71 results on '"stark broadening"'
Search Results
2. Better Understanding of Hydrogen Pellet Ablation Cloud Spectra through the Occupation Probability Formalism in LHD
- Author
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Motoshi Goto, Gen Motojima, Ryuichi Sakamoto, Bernard Pégourié, Akinobu Matsuyama, Tetsutarou Oishi, Tomoko Kawate, and Yasuko Kawamoto
- Subjects
hydrogen pellet ,ablation cloud ,spectroscopy ,Stark broadening ,local thermodynamic equilibrium ,occupation probability formalism ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
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.
- Published
- 2024
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3. Effects of Spiralling Trajectories on White Dwarf Spectra: High Rydberg States
- Author
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Spiros Alexiou
- Subjects
Stark broadening ,external magnetic field ,quadratic Zeeman effect ,line narrowing ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
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.
- Published
- 2023
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4. The Fingerprints of Periodic Electric Fields on Line Shapes Emitted in Plasmas
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Ibtissem Hannachi and Roland Stamm
- Subjects
stark broadening ,periodic electric fields ,computer simulation ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
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.
- Published
- 2023
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5. Analysis of Plasma Emission Experiments and ‘Dips’
- Author
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Spiros Alexiou
- Subjects
stark broadening ,external elecric field ,satellites ,Floquet ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
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.
- Published
- 2023
- Full Text
- View/download PDF
6. The Semiclassical Limit of the Gailitis Formula Applied to Electron Impact Broadening of Spectral Lines of Ionized Atoms
- Author
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Sylvie Sahal-Bréchot
- Subjects
feshbach resonances ,electron collisions with ionized atoms ,stark broadening ,impact approximation ,isolated lines ,semiclassical-perturbation picture ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
The present paper revisits the determination of the semi-classical limit of the Feshbach resonances which play a role in electron impact broadening (the so-called “Stark“ broadening) of isolated spectral lines of ionized atoms. The Gailitis approximation will be used. A few examples of results will be provided, showing the importance of the role of the Feshbach resonances.
- Published
- 2021
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7. Methods for Line Shapes in Plasmas in the Presence of External Electric Fields
- Author
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Spiros Alexiou
- Subjects
stark broadening ,external elecric field ,satellites ,Floquet ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Line broadening is usually dominated by interactions of an atomic system with a stochastic, random medium. When, in addition to the random medium, a non-random field (such as a laser) is applied, the line profile may be modified in significant ways. The present work discusses these modifications and the methods to deal with them.
- Published
- 2021
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8. Stark-Broadening of Ar K-Shell Lines: A Comparison between Molecular Dynamics Simulations and MERL Results
- Author
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Marco A. Gigosos, Roberto C. Mancini, Juan M. Martín-González, and Ricardo Florido
- Subjects
stark broadening ,electron broadening ,recombination broadening ,simulations ,molecular dynamics ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Analysis of Stark-broadened spectral line profiles is a powerful, non-intrusive diagnostic technique to extract the electron density of high-energy-density plasmas. The increasing number of applications and availability of spectroscopic measurements have stimulated new research on line broadening theory calculations and computer simulations, and their comparison. Here, we discuss a comparative study of Stark-broadened line shapes calculated with computer simulations using non-interacting and interacting particles, and with the multi-electron radiator line shape MERL code. In particular, we focus on Ar K-shell X-ray line transitions in He- and H-like ions, i.e., Heα, Heβ and Heγ in He-like Ar and Lyα, Lyβ and Lyγ in H-like Ar. These lines have been extensively used for X-ray spectroscopy of Ar-doped implosion cores in indirect- and direct-drive inertial confinement fusion (ICF) experiments. The calculations were done for electron densities ranging from 1023 to 3×1024 cm−3 and a representative electron temperature of 1 keV. Comparisons of electron broadening only and complete line profiles including electron and ion broadening effects, as well as Doppler, are presented. Overall, MERL line shapes are narrower than those from independent and interacting particles computer simulations performed at the same conditions. Differences come from the distinctive treatments of electron broadening and are more pronounced in α line transitions. We also discuss the recombination broadening mechanism that naturally emerges from molecular dynamics simulations and its influence on the line shapes. Furthermore, we assess the impact of employing either molecular dynamics or MERL line profiles on the diagnosis of core conditions in implosion experiments performed on the OMEGA laser facility.
- Published
- 2021
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9. Analysis of Plasma Emission Experiments and ‘Dips’
- Author
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Alexiou, Spiros
- Subjects
Floquet ,satellites ,stark broadening ,external elecric field - Abstract
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.
- Published
- 2023
- Full Text
- View/download PDF
10. Plasma Spectroscopy on an Aluminum-Pellet Ablation Cloud in an LHD Plasma with an Echelle Spectrometer
- Author
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Hirotaka Tanaka, Keisuke Fujii, Taiichi Shikama, Shigeru Morita, Motoshi Goto, and Masahiro Hasuo
- Subjects
pellet ablation plasma ,LHD ,plasma spectroscopy ,aluminum atoms and ions ,stark broadening ,echelle spectrometer ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
We developed an echelle spectrometer for the simultaneous observation of the whole visible range with a high instrumental resolution, for example, 0.055 nm (full width at the half maximum) at 400 nm and 0.10 nm at 750 nm. With the spectrometer, the emission from an ablation cloud of an aluminum pellet injected into a high-temperature plasma generated in the Large Helical Device (LHD) was measured. We separated the emission lines into Al I, II, III and IV groups, and estimated the electron temperature and density of the ablation cloud from the line intensity distribution and Stark broadening respectively, of each of the Al I, II and III groups. We also determined the Stark broadening coefficients of many Al II and III lines from the respective Stark widths with the estimated electron temperature and density.
- Published
- 2020
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11. Theoretical Stark Broadening Parameters for UV–Blue Spectral Lines of Neutral Vanadium in the Solar and Metal-Poor Star HD 84937 Spectra
- Author
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Cristóbal Colón, María Isabel de Andrés-García, Lucía Isidoro-García, and Andrés Moya
- Subjects
atomic data ,atomic processes ,stark broadening ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Using Griem’s semi-empirical approach, we have calculated the Stark broadening parameters (line widths and shifts) of 35 UV–Blue spectral lines of neutral vanadium (V I). These lines have been detected in the Sun, the metal-poor star HD 84937, and Arcturus, among others. In addition, these parameters are also relevant in industrial and laboratory plasma. The matrix elements required were obtained using the relativistic Hartree–Fock (HFR) method implemented in Cowan’s code.
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- 2020
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12. The Spectroscopic Atomic and Molecular Databases at the Paris Observatory
- Author
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Evelyne Roueff, Sylvie Sahal-Bréchot, Milan S. Dimitrijević, Nicolas Moreau, and Hervé Abgrall
- Subjects
atomic and molecular physics ,stark broadening ,UV spectra ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
This paper is intended to give a comprehensive overview of the current status and developments of the Paris Observatory STARK-B, MOLAT and SESAM databases which can be interrogated thanks to interoperability tools. The STARK-B database provides shifting and broadening parameters of different atomic and ionic transitions due to impacts with charged particles (the so-called Stark broadening) for different temperatures and densities. The spectroscopic MOLAT and SESAM databases provide the wavelengths, the oscillator strengths or Einstein spontaneous emission coefficients of H 2 , CO and isotopologues molecules.
- Published
- 2020
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13. Electron Broadening Operator Including Penetrating Collisions for Hydrogen
- Author
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Jean-Christophe Pain and Franck Gilleron
- Subjects
line-shape profile ,stark broadening ,electron broadening ,collision operator ,standard theory ,penetration standard theory ,strong collisions ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
The expression of the electron broadening operator including the effect of penetrating collisions, i.e., for which the incoming electron enters the extent of bound-electron wave-functions, is rather complicated, even for hydrogen. It involves integrals of special functions, the evaluation of which deserves scrutiny. We present a simple approximate form of the electron collision operator for hydrogen including penetration effects, both in direct and interference terms. The new expression is accurate and easy to compute. In the Penetration Standard Theory, the collision operator is convergent whatever the value of the maximum impact parameter. However, when penetration theory is not valid anymore, it should be questioned. We discuss the problem of strong collisions when penetration effects are taken into account.
- Published
- 2020
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14. On the Application of Stark Broadening Data Determined with a Semiclassical Perturbation Approach
- Author
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Milan S. Dimitrijević and Sylvie Sahal-Bréchot
- Subjects
Stark broadening ,isolated lines ,impact approximation ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
The significance of Stark broadening data for problems in astrophysics, physics, as well as for technological plasmas is discussed and applications of Stark broadening parameters calculated using a semiclassical perturbation method are analyzed.
- Published
- 2014
- Full Text
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15. Ion Dynamics Effect on Stark-Broadened Line Shapes: A Cross-Comparison of Various Models
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Sandrine Ferri, Annette Calisti, Caroline Mossé, Joël Rosato, Bernard Talin, Spiros Alexiou, Marco A. Gigosos, Manuel A. González, Diego González-Herrero, Natividad Lara, Thomas Gomez, Carlos Iglesias, Sonja Lorenzen, Roberto C. Mancini, and Evgeny Stambulchik
- Subjects
Stark broadening ,line shapes ,plasmas ,numerical simulations ,models ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Modeling the Stark broadening of spectral lines in plasmas is a complex problem. The problem has a long history, since it plays a crucial role in the interpretation of the observed spectral lines in laboratories and astrophysical plasmas. One difficulty is the characterization of the emitter’s environment. Although several models have been proposed over the years, there have been no systematic studies of the results, until now. Here, calculations from stochastic models and numerical simulations are compared for the Atoms 2014, 2 300 Lyman-α and -β lines in neutral hydrogen. Also discussed are results from the Helium-α and -β lines of Ar XVII.
- Published
- 2014
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16. Ideal Coulomb Plasma Approximation in Line Shape Models: Problematic Issues
- Author
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Joel Rosato, Hubert Capes, and Roland Stamm
- Subjects
Stark broadening ,hydrogen plasmas ,numerical simulations ,collision operators ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
In weakly coupled plasmas, it is common to describe the microfield using a Debye model. We examine here an “artificial” ideal one-component plasma with an infinite Debye length, which has been used for the test of line shape codes. We show that the infinite Debye length assumption can lead to a misinterpretation of numerical simulations results, in particular regarding the convergence of calculations. Our discussion is done within an analytical collision operator model developed for hydrogen line shapes in near-impact regimes. When properly employed, this model can serve as a reference for testing the convergence of simulations.
- Published
- 2014
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17. Widths and Shifts of Isolated Lines of Neutral and Ionized Atoms Perturbed by Collisions With Electrons and Ions: An Outline of the Semiclassical Perturbation (SCP) Method and of the Approximations Used for the Calculations
- Author
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Sylvie Sahal-Bréchot, Milan S. Dimitrijević, and Nabil Ben Nessib
- Subjects
Stark broadening ,impact approximation ,isolated lines ,semiclassical perturbation picture ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
“Stark broadening” theory and calculations have been extensively developed for about 50 years. The theory can now be considered as mature for many applications, especially for accurate spectroscopic diagnostics and modeling, in astrophysics, laboratory plasma physics and technological plasmas, as well. This requires the knowledge of numerous collisional line profiles. In order to meet these needs, the “SCP” (semiclassical perturbation) method and numerical code were created and developed. The SCP code is now extensively used for the needs of spectroscopic diagnostics and modeling, and the results of the published calculations are displayed in the STARK-B database. The aim of the present paper is to introduce the main approximations leading to the impact of semiclassical perturbation method and to give formulae entering the numerical SCP code, in order to understand the validity conditions of the method and of the results; and also to understand some regularities and systematic trends. This would also allow one to compare the method and its results to those of other methods and codes. 1
- Published
- 2014
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18. The Second Workshop on Lineshape Code Comparison: Isolated Lines
- Author
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Spiros Alexiou, Milan S. Dimitrijević, Sylvie Sahal-Brechot, Evgeny Stambulchik, Bin Duan, Diego González-Herrero, and Marco A. Gigosos
- Subjects
Stark broadening ,isolated lines ,impact approximation ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
In this work, we briefly summarize the theoretical aspects of isolated line broadening. We present and discuss test run comparisons from different participating lineshape codes for the 2s-2p transition for LiI, B III and NV.
- Published
- 2014
- Full Text
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19. Tracking Temporal Development of Optical Thickness of Hydrogen Alpha Spectral Radiation in a Laser-Induced Plasma
- Author
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David M. Surmick and Christian G. Parigger
- Subjects
atomic spectroscopy ,radiation transfer ,hydrogen ,laser-induced breakdown spectroscopy ,stark broadening ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
In this paper, we consider the temporal development of the optical density of the H α spectral line in a hydrogen laser-induced plasma. This is achieved by using the so-called duplication method in which the spectral line is re-imaged onto itself and the ratio of the spectral line with it duplication is taken to its measurement without the duplication. We asses the temporal development of the self-absorption of the H α line by tracking the decay of duplication ratio from its ideal value of 2. We show that when 20% loss is considered along the duplication optical path length, the ratio is 1.8 and decays to a value of 1.25 indicating an optically thin plasma grows in optical density to an optical depth of 1.16 by 400 ns in the plasma decay for plasma initiation conditions using Nd:YAG laser radiation at 120 mJ per pulse in a 1.11 × 10 5 Pa hydrogen/nitrogen gas mixture environment. We also go on to correct the H α line profiles for the self-absorption impact using two methods. We show that a method in which the optical depth is directly calculated from the duplication ratio is equivalent to standard methods of self-absorption correction when only relative corrections to spectral emissions are needed.
- Published
- 2019
- Full Text
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20. Line Shapes in a Magnetic Field: Trajectory Modifictions II: Full Collision-Time Statistics
- Author
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Spiros Alexiou
- Subjects
stark broadening ,magnetic field ,spiralling trajectories ,collision-time statistics ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
In a previous paper, a variation of the Collision-time Statistics method was applied to identify the relevant perturbers for line broadening under the action of a constant magnetic field. As discussed, that version was simplified and inadequate for low magnetic field and/or large perturber mass (ions). The purpose of the present work is to augment the previous work, so that such cases can be handed efficiently. The results may also be used to construct analytic, i.e., impact/unified models under the usual assumptions in these models.
- Published
- 2019
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21. Effect of the Ions on the Electron Collision Operator through Electronic Trajectory Modification
- Author
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Yasmina Ben Nana, Fethi Khelfaoui, Said Douis, Eshrat Sadeghzadeh Lari, and Mohammed Tayeb Meftah
- Subjects
stark broadening ,electron broadening ,plasma ,neutral helium ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
We investigate the ion effect on the broadening of the spectral line profile by the free electrons collisions with the emitters in plasmas. We only considered the weak collisions’ contribution. This effect has a consequence on the trajectories of the free electrons through the electric microfield created by the ions of the plasma. Thanks to the Meijer’s functions, the calculation of the electronic Stark broadening is precisely established.
- Published
- 2019
- Full Text
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22. Line Shapes in a Magnetic Field: Trajectory Modifications I: Electrons
- Author
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Spiros Alexiou
- Subjects
stark broadening ,magnetic field ,spiralling trajectories ,collision-time statistics ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
In recent work, the effect of a magnetic field on the line shapes via the modification of electron perturber trajectories was considered. In the present paper we revisit this idea using a variation of the Collision-time Statistics method, in order to account for a l l relevant perturbers. We also obtain line profiles for the hydrogen L α line for conditions of astrophysical interest. Although the Collision-time statistics method works for both electrons and ions, we apply a simplification here that results in an excessive number of ions having to be simulated. As a result, the present, simplified version, is typically only appropriate for electrons.
- Published
- 2019
- Full Text
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23. Spectral Modeling of Hydrogen Radiation Emission in Magnetic Fusion Plasmas
- Author
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Mohammed Koubiti and Roshin Raj Sheeba
- Subjects
plasma spectroscopy ,Stark broadening ,plasma diagnostics ,line shape modeling ,Zeeman-Doppler broadening ,Balmer line series ,radiative recombination ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Modeling of the spectral line and continuum radiation emitted by hydrogen isotopes in peripheral regions of magnetic fusion is presented through profiles of the Zeeman-Doppler broadened Hα/Dα line and those of the Stark broadened high-n Balmer lines extending beyond the series limit for recombining plasmas. The Hα/Dα line profiles should be modelled while accounting for several populations of neutrals to mimic real situations and analyze experimental data for isotopic ratio determination. On the other side, high-n Balmer lines of hydrogen are used for plasma electron density and temperature diagnostics. Moreover, modelling whole spectra including the continuum radiation contributes to the development of synthetic diagnostics for future magnetic fusion devices for which they can give predictive results through coupling to numerical simulation tools.
- Published
- 2019
- Full Text
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24. Stark Widths of Yb III and Lu IV Spectral Lines
- Author
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Milan S. Dimitrijević
- Subjects
Stark broadening ,line profiles ,atomic data ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Rare Earth Elements are important for stellar atmosphere analysis but the corresponding Stark broadening data are scarce. For Yb III and Lu IV theoretical as well as experimental data on Stark broadening parameters of spectral lines are absent in the literature. Using the modified semiempirical method of Dimitrijević and Konjević, we determined Stark widths for four Yb III and four Lu IV transitions, belonging to the erbium isoelectronic sequence. The obtained results are also used to discuss similarities between homologous transitions in the erbium isoelectronic sequence. We note as well that calculated widths will be implemented in the STARK-B database which is also a part of the Virtual Atomic and Molecular Data Center.
- Published
- 2019
- Full Text
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25. Review of Recent Advances in the Analytical Theory of Stark Broadening of Hydrogenic Spectral Lines in Plasmas: Applications to Laboratory Discharges and Astrophysical Objects
- Author
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Eugene Oks
- Subjects
Stark broadening ,analytical theory ,shapes and shifts of spectral lines ,laboratory plasmas ,astrophysical plasmas ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
There is presented an overview of the latest advances in the analytical theory of Stark broadening of hydrogenic spectral lines in various types of laboratory and astrophysical plasmas. They include: (1) advanced analytical treatment of the Stark broadening of hydrogenic spectral lines by plasma electrons; (2) center-of-mass effects for hydrogen atoms in a nonuniform electric field: applications to magnetic fusion, radiofrequency discharges, and flare stars; (3) penetrating-ions-caused shift of hydrogenic spectral lines in plasmas; (4) improvement of the method for measuring the electron density based on the asymmetry of hydrogenic spectral lines in dense plasmas; (5) Lorentz–Doppler broadening of hydrogen/deuterium spectral lines: analytical solution for any angle of observation and any magnetic field strength, and its applications to magnetic fusion and solar physics; (6) Revision of the Inglis-Teller diagnostic method; (7) Stark broadening of hydrogen/deuterium spectral lines by a relativistic electron beam: analytical results and applications to magnetic fusion; (8) Influence of magnetic-field-caused modifications of the trajectories of plasma electrons on shifts and relative intensities of Zeeman components of hydrogen/deuterium spectral lines: applications to magnetic fusion and white dwarfs; (9) Influence of magnetic-field-caused modifications of trajectories of plasma electrons on the width of hydrogen/deuterium spectral lines: applications to white dwarfs; (10) Stark broadening of hydrogen lines in plasmas of electron densities up to or more than Ne~1020 cm−3; and, (11) The shape of spectral lines of two-electron Rydberg atoms/ions: a peculiar Stark broadening.
- Published
- 2018
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26. Measurement of Electron Density from Stark-Broadened Spectral Lines Appearing in Silver Nanomaterial Plasma
- Author
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Ashraf M. EL Sherbini, Ahmed E. EL Sherbini, and Christian G. Parigger
- Subjects
laser-induced plasma ,Stark broadening ,electron density ,nanomaterial ,atomic spectroscopy ,silver ,hydrogen ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
This work communicates results from optical emission spectroscopy following laser-induced optical breakdown at or near nanomaterial. Selected atomic lines of silver are evaluated for a consistent determination of electron density. Comparisons are presented with Balmer series hydrogen results. Measurements free of self-absorption effects are of particular interest. For several silver lines, asymmetries are observed in the recorded line profiles. Electron densities of interest range from 0.5 to 3 × 1017 cm−3 for five nanosecond Q-switched Nd:YAG radiation at wavelengths of 1064 nm, 532 nm, and 355 nm and for selected silver emission lines including 328.06 nm, 338.28 nm, 768.7 nm, and 827.3 nm and the hydrogen alpha Balmer series line at 656.3 nm. Line asymmetries are presented for the 328.06-nm and 338.28-nm Ag I lines that are measured following generation of the plasma due to multiple photon absorption. This work explores electron density variations for different irradiance levels and reports spectral line asymmetry of resonance lines for different laser fluence levels.
- Published
- 2018
- Full Text
- View/download PDF
27. Interaction of Ultrashort Laser Pulses with Atoms in Plasmas
- Author
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V. A. Astapenko and V. S. Lisitsa
- Subjects
ultra-short laser pulse ,photo-absorption ,spectral line shape ,Stark broadening ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
The paper is devoted to the investigation of the absorption of ultrashort laser pulses on atoms in plasmas, accounting for the different broadening mechanisms of atomic resonant transitions. The analysis is made in terms of the absorption probability during the entire interaction between the laser pulse and atom. Attention is mainly given to dependence of probability upon the pulse duration and the carrier frequency of the pulse. The results are presented via dimensionless parameters and functions describing the effect of finite pulse duration on atomic spectra for different broadening mechanisms, namely Doppler, Voigt, Holtsmark and their combinations, as well as the Stark line broadening of Rydberg atomic lines.
- Published
- 2018
- Full Text
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28. H-β Line in a Corona Helium Plasma: A Multi-Code Line Shape Comparison
- Author
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Roshin Raj Sheeba, Mohammed Koubiti, Nelly Bonifaci, Franck Gilleron, Caroline Mossé, Jean-Christophe Pain, Joël Rosato, and Evgeny Stambulchik
- Subjects
Stark broadening ,van der Waals broadening ,line shapes ,helium plasma ,corona discharge ,plasma diagnostics ,code comparison ,neutral broadening ,pressure broadening ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Many spectroscopic diagnostics are routinely used as techniques to infer the plasma parameters from line emission spectra, but their accuracy depends on the numerical model or code used for the fitting process. However, the validation of a line shape code requires some steps: the comparison of the line shape code with other similar codes for some academic (simple) cases and then for more complex ones, the comparison of the fitting parameters obtained from the best fit of the experimental spectra with those obtained with other diagnostic techniques, and/or the comparison of the fitting parameters obtained by different codes to fit the same experimental data. Here we compare the profiles of the hydrogen Balmer β line in helium plasma computed by five codes for a selected set of plasma parameters and we report on the plasma parameters inferred by each of them from the fitting to a number of experimental spectra measured in a helium corona discharge where the pressure was in the range of 1–5 bars.
- Published
- 2018
- Full Text
- View/download PDF
29. The Third and Fourth Workshops on Spectral Line Shapes in Plasma Code Comparison: Isolated Lines
- Author
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Sylvie Sahal-Bréchot, Evgeny Stambulchik, Milan S. Dimitrijević, Spiros Alexiou, Bin Duan, and Véronique Bommier
- Subjects
spectral line shapes ,Stark broadening ,cross-sections ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
The purpose of the Spectral Line Shapes in Plasmas (SLSP) code comparison workshop is to compare different computational and analytical methods, in order to pinpoint sources of disagreements, infer limits of applicability, and assess accuracy. The present paper reviews a part of the results of the third (2015) and fourth (2017) workshops related to isolated lines.
- Published
- 2018
- Full Text
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30. Broadening of the Neutral Helium 492 nm Line in a Corona Discharge: Code Comparisons and Data Fitting
- Author
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Roshin Raj Sheeba, Mohammed Koubiti, Nelly Bonifaci, Franck Gilleron, Jean-Christophe Pain, and Evgeny Stambulchik
- Subjects
stark broadening ,van der Waals broadening ,line shapes ,helium plasma ,corona discharge ,plasma diagnostics ,code comparison ,neutral broadening ,pressure broadening ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Passive plasma spectroscopy is a well-established non-intrusive diagnostic technique. Depending on the emitter and its environment which determine the dominant interactions and effects governing emission line shapes, passive spectroscopy allows the determination of electron densities, emitter and perturber temperatures, as well as other quantities like relative abundances. However, using spectroscopy requires appropriate line shape codes retaining all the physical effects governing the emission line profiles. This is required for line shape code developers to continuously correct or improve them to increase their accuracy when applied for diagnostics. This is exactly the aim expected from code–code and code–data comparisons. In this context, the He i 492 nm line emitted in a helium corona discharge at room temperature represents an ideal case since its profile results from several broadening mechanisms: Stark, Doppler, resonance, and van der Waals. The importance of each broadening mechanism depends on the plasma parameters. Here the profiles of the He i 492 nm in a helium plasma computed by various codes are compared for a selected set of plasma parameters. In addition, preliminary results related to plasma parameter determination using an experimental spectrum from a helium corona discharge at atmospheric pressure, are presented.
- Published
- 2018
- Full Text
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31. Stark Broadening of Cr III Spectral Lines: DO White Dwarfs
- Author
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Milan S. Dimitrijević and Abhishek Chougule
- Subjects
Stark broadening ,line profiles ,atomic data ,DO white dwarfs ,stellar spectra ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Using the modified semiempirical method of Dimitrijević and Konjević, Stark widths have been calculated for six Cr III transitions, for an electron density of 10 17 cm ‒ 3 and for temperatures from 5000–80,000 K. Results have been used for the investigation of the influence of Stark broadening on spectral lines in cool DO white dwarf atmospheres. Calculated Stark widths will be implemented in the STARK-B database, which is also a part of the Virtual Atomic and Molecular Data Center (VAMDC).
- Published
- 2018
- Full Text
- View/download PDF
32. Quantum and Semiclassical Stark Widths for Ar VII Spectral Lines
- Author
-
Rihab Aloui, Haykel Elabidi, Sylvie Sahal-Bréchot, and Milan S. Dimitrijević
- Subjects
Stark broadening ,Ar VII line profiles ,stars ,white dwarfs ,atomic data ,scattering ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
We present in this paper the results of a theoretical study of electron impact broadening for several lines of the Ar VII ion. The results have been obtained using our quantum mechanical method and the semiclassical perturbation one. Results are presented for electron density 1018 cm−3 and for electron temperatures ranging from 2 × 10 4 to 5 × 10 5 K required for plasma modeling. Our results have been compared to other semiclassical ones obtained using different sources of atomic data. A study of the strong collisions contributions to line broadening has been performed. The atomic structure and collision data used for the calculations of line broadening are also calculated by our codes and compared to available theoretical results. The agreement found between the two calculations ensures that our line broadening procedure uses adequate structure and collision data.
- Published
- 2018
- Full Text
- View/download PDF
33. Influence of Helical Trajectories of Perturbers on Stark Line Shapes in Magnetized Plasmas
- Author
-
J. Rosato, S. Ferri, and R. Stamm
- Subjects
Stark broadening ,magnetized plasmas ,numerical simulations ,cyclotron motion ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
In plasmas subject to a strong magnetic field, the dynamical properties of the microfield are affected by the cyclotron motion, which can alter Stark-broadened lines. We illustrate this effect through calculations of the hydrogen Lyman α line in an ideal one-component plasma. A focus is put on the central Zeeman component. It is shown that the atomic dipole autocorrelation function decreases more slowly if the cyclotron motion is retained. In the frequency domain, this denotes a reduction of the line broadening. A discussion based on numerical simulations and analytical estimates is done.
- Published
- 2018
- Full Text
- View/download PDF
34. ZEST: A Fast Code for Simulating Zeeman-Stark Line-Shape Functions
- Author
-
Franck Gilleron and Jean-Christophe Pain
- Subjects
line shapes ,Stark broadening ,Zeeman pattern ,quasi-static approximation ,impact approximation ,binary collision relaxation theory ,microfield distribution ,ion dynamics effects ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
We present the ZEST code, dedicated to the calculation of line shapes broadened by Zeeman and Stark effects. As concerns the Stark effect, the model is based on the Standard Lineshape Theory in which ions are treated in the quasi-static approximation, whereas the effects of electrons are represented by weak collisions in the framework of a binary collision relaxation theory. A static magnetic field may be taken into account in the radiator Hamiltonian in the dipole approximation, which leads to additional Zeeman splitting patterns. Ion dynamics effects are implemented using the fast Frequency-Fluctuation Model. For fast calculations, the static ion microfield distribution in the plasma is evaluated using analytic fits of Monte-Carlo simulations, which depend only on the ion-ion coupling parameter and the electron-ion screening factor.
- Published
- 2018
- Full Text
- View/download PDF
35. Stark Broadening of Se IV, Sn IV, Sb IV and Te IV Spectral Lines
- Author
-
Milan S. Dimitrijević, Zoran Simić, Roland Stamm, Joël Rosato, Nenad Milovanović, and Cristina Yubero
- Subjects
Stark broadening ,line profiles ,atomic data ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Stark broadening parameters, line width and shift, are needed for investigations, analysis and modelling of astrophysical, laboratory, laser produced and technological plasmas. Especially in astrophysics, due to constantly increasing resolution of satellite borne spectrographs, and large terrestrial telescopes, data on trace elements, which were previously insignificant, now have increasing importance. Using the modified semiempirical method of Dimitrijević and Konjević, here, Stark widths have been calculated for 2 Se IV, 6 Sn IV, 2 Sb IV and 1 Te IV transitions. Results have been compared with existing theoretical data for Sn IV. Obtained results will be implemented in the STARK-B database, which is also a part of Virtual atomic and molecular data center (VAMDC).
- Published
- 2018
- Full Text
- View/download PDF
36. Regularities and Systematic Trends on Zr IV Stark Widths
- Author
-
Zlatko Majlinger, Milan S. Dimitrijević, and Zoran Simić
- Subjects
Stark broadening ,line profiles ,atomic data ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Regularities and systematic trends among the Stark widths of 18 Zr IV spectral lines obtained by modified semiempirical approach have been discussed. Also we compared those calculated Stark broadening parameters with estimates according to Cowley, Purić et al. and Purić and Šćepanović and checked the possibility to find some new estimates. It is demonstrated as well that the formula of Cowley (1971) overestimates Stark widths, obtained by using modified semiempirical method, with the increase of angular orbital momentum quantum number due to its neglection. It is also found that the results obtained by using formula for simple estimates of Purić et al. (1991) are in agreement with the modified semiempirical results within the estimated error bars of both methods, while the estimates using formula of Purić and Šćepanović (1999) are in strong disagreement which increases with the increase of angular orbital momentum quantum number.
- Published
- 2017
- Full Text
- View/download PDF
37. A New Analysis of Stark and Zeeman Effects on Hydrogen Lines in Magnetized DA White Dwarfs
- Author
-
Ny Kieu, Joël Rosato, Roland Stamm, Jelena Kovačević-Dojcinović, Milan S. Dimitrijević, Luka Č. Popović, and Zoran Simić
- Subjects
line shapes ,Stark broadening ,Zeeman effect ,white dwarfs ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
White dwarfs with magnetic field strengths larger than 10 T are understood to represent more than 10% of the total population of white dwarfs. The presence of such strong magnetic fields is clearly indicated by the Zeeman triplet structure visible on absorption lines. In this work, we discuss the line broadening mechanisms and focus on the sensitivity of hydrogen lines on the magnetic field. We perform new calculations in conditions relevant to magnetized DA stellar atmospheres using models inspired from magnetic fusion plasma spectroscopy. A white dwarf spectrum from the Sloan Digital Sky Survey (SDSS) database is analyzed. An effective temperature is provided by an adjustment of the background radiation with a Planck function, and the magnetic field is inferred from absorption lines presenting a Zeeman triplet structure. An order-of-magnitude estimate for the electron density is also performed from Stark broadening analysis.
- Published
- 2017
- Full Text
- View/download PDF
38. Stark-Zeeman Line Shape Modeling for Magnetic White Dwarf and Tokamak Edge Plasmas: Common Challenges
- Author
-
Joël Rosato, Ny Kieu, Ibtissem Hannachi, Mohammed Koubiti, Yannick Marandet, Roland Stamm, Milan S. Dimitrijević, and Zoran Simić
- Subjects
line shapes ,Stark broadening ,Zeeman effect ,tokamaks ,white dwarfs ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
The shape of atomic spectral lines in plasmas contains information on the plasma parameters, and can be used as a diagnostic tool. Under specific conditions, the plasma located at the edge of tokamaks has parameters similar to those in magnetic white dwarf stellar atmospheres, which suggests that the same line shape models can be used. A problem common to tokamak and magnetic white dwarfs concerns the modeling of Stark broadening of hydrogen lines in the presence of an external magnetic field and the related Zeeman effect. In this work, we focus on a selection of issues relevant to Stark broadening in magnetized hydrogen plasmas. Various line shape models are presented and discussed through applications to ideal cases.
- Published
- 2017
- Full Text
- View/download PDF
39. Line Shape Modeling for the Diagnostic of the Electron Density in a Corona Discharge
- Author
-
Joël Rosato, Nelly Bonifaci, Zhiling Li, and Roland Stamm
- Subjects
line shapes ,stark broadening ,neutral broadening ,corona discharge ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
We present an analysis of spectra observed in a corona discharge designed for the study of dielectrics in electrical engineering. The medium is a gas of helium and the discharge was performed at the vicinity of a tip electrode under high voltage. The shape of helium lines is dominated by the Stark broadening due to the plasma microfield. Using a computer simulation method, we examine the sensitivity of the He 492 nm line shape to the electron density. Our results indicate the possibility of a density diagnostic based on passive spectroscopy. The influence of collisional broadening due to interactions between the emitters and neutrals is discussed.
- Published
- 2017
- Full Text
- View/download PDF
40. Stark Broadening from Impact Theory to Simulations
- Author
-
Roland Stamm, Ibtissem Hannachi, Mutia Meireni, Laurence Godbert-Mouret, Mohammed Koubiti, Yannick Marandet, Joël Rosato, Milan S. Dimitrijević, and Zoran Simić
- Subjects
stark broadening ,impact approximation ,numerical simulation ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Impact approximation is widely used for calculating Stark broadening in a plasma. We review its main features and different types of models that make use of it. We discuss recent developments, in particular a quantum approach used for both the emitter and the perturbers. Numerical simulations are a useful tool for gaining insight into the mechanisms at play in impact-broadening conditions. Our simple model allows the integration of the Schrödinger equation for an emitter submitted to a fluctuating electric field. We show how we can approach the impact results, and how we can investigate conditions beyond the impact approximation. The simple concepts developed in impact and simulation approaches enable the analysis of complex problems such as the effect of plasma rogue waves on hydrogen spectra.
- Published
- 2017
- Full Text
- View/download PDF
41. Stark Widths of Ar II Spectral Lines in the Atmospheres of Subdwarf B Stars
- Author
-
Rafik Hamdi, Nabil Ben Nessib, Sylvie Sahal Bréchot, and Milan S. Dimitrijević
- Subjects
stark broadening ,atomic data ,subdwarfs B stars ,Ar II ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Stark broadening parameters are of interest for many problems in astrophysics and laboratory plasmas investigation. Ar II spectral lines are observed in many kinds of stellar atmospheres such as the atmospheres of B-Type stars and subdwarf B stars. In this work, we present theoretical Stark widths for Ar II spectral lines. We use the impact semiclassical perturbation approach. Our results are compared with the available experimental values. Finally, the importance of the Stark broadening mechanism is studied in atmospheric conditions of subdwarf B stars.
- Published
- 2017
- Full Text
- View/download PDF
42. Stark Widths of Na IV Spectral Lines
- Author
-
Milan S. Dimitrijević, Zoran Simić, Aleksandar Valjarević, and Cristina Yubero
- Subjects
stark broadening ,line profiles ,atomic data ,Na IV ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Sodium is a very important element for the research and analysis of astrophysical, laboratory, and technological plasmas, but neither theoretical nor experimental data on Stark broadening of Na IV spectral lines are present in the literature. Using the modified semiempirical method of Dimitrijević and Konjević, here Stark widths have been calculated for nine Na IV transitions. Na IV belongs to the oxygen isoelectronic sequence, and we have calculated Stark widths belonging to singlets, triplets, and quintuplets, as well as with different parent terms. This is used to discuss similarities within one transition array with different multiplicities and parent terms. Additionally, calculated widths will be implemented in the STARK-B database (http://stark-b.obspm.fr) which is also a part of the Virtual Atomic and Molecular Data Center (VAMDC—http://www.vamdc.org/).
- Published
- 2017
- Full Text
- View/download PDF
43. Semiclassical Stark Broadening Parameters of Ar VII Spectral Lines
- Author
-
Milan S. Dimitrijević, Aleksandar Valjarević, and Sylvie Sahal-Bréchot
- Subjects
stark broadening ,atomic data ,atomic processes ,line profiles ,Ar VII ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Using the semi-classical perturbation approach in the impact approximation, full width at half maximum and shift have been determined for eight spectral lines of Ar VII, for broadening by electron-, proton-, and He III-impacts. The results are provided for temperatures from 20,000 K to 500,000 K, and for an electron density of 10 18 cm − 3 . The obtained results will be included in the STARK-B database, which is also in the virtual atomic and molecular data center (VAMDC).
- Published
- 2017
- Full Text
- View/download PDF
44. Methods for Line Shapes in Plasmas in the Presence of External Electric Fields
- Author
-
S. Alexiou
- Subjects
Physics ,Floquet theory ,Nuclear and High Energy Physics ,Work (thermodynamics) ,Field (physics) ,Plasma ,QC770-798 ,Condensed Matter Physics ,Laser ,Atomic and Molecular Physics, and Optics ,Computational physics ,law.invention ,Floquet ,symbols.namesake ,satellites ,Stark effect ,law ,Electric field ,Nuclear and particle physics. Atomic energy. Radioactivity ,symbols ,stark broadening ,external elecric field ,Line (formation) - Abstract
Line broadening is usually dominated by interactions of an atomic system with a stochastic, random medium. When, in addition to the random medium, a non-random field (such as a laser) is applied, the line profile may be modified in significant ways. The present work discusses these modifications and the methods to deal with them.
- Published
- 2021
- Full Text
- View/download PDF
45. Plasma Spectroscopy on an Aluminum-Pellet Ablation Cloud in an LHD Plasma with an Echelle Spectrometer
- Author
-
Masahiro Hasuo, Shigeru Morita, Taiichi Shikama, Motoshi Goto, Hirotaka Tanaka, and Keisuke Fujii
- Subjects
Nuclear and High Energy Physics ,Materials science ,010504 meteorology & atmospheric sciences ,Analytical chemistry ,01 natural sciences ,010305 fluids & plasmas ,symbols.namesake ,Large Helical Device ,0103 physical sciences ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,stark broadening ,Emission spectrum ,0105 earth and related environmental sciences ,Line (formation) ,echelle spectrometer ,Spectrometer ,Resolution (electron density) ,Plasma ,pellet ablation plasma ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,aluminum atoms and ions ,Stark effect ,symbols ,Electron temperature ,lcsh:QC770-798 ,LHD ,plasma spectroscopy - Abstract
We developed an echelle spectrometer for the simultaneous observation of the whole visible range with a high instrumental resolution, for example, 0.055 nm (full width at the half maximum) at 400 nm and 0.10 nm at 750 nm. With the spectrometer, the emission from an ablation cloud of an aluminum pellet injected into a high-temperature plasma generated in the Large Helical Device (LHD) was measured. We separated the emission lines into Al I, II, III and IV groups, and estimated the electron temperature and density of the ablation cloud from the line intensity distribution and Stark broadening respectively, of each of the Al I, II and III groups. We also determined the Stark broadening coefficients of many Al II and III lines from the respective Stark widths with the estimated electron temperature and density.
- Published
- 2020
- Full Text
- View/download PDF
46. Theoretical Stark Broadening Parameters for UV–Blue Spectral Lines of Neutral Vanadium in the Solar and Metal-Poor Star HD 84937 Spectra
- Author
-
Andrés Moya, Cristóbal Colón, María Isabel de Andrés-García, and Lucía Isidoro-García
- Subjects
Nuclear and High Energy Physics ,atomic processes ,Vanadium ,chemistry.chemical_element ,02 engineering and technology ,01 natural sciences ,Spectral line ,Metal ,Matrix (mathematics) ,symbols.namesake ,0103 physical sciences ,Arcturus ,atomic data ,stark broadening ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,010303 astronomy & astrophysics ,Line (formation) ,Physics ,Plasma ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,chemistry ,Stark effect ,visual_art ,symbols ,visual_art.visual_art_medium ,lcsh:QC770-798 ,Atomic physics ,0210 nano-technology - Abstract
Using Griem&rsquo, s semi-empirical approach, we have calculated the Stark broadening parameters (line widths and shifts) of 35 UV&ndash, Blue spectral lines of neutral vanadium (V I). These lines have been detected in the Sun, the metal-poor star HD 84937, and Arcturus, among others. In addition, these parameters are also relevant in industrial and laboratory plasma. The matrix elements required were obtained using the relativistic Hartree&ndash, Fock (HFR) method implemented in Cowan&rsquo, s code.
- Published
- 2020
47. Tracking Temporal Development of Optical Thickness of Hydrogen Alpha Spectral Radiation in a Laser-Induced Plasma
- Author
-
Christian G. Parigger and David M. Surmick
- Subjects
Nuclear and High Energy Physics ,Materials science ,010504 meteorology & atmospheric sciences ,atomic spectroscopy ,Physics::Optics ,Radiation ,01 natural sciences ,Spectral line ,law.invention ,law ,radiation transfer ,stark broadening ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,Laser-induced breakdown spectroscopy ,Optical path length ,Optical depth ,0105 earth and related environmental sciences ,Line (formation) ,010401 analytical chemistry ,Plasma ,Condensed Matter Physics ,Laser ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,laser-induced breakdown spectroscopy ,hydrogen ,lcsh:QC770-798 ,Atomic physics - Abstract
In this paper, we consider the temporal development of the optical density of the H &alpha, spectral line in a hydrogen laser-induced plasma. This is achieved by using the so-called duplication method in which the spectral line is re-imaged onto itself and the ratio of the spectral line with it duplication is taken to its measurement without the duplication. We asses the temporal development of the self-absorption of the H &alpha, line by tracking the decay of duplication ratio from its ideal value of 2. We show that when 20% loss is considered along the duplication optical path length, the ratio is 1.8 and decays to a value of 1.25 indicating an optically thin plasma grows in optical density to an optical depth of 1.16 by 400 ns in the plasma decay for plasma initiation conditions using Nd:YAG laser radiation at 120 mJ per pulse in a 1.11 ×, 10 5 Pa hydrogen/nitrogen gas mixture environment. We also go on to correct the H &alpha, line profiles for the self-absorption impact using two methods. We show that a method in which the optical depth is directly calculated from the duplication ratio is equivalent to standard methods of self-absorption correction when only relative corrections to spectral emissions are needed.
- Published
- 2019
48. Line Shapes in a Magnetic Field: Trajectory Modifictions II: Full Collision-Time Statistics
- Author
-
S. Alexiou
- Subjects
Physics ,Nuclear and High Energy Physics ,Work (physics) ,spiralling trajectories ,magnetic field ,Condensed Matter Physics ,Collision ,01 natural sciences ,collision-time statistics ,Atomic and Molecular Physics, and Optics ,Action (physics) ,Magnetic field ,symbols.namesake ,Stark effect ,0103 physical sciences ,Statistics ,Line (geometry) ,Trajectory ,symbols ,lcsh:QC770-798 ,stark broadening ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,010306 general physics ,Constant (mathematics) ,010303 astronomy & astrophysics - Abstract
In a previous paper, a variation of the Collision-time Statistics method was applied to identify the relevant perturbers for line broadening under the action of a constant magnetic field. As discussed, that version was simplified and inadequate for low magnetic field and/or large perturber mass (ions). The purpose of the present work is to augment the previous work, so that such cases can be handed efficiently. The results may also be used to construct analytic, i.e., impact/unified models under the usual assumptions in these models.
- Published
- 2019
49. Effect of the Ions on the Electron Collision Operator through Electronic Trajectory Modification
- Author
-
F. Khelfaoui, Eshrat Sadeghzadeh Lari, S. Douis, Yasmina Ben Nana, and Mohammed Tayeb Meftah
- Subjects
Free electron model ,Physics ,Nuclear and High Energy Physics ,Operator (physics) ,Plasma ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Spectral line ,Ion ,neutral helium ,symbols.namesake ,Stark effect ,Physics::Plasma Physics ,electron broadening ,Electron collision ,symbols ,lcsh:QC770-798 ,Physics::Accelerator Physics ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,stark broadening ,Atomic physics ,Nuclear Experiment ,Trajectory (fluid mechanics) ,plasma - Abstract
We investigate the ion effect on the broadening of the spectral line profile by the free electrons collisions with the emitters in plasmas. We only considered the weak collisions&rsquo, contribution. This effect has a consequence on the trajectories of the free electrons through the electric microfield created by the ions of the plasma. Thanks to the Meijer&rsquo, s functions, the calculation of the electronic Stark broadening is precisely established.
- Published
- 2019
- Full Text
- View/download PDF
50. Line Shapes in a Magnetic Field: Trajectory Modifications I: Electrons
- Author
-
S. Alexiou
- Subjects
Nuclear and High Energy Physics ,Work (thermodynamics) ,Hydrogen ,chemistry.chemical_element ,spiralling trajectories ,magnetic field ,Electron ,01 natural sciences ,collision-time statistics ,Ion ,symbols.namesake ,0103 physical sciences ,stark broadening ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,010306 general physics ,010303 astronomy & astrophysics ,Line (formation) ,Physics ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Computational physics ,Magnetic field ,chemistry ,Stark effect ,Trajectory ,symbols ,Computer Science::Programming Languages ,lcsh:QC770-798 - Abstract
In recent work, the effect of a magnetic field on the line shapes via the modification of electron perturber trajectories was considered. In the present paper we revisit this idea using a variation of the Collision-time Statistics method, in order to account for a l l relevant perturbers. We also obtain line profiles for the hydrogen L &alpha, line for conditions of astrophysical interest. Although the Collision-time statistics method works for both electrons and ions, we apply a simplification here that results in an excessive number of ions having to be simulated. As a result, the present, simplified version, is typically only appropriate for electrons.
- Published
- 2019
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