Images of Nanosecond Pulse-Driven Low Temperature Atmospheric Pressure Plasma Using Dielectric-Free Parallel Electrodes

Images of intensified charged coupled device and optical emission spectra are presented for a low temperature atmospheric pressure plasma jet, which is pulse-driven with a duration of 350 ns at a frequency of 40 kHz. He gas is injected with a gas flow rate of 5-30 L/min through two parallel electrodes that are exposed to the air and have a submillimeter gap. Driving voltage ranges from 400 to 600 V. The total power consumption is less than 2 W, and the plasma does not transit to an arc mode because of the short pulse duration.