Comparison of optical spectra recorded during DPF-1000U plasma experiments with gas-puffing (original) (raw)
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IOP, 2020
: In this study, the emission spectra of plasma generated from the argon gas in a plasma jet system were measured under normal atmospheric pressure, at constant voltage and for different flow rates from 1–5L/min. The plasma parameters were calculated based on electron density, frequency of plasma, the temperature of an electron, Debye length and the number of particles in the Debye sphere. We employed optical emission spectrometer (OES) technology, which captured the spectrum resulting from the plasma at various flow rates of argon gas. While the flow rate of argon gas to the plasma generated from the discharge current (D.C.) increased, the ranges of the temperature and density of the electron (Te) were 0.075– 0.1eV and 6.15–9.75x1017cm-3 , respectively. In contrast, a rise in the intensity of spectral lines was observed.
Physics of Plasmas
Several series of high-current discharges were carried out within the PF-1000U facility at various gas conditions. The initial filling pressures were p 0 ¼ 1.2 hPa D 2 , 1.06 hPa D 2 þ 10% He, or 0.53 hPa D 2 þ 25% Ne. The discharges were performed with or without an additional gas puffing. In shots with the puffing, 1 cm 3 of gas (or mixture), compressed to the pressure of (0.13-0.20) MPa, was injected 1.5 ms before the discharge initiation. Pure D 2 , He, Ne, or a mixture of 50% He þ 50% Ne was used for puffing. The optical spectroscopic measurements were performed at a distance of 16 or 27 cm from the electrode outlets. Almost all discharges produced a dense plasmafocus (of about 10 cm in length) and a long plasma jet, which was observed for several ls. The ambient plasma density at the investigated gas-conditions was about 10 16 cm À3 , but an admixture of 10% He or 25% Ne (added to the D 2-filling) induced an increase in this density by factor 1.8-2.5. In all the cases, the plasma jet density was above 10-times higher than that of ambient plasma. At the He-or Ne-puffing, this density reached (3.5-6) Â 10 17 cm À3. Electron temperatures in the plasma jet changed from about 5.0 to about 3 eV in 5-7 ls.
Optical diagnostics of atmospheric pressure air plasmas
Plasma Sources Science & Technology, 2003
Atmospheric pressure air plasmas are often thought to be in local thermodynamic equilibrium owing to fast interspecies collisional exchange at high pressure. This assumption cannot be relied upon, particularly with respect to optical diagnostics. Velocity gradients in flowing plasmas and/or elevated electron temperatures created by electrical discharges can result in large departures from chemical and thermal equilibrium. This paper reviews
Open Journal of Applied Sciences
The results of diagnostics of spectral, temporal and energy characteristics of the radiation of gas-discharge plasma in a mixture of mercury diiodide vapor with helium in the spectral range of 350-900 nm, and the plasma parameters in the range of reduced electric field E/N = 1-100 Td are presented. The plasma is created in the barrier discharge device with a cylindrical aperture. The electrodes are placed 0.2 m in length at a distance of 0.015 m. The amplitude of the pump pulse, the duration and frequency were 20-30 kV, 150 ns and 1-20 kHz, respectively. Radiation in the visible region of the spectrum of mercury monoiodide exciplex molecule is revealed. Regularities in the optical characteristics of the plasma, depending on the partial pressures of the components of the mixture, the electron energy distribution function, mean electron energy, specific losses of discharge power on the process of dissociative excitation of mercury monoiodide (state 2 1 2 В + Σ) molecules as well as the rate constant of dissociative excitation of mercury monoiodide molecules in working mixture depending on the given reduced electric field are established.
Plasma, 2019
A helium-based atmospheric pressure plasma jet (APPJ) with various flow rates of argon gas as a variable working gas was characterized by utilizing optical emission spectroscopy (OES) alongside the plasma jet. The spectroscopic characterization was performed through plasma exposure in direct and indirect interaction with and without de-ionized (DI) water. The electron density and electron temperature, which were estimated by Stark broadening of atomic hydrogen (486.1 nm) and the Boltzmann plot, were investigated as a function of the flow rate of argon gas. The spectra obtained by OES indicate that the hydroxyl concentrations reached a maximum value in the case of direct interaction with DI water as well as upstream of the plasma jet for all cases. The relative intensities of hydroxyl were optimized by changing the flow rate of argon gas.
Measurements of Gaseous Hydrogen-Nitrogen Laser-Plasma
Atoms, 2019
This work communicates laser-plasma experiments in a gaseous mixture of hydrogen and nitrogen. Time-resolved spectroscopy measures the first four Balmer-series hydrogen lines together with selected neutral and ionized nitrogen lines. Optical breakdown plasma is generated in a 1:1 hydrogen:nitrogen mixture at ambient temperature and 0.27-atm pressure. Time-resolved spectroscopy records emitted radiation with spatial resolution along the slit height for the H α , H β , H γ , and H δ lines. For 13 selected time delays from 0.25 µs to 3.25 µs and 0.025 µs gate-widths, micro-plasma diagnostics is evaluated. Of interest are the peak separation and width of H δ and width of H γ for electron densities in the range of 0.1 to 1.0 ×10 17 cm −3 , and comparisons with H β and H α diagnostics. Integral inversions interrogate spatial distributions of the plasma expansion. Applications include laboratory and stellar astrophysics plasma diagnosis.
Optical emission spectroscopy of atmospheric pressure plasma jets in various background gases
2016
Optical emission spectroscopy was performed during atmospheric pressure plasma needle helium jet treatment of various toothbleaching gels. When the gel sample was inserted under the plasma plume, the intensity of all the spectral features increased approximately two times near the plasma needle tip and up to two orders of magnitude near the sample surface. The color change of the hydroxylapatite pastille treated with bleaching gels in conjunction with the atmospheric pressure plasma jet was found to be in correlation with the intensity of OH emission band (309 nm). Using argon as an additive to helium flow (2 L/min), a linear increase (up to four times) of OH intensity and, consequently, whitening (up to 10%) of the pastilles was achieved. An atmospheric pressure plasma jet activates bleaching gel, accelerates OH production, and accelerates tooth bleaching (up to six times faster).
Spectroscopic investigations of corona discharge in high pressure helium at 300 K
The European Physical Journal Applied Physics, 2011
Gaseous Helium at 300K and pressure (0.1-3)MPa was excited using a corona discharge both for negative and positive high voltages. The light emitted from the ionization zone of the discharge was analyzed. The atomic lines observed was shifted and broadened due to interaction of radiators with surrounding atoms (the pressure broadening). Asymmetric shape of atomic line 706nm was recorded. Blue wing of the line is more intensive than its red wing. The reason of the phenomenon is the repulsive interaction between excited atoms with atoms in the ground state. The line shape is described as a convolution of Lorentz profile of the line center and a quasi-statistical profile of a blue wing of the line. Such analysis allows us to predict a weak heating of the gas in the ionization zone for positive corona and considerable heating for negative corona.