- Stimulation by extreme heating of a gas. This method for Plasma Stimulation only exists in nature. (Hydrogene plasma of stars)
- Stimulation by high energy radiation. When extremely high energy radiation is absorbed by a molecule, electrons can be separated from the molcule or atom which is transformed into an ion. This process forms the Ionosphere in the upper atmosphere.
- Stimulation by a high voltage electric field. This is the method to create flashes, Corona and atmospheric plasma.
- HF-Stimulation. Stimulation by an electric field oscillating at high frequency. (Frequency Kilohertz up to Gigahertz). This method is applied to stimulate Low Pressure Plasma.
- In a stimulated atom one or more valence electrons are lifted onto an elevated discrete energy level by energy absorption. Stimulated atoms are very reactive because such valence electrons easily can change position to another atom.In a plasma not all atoms are transformed into an ion. Many atoms which are essential for plasma reactions are only stimulated to a higher energy level. Valence electrons stimulated to a higher energy level which are not immediately essential for a chemical reaction, return back to their base level. The energy difference between base level and stimulated level is emitted in form of radiation usually in the visible frequency range. This radiation is responsible for the typical colour of a process gas.