Understanding pressure changes in smouldering thermal porous media reactors (original) (raw)

It is shown that recently measured cross sections for double ionization of negative ions (H -, O -, and C -) possess a universal shape when plotted in suitable dimensionless units. The shape can be represented with a simple analytical function, following the same principles as it has been done in establishing a universal shape function for single ionization [Rost and Pattard 1997 Phys. Rev. A 55 R5]. Thereby, it is demonstrated that direct double ionization dominates the cross section for the targets considered.