Pulsed Electron Heating of Atmospheric Pressure Air Glow Discharges

By applying electric field pulses of short duration (compared to the time constant for glow-to-arc transitions) to a weakly ionized gas, the electron energy distribution can be temporarily shifted to higher energies. This effect causes a nonlinear increase in the ionization rate and consequently a larger electron decay time. This effect has been demonstrated using single pulse operation.3 In order to generate plasma with semi-continuous electron density, repetitive operation is required. As a first step towards repetitive pulsed electric field operation, the temporal development of the voltage across the plasma for two subsequent pulses was measured. The dual pulse generator, built for this purpose, utilizes two 10 Ω striplines with high-pressure spark gaps as switches, which deliver two subsequent pulses directly to the load. The trigger pulses for the two systems can be adjusted in time between 1 µs and 10 ms. Operation in atmospheric pressure air with applied electric fields of 20 kV/cm and 10ns duration allowed us to increase the electron density for a time of 2.3 µs to such values that the discharge voltage stayed below 30 V. Continuous operation in this discharge state would consequently require repetition rates of 450 kHz. This nonequilibrium electron heating effect can be used to reduce the power consumption of repetitive operated glow discharges.7