ABSTRACT
In a thermal plasma, all three major plasma constituents (electrons, ions, neutrals) have the same average energy or 'temperature' and for polyatomic species the rotational, vibrational and translational temperatures are in equilibrium. The temperature of thermal plasmas may range from a few thousand Kelvin (e.g. for plasma torches) to a few million Kelvin (in the interior of stars or in fusion plasmas). In contrast, non-thermal or cold plasmas are characterized by the fact that the energy is preferentially channeled into the electron component of the plasma and/or vibrational non-equilibrium of the polyatomic species. In non-thermal plasmas, the electrons may be much hotter (with temperatures in the range of tens of thousands up to a hundred thousand Kelvin) than the ions and neutrals, whose translational temperatures are essentially equal and typically range from room temperature to a few times the room temperature. Non-thermal plasmas thus represent environments where very energetic chemical processes can occur (via the plasma electrons) at low ambient temperatures (defined by the neutrals and ions in the plasma).
