The Ionization subnode is available from the context menu (right-click the Collisions parent node) or from the Physics toolbar, Attributes menu. The Ionization subnode causes particles to ionize background gas molecules, releasing secondary electrons into the simulation. Optionally, the ionized background gas molecule can also be released. Typically, the primary particles subjected to this collision type are electrons and the ionized particle is taken from the background gas.

See Elastic for information about the Collision Statistics and New Value of Auxiliary Dependent Variables sections.

These settings are the same as for the Elastic subnode with additional options to enter a value for the Energy loss ΔE (SI unit: J) and to specify which species to release during a collision. You may select or clear any of the following check boxes:

Typical energy loss values for electron impact collisions are between 12 eV and 24 eV.

This section is shown when either the Release primary electron check box or the Release secondary electron check box is selected. Select an option from the Electron properties list, which may be any Particle Properties node that has been added to the physics interface.

This section is available when the Release ionized particle check box is selected. Select an option from the Ion properties list, which can be any Particle Properties node that has been added to the physics interface.

For each auxiliary dependent variable that is defined in the model, enter the initial value of the auxiliary dependent variable for the electron and ionized particle that are released as a result of the ionization reaction. The default value is 0.