twoColumnFile

Two-Column File Format

Use this kind for the RxnRate sub-block to set the cross section using a two-column data file. The data file should have no header.

The units for the dependent variable (first column in the data file) must be either m/s (meters per second) or eV (electron volts). The user sets which with the crossSectionVariable parameter.

The units for the cross section (second column) must be in square meters (not barns). Beware, that the eedl dataset is in units of MeV and barns and so requires conversion: 1 MeV = 1.e6 eV, and 1 barn = 1.e-28 square meters. (https://www.oecd-nea.org/dbdata/data/manual-endf/nds_eval_eedl.pdf)

With reference to the table in the link above, one may find the impact ionization of Argon, by scanning down to the dataset with top line starting 18000 9 0 (Z=18 for Argon, followed by A=000, Yi=9=electrons, Yo=0=no outgoing).

Second header line starts 81  0 91 0.00000e+00 1.10000e+01 where:

  • C=81=ionization,
  • I=0 for reaction property,
  • S=91 for the reaction modifier,
  • 0.00000e+00 is unused in this format in columns 9-21
  • 11 in E11.4 format would be the appropriate M3 subshell designator.

The LxCat database (https://fr.lxcat.net/data/set_type.php) contains a wide range of cross sections which can be imported into VSim.

Note

headers must be removed, and units must be correct before importing into VSim.

twoColumnFile Attributes

crossSectionVariable (string, required)

The unit of the values in the first column of the two column data file. There are two options:

  • energy
  • velocity
file (string, required)

The name of the data file containing the cross section as a function of the crossSectionVariable

Example twoColumnFile Block

<RxnRate rxnRate>
  kind = twoColumnFile
  crossSectionVariable = energy
  file = ArArIonization.dat
</RxnRate>