TY - CONF A1 - Gornushkin, Igor B. T1 - Calibration-free LIBS of steel samples N2 - An improved algorithm for calibration-free laser induced breakdown spectroscopy (CF LIBS) is presented which includes several novel features in comparison with previously proposed similar algorithms. In particular, it allows using spectral lines with arbitrary optical thickness for the construction of Saha-Boltzmann plots, retrieves the absorption path length (plasma diameter) directly from a spectrum, replaces the Lorentzian line profile function by the Voigt function, and allows for self-absorption correction using pre-calculated and tabulated data rather than approximating functions. The tabulated data embody the solutions of the radiative transfer equation for numerous combinations of optical thicknesses and line widths. The algorithm is used to analyze 100 low alloy steel spectra. T2 - 20.06.2019 LTB workshop on LIBS analysis of steel CY - Berlin, LTB, Germany DA - 20.06.2019 KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Plasma diagnostics KW - Chemical reactors PY - 2019 AN - OPUS4-48600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Kazakov, Alexander Ya. T1 - Model of stimulated emission in aluminum laser-induced plasma produced by resonance pumping N2 - Stimulated emission observed experimentally in aluminum laser induced plasma is modeled via a kinetic approach. The simulated emission at several cascade transitions is created by a pump laser guided through the plasma at several microseconds after its creation and tuned in resonance with the strong transition at 266 nm. A two-dimensional space-time collisional radiative plasma model explains the creation of the population inversion and lasing at wavelengths 2.1 μm and 396.1 nm. The population inversion for lasing at 2.1 μm is created by depopulation of the ground state and population of the upper state via absorption of resonant radiation at 266 nm. The population inversion for lasing at 396.1 nm occurs during the laser pulse via the decay of the population of the pumped upper state to the lasing state via cascade transitions driven optically and by collisions. The model predicts that the population inversion and corresponding gain may reach high values even at moderate pump energies of several μJ per pulse. The efficiency of lasing at 2.1 μm and 396.1 nm is estimated to be on the order of a percent of laser pump energy. The polarization effect that the pump radiation at 266 nm imposes on the stimulated emission at 396.1 nm is discussed. The calculated results are favorably compared to experiment. T2 - FLAMN, June 30- July 4 2019 CY - St. Petersburg, Russia DA - 30.06.2019 KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Plasma diagnostics PY - 2019 AN - OPUS4-48598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Laser induced Plasma: Modeling and diagnostics N2 - Laser-induced plasmas are widely used in many areas of science and technology; examples include spectrochemical analysis, thin film deposition, material processing, and even jet propulsion. Several topics will be addressed. First, general phenomenology of laser-induced plasmas will be discussed. Then, a chemical model will be presented based on a coupled solution of Navier-Stokes, state, radiative transfer, material transport, and chemical (Guldberg-Waage) equations. Results of computer simulations for several chemical systems will be shown and compared to experimental observations obtained by optical imaging, spectroscopy, and tomography. The latter diagnostic tools will also be briefly discussed. T2 - Lecture at the Dept of Chemistry of Czeged University (Hungary) on 31.05.2019 CY - Czeged, Hungary DA - 31.05.2019 KW - Plasma KW - LIBS KW - Plasma modeling PY - 2019 AN - OPUS4-48188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Palásti, David J. A1 - Veres, M. A1 - Rigó, I. A1 - Geretovszky, Z. A1 - Kovács-Széles, É. A1 - Gojani, Ardian A1 - Galbács, Gábor T1 - Optimization and detailed spectroscopic characterization of an improved SH-LIBS setup N2 - The spatial heterodyne detection principle has a great potential in spectroscopy. It has an optical setup similar to that of a Michelson interferometer, with the mirrors replaced by diffraction gratings positioned at fixed, equal distances from the beamsplitter and are slightly tilted. The resulting interference pattern is recorded by a digital camera and the spectrum is recovered by using Fourier transformation. Although SHS was initially developed for astronomical and satellite-based atmospheric measurements, but in recent years it has been started to be applied in other branches of spectroscopy too. Recently the area of laser-induced breakdown spectroscopy (LIBS) has also discovered the potential of SHS. The main appeal of SHS detection in LIBS includes the compactness and robustness of the setup (in view of field applications) and the flexibility to optimize the setup for either high sensitivity or for high resolution, which can be benficially exploited in applications like stand-off measurements, quantitative analysis with isotope resolution, etc. In the present work, we have improved and further optimized our initial LIBS-SHS setup described in a previous conference. By using optical simulations, we have modelled the light transmission efficiency, instrumental function and imaging properties of the system. We significantly improved and automated the spectral and image data processing sequence. The optimizations carried out resulted in an improved spectral resolution and repeatability, a lower spectral background and the elimination of the central line artifact originating from the Fourier transformation procedure. A detailed characterization of the LIBS spectroscopy performance (e.g. resolution, spectral coverage, tuning range, linearity, etc.), including a comparison with that of a LIBS setup based on a conventional dispersion CCD spectrometer was also performed. T2 - European Winter Conference on Plasma Spectrochemistry (EWSPS-2019) CY - Pau, France DA - 03.02.2019 KW - SHS KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Spatial heterodyne spectrometer PY - 2019 AN - OPUS4-48047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Shabanov, Sergej V. T1 - Modeling chemistry in laser-induced and other types of plasmas N2 - A goal of this work is to extend the model, which was initially developed for laser induced plasmas, to plasmas used in chemical reactors, in particular, the inductively-coupled-RF discharge plasma. The model predicts equilibrium chemical compositions of reaction mixtures as functions of plasma temperature and stoichiometry of reactants. The mixtures investigated are BCl3/H2/Ar and BF3/H2/Ar where Ar serves as the plasma-forming gas and H2 as a binding agent which binds the active species Cl and F and Cl- and F-containing intermediates to produce gaseous B and its condensate. An additional goal is to obtain information about intermediate reaction products for different ratios of BCl3/H2 and BF3/H2 and at different temperatures and different Ar flow rates. It is found that the desired components B and B2 appear at appreciable concentrations of >0.1% and ~0.01% respectively only at temperatures above 3000 K. It is also established that the effect of charged species on the reaction products is miniscule for temperatures below 5000 K. The expected yield of boron as a function of the original mole fraction H2/BCl3 and H2/BF3 is calculated. The mole fractions are varied in the range 0.1-1000 and the temperature in the range 1000-10000 K. It is shown that the yield of boron increases with increasing the molar ratio H2/BCl3 and H2/BF3 up to ~100 in the temperature range 2000-5000 K. At higher temperatures, T>5000 K, the boron concentration reaches its maximum and does not depend on the concentration of hydrogen; all molecules dissociate and chemical reactions proceed only between charged particles (mostly elemental ions) and electrons. The calculated plasma parameters and composition are compared with experimental data obtained by optical emission spectroscopy. The calculated plasma temperature and electron density are shown to be in good agreement with the measured ones. T2 - Workshop on Laser and Plasmas Applications CY - Bari, Italy DA - 04.03.2019 KW - Plasma KW - LIBS KW - Plasma modeling PY - 2019 AN - OPUS4-47545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Sergei, S. A1 - Kornev, R.A. A1 - Sennikov, P. G. T1 - Equilibrium chemistry of boron halides in plasma chemical reactors N2 - High purity halides of III-VI group elements, especially chloride and fluorides, are used in gas phase technologies for obtaining high purity materials and coatings. The reduction of halides in hydrogen-halide mixtures can be achieved in various discharge plasmas, e.g. inductively coupled, ark, and even laser-induced plasmas. Existing models of such plasmas are not sufficiently accurate to predict a yield of the targeted compounds and to describe the plasma processes involved in formation of these compounds. Besides, a construction of costly plasma-chemical reactors can be alleviated by the prior modeling of plasma processes that may occur in such reactors. A goal of this work is to extend the model, which was initially developed for laser induced Plasmas, to plasmas used in chemical reactors, in particular, the inductively-coupled-RF discharge Plasma. The model predicts equilibrium chemical compositions of reaction mixtures as functions of plasma temperature and stoichiometry of reactants. The mixtures investigated are BCl3/H2/Ar and BF3/H2/Ar where Ar serves as the plasma-forming gas and H2 as a binding agent which binds the active species Cl and F and Cl- and F-containing intermediates to produce gaseous B and its condensate. An additional goal is to obtain information about intermediate reaction products for different ratios of BCl3/H2 and BF3/H2 and at different temperatures and different Ar flow rates. It is found that the desired components B and B2 appear at appreciable concentrations of >0.1% and ~0.01% respectively only at temperatures above 3000 K. It is also established that the effect of charged species on the reaction products is miniscule for temperatures below 5000 K. The expected yield of boron as a function of the original mole fraction H2/BCl3 and H2/BF3 is calculated. The mole fractions are varied in the range 0.1-1000 and the temperature in the range 1000-10000 K. It is shown that the yield of boron increases with increasing the molar ratio H2/BCl3 and H2/BF3 up to ~100 in the temperature range 2000-5000 K. At higher temperatures, T>5000 K, the boron concentration reaches its maximum and does not depend on the concentration of hydrogen; all molecules dissociate and chemical reactions proceed only between charged particles (mostly elemental ions) and electrons. The calculated plasma parameters and composition are compared with experimental data obtained by optical emission spectroscopy. The calculated plasma temperature and electron density are shown to be in good agreement with the measured ones. T2 - European Winter Conference on Plasma Spectrochemistry (EWSPS-2019) CY - Pau, France DA - 03.02.2019 KW - Chemical reactors KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Plasma diagnostics PY - 2019 AN - OPUS4-47541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Völker, Tobias A1 - Kazakov, Alexander Ya. T1 - Improved algorithm for calibration-free laser induced breakdown spectroscopy N2 - An improved algorithm for calibration-free laser induced breakdown spectroscopy (CF LIBS) will be presented which includes several novel features in comparison with previously proposed similar algorithms. In particular, it allows using spectral lines with arbitrary optical thickness for the construction of Saha-Boltzmann plots, retrieves the absorption path length (plasma diameter) directly from a spectrum, replaces the Lorentzian line profile function by the Voigt function, and allows for self-absorption correction using pre-calculated and tabulated data rather than approximating functions. The tabulated data embody the solutions of the radiative transfer equation for numerous combinations of optical thicknesses and line widths. The algorithm is thoroughly verified using synthetic spectra. T2 - LIBS 2018 at SciX 2018 CY - Atlanta, GA, USA DA - 21.10.2018 KW - Plasma diagnostics KW - Laser induced plasma KW - LIBS KW - Plasma modeling PY - 2018 AN - OPUS4-46930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Shabanov, Sergej V. T1 - Chemistry in laser‑induced plasmas at local thermodynamic equilibrium JF - Applied physics A N2 - The equation of state for plasmas containing negative and positive ions of elements and molecules formed by these elements is modeled under the assumption that all ionization processes and chemical reactions are at local thermal equilibrium and the Coulomb interaction in the plasma is described by the Debye–Hückel theory. The hierarchy problem for constants of molecular reactions is resolved by using three different algorithms for high, medium, and low temperatures: the contraction principle, the Newton–Raphson method, and a scaled Newton–Raphson method, respectively. These algorithms are shown to have overlapping temperature ranges in which they are stable. The latter allows one to use the developed method for calculating the equation of state in combination with numerical solvers of Navier–Stokes equations to simulate laser-induced Plasmas initiated in an atmosphere and to study formation of molecules and their ions in such plasmas. The method is applicable to a general chemical network. It is illustrated with examples of Ca–Cl and C–Si–N laser-induced plasmas. KW - Plasma KW - LIBS KW - Plasma modeling PY - 2018 DO - https://doi.org/10.1007/s00339-018-2129-9 SN - 1432-0630 SN - 0947-8396 VL - 124 IS - 10 SP - 716, 1 EP - 21 PB - Springer AN - OPUS4-46112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Shabanov, Sergej V. T1 - Dynamical chemical model of laser induced plasma N2 - Laser induced plasma (LIP) is a highly dynamic, short living event which presents significant difficulty for both diagnostics and modeling. The former requires precise spatially- and time-resolved measurements on a micron-nanosecond scale while the latter needs numerous descriptive parameters; many of them can only be obtained from experiment. Diagnostics and modeling should always complement each other for obtaining a truthful picture of LIP. In this presentation, a newly developed collisional-dominated model will be presented. The model is based on the coupled Navier-Stokes, state, radiative transfer, material transport, and chemical equations. The model incorporates plasma chemistry through the equilibrium approach that relies on atomic and molecular partition functions. Several chemical systems are modeled including Si-C-Cl-N and B-H-Cl systems. The model is used to study the equilibrium states of the systems as functions of the concentrations of plasma species and plasma temperature. The model also predicts the evolution of number densities of atomic and molecular species in the expanding plasma plume. T2 - 18.09.2018, 9th International Conference on PLASMA PHYSICS AND PLASMA TECHNOLOGY (PPPT‐9) CY - Minsk, Belorussia DA - 17.09.2018 KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Plasma diagnostics PY - 2018 AN - OPUS4-46111 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Improved algorithm for calibration-free laser induced breakdown spectroscopy N2 - An improved algorithm for calibration-free laser induced breakdown spectroscopy (CF LIBS) is presented which includes several novel features in comparison with previously proposed similar algorithms. In particular, it allows using spectral lines with arbitrary optical thickness for the construction of Saha-Boltzmann plots, retrieves the absorption path length (plasma diameter) directly from a spectrum, replaces the Lorentzian line profile function by the Voigt function, and allows for self-absorption correction using pre-calculated and tabulated data rather than approximating functions. The tabulated data embody the solutions of the radiative transfer equation for numerous combinations of optical thicknesses and line widths. The algorithm is thoroughly verified with synthetic spectra. T2 - 14TH European Workshop on Laser Ablation 2018 (EWLA2018) CY - Pau, France DA - June 26 - 29, 2018 KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Plasma diagnostics KW - Calibration free LIBS PY - 2018 AN - OPUS4-45343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -