Cross-correlation spectroscopy study of the transient spark discharge in atmospheric pressure air

Abstract

A streamer-to-spark transition in a self-pulsing transient spark (TS) discharge of positive polarity in air was investigated using cross-correlation spectroscopy. The entire temporal evolution of the TS was recorded for several spectral bands and lines: the second positive system of N 2 (337.1 nm), the first negative system of N 2 + (391.4 nm), and atomic oxygen (777.1 nm). The results enable the visualization of the different phases of discharge development including the primary streamer, the secondary streamer, and the transition to the spark. The spatio-temporal distribution of the reduced electric field strength during the primary streamer phase of the TS was determined and discussed. The transition from the streamer to the spark proceeds very fast within about 10 ns for the TS with a current pulse repetition rate in the range 8-10 kHz. This is attributed to memory effects, leading to a low net electron attachment rate and faster propagation of the secondary streamer. Gas heating, accumulation of species such as oxygen atoms from the previous TS pulses, as well as generation of charged particles by stepwise ionization seem to play important roles contributing to this fast streamer-to-spark transition.

Filamentary nanosecond surface dielectric barrier discharge. Plasma properties in the filaments

“…The authors [33] remark that the nature of the observed electron cloud is still under discussion and mention the field emission in strong electric field and a possibility of production of a supercritical fluid during explosive heating of a single spike or multiple spikes on the cathode. Non-numerous experimental observations [11,13,14,37] obtained in mm or sub-mm pin-to-pin gaps report the start of the filament from the cathode, then, with a delay of the order of 1 ns -from the anode, and then the filaments merge in the middle of the gap [13,37]. Significant decrease of the streamer radius, by a factor of 3 − 5, on the time scale 0.5 ns before the filamentation is recently reported [13].…”

“…The decay of the electron density was slow, a few tens of nanoseconds. Later experimental observations of nanosecond repetitive plasma (NRP) at atmospheric pressure [11][12][13] also report densities of electrons on the level n e ∼ 10 18 − 10 19 cm −3 , constriction of the discharge channel, high electron temperatures reaching a few electronvolts and slow plasma decay, tens of nanoseconds. The authors of [14] measured the ultra-fast gas heating observed by optical emission spectroscopy on the axis of the streamer before the constriction of the channel.…”

Recent Progress of Plasma-Assisted Nitrogen Fixation Research: A Review

“…As one of the most explored plasma reactors Another type of warm plasma, the so-named transient spark discharge, was used by Janda et al [73] for NO x production. The transient spark discharge starts from a streamer phase, which is considered as non-thermal plasma and is subsequently transformed into short spark current pulses which generate thermal plasma [74,75]. Due to the self-pulsing feature, thermalization of the plasma can be avoided.…”

Non-equilibrium plasma for ignition and combustion enhancement

“…The decay of the electron density was slow, a few tens of nanoseconds. Later experimental observations of nanosecond repetitive plasma (NRP) in mm or sub-mm pin-to-pin gaps at atmospheric pressure [129][130][131][132] also report densities of electrons on the level n e ∼ 10 18 − 10 19 cm −3 , constriction of the discharge channel, high electron temperatures reaching a few electronvolts and slow plasma decay, tens of nanoseconds. The authors of [133] measured the ultrafast gas heating observed by optical emission spectroscopy on the axis of the streamer before the constriction of the channel.…”