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An experimental study was conducted to test the effect of changing the frequency of a 10 kV alternating voltage source on the properties of a plasma jet. Optical emission spectra of the plasma were recorded and analyzed. In plasma physics, the electron temperature and density are key parameters. These were determined using a Boltzmann plot and the Stark broadening of the argon line at 763.153 nm, respectively. As the frequency of the alternating voltage source was increased from 10 to 30 kHz (in increments of 5 kHz), the electron temperature increased from 0.995 to 1.357 eV and the electron density rose from 12.027 × 1017 to 12.838 × 1017 cm−3. A strong correlation between the plasma parameters and the frequency of the alternating voltage source was evident. Measurements were also taken on the length of the plasma torch, which was found to grow from 0.041 to 0.051 m as the frequency of the supply voltages was increased. Furthermore, the effect of plasma on the temperature of a silicon target was investigated for a range of frequencies of the supply voltage. It was observed that a slight increase in temperature occurred with increasing frequency, at a constant argon gas flow rate. The effect of plasma jetting on a silicon target was studied at a fixed voltage frequency and a variable gas flow rate. Only a small increase in target temperature was observed. This ensures that no damage or unwanted effects occur on the material being processed. [ABSTRACT FROM AUTHOR]

In this study the electron density of an atmospheric plasma generated between a pin electrode and a water surface is measured by determining the Stark broadening of H α and H β emission lines. Comparable values for the electron density are achieved using the H α and H β broadening obtained in separate measurements. During the temporally evolving system, increasing electron densities are measured of 0.5 − 3 ⋅ 10 15 cm−3 during the plasma treatment of 5–10 min. The effect of the water temperature on plasma-water interaction is investigated by heating the water to ≈ 70 ∘ C prior to the measurements. This resulted in higher gas temperatures during the discharge up to 2500 K and 4000 K for positively and negatively pulsed discharge, respectively. Furthermore, an earlier increase of electron density and conductivity of the water is measured for the preheated experiments. The humidity of the gas is likely to be an important parameter causing the observed results. [ABSTRACT FROM AUTHOR]

The effects of the helical trajectories of the perturbing electrons in magnetized plasmas on the dynamical Stark width of hydrogen or deuterium spectral lines have been studied analytically in our previous two papers—specifically in the situation where the magnetic field B is so strong that the dynamical Stark width of these lines reduces to the so-called adiabatic Stark width because the so-called nonadiabatic Stark width is completely suppressed. This situation corresponds, for example, to DA and DBA white dwarfs. We obtained those analytical results by using the formalism of the so-called conventional (or standard) theory of the impact Stark broadening: namely, by performing calculations in the second order of the Dyson perturbation expansion. The primary outcome was that the dynamical Stark broadening was found to not depend on the magnetic field B (for sufficiently strong B). In the present paper, we use the O4 symmetry of hydrogen atoms for performing the corresponding non-perturbative analytical calculations equivalent to accounting for all orders of the Dyson perturbation expansion. The results, obtained by using the O4 symmetry of hydrogen atoms, differ from our previous ones not only quantitatively, but—most importantly—qualitatively. Namely, the dynamical Stark broadening does depend on the magnetic field B, even for strong B. These results should be important for revising the interpretation of the hydrogen Balmer lines observed in DA and DBA white dwarfs. We also address confusion in the literature on this subject. [ABSTRACT FROM AUTHOR]

Data on Stark broadening parameters, spectral line widths, and shifts for 15 multiplets of N VI, whose spectral lines are broadened by collisions with electrons, protons, alpha particles (He III) and B III, B IV, B V and B VI ions, are presented. They have been calculated using the semiclassical perturbation theory, for temperatures from 50,000 K to 2,000,000 K, and perturber densities from 1016 cm−3 up to 1024 cm−3. The data for e, p and He III are of particular interest for the analysis and modelling of atmospheres of hot and dense stars, as, e.g., white dwarfs, and for investigation of their spectra, and data for boron ions are used for analysis and modelling of laser-driven plasma in proton–boron fusion research. Dataset: The dataset is submitted as a Supplementary File. Dataset License: CC-BY 4.0 [ABSTRACT FROM AUTHOR]

This work used spectroscopic plasma emission analysis to investigate the parameters of ZnTi plasma formed in the atmosphere by a Q-switched Nd:YAG nanosecond laser system emitting infrared (1064 nm) laser light with an energy output spanning 200-500 mJ. The spectrometer was used to examine and record the emission spectrum profiles of (ZnTi), which helped to extract crucial plasma characteristics (i.e., T e and n e). The electron density was measured using the Stark broadening, and the plasma temperature was calculated using the Boltzmann plot technique. The electron temperature was between 2.04 and 2.15 eV, and the electron density was between (15.72 and 18.99) × 10 1 6 cm − 3 . The Debye length (l) , the number of particles in the Debye sphere ( N d) , and the plasma frequency ( f p) can all be estimated from the electron temperature ( T e) and the electron density ( n e) ( f p). [ABSTRACT FROM AUTHOR]

Spectral line shapes code in plasmas (SLSPs) code comparison workshops have been organized in the last decade with the aim of comparing the spectra obtained with independently developed analytical and numerical models. Here, we consider the simultaneous effect of a plasma microfield and a periodic electric field on the hydrogen lines Lyman-α, Lyman-β, Balmer-α, and Balmer-β for plasma conditions where the Stark effect usually dominates line broadening. [ABSTRACT FROM AUTHOR]

Recently, plasma-based pyrolysis has gained increasing prominence as a technology in response to the growing challenges in waste disposal and the recognition of opportunities to generate valuable by-products. The efficiency of the pyrolysis process is intricately tied to the characteristics of the plasma involved, particularly the effective electron temperature (Teff) and plasma density (ne). This study aimed to conduct a comprehensive examination of the essential features and optimal operational parameters of a developed RF-ICP torch specifically designed for small-scale municipal solid waste (MSW) pyrolysis (mixture of paper and polypropylene) with the goal of controlling both the torch and the overall process. Using optical emission spectroscopy (OES), we measured plasma parameters, specifically (Teff) and (ne), while varying argon gas flow rates and RF powers. The (Teff) and (ne)were determined using the Boltzmann plot and Stark broadening, respectively. The RF torch was found to generate (ne) up to approximately 2.8 × 10 20   cm − 3 and (Teff) up to around 8200 K, with both parameters being controlled by the discharge power and gas flow rate. Additionally, a power-losing mechanism, namely the anomalous skin effect, was detected during the study, which is uncommon in atmospheric plasma discharge. [ABSTRACT FROM AUTHOR]

We have recently incorporated the occupation probability formalism (OPF) in the simulation model [C. Stehlé and S. Jacquemot, Astron. Astrophys. 271, 348 (1993)] to have a smooth transition from discrete lines to continuum spectrum in the wavelength range near the Balmer series limit. We have analyzed spectra measured for the hydrogen pellet ablation cloud in the Large Helical Device with the revised model, and have found that the electron density in the ablation cloud has a close correlation with the electron temperature of the background plasma. This type of correlation is first confirmed in the present analysis and should give a new insight in the simulation studies of pellet ablation for the magnetically confined fusion plasma. [ABSTRACT FROM AUTHOR]

Stark broadening parameters, line widths and shifts, for 15 N VI multiplets are calculated using semiclassical perturbation theory for temperatures from 50,000 K to 2,000,000 K, and perturber density of 10 16 cm − 3 . As perturbers have been taken electrons, protons and He III ions (alpha particles), which are of interest particularly for white dwarfs. Moreover, B III, B IV, B V and B VI ions have been taken as well, due to their significance for proton-boron fusion investigations. An example of the importance of Stark broadening in comparison with thermal Doppler broadening in atmospheres of spectral class DO white dwarfs is also presented. The obtained results are of interest particularly for white dwarf atmospheres modelling and analysis and synthesis of their spectra as well as for laser driven plasma in proton-boron fusion investigations. [ABSTRACT FROM AUTHOR]

This work used spectroscopic plasma emission analysis to investigate the parameters of Zn–Cd plasma formed in the atmosphere by a Q-switched Nd:YAG nanosecond laser system emitting infrared (1064 nm) laser light with an energy output spanning 200 mJ to 500 mJ. The spectrometer was used to examine and record the emission spectrum profiles of (ZnCd), which helped to extract crucial plasma characteristics (i.e., T e and n e). The electron density was measured using the Stark broadening, and the plasma temperature was calculated using the Boltzmann plot technique. The electron temperature was between 1.02 eV and 1.39 eV, and the electron density was between (39.05 and 50.66) × 1 0 1 6 cm − 3 . The Debye length (l), the number of particles in the Debye sphere ( N d) and the plasma frequency ( f p) can all be estimated from the electron temperature ( T e) and the electron density ( n e) ( f p). Results indicate that plasma parameters are proportional to the energy of laser due to the increase in the intensity of spectral lines energy, and that plasma shielding of ZnCd increases with laser energy in the range of (1.20–1.23). [ABSTRACT FROM AUTHOR]

The effects of the helical trajectories of the perturbing electrons in magnetized plasmas on the dynamical Stark width of hydrogen or deuterium spectral lines have been studied analytically in our previous two papers—specifically in the situation where the magnetic field B is so strong that the dynamical Stark width of these lines reduces to the so-called adiabatic Stark width because the so-called nonadiabatic Stark width is completely suppressed. This situation corresponds, for example, to DA and DBA white dwarfs. We obtained those analytical results by using the formalism of the so-called conventional (or standard) theory of the impact Stark broadening: namely, by performing calculations in the second order of the Dyson perturbation expansion. The primary outcome was that the dynamical Stark broadening was found to not depend on the magnetic field B (for sufficiently strong B). In the present paper, we use the O4 symmetry of hydrogen atoms for performing the corresponding non-perturbative analytical calculations equivalent to accounting for all orders of the Dyson perturbation expansion. The results, obtained by using the O4 symmetry of hydrogen atoms, differ from our previous ones not only quantitatively, but—most importantly—qualitatively. Namely, the dynamical Stark broadening does depend on the magnetic field B, even for strong B. These results should be important for revising the interpretation of the hydrogen Balmer lines observed in DA and DBA white dwarfs. We also address confusion in the literature on this subject.

It has been recently suggested that white dwarf diagnostics could be in error and should be revised because of the effect of the magnetic field on spiralling trajectories of the plasma particles (mainly electrons), predicting a dramatic width increase for high densities of Balmer- β and especially for the δ and ϵ lines. These suggestions overlook important physics and are shown here to be incorrect. Specifically, exact calculations are carried out that can assess the importance of various physical effects neglected in the erroneous analysis mentioned. The net result of accounting for spiralling electron trajectories is typically a small to modest reduction in the line widths, at least for the parameters considered. [ABSTRACT FROM AUTHOR]

Recently developed excitation frequency‐controlled cold atmospheric pressure plasma has shown its efficacy in producing tunable effects with different excitation frequencies in terms of reactive species generation and cancer cell death. This study investigates the electron number density of plasma produced at 11 kHz excitation from stark broadened Hα line, discharge characteristics through simultaneous recording of voltage‐current signals, and high‐speed images of the discharge zone. Malignant breast cancer cells (MCF‐7) and nonmalignant breast cells (MCF‐10A) were used in selectivity experiments. Proliferation and clonogenic assays revealed selective death of cancer cells. DNA damage and DNA repair kinetics were studied using time‐dependent γ‐H2AX foci formation assessment and the selective killing of cancerous cells was established for the 60 s of plasma treatment. [ABSTRACT FROM AUTHOR]

Periodic electric fields are found in many kinds of plasmas and result from the presence of collective fields amplified by plasma instabilities, or they are created by external sources such as microwave generators or lasers. The spectral lines emitted by atoms or ions in a plasma exhibit a frequency profile characteristic of plasma conditions, such as the temperature and density of charged particles. The fingerprints of periodic electric fields appear clearly on the line shape for a large range of frequencies and magnitudes of the oscillating electric field. Satellite structures appear near to multiples of the oscillation frequency and redistribute the intensity of the line far from the line center. The modeling of the simultaneous effects of the plasma microfield and of a periodic electric field has been active since the seventies, but it remains difficult to be conducted accurately since the quantum emitter is submitted to several time-dependent electric fields, each with their own characteristic time. We describe here a numerical approach which couples a simulation of the motion of charged plasma particles with an integration of the emitter Schrödinger equation. Resulting hydrogen line shapes are presented for different plasmas and periodic fields encountered in laboratory and astrophysical plasmas. [ABSTRACT FROM AUTHOR]

Data on Stark broadening parameters, spectral line widths, and shifts for 15 multiplets of N VI, whose spectral lines are broadened by collisions with electrons, protons, alpha particles (He III) and B III, B IV, B V and B VI ions, are presented. They have been calculated using the semiclassical perturbation theory, for temperatures from 50,000 K to 2,000,000 K, and perturber densities from 1016 cm−3 up to 1024 cm−3. The data for e, p and He III are of particular interest for the analysis and modelling of atmospheres of hot and dense stars, as, e.g., white dwarfs, and for investigation of their spectra, and data for boron ions are used for analysis and modelling of laser-driven plasma in proton–boron fusion research.

Spectral line shapes code in plasmas (SLSPs) code comparison workshops have been organized in the last decade with the aim of comparing the spectra obtained with independently developed analytical and numerical models. Here, we consider the simultaneous effect of a plasma microfield and a periodic electric field on the hydrogen lines Lyman-α, Lyman-β, Balmer-α, and Balmer-β for plasma conditions where the Stark effect usually dominates line broadening.

Stark widths for 23 transitions in Al IV have been calculated by employing the modified semiempirical method. The results are obtained for an electron density of 10 17 cm − 3 and temperatures from 10,000 K to 160,000 K. The results obtained in this investigation are used for the examination of the influence of Stark broadening in Al IV stellar spectra, as well as to check the Stark width regular behavior and similarites within the Al IV spectrum. [ABSTRACT FROM AUTHOR]

Recently, plasma-based pyrolysis has gained increasing prominence as a technology in response to the growing challenges in waste disposal and the recognition of opportunities to generate valuable by-products. The efficiency of the pyrolysis process is intricately tied to the characteristics of the plasma involved, particularly the effective electron temperature (Teff) and plasma density (ne). This study aimed to conduct a comprehensive examination of the essential features and optimal operational parameters of a developed RF-ICP torch specifically designed for small-scale municipal solid waste (MSW) pyrolysis (mixture of paper and polypropylene) with the goal of controlling both the torch and the overall process. Using optical emission spectroscopy (OES), we measured plasma parameters, specifically (Teff) and (ne), while varying argon gas flow rates and RF powers. The (Teff) and (ne)were determined using the Boltzmann plot and Stark broadening, respectively. The RF torch was found to generate (ne) up to approximately 2.8×1020 cm−3 and (Teff) up to around 8200 K, with both parameters being controlled by the discharge power and gas flow rate. Additionally, a power-losing mechanism, namely the anomalous skin effect, was detected during the study, which is uncommon in atmospheric plasma discharge.

We have recently incorporated the occupation probability formalism (OPF) in the simulation model [C. Stehlé and S. Jacquemot, Astron. Astrophys. 271, 348 (1993)] to have a smooth transition from discrete lines to continuum spectrum in the wavelength range near the Balmer series limit. We have analyzed spectra measured for the hydrogen pellet ablation cloud in the Large Helical Device with the revised model, and have found that the electron density in the ablation cloud has a close correlation with the electron temperature of the background plasma. This type of correlation is first confirmed in the present analysis and should give a new insight in the simulation studies of pellet ablation for the magnetically confined fusion plasma.

Stark broadening parameters, line widths and shifts, for 15 N VI multiplets are calculated using semiclassical perturbation theory for temperatures from 50,000 K to 2,000,000 K, and perturber density of 1016 cm−3. As perturbers have been taken electrons, protons and He III ions (alpha particles), which are of interest particularly for white dwarfs. Moreover, B III, B IV, B V and B VI ions have been taken as well, due to their significance for proton-boron fusion investigations. An example of the importance of Stark broadening in comparison with thermal Doppler broadening in atmospheres of spectral class DO white dwarfs is also presented. The obtained results are of interest particularly for white dwarf atmospheres modelling and analysis and synthesis of their spectra as well as for laser driven plasma in proton-boron fusion investigations.

It has been claimed that recent experiments using high-powered lasers have identified dip structures in spectral line profiles in plasmas and that these were successfully used to reliably infer both plasma parameters and information on high and low-frequency turbulence. The analysis of those experiments relies on a flawed theory. In the present work, we computed the line spectra correctly using the parameters inferred in the original papers. The results bear little resemblance to the experimental profiles. The only way to reconcile the parameters deduced in these experiments is to invoke very broadband turbulence, with the relevant distribution functions that are neither known nor measured playing critical roles. Furthermore, the dip positions are shown to be sensitive to details such as field directionality and variations in the frequency and field amplitude. Hence, dips cannot be used to reliably diagnose such plasmas. [ABSTRACT FROM AUTHOR]

Stark broadening parameters - full widths at half maximum (FWHM) and shifts for 11 Re II lines have been calculated. The plasma parameters used were electron density of 10 17 cm−3 and temperature from 5 000 K to 80 000 K. Calculations were performed using the simplified modified semiempirical (SMSE) approach and compared with calculations by Cowley's approximative Stark broadening formula at 10000 K, usefull in spectrum synthesis. The results have also been considered in the atmosphere model of A type star and for DB white dwarfs. [ABSTRACT FROM AUTHOR]

Stark broadening parameters are useful in solving various problems e.g., in astrophysics, opacity calculations, design of lasers, laser-produced plasma and for the evaluation of the physical conditions in stellar atmospheres. Our objectives in this research work are to obtain, for electron collisions, new atomic data for Stark broadening of astrophysically important S II lines using semi-classical perturbation (SCP) and modified semi-empirical (MSE) theory with the needed energy levels and oscillator strengths from NIST database. After calculating the Stark broadening data, we compared them with experimental and theoretical data. [ABSTRACT FROM AUTHOR]

The electron-impact widths for 13 Si II multiplets, belonging to the 3s3p( 3 P o )nl configuration, have been calculated by using the modified semiempirical method. Since a number of these lines is in visible, they are of interest and for analysis and synthesis of stellar Si II lines, abundance determination and modelling of stellar atmospheres.The obtained results have been compared with available experimental and theoretical data and used for the investigation of regularities within supermultiplets. [ABSTRACT FROM AUTHOR]

The second-order spectral line width formulae from the projection operator and kinetic theory methods were recently compared. It was shown that a systematic expansion of the projection operator width expression including initial correlations formally agrees with the second-order kinetic theory result. It is now shown that the second-order dynamic shifts are also formally the same. The static shifts, however, differ due to an ad hoc treatment of electron-electron correlations in the projection operator method. The approximation is necessary in order to screen the radiator-electron interactions. The differences, however, are expected to be small. The results suggest using the rigorous and more compact second-order width and shift expressions from the kinetic theory method as the starting point for spectral line shape calculations. At line center, however, the projection operator second-order expression for the width and shift simplifies and reduces to the kinetic theory result. [ABSTRACT FROM AUTHOR]

It has been recently suggested that white dwarf diagnostics could be in error and should be revised because of the effect of the magnetic field on spiralling trajectories of the plasma particles (mainly electrons), predicting a dramatic width increase for high densities of Balmer-β and especially for the δ and ϵ lines. These suggestions overlook important physics and are shown here to be incorrect. Specifically, exact calculations are carried out that can assess the importance of various physical effects neglected in the erroneous analysis mentioned. The net result of accounting for spiralling electron trajectories is typically a small to modest reduction in the line widths, at least for the parameters considered.

Periodic electric fields are found in many kinds of plasmas and result from the presence of collective fields amplified by plasma instabilities, or they are created by external sources such as microwave generators or lasers. The spectral lines emitted by atoms or ions in a plasma exhibit a frequency profile characteristic of plasma conditions, such as the temperature and density of charged particles. The fingerprints of periodic electric fields appear clearly on the line shape for a large range of frequencies and magnitudes of the oscillating electric field. Satellite structures appear near to multiples of the oscillation frequency and redistribute the intensity of the line far from the line center. The modeling of the simultaneous effects of the plasma microfield and of a periodic electric field has been active since the seventies, but it remains difficult to be conducted accurately since the quantum emitter is submitted to several time-dependent electric fields, each with their own characteristic time. We describe here a numerical approach which couples a simulation of the motion of charged plasma particles with an integration of the emitter Schrödinger equation. Resulting hydrogen line shapes are presented for different plasmas and periodic fields encountered in laboratory and astrophysical plasmas.

This paper presents the experimental results on electron, ion temperatures and densities in a pulsed plasma accelerator. The values of electron densities and temperatures were computed using the methods of relative intensities of Hα and Hβ lines, Hβ Stark broadening, and the technique is based on Faraday cup beam current measurements. In this work, a linear optical spectrometer S-100 was used to acquire the emission spectra of hydrogen and air plasmas. In this spectrum, there are some lines due to Fe, Cu, N2, O2, and H2. The series of visible lines in the hydrogen atom spectrum are named the Balmer series. The spectral emissions of iron and copper occur throughout the gas breakdown and ignition of an arc discharge, during the erosion and sputtering of materials. The vacuum chamber and coaxial electrodes were made. The electron temperatures and densities in a pulsed plasma accelerator, measured via relative intensities of spectral lines and Stark broadening, at a charging voltage of a capacitor bank of 3 kV and a working gas pressure in a vacuum chamber of 40 mTorr, were 2.6 eV and 1.66 · 1016 cm−3 for hydrogen plasma. These results were compared with the Faraday cup beam current measurements. However, no match was found. Considering and analyzing this distinction, we concluded that the spectral method of plasma diagnostics provides more accurate results than electrical measurement. The theory of probe measurements can give approximate results in a moving plasma.

Stark widths for spectral lines within 24 multiplets of Zn III singlets and triplets have been calculated using modified semiempirical method for an electron density of 1017 cm−3 and temperatures from 5000 K up to 100,000 K. The obtained results have been used for the investigation of the influence of Stark broadening on Zn III spectral lines in stellar atmospheres and for the considerations of Stark width similarites within supermultiplets and transition arrays. [ABSTRACT FROM AUTHOR]

The advantages of pulsed low-current high-voltage discharges operated at atmospheric pressure and the ease with which such discharges can be implemented industrially contributed to their popularity. However, the high reactivity of a pulsed plasma implies that thorough diagnostics are needed to fully understand the interactions inside these plasmas. Some of the key parameters determining plasma properties of low-current discharges are the electron number density and the temperature of heavy particles. Both parameters can be determined experimentally with spectroscopic techniques, for example by investigating the broadening of spectral lines due to the Stark effect and by fitting synthetic spectra to molecular transitions. To the authors' knowledge, experimentally determined electron densities for pulsed low-current discharges operated in a power range between 300 W and 1000 W have not been performed in previous works. Thus, in this work, the electron number density and temperature of heavy particles of one of several commercially available plasma systems are determined by means of emission spectroscopy. [ABSTRACT FROM AUTHOR]

The study of the surface plasma characteristics under atmospheric pressure is a new branch and tool in physics. Building generation dielectric barrier discharge (DBD) system at atmospheric pressure and studying its thermal characterizations. The discharge was produced by applying a high voltage of 20 kV with a frequency of 8 kHz. The thermal characterization was done by measuring discharge temperature for different horizontal surface areas and different types of insulating material. The results indicated that the effect of the area and the type of insulator affect the discharge (increasing or decreasing) according to the operation conditions because they affect, as expected, the DBD . The plasma temperature increased with the decrease of the surface area, which resulted in the increase of the discharge voltage across the gap; accordingly, the discharge across the gap grew. [ABSTRACT FROM AUTHOR]

Various types of electric fields contained in the laboratory and astrophysical plasma cause a Stark broadening of spectral lines in plasma. Therefore, a large number of spectroscopic diagnostics of laboratory and astrophysical plasma are based on experimental and theoretical studies of Stark broadening of spectral lines in plasma. The topic of the present investigation is the Stark broadening caused by free electrons in plasma and its dependence on certain atomic parameters using a new method based on the machine learning (ML) approach. Analysis of empirical data on atomic parameters was done by ML algorithms with more success that it was previously done by classical methods of data analysis. The correlation parameter obtained by artificial intelligence (AI) is slightly better than the one obtained by classical methods, but the scope of application is much wider. AI conclusions are applicable to any physical system while conclusions made by classical analysis are applicable only to a small portion of these systems. ML algorithms successfully identified quantum nature by analyzing atomic parameters. The biggest issue of classical analysis, which is infinite spectral line broadening for high ionization stages, was resolved by AI with a saturation tendency. [ABSTRACT FROM AUTHOR]

Underwater discharge plasmas are widely acclaimed for their potential applications in wastewater treatment, biomedical sciences, and industry. This article reports on pre- and post-breakdown characteristics of nanosecond pulsed plasma discharge generated in oxygen–water mixture flowing through a quartz capillary tube. In pre-breakdown region of applied voltage range of 4–4.5 kV, medium capacitance varies between 20 and 26 pF. For applied voltage range of 5–9 kV, a plasma discharge was observed during which the prominent current and voltage peaks show 5–10-ns phase difference. Electron number density was estimated using current density and Stark broadening techniques. It was noted that electron number density estimated from current density values ranges from 0.08 $\times \,\,10^{\mathrm {23 {}}}\,\,\text{m}^{-3}$ to 0.18 $\times \,\,10^{23}\,\,\text{m}^{-3}$ , while the electron number density estimated from Stark broadening of Balmer series hydrogen $H_{\alpha }$ and $H_{\beta }{}$ lines was found between 1.26 $\times \,\,10^{23}\,\,\text{m}^{-3}$ –2.69 $\times \,\,10^{23}\,\,\text{m}^{-3}$ and 1.25 $\times \,\,10^{23}\,\,\text{m}^{-3}$ –2.52 $\times \,\,10^{23}\,\,\text{m}^{-3}$ , respectively. The estimated values of plasma coupling parameter were in the range of 0.031–0.21, indicating the generated plasma to be on the margins of noncoupling ideal plasma to nonideal weakly coupled plasma. Effect of oxygen–water mixture flow direction on discharge stability and other plasma parameters was also monitored. It was observed that plasma discharge was more stable with higher electron number density in the direction of fluid flow. [ABSTRACT FROM AUTHOR]

Stark broadening parameters, full widths at half maximum (FWHM) and shifts for spectral lines within six multiplets of doubly charged ruthenium ions have been calculated, for an electron density of 10 17 cm-3 and temperature range from 10 000 K to 160 000 K. Calculations have been performed with the simplified modified semiempirical (SMSE) approach. In the case of two multiplets, it is possible to apply the full modified semiempirical method. The corresponding calculations have been performed and results are compared in order to test and determine the accuracy of the SMSE approach. The results are also used for the consideration of Stark width and shift regularities in Ru III spectrum

In this work, the effect of preparing a composite of copper oxide nanoparticles with carbon on some of its optical properties was studied. The composite preparing process was carried out by exploding graphite electrodes in an aqueous suspension of copper oxide. The properties of the plasma which is formed during the explosion were studied using emission spectroscopy in order to determine the most important elements that are present in the media. The electron’s density and their energy, which is the main factor in the composite process, were determined. The particle properties were studied before and after the exploding process. The XRD showed an additional peak in the copper oxides pattern corresponding to the hexagonal graphite structure for the composite. The UV-visible absorbance for the composite was significantly enhanced. The direct bandgap decreased from 2.55 to 2.4 eV, and the indirect bandgap decreased from 1.1 to 1 eV, for the composite.

In this work, the effect of preparing a composite of copper oxide nanoparticles with carbon on some of its optical properties was studied. The composite preparing process was carried out by exploding graphite electrodes in an aqueous suspension of copper oxide. The properties of the plasma which is formed during the explosion were studied using emission spectroscopy in order to determine the most important elements that are present in the media. The electron's density and their energy, which is the main factor in the composite process, were determined. The particle properties were studied before and after the exploding process. The XRD showed an additional peak in the copper oxides pattern corresponding to the hexagonal graphite structure for the composite. The UV-visible absorbance for the composite was significantly enhanced. The direct bandgap decreased from 2.55 to 2.4 eV, and the indirect bandgap decreased from 1.1 to 1 eV, for the composite. [ABSTRACT FROM AUTHOR]

The present work investigated the effect of distance from target surface on the parameters of lead plasma excited by 1064nm Q-switched Nd:YAG laser. The excitation was conducted in air, at atmospheric pressure, with pulse length of 5 ns, and at different pulse laser energies. Electron temperature was calculated by Boltzmann plot method based on the PbI emission spectral lines (369.03 nm, 416.98 nm, 523.48, and 561.94 nm). The PbI lines were recorded at different distances from the target surface at laser pulse energies of 260 and 280 mJ. The emission intensity of plasma increased with increasing the lens-to-target distance. The results also detected an increase in electron temperature with increasing the distance between the focal lens and the surface of the target in all laser energies under study. In addition, the electron number density was determined by using the Stark broadening method. The data illustrated that the electron number density was increased with increasing the distance from target surface, reaching the maximum at a distance of 11 cm for all pulse laser energy levels under study. [ABSTRACT FROM AUTHOR]

Stark broadening parameters, full widths at half maximum (FWHM) and shifts for 13 Os II lines have been calculated. The plasma parameters are: electron density of 1017 cm-3 and temperatures from 5 000 K to 80 000 K. Calculations have been performed with the simplified modified semiempirical (SMSE) approach. The results are also used for the consideration of Strak width and shift regularities within the Os II 6s6D-6p6Do multiplet.

Stark full widths at half maximum (FWHM) for 26 6s-6p transitions in Tb III spectrum have been calculated for electron density of 1017 cm-3 within a temperature range of 5 000 K to 80 000 K, by using the simplified modified semiempirical (SMSE) method. The results obtained are used for the consideration of Stark width regularities within the investigated transition array.

Stark widths for 23 transitions in Al IV have been calculated by employing the modified semiempirical method. The results are obtained for an electron density of 1017 cm−3 and temperatures from 10,000 K to 160,000 K. The results obtained in this investigation are used for the examination of the influence of Stark broadening in Al IV stellar spectra, as well as to check the Stark width regular behavior and similarites within the Al IV spectrum.

It has been claimed that recent experiments using high-powered lasers have identified dip structures in spectral line profiles in plasmas and that these were successfully used to reliably infer both plasma parameters and information on high and low-frequency turbulence. The analysis of those experiments relies on a flawed theory. In the present work, we computed the line spectra correctly using the parameters inferred in the original papers. The results bear little resemblance to the experimental profiles. The only way to reconcile the parameters deduced in these experiments is to invoke very broadband turbulence, with the relevant distribution functions that are neither known nor measured playing critical roles. Furthermore, the dip positions are shown to be sensitive to details such as field directionality and variations in the frequency and field amplitude. Hence, dips cannot be used to reliably diagnose such plasmas.

In this paper, we investigate a new method to control the plasma electron number density of copper metal using a near-infrared (NIR) picosecond Nd:YAG laser-induced plasma spectroscopy (LIPS) technique. The applied laser parameters are as follows; laser pulse energy and intensity varied from 29.2 to 59.4 mJ ± 3% and from 6.01x1010 to 12.35x1010 W/cm² ± 5%, respect ively, for a s ingle pulse at 170 ps pulse duration, and beam diameter about 0.5 ± 0.1 mm. By considering the Stark broadening of a specific spectral line, electron density can be calculated using a neutral copper line at 521.8 nm, assuming the local thermodynamic equilibrium (LTE) condition. The observed electron density values were 1.09x1016, 2.24x1016, 3.60x1016, and 4.75x1016 cm-3 for the laser pulse energies 29.2, 41, 52.4, and 59.4 mJ, respectively. The plasma electron density values are increased with the increase in laser pulse energy. Such findings were interpreted due to an increase in the mass ablation rates with laser pulse energy. The obtained results explore the ability to control the plasma electron density by controlling the picosecond pulse energy. These results can contribute to the development of plasma technologies and their applications in many fields. [ABSTRACT FROM AUTHOR]

The knowledge of the spectroscopic parameters of the elemental emission lines is important for diagnostics of laser-induced plasmas and the application of calibration-free/fundamental parameters analytical methods. In this paper, we used the recently proposed time-independent extended C-sigma method for determining, for the first time, the transition probabilities and Stark broadening coefficients of several neutral (TIECS) and ionic silver emission lines. The method allows for a compensation of self-absorption in the plasma, thus providing a measure of the spectroscopic parameters which is not affected by the optical thickness of the plasma. Graphical Abstract [ABSTRACT FROM AUTHOR]

• Stark profiles of He I 388.865 nm were measured using the wall-stabilized arc operated at atmospheric pressure in helium with small admixtures of hydrogen and nitrogen. • Stark profiles of He I 388.865 nm were calculated using a semi-classical method and by computer simulations. • Results of our measurements, calculations and simulations are compared with results of other authors. We report the results of comprehensive (both experimental and theoretical) studies of Stark broadening parameters (width and shift) of the He I 388.865 nm (2s 3S – 3p 3Po) spectral line. Measurements have been performed using the wall-stabilized arc operated in a helium gas with small admixture of hydrogen and nitrogen at atmospheric pressure. The radiation of the plasma emitted in an end-on direction was measured with the use of a grating spectrometer equipped with a CCD detector. We compare the above experimental results with those of computer simulations (CSM) as well as with theoretical ones based on the modified Griem perturbation theory. The comparison of the above results with those from the literature shows that they provide reliable data for helium plasmas with low electron densities not exceeding 1·1022 m−3. [ABSTRACT FROM AUTHOR]

Frequently used second-order spectral line width formulae from the projector operator and kinetic theory methods have not been formally compared previously. It is shown that a systematic second-order expansion of the projection operator expression including initial correlations agrees with the second-order kinetic theory result. The agreement assumes a common approximation in the projector operator method that introduces a screened radiator–perturber interaction to account for neglected electron–electron correlations. On the other hand, it is shown that the usual width expression from the projection operator approach neglecting initial correlations differs from kinetic theory. The differences, however, are at least third order in the radiator–perturber interaction. The comparisons suggest using the more compact width expression from kinetic theory, which includes initial correlations and a systematic screening of the radiator–perturber interactions, as the starting point for second-order width calculations. [ABSTRACT FROM AUTHOR]

Stark widths for spectral lines within 24 multiplets of Zn III singlets and triplets have been calculated using modified semiempirical method for an electron density of 1017 cm−3 and temperatures from 5000 K up to 100,000 K. The obtained results have been used for the investigation of the influence of Stark broadening on Zn III spectral lines in stellar atmospheres and for the considerations of Stark width similarites within supermultiplets and transition arrays.

The advantages of pulsed low-current high-voltage discharges operated at atmospheric pressure and the ease with which such discharges can be implemented industrially contributed to their popularity. However, the high reactivity of a pulsed plasma implies that thorough diagnostics are needed to fully understand the interactions inside these plasmas. Some of the key parameters determining plasma properties of low-current discharges are the electron number density and the temperature of heavy particles. Both parameters can be determined experimentally with spectroscopic techniques, for example by investigating the broadening of spectral lines due to the Stark effect and by fitting synthetic spectra to molecular transitions. To the authors’ knowledge, experimentally determined electron densities for pulsed low-current discharges operated in a power range between 300 W and 1000 W have not been performed in previous works. Thus, in this work, the electron number density and temperature of heavy particles of one of several commercially available plasma systems are determined by means of emission spectroscopy.