Strong double-layer formation by shock waves in nonequilibrium plasmas

Strong double-layer formation by acoustic shock wave (=2) propagation in a low-pressure, N₂ positive column plasma has been quantified, near the shock front, by measurements of the voltage jump and the enhancements of both the B³Πg--A³Σᵤ⁺ plasma emission and the electron density. The large polarity dependence (or shock direction) of these effects and potential jumps of more than 20kTₑ across the shock-created interface indicate that the measured shock-induced electron heating effects (localized excitation and ionization rate) are caused by the formation of strong double layers maintained by the traveling shock front.