The plasma is created with a homemade 4 kW water-cooled laboratory type plasma gun. The arc burning between a thoriated tungsten cathode and a Laval nozzle acting as anode is superimposed by a gas flow of argon and/or hydrogen. A plasma jet expands supersonically into a vacuum vessel in which a pressure of a few mbar is sustained by means of a roots blower.

Hydrocarbons or other gases can be injected into the expanding plasma jet. A temperature-controlled substrate holder can be placed at any position along the axis of the plasma jet. The plasma plume can be analysed by either mass spectrometry or optical spectroscopy.