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

Abstract

In this paper, the radiation of argon and hydrogen in a repetitively pulsed diffuse discharge formed in an inhomogeneous electric field at elevated gas pressure have been studied. The emission spectra are measured under a series of short voltage pulses with the durations of 0.7 ns and 160 ns. It is shown that for the diffuse discharge in pure argon, the transition of argon dimers (Ar2*, λmax = 126 nm) have the highest intensity. Small addition of Xe to Ar contributes to the disappearance of Ar2* radiation bands and the appearance of those of ArXe* and Xe2* dimers in the plasma emission spectrum. In hydrogen, emission at the maximum wavelength of 160 nm is dominated in the spectra of the diffuse discharge and the luminescence intensity in the region of 220-280 nm is relatively low. If Ar is added to H2, the diffuse discharge behaves non-uniform. The luminescence band with the peak at 160 nm narrows, strong argon ion line (Ar+, λmax = 191 nm) appears in the spectra, and the luminescence in the spectral region 220-280 nm reappears. The excitation temperature and electron density are diagnosed using emission spectra and images of the discharge plasma. It is shown that both the excitation temperature and electron density increase as the electric field is enhanced, while the excitation temperature decreases as the gas pressure increases.

VUV lasing in diffuse discharges formed by runaway electrons

“…Thus, short high-voltage pulses were applied to the gaps, providing a sharply inhomogeneous electric field near electrodes. With a high degree of probability, it can be concluded that in the above references, runaway electrons could appear and, similarly to [9][10][11][12][13][14], provide preionization and diffuse discharge formation.…”

“…It is known that quite uniform diffuse plasma can be produced without additional preionization in gaps formed by electrodes with a small radius of curvature [9][10][11][12]. When a high-voltage pulse with a short rise time is applied to electrodes providing a sharply non-uniform electric field in a gap, a diffuse discharge is formed in pressured gases due to breakdown initiation by runaway electrons and x-ray radiation.…”

“…When a high-voltage pulse with a short rise time is applied to electrodes providing a sharply non-uniform electric field in a gap, a diffuse discharge is formed in pressured gases due to breakdown initiation by runaway electrons and x-ray radiation. Therewith, the diffuse plasma can effectively emit VUV spontaneously and stimulated radiation [11][12][13].…”

Long pulse UV and VUV gas discharge lasers

“…We have developed excitation technique bused on a double discharge circuit with a pre-pulse formed by a generator with an inductive energy storage device and semiconductor opening switch made on the base of industrial SOS-diodes [6]. It is known that high-power nanosecond excitation pulses can be realized without using an additional source for gap preionization in lasers with electrodes having a small radius of curvature [7][8][9][10]. At a short rise time of the voltage pulse, the breakdown initiated by runaway electrons gives rise to a diffuse plasma, which, at high pressures, serves as an efficient source of spontaneous and stimulated emission at different wavelengths, including the VUV range [9,10].…”

“…It is known that high-power nanosecond excitation pulses can be realized without using an additional source for gap preionization in lasers with electrodes having a small radius of curvature [7][8][9][10]. At a short rise time of the voltage pulse, the breakdown initiated by runaway electrons gives rise to a diffuse plasma, which, at high pressures, serves as an efficient source of spontaneous and stimulated emission at different wavelengths, including the VUV range [9,10].…”