Wall-association processes in expanding thermal hydrogen plasmas

The amount of ions and atomic radicals contained in an expanding thermal hydrogen plasma, which is produced by a wall-stabilized de arc, depends on the source nozzle geometry and material. The nature of the radiation emanating from the plasma jet is also influenced by the nozzle properties. In the light of experimental data obtained by means of laser-aided diagnostics, these striking facts can be explained by the wall-association processes of hydrogen atoms to form vibrationally excited hydrogen molecules.