DC generated Ar–CO₂ discharge for plasma mixtures at 2.0 Torr is investigated to evaluate the variation in the electron temperature and density, electron energy distribution function, and population densities of the reactive atomic, molecular, and ionic species of CO₂–Ar plasmas as a function of the Ar percentage in the mixtures. Optical emission spectroscopy and quadrupole mass spectrometry are used to determine the reactive species in the Ar–CO₂ plasma in the DC discharge mode as a function of the Ar percentage. The species observed in the plasma mixtures were CO₂, O₂, CO, O, C₂, and Ar, which agree very well with the mass spectroscopy observation. In addition, single Langmuir probes are employed to characterize the plasma. The CO species are observed to increase to 40% Ar in the mixture and then decrease. The electron temperatures and density are found to be between 1.9-3.1 eV and (0.8–2.0) × 10¹⁰cm⁻³, respectively.

The dynamics of vertically vibrating liquid drops has been studied by several researchers and different phenomena have been reported. In the present work, we report experimental results for some interesting phenomena that can be observed in a liquid drop subjected to vertical vibrations. For this purpose, a drop of Mercury was kept on a spherical watch glass and it was perturbed with different amplitudes and frequencies. The oscillations of the drop were recorded using a video camera and image analysis was used to further understand its behavior. The method of correlation was then employed to analyze the videos recorded with different perturbations. We report phenomena like subharmonic oscillations and rotation of the drop; and also the resonance and superpropulsion in the droplet ejection.

We present a detailed Langmuir probe, optical emission spectroscopy (OES), and quadrupole mass spectrometry (QMS) characterization of a DC CO₂–H₂ plasma mixture, complemented by calculations of the electron energy distribution functions (EEDFs) and ionization rates of CO₂ plasma with varying H₂ ratios using Boltzmann equation (BE) solver BOLSIG+, assuming a bi-Maxwellian distribution. Both the measured and calculated EEDFs as a function of the H₂ concentration agreed well and showed a bi-Maxwellian distribution. The measured and calculated electron temperatures T_e as a function of the increment in the H₂ concentration (0–100%) increased in the range of 2.5–3.1 eV. The measured and calculated electron densities (N_e) as a function of H₂ concentration exhibited the same increasing behavior (approximately 10¹⁰ cm⁻³), which confirms that the mixture composition directly influences the plasma-related parameters and results in a large fraction of H atoms by reaction e + H₂ → H + H. An ascending T_e would result in higher ionization rates (explaining the observed increase in electron densities), which agrees with the ionization rate behavior obtained by the BE calculation. Both OES and QMS techniques detected the species H (through the lines H_α, H_β, and Hγ), CO, CO₂, CO₂⁺, O₂, OH, O, C₂, CO, and CO⁺. An analysis of the CO/CO₂ and O₂/CO₂ ratios would clarify that OH is formed from O₂ + H → OH + O rather than other reactions involving CO species. At a 100% CO₂ concentration, CO and O₂ formations proceed in accordance with the stoichiometry of 2CO₂ → 2CO + O₂.

The electronegativity of the $Ar-C{O}_2$ gas mixture was investigated, and the total relative negative oxygen ion density O₂⁻ + O⁻ in the bulk of a dc discharge has been determined employing Langmuir probe assisted laser photo-detachment. The relative electron density and absolute temperature were obtained for the mixture at discharge powers between 200 and 3000 mW and pressures between 0.2 and 0.6 mbar, employing the collisional radiative model for several Ar gas mixtures. The absolute metastable number density for 1s₃ and 1s₅ levels was measured, and both showed an increasing trend as a function of pressure and power. The absolute number density of the 1s₅ level was found to be higher than that of the 1s₃ level. Electronegativity was found to decrease as a function of power and as a function of the increasing Ar percentage in the gas mixture.

We report in this article the optical emission spectroscopy (OES) measurements for N₂O dc discharge in the pressure range between 0.1 and 0.6 mbar. The emission bands were observed and measured in the wavelength range of 200-1100 nm. The intensity of the principal species observed for N₂, N₂⁺, O⁺, O₂, O₂⁺, NO, and N₂O⁺ was investigated as a function of pressure and discharge power. The origin of emission bands and lines was discussed. N₂⁺ and N₂ were observed to be the dominant emission lines, on one hand, while no emission lines were observed for atomic oxygen and nitrogen.