Plasma afterglow

A plasma afterglow (also afterglow) is the radiation emitted from a plasma after the source of ionization is removed The external electromagnetic fields that sustained the plasma glow are absent or insufficient to maintain the discharge. A plasma afterglow can either be a temporal, due to an interrupted (pulsed) plasma source, or a spatial one, due to a distant plasma source. In the afterglow, plasma-generated species de-excite and participate in secondary chemical reactions that tend to form stable species. Depending on the gas composition, super-elastic collisions may continue to sustain the plasma in the afterglow for a while by releasing the energy stored in rovibronic degrees of freedom of the atoms and molecules of the plasma. Especially in molecular gases, the plasma chemistry in the afterglow is significantly different from the plasma glow.