Various concentric-ring patterns formed in a water-anode glow discharge operated at atmospheric pressure

Pattern formation is a very interesting phenomenon formed above a water anode in atmospheric pressure glow discharge. Up to now, concentric-ring patterns only less than four rings have been observed in experiments. In this paper, atmospheric pressure glow discharge above a water anode is conducted to produce diversified concentric-ring patterns. Results indicate that as time elapses, the number of concentric rings increases continuously and up to five rings have been found in the concentric-ring patterns. Moreover, the ring number increases continuously with increasing discharge current. The electrical conductivity of the anode plays an important role in the transition of the concentric patterns due to its positive relation with ionic strength. Hence, the electrical conductivity of the water anode is investigated as a function of time and discharge current. From optical emission spectrum, gas temperature and intensity ratio related with density and temperature of electron have been calculated. The various concentric-ring patterns mentioned above have been simulated at last with an autocatalytic reaction model.

SDBD Flexible Plasma Actuator with Ag-Ink Electrodes: Experimental Assessment

In the present work, a single dielectric barrier discharge (SDBD)-based actuator is developed and experimentally tested by means of various diagnostic techniques. Flexible dielectric barriers and conductive paint electrodes are used, making the design concept applicable to surfaces of different aerodynamic profiles. A technical drawing of the actuator is given in detail. The plasma is sustained by audio frequency sinusoidal high voltage, while it is probed electrically and optically. The consumed electric power is measured, and the optical emission spectrum is recorded in the ultraviolet–near infrared (UV–NIR) range. High-resolution spectroscopy provides molecular rotational distributions, which are treated appropriately to evaluate the gas temperature. The plasma-induced flow field is spatiotemporally surveyed with pitot-like tube and schlieren imaging. Briefly, the actuator consumes a mean power less than 10 W and shows a fair stability over one day, the average temperature of the gas above its surface is close to 400 K, and the fluid speed rises to 4.5 m s−1. A long, thin layer (less than 1.5 mm) of laminar flow is unveiled on the actuator surface. This thin layer is interfaced with an outspread turbulent flow field, which occupies a centimeter-scale area. Molecular nitrogen-positive ions appear to be part of the charged heavy species in the generated filamentary discharge, which can transfer energy and momentum to the surrounding air molecules.

Determination of the reduced electric field in surface dielectric barrier discharge plasmas

In this paper, the experimental determination of the reduced electric field (E/n) in plasma of dielectric coplanar surface barrier discharge (DCSBD) at atmospheric pressure was demonstrated. The plasma characteristics and the experimental setup properties were described, and the optical emission spectrum of the plasma was also measured. The results of optical emission spectroscopy showed the presence of nitrogen molecular bands in the emission spectrum of DCSBD. In particular, the second positive and the first negative systems, as well as low intensity OH and NO lines were identified. The main transport properties of electrons, such as mobility, mean average energy, and diffusion coefficients were calculated using the BOLSIG+ open source software. The dependence of the ratio of intensities of the nitrogen spectral lines on the reduced electric field, the dependence of the E/n on plasma power, and the dependence of the electron energy distribution function (EEDF) on E/n were obtained. An algorithm in the form of a block diagram for determining the reduced electric field by the BOLSIG + program and experimentally measured spectral line intensities are presented. The utilized method is quite simple, accessible and versatile.

Spectroscopic Diagnosis of the CdO:CoO Plasma Produced by Nd:YAG Laser

In this paper, the optical emission spectrum (OES) technique was used to analyze the spectrum resulting from the (CdO:CoO) plasma in air, produced by Nd:YAG laser with λ=1064 nm, τ=10 ns, a focal length of 10 cm, and a range of energy of 200-500 mJ. We identified laser-induced plasma parameters such as electron temperature (Te) using Boltzmann plot method, density of electron (ne), length of Debye (λD), frequency of plasma (fp), and number of Debye (ND), using two-Line-Ratio method. At a mixing ratio of X= 0.5, the (CdO:CoO) plasma spectrum was recorded for different energies. The results of plasma parameters caused by laser showed that, with the increase in laser energy, the values of Te, ne and fp were increased, while the value of λD was decreased. The calculated electron temperature value was in the range of 0.449-0.619 eV at ratio X=0.5

Monitoring of Oxygen in Simulated Electrolytic Reduction Salt of Pyroprocessing Using Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was explored as a method of monitoring oxygen (O) concentration in electrolytic reduction salt of pyroprocessing. Simulated salt samples were fabricated, and each sample was put in a transparent and sealed vial filled with argon gas. An Nd:YAG laser pulse was applied to the sample through the vial surface, and the optical emission spectrum was measured. O(I) 777.2 nm lines were clearly identified in the spectrum of a sample containing Li2O, and the intensity of the O peak and the intensity ratio of O and lithium (Li) peaks, in which Li was used as the normalization, increased linearly as the O concentration in the salt sample was increased. The limit of detection and root mean square error were calculated for the cases of O peak area, O peak height, peak area ratio of O–Li, and the peak height ratio of O–Li, and all the cases could indicate that the O concentration in the electrolytic reduction salt was out of normal range. Our result shows that LIBS has the possibility to be used as a method for monitoring of O in electrolytic reduction salt.

Searching for 3D effects in the optical, high spectral resolution emission spectrum of KELT-9b

<p>Ultra-hot Jupiters (UHJs; T<sub>eq</sub> ≥ 2500 K) are the hottest gaseous giants known. They emerged as ideal laboratories to test theories of atmospheric structure and its link to planet formation. Indeed, because of their high temperatures, (1) they likely host atmospheres in chemical equilibrium and (2) clouds do not form in their day-side. Their continuum, which can be measured with space-facilities, can be mostly attributed to H- opacity, an indicator of metallicity. From the ground, the high spectral resolution emission spectra of UHJs contains thousands of lines of refractory (Fe, Ti, TiO, …) and volatile species (OH, CO, …), whose combined atmospheric abundances could track planet formation history in a unique way. In this talk, we take a deeper look to the optical emission spectrum of KELT-9b covering planetary phases 0.25 - 0.75 (i.e. between secondary eclipse and quadrature), and search for the effect of atmospheric dynamics and three-dimensionality of the planet atmosphere on the resolved line profiles, in the context of a consolidated statistical framework. We discuss the suitability of the traditionally adopted 1D models to interprete phase-resolved observations of ultra-hot Jupiters, and the potential of this kind of observations to probe their 3D atmospheric structure and dynamics. Ultimately, understanding which factors affect the line-shape in UHJs will also lead to more accurate and more precise abundance measurements, opening a new window on exoplanet formation and evolution.</p>

Synthesis Emission Spectra of (LIPS) Technique for Cu, Ag Nanoparticles and their Antibacterial Activity

A spectroscope presents the optical emission spectroscopy (OES) technique on laser-produced copper and silver plasmas. The optical emission spectrum technique was used to analyzes the spectrum arising from the Cu, Ag Laser Nd: YAG plasmas with a wavelength of (1064) nm, a span of (10) ns, and a focal length of (10) cm in the energy range (300-800) mJ. The electron temperature (Te) was determined while the Saha-Boltzmann equation was used to measure the electron density (ne). Other plasma parameters, (λD), (fp), (ND), were also measured. For various energies, the plasma spectrum was registered copper and silver. Q-switched Nd: YAG liquid laser ablation technique (PLAL) was used to produce nanoparticles (NPs), silver, and copper particles using distilled water at room temperature at different energies (300-600-800) mJ. With a constant wavelength (1064nm). At a constant frequency (6Hz), 300 laser pulses were used to ablate the target placed in distilled water to study the effect of these materials in inhibiting bacteria. Bacteria were used (Staphylococcus). This study showed that (Ag-NPs) and (Cu-NPs) that are synthesized by laser ablation have a great effect on Staphylococcus (antibiotic-resistant) bacteria.

Development of Virtual Metrology Using Plasma Information Variables to Predict Si Etch Profile Processed by SF6/O2/Ar Capacitively Coupled Plasma

In the semiconductor etch process, as the critical dimension (CD) decreases and the difficulty of the process control increases, in-situ and real-time etch profile monitoring becomes important. It leads to the development of virtual metrology (VM) technology, one of the measurement and inspection (MI) technology that predicts the etch profile during the process. Recently, VM to predict the etch depth using plasma information (PI) variables and the etch process data based on the statistical regression method had been developed and demonstrated high performance. In this study, VM using PI variables, named PI-VM, was extended to monitor the etch profile and investigated the role of PI variables and features of PI-VM. PI variables are obtained through analysis on optical emission spectrum data. The features in PI-VM are investigated in terms of plasma physics and etch kinetics. The PI-VM is developed to monitor the etch depth, bowing CD, etch depth times bowing CD (rectangular model), and etch area model (non-rectangular model). PI-VM for etch depth and bowing CD showed high prediction accuracy of R-square value (R2) 0.8 or higher. The rectangular and non-rectangular etch area model PI-VM showed prediction accuracy R2 of 0.78 and 0.49, respectively. The first trial of virtual metrology to monitor the etch profile will contribute to the development of the etch profile control technology.

Electron Induced Emission of Nitrous Oxide in the UV-VIS Spectral Range

The electron impact excitation of N2O was studied using the crossed electron-molecular beams method. Optical emission spectrum initiated by 50 eV electron impact was recorded within the range 200-700 nm. Main emission bands arise from excited ion state N2O+(A2Σ) and dissociative excitation into N2+(B2Σ+u). The rotationally un-resolved excitation-emission cross sections for selected ion transitions were scaled to absolute values and their dependence on electron energy was determined. Several of them were determined for the first time.