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We have investigated Stark line broadening within the spectral series of potassium-like and copper-like emitters, both separately and together. The analysis was performed for fixed values of electronic density N e = 1022 m−3 and temperature |$T = 100\, 000$|  K. Algorithms made for fast data processing also serve for temperature and density normalization of data. Relations obtained using the regularity-based analysis enable predictions of Stark widths for transitions that have not yet been calculated or measured. Results of present investigation can be used for quality control of available Stark width data. [ABSTRACT FROM AUTHOR]

Stark-width dependences on the upper-level ionization potential within different spectral series of neutral lithium have been studied and discussed. Similar dependences have been found for electron- and proton-impact contributions to the Stark widths. The emphasis is on the term structure influence on the studied Stark-width dependences. The effect of series merging with increasing temperature was found. Some lines with deviations from the corresponding series dependences can be explained by the absence of close perturbing states to the transition states. After establishing these dependences, the relations found were used for Stark-width prediction of the missed lines, thus avoiding much more complicated calculation procedures. [ABSTRACT FROM PUBLISHER]

ABSTRACT Stark width experimental and theoretical data of neutral helium spectral lines have been used to demonstrate their dependence on the upper-level ionization potential within different spectral series. The emphasis is on the term describing structure influence on the studied Stark-width dependences. After establishing these dependences, predictions were made for electron, proton and ionized helium impact contributions to the Stark widths of neutral helium spectral lines that have not been measured experimentally or calculated theoretically until now (transitions from high levels of He i). The accuracy of the data obtained is comparable with the accuracies of the experimental and theoretical values used in establishing the dependences. [ABSTRACT FROM AUTHOR]

BSTRACT [ABSTRACT FROM AUTHOR]

Abstract: In many experiments plasma guns have been used to study the possibility of lowering the erosion due to disruptions and edge localized modes (ELMs) of great interest for the International Thermonuclear Experimental Reactor (ITER) safe operation. Modification of silicon single crystal surfaces by the action of supersonic compression plasma flow (CPF) generated by magnetoplasma compressor (MPC) has been studied. MPC plasma flow parameters (1 MJ/m2 in 0.1 ms) simulated transient peak thermal loads during Type I ELMs and disruptions. Analysis of the target’s erosion, brittle destruction, melting processes and dust formation has been performed. The layer with some of regular structures (rhombic on the Si (111) and rectangular on Si (100) surface) can be separated from the underlying bulk, being ejected as the blocks from the surface. These surface phenomena are results of specific conditions during CPF interaction with target surface and differential stresses produced in a near surface layer. High plasma flow energy density, large dynamic pressure, thermodynamic parameters gradients and induced magnetic field on treated surfaces cause rapid heating and melting of the surface layer, prolonged existence of the molten layer and fast cooling and recrystallisation, as well as surface fracturing. [ABSTRACT FROM AUTHOR]

Abstract: Periodic submicron cylindrical structures (SCS) produced in a single pulse treatment of silicon single crystal by supersonic compression plasma flow have been studied. The nitrogen quasistationary plasma flow generated by magnetoplasma compressor is used for modification of Si (100) surface. SCS have been analyzed using optical microscopy, scanning electron microscopy and atomic force microscopy. Typical species of cylindrical structures formed at the silicon surface have been discussed. These structures are induced by the plasma flow action and then quenched from the molten state during fast cooling and resolidification. SCS have been compared to periodical silicon surface structures made by plasma, ion beams and laser interaction with silicon. [Copyright &y& Elsevier]

Stark widths within spectral series of sodium isoelectronic sequence have been studied. This is a unique approach that includes both neutrals and ions. Two levels of problem are considered: if the required atomic parameters are known, Stark widths can be calculated by some of the known methods (in present paper modified semiempirical formula has been used), but if there is a lack of parameters, regularities enable determination of Stark broadening data. In the framework of regularity research, Stark broadening dependence on environmental conditions and certain atomic parameters has been investigated. The aim of this work is to give a simple model, with minimum of required parameters, which can be used for calculation of Stark broadening data for any chosen transitions within sodium like emitters. Obtained relations were used for predictions of Stark widths for transitions that have not been measured or calculated yet. This system enables fast data processing by using of proposed theoretical model and it provides quality control and verification of obtained results. [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]

Oriented submicron cylindrical structures obtained in a single pulse treatment of silicon monocrystal by compression plasma flow are described. The nitrogen plasma flow generated by magnetoplasma compressor is used for modification of Si (1 1 1) monocrystal surface. The speed of plasma flow was up to 40 km/s depending on input energy and gas used and its pressure. The electron density and temperature within the region of plasma flow maximal compression was up to 2×1017 cm−3 and 20,000 K, respectively. Silicon samples placed perpendicular to the flow were exposed to a single 100 μs plasma pulse driven by the discharge current of 70 kA. Typical dimensions of cylindrical structures formed at the crystal surface are 0.1–2 μm in diameter and up to 200 μm in length. The influence of external magnetic field on the dimensions of the cylindrical structures was also investigated. The large diameter cylindrical structures have been noticed to exhibit the hollow features. The catalyst was not used in the process of silicon surface modification. [Copyright &y& Elsevier]

Abstract: In this paper several examples of line spectra from five different laboratory plasma sources are presented. Polarization Stark spectroscopy using hydrogen and helium lines is used for measuring electric field strength in the discharge. Doppler shifted and excessively broadened profiles are obtained showing presence of atoms with velocities close to those in the narrow line region of AGN. Radiation from a high energy, high density plasma source features very broad profiles used for determination of plasma density. Careful interpretation of spectra is needed in the conditions where several effects are present simultaneously: electric and magnetic field, Doppler effect and plasma inhomogeneity. Examples of line of sight influence on profile are also presented. Similarity between laboratory and astrophysical profiles open a possible field for experimental simulation of astrophysical plasmas. [Copyright &y& Elsevier]