the reaction frequency at that time step. If you time average, you will see the reaction frequency averaged over the previous rxnFrequencyPeriod steps.

verbosity (int, optional)

A verbosity setting determines the level of output messaging provided by the engine. If no value is provided the top level verbosity will be used (see Global Variables). If a value is provided in this block it will overwrite the top level verbosity. A verbosity setting of 127 or lower will show the number of reactions that occur. A setting of 128 or larger will suppress the number of reactions.

randomSeed (int, optional, default: random int)

Manually set the random seed used in the selection of reactant particles.

The default is to choose a random seed at run time. To produce identical simulations, advanced users may want to manually set a seed. It is recommended not to include this parameter so that a different random number will be generated for each run.

Example RxnProcess Block

<RxnProcess impactElasticPrimaryElectrons>
  kind = collisionProcess
  reactants = [electronsRct neutralArgonRct]
  products = [electronsRct neutralArgonRct]
  rxnPhysics = impactElasticPrimaryElectronsbinaryElastic
  #rxnFrequencyField = regularCrossDev field
  #rxnFrequencyPeriod = 1
  #verbosity = 127
  #randomSeed = 423
</RxnProcess>

<Reactant electronsRct>
  kind = particle
  ptclSpeciesName = electrons
</Reactant>

<Reactant neutralArgonRct>
  kind = neutralGas
  neutralGasName = neutralArgon
</Reactant>