Electrical and optical study of DC driven repetitively pulsed transient spark discharge in atmospheric air

Abstract

We present a study of electrical properties and optical emission of transient spark (TS) - streamer-to-spark transition discharge in atmospheric pressure air. TS was succesfully applied for flue gas cleaning or biodecontamination and has a potential in plasma shielding, combustion, and flow control applications. Despite the DC applied voltage, TS has a pulsed character with short (∼10 –100 ns) high current (>1 A) pulses, with repetitive frequencies 1–20 kHz. Estimation of the temporal evolution of electron density ne using discharge diameter measured by time-resolved iCCD imaging, supported by preliminary spectroscopic ne measurements from Hα broadening, show that ne ≈ 10 16 -10 17 cm −3 at maximum and ∼10 11 cm −3 in average are reached using relatively low power delivered to the plasma (0.2–3 W). Thanks to the high repetition frequency, ne between two current pulses does not fall below a critical value and therefore plasma exists during the whole time. A detailed analysis of the TS control by electrical circuit parameters is presented. With appropriate circuit components, the current pulse tail (>1 mA) can be extended and the electron density can be held above ∼10 13 cm −3 for several tens of μs.