High electron density, atmospheric pressure air glow discharges

The pulsed electron heating effect has been studied on an atmospheric pressure air glow discharge. Application of a high voltage pulse causes a shift in the electron energy distribution function to higher energies. This causes a temporary increase of the ionization rate and consequently an increase of the electron density. The electron density after a 10 ns pulse application to a direct current glow discharge increased from its DC value of 2 10¹³ cm^-3 to 2.8 10¹⁵ cm^-3. The average power density, required for sustaining the high pressure plasma with a given minimum electron density, was found to be lowered when the discharge was operated in a repetitive pulsed mode compared to a DC mode. For an atmospheric pressure air plasma, an average power density of 1.5 kw/cm³ and 50 w/cm³ is required for an average electron density of 10¹³ cm^-3 and 10¹² cm^-3, respectively. This value is less by a factor of three than that required to sustain a DC plasma with the same base electron density.