31 https://uvadoc.uva.es/handle/10324/1157 2026-04-25T11:57:33Z 2026-04-25T11:57:33Z Xiong, Qing Nikiforov, Anton Yu González, Manuel Á Leys, Christophe Lu, Xin Pei https://uvadoc.uva.es/handle/10324/84268 2026-04-22T19:00:52Z 2013-01-01T00:00:00Z

The characteristics of plasma temperatures (gas temperature and electron excitation temperature) and electron density in a pulsed-dc excited atmospheric helium plasma jet are studied by relative and absolute optical emission spectroscopy (OES). High-resolution OES is performed for the helium and hydrogen lines for the determination of electron density through the Stark broadening mechanism. A superposition fitting method composed of two component profiles corresponding to two different electron densities is developed to fit the investigated lines. Electron densities of the orders of magnitude of 1021 and 1020 m−3 are characterized for the center and edge regions in the jet discharge when the applied voltage is higher than 13.0 kV. The atomic state distribution function (ASDF) of helium demonstrates that the discharge deviates from the Boltzmann–Saha equilibrium state, especially for the helium lower levels, which are significantly overpopulated. Local electron excitation temperatures T13 and Tspec corresponding to the lower and upper parts of the helium ASDF are defined and found to range from 1.2 eV to 1.4 eV and 0.2 eV to 0.3 eV, respectively. A comparative analysis shows that the Saha balance is valid in the discharge for helium atoms at high excited states.

2013-01-01T00:00:00Z Ivković, M. Gonzalez, M.A. Lara, N. Gigosos, M.A. Konjević, N. https://uvadoc.uva.es/handle/10324/84267 2026-04-22T19:00:51Z 2013-01-01T00:00:00Z

We present the results of an experimental study of the He I 492.2 nm line with forbidden components emitted by low-electron temperature and high electron number density helium plasma with or without addition of hydrogen. The shapes of the He I 447.1 nm and 501.6 nm lines and hydrogen Hβ line were used to measure electron number density in the range (1–5) 1023 m−3, while electron temperatures in the range from 5,000 K to 35,000 K were determined from the line to underlying continuum ratio of He I lines at 388.8, 667.8, 706.5 and 728.1 nm. The experimental profiles of the He I lines are compared with the results of a computer simulation method. The comparison was performed by use of a program for simultaneous interpolation of data tables obtained by computer simulation for 492.2 and 501.6 nm He I and hydrogen Hβ lines. The electron number densities obtained from this comparison agree within 10% with corresponding values determined from the 447.1 nm He I line which is well within theoretical and experimental uncertainties for all lines included in comparison.

2013-01-01T00:00:00Z Lara, N. González Delgado, Manuel Ángel Gigosos Pérez, Marco Antonio https://uvadoc.uva.es/handle/10324/84264 2026-04-22T19:00:50Z 2012-01-01T00:00:00Z

Context. We studied the Stark broadening of the He I 492.2 nm line, which is sometimes used for plasma diagnostics or to obtain information on different stellar parameters. Aims. The final aim of this study is to obtain tables of lines shapes as well as the relationships between different line parameters and the plasma electron density, temperature, or composition. The tables of profiles and the mathematical expressions obtained will be used in plasma diagnostics. Methods. We performed computer simulations and used a physical model that considers a weakly coupled plasma. Our computer simulations naturally take into account ion dynamical effects, which has permitted us to study the influence on the line shapes of imbalances in the plasma caused by different electron and gas temperatures. Results. Our computer simulations considered electron densities between 1019 and 1024 m−3, electron temperatures between 5000 and 40 000 K, and plasmas of different compositions. The dependences obtained in the simulations for the line width, the ratio of intensities between the allowed and the forbidden components, or the distances between those components’ peaks on the plasma conditions are shown and compared with experimental data. Numerical expressions for the line width and for the peak distances against the electron density were obtained from the simulation results and can be applied to obtain the electron density from experimental results. Full line profile tables are also supplied for use in plasma diagnostics.

2012-01-01T00:00:00Z Stambulchik, Evgeny Calisti, Annette Chung, Hyun-Kyung González Delgado, Manuel Ángel https://uvadoc.uva.es/handle/10324/84263 2026-04-22T19:00:50Z 2019-01-01T00:00:00Z

The Spectral Line Shapes in Plasmas (SLSP) code comparison workshop series [1] has gained a steady momentum, with four meetings organized thus far—in 2012, 2013, 2015, and 2017. A large number of diverse problems have been analyzed, advancing understanding of the phenomena involved and increasing accuracy of the models. Doubtlessly, this has significantly aided in improving theoretical aspects of line-shape analysis—one of the most important tools for diagnostics of both laboratory and space plasmas. The first Special Issue of Atoms under this title was published in 2014 [2,3], covering selected topics from the first two workshops. With the hope of establishing tradition, we decided to arrange for the present Special Issue as a place for disseminating new results obtained in the course of the 3rd and 4th SLSP workshops.

2019-01-01T00:00:00Z Nikiforov, A Yu Leys, Ch González Delgado, Manuel Ángel Walsh, J L https://uvadoc.uva.es/handle/10324/84242 2026-04-21T19:21:17Z 2015-01-01T00:00:00Z

Electron density is one of the key parameters in the physics of a gas discharge. In this contribution the application of the Stark broadening method to determine the electron density in low temperature atmospheric pressure plasma jets is discussed. An overview of the available theoretical Stark broadening calculations of hydrogenated and non-hydrogenated atomic lines is presented. The difficulty in the evaluation of the fine structure splitting of lines, which is important at low electron density, is analysed and recommendations on the applicability of the method for low ionization degree plasmas are given. Different emission line broadening mechanisms under atmospheric pressure conditions are discussed and an experimental line profile fitting procedure for the determination of the Stark broadening contribution is suggested. Available experimental data is carefully analysed for the Stark broadening of lines in plasma jets excited over a wide range of frequencies from dc to MW and pulsed mode. Finally, recommendations are given concerning the application of the Stark broadening technique for the estimation of the electron density under typical conditions of plasma jets.

2015-01-01T00:00:00Z González Delgado, Manuel Ángel Gigosos Pérez, Marco Antonio https://uvadoc.uva.es/handle/10324/84238 2026-04-21T19:21:17Z 2007-01-01T00:00:00Z

The authors of a recent paper [1] show experimental results of hydrogen Balmer-b and -g line profiles, analysing the dependences of those spectral lines on the fill pressure of the plasma chamber and the discharge power.

2007-01-01T00:00:00Z Gigosos, Marco Antonio González, Manuel Ángel https://uvadoc.uva.es/handle/10324/84235 2026-04-21T19:21:16Z 2007-01-01T00:00:00Z

In this note we want to clarify the applicability of the SO(4) symmetry of the hydrogen atom for the calculation of line broadening for emitters in a plasma with magnetic fields.

2007-01-01T00:00:00Z Ferri, S. Calisti, A. Mossé, C. Talin, B. Gigosos Pérez, Marco Antonio González Delgado, Manuel Ángel https://uvadoc.uva.es/handle/10324/84233 2026-04-21T19:21:16Z 2007-01-01T00:00:00Z

A study of hydrogen lines emitted in warm (Te w1 eV) and dense (Ne 1018 cm 3) plasmas is presented. Under such plasma conditions, the electronic and the ionic contributions to the line width are comparable, and the general question related to a transition from impact to quasi-static broadening arises not only for the far wings but also for the core of spectral lines. The transition from impact to quasi-static broadening for electrons is analyzed by means of Frequency Fluctuation Model (FFM). In parallel, direct integration of the semi-classical evolution equation is performed using electron electric fields calculated by Molecular Dynamics (MD) simulations that permit one to correctly describe the emitter environment. New cross comparisons between benchmark MD simulations and FFM are carried out for electron broadening of the Balmer series lines, and, especially, for the Ha line, for which a few experiments in the warm and dense plasma regimes are available.

2007-01-01T00:00:00Z Gigosos, M. A. González, M. Á. Talin, B. Calisti, A. https://uvadoc.uva.es/handle/10324/84231 2026-04-21T19:21:15Z 2007-01-01T00:00:00Z

Aims. Recent measurements on the Stark broadening of radio recombination lines show values and trends in disagreement with conventional theories. Different attemps to explain those disagreements have not been successfull for any of the employed theoretical models. In particular, the impact model that describes well the physical conditions at which the studied broadenings occur, shows a functional trend upon the principal quantum number of the studied transitions that does not correspond to the experimental observations. Methods. High values of the principal quantum number require computable formulas for the calculation of transition probabilities. Some of those expressions have been published, leading to approximate formulas on the dependence of the line width versus the principal quantum number of the upper level of the transition. Results. In this work an exact expression for the hydrogen Stark width in the frame of impact approximation is given.; Aims. Recent measurements on the Stark broadening of radio recombination lines show values and trends in disagreement with conventional theories. Different attemps to explain those disagreements have not been successfull for any of the employed theoretical models. In particular, the impact model that describes well the physical conditions at which the studied broadenings occur, shows a functional trend upon the principal quantum number of the studied transitions that does not correspond to the experimental observations. Methods. High values of the principal quantum number require computable formulas for the calculation of transition probabilities. Some of those expressions have been published, leading to approximate formulas on the dependence of the line width versus the principal quantum number of the upper level of the transition. Results. In this work an exact expression for the hydrogen Stark width in the frame of impact approximation is given.

2007-01-01T00:00:00Z Gigosos, M. A. González, M. Á. Konjević, N. https://uvadoc.uva.es/handle/10324/84165 2026-04-17T19:00:56Z 2006-01-01T00:00:00Z

We report results of the Stark broadening calculations for Sr+ and Ba+ resonance lines in ultra- cold plasmas using semiempirical formulas and numerical computer simulation technique. The simulation results show that strong collisions dominate Stark broadening at very low electron temperatures and weak collision approximation used recently by Vrinceanu et al. cannot be applied in this temperature region. Consequently, the temperature trend of Stark widths and shifts changes from 1/ T successfully used at elevated temperatures to an increasing trend with temperature, which is characteristic for strong collisions at low temperature.

2006-01-01T00:00:00Z Dufour, Emmanuelle Calisti, Annette Talin, Bernard Gigosos, Marco A. González, Manuel A. del Río Gaztelurrutia, Teresa Dufty, James W. https://uvadoc.uva.es/handle/10324/84163 2026-04-17T19:00:56Z 2005-01-01T00:00:00Z

Studies of charge-charge (ion-ion, ion-electron, and electron-electron) coupling properties for ion impurities in an electron gas are carried out on the basis of a regularized electron-ion potential without short-range Coulomb divergence. This work is motivated, in part, by questions arising from recent spectroscopic measurements revealing discrepancies with present-day theoretical descriptions. Many of the current radiative property models for plasmas include only single electron-emitter collisions and neglect some or all charge-charge interactions. A molecular-dynamics simulation of dipole relaxation is proposed here to allow proper account of many electron-emitter interactions and all charge-charge couplings. As illustrations, molecular-dynamics simulations are reported for the cases of a single ion embedded in an electron plasma and for a two-component ion-electron plasma. Charge-charge coupling effects are discussed for hydrogenlike Balmer alpha lines at weak coupling conditions.

2005-01-01T00:00:00Z Gigosos, Marco A. González, Manuel Á. Cardeñoso, Valentı́n https://uvadoc.uva.es/handle/10324/84161 2026-04-17T19:00:55Z 2003-01-01T00:00:00Z

Balmer-alpha, -beta and -gamma lines have been calculated using computer simulations including ion dynamics effects for equilibrium and non-equilibrium conditions. The results obtained allow us to supply diagnostic maps based on the widths of those lines, as well as the Stark broadened full line profiles and the dipolar correlation functions obtained in the simulations. These profiles and correlation functions are a better diagnostic tool than the widths of the profiles in case of non-equilibrium plasmas. Calculations cover the range of electron densities between 1020 and 1025 m3 and of electron temperatures between 1000 and 175 000 K. The emitter and the perturber ions kinetic temperature may vary between the value of the electrons temperature and one tenth of it.

2003-01-01T00:00:00Z Dufour, Emmanuelle Calisti, Annette Talin, Bernard A. Gigosos, Marco González, Manuel A. Dufty, James W. https://uvadoc.uva.es/handle/10324/84160 2026-04-17T19:00:53Z 2003-01-01T00:00:00Z

Electron broadening for ion emitters is investigated with a molecular dynamics based spectral line shape simulation. A regularized Coulomb potential that removes the divergence at short distances is used for the ion–electron interaction. The method presented here allows one to account for all the correlations between charged particles, which is in distinction to the standard electron broadening of the impact approximation. Two cases are considered: 8rst, a single ion impurity embedded into an electron gas is considered; and second,two-component ion–electron plasma is studied. Simulations show non-negligible charge correlation effects on line shapes opening new possibilities to improve line shape models and interpretations of experiments. a

2003-01-01T00:00:00Z Talin, B Dufour, E Calisti, A Gigosos, M A Gonz lez, M A Gaztelurrutia, T del R o Dufty, J W https://uvadoc.uva.es/handle/10324/84035 2026-04-14T19:03:55Z 2003-01-01T00:00:00Z

The ion–electron coupling properties for an ion impurity in an electron gas and for a two-component plasma are carried out on the basis of a regularized electron–ion potential removing the short-range Coulomb divergence. This work is largely motivated by the study of radiator dipole relaxationplasmas which makes a real link between models and experiments. Current radiative property models for plasmas include single electron collisions neglecting charge–charge correlations within the classical quasi-particle approach commonly used in this field. The dipole relaxation simulation based on electron–ion molecular dynamics proposed here will provide a meansbenchmark and improve model developments. Benefiting from a detailed study of a single ion embedded in an electron plasma, the challenging two-component ion–electron molecular dynamics simulations are proved accurate. They open new possibilities of obtaining reference lineshape data.

2003-01-01T00:00:00Z Žikić, R. Gigosos, M.A. Ivković, M. González, M.Á. Konjević, N. https://uvadoc.uva.es/handle/10324/84034 2026-04-14T19:03:54Z 2002-01-01T00:00:00Z

A program for the determination of plasma electron number density, 10 20F(Ne )F10 23 m y3 , from the comparison of experimental and theoretical hydrogen Balmer beta (Hb) line profiles is described in detail. Three theoretical data sets (one set is calculated within the framework of this paper) are included with the program and may be selected as a user’s choice. Apart from Ne determination from the comparison of the whole experimental and theoretical profiles, this program offers a fast estimation of Ne from the halfwidth of the experimental line shape. If necessary, certain parts of the experimental profile may be neglected in the procedure of comparison with theory. This possibility enables the use of noisy line shape recordings for N e determination. The H b asymmetry study may be carried out by generating the difference between experimental and best-fitted theoretical line profiles.

2002-01-01T00:00:00Z González, Manuel Á Arranz, Gloria Portales, Raúl Tamayo, Miguel González, Alberto https://uvadoc.uva.es/handle/10324/84033 2026-04-14T19:03:53Z 2002-01-01T00:00:00Z

A virtual physics laboratory is being developed in the Escuela Técnica Superior de Ingenierı́a Informática of the Universidad de Valladolid (UVA). This laboratory will be accessible via the internet, and its main aim is to provide support for the real physics laboratory. In this paper we describe the main steps taken to develop such a laboratory. This virtual laboratory is currently accessible from http://cawdor.fa2.etit.uva.es/laboratorio/index.html.

2002-01-01T00:00:00Z