<title>Kinetics of VUV-VIS spontaneous emission of high-current pulsed volume discharge in argon</title>

Abstract

Spatial-time behavior of the main excited atomic and molecular excimer species were monitored with ns-gated ICCD camera (200-850 nm) and solar-blind PMT (1 15-300 nm) from spontaneous emission spectra ofhomogeneous volume discharge in high-pressure (up to 0 bar) argon. It is revealed, that broad (200-700 nm) UV-VIS continuum is caused mainly by radiative recombination of free plasma electrons with Ar2 ions. Emission intensities from this continuum and red Ar lines have a typical recombination behavior in the afterglow stage of the discharge (square root of its intensity is proportional to the electron density). Observed UV-VIS continuum spectrum is modeling by free-bound photorecombination transitions to manifold of4s, 4s , 4p, 4p , 3d, 3d Ar* levels. Peak intensity ofthe second continuum vUv emission from Ar2 excimers (126 nm) increases approximately quadratically with the gas pressure. This behavior is observed at pressure range of 1-2 bar, however at higher pressures the peak intensity has a tendency to the saturation. vUv emission from Ar2* '(O) molecules increases during small-power secondary pumping pulses due to better mixing of singlet and triplet Ar2* states by additional electrons.

On the green aurora emission of Ar atmospheric pressure plasma

“…As reported by Treshchalov et al [21], the intensity of the continuum emission is proportional to the square of the electron density. It can be found from figures 5 and 6 that the continuum emission intensity is highest at the position 4 and at the position 3 between the two electrodes the continuum emission intensity is about half of that at position 4.…”

“…The strong green emission can always be observed at the position without the continuum emission. As reported by Treshchalov et al [21], the continuum emission is due to the interaction of free electrons with ions or neutral atoms, including the process of photo-recombination, slowing down of electrons on ions and atoms. In high pressure Ar plasma, the main positive charge species are Ar 2 + ions.…”

“…Recently, Jaiswal et al reported intense green aurora emission from an Ar APPJ driven by kHz AC power supply [19]. Since Ar plasma jet is easy to build [21][22][23][24][25][26], it might be a potential source of the artificial aurora emission.…”

Emission spectra of argon and hydrogen excited by pulses with durations of 0.7 and 160 ns in an inhomogeneous electric field

“…From the other hand, in figure 8(a), the Ar 2 * emission power starts to increase after the arrival of reflected pulses. It can be explained by the additional power input from these pulses, as well as by a decrease in the recombination rate and the formation of excited argon molecules [34,35]. This mechanism of a decrease of the argon dimers radiation intensity is confirmed by adding He to Ar.…”

“…It should be emphasized that the hydrogen radical density and discharge characteristics of the non-thermal plasma excited by the nanosecond power source were investigated in [33]. In addition, the optical and discharge characteristics were studied in detail when Ar was excited by a volume discharge in a relatively uniform electric field using an external preionization source [34,35].…”