Spectral Line Shapes Software

The main goal of Spectral Line Shapes (SLS) is to provide easy-to-use software tools for government, commercial, and academic research and development. The SLS software tools are also helpful for graduate and undergraduate research and education. The SLS software features a graphical user interface to simplify selecting observed atomic transitions and their corresponding atomic data, and to visualize the dependence of the predicted spectral line profiles on selected plasma parameters. All software-supported output files and figures can be imported into the reporting documents with a simple 'copy-paste' operation. The spreadsheet files are saved in two standard formats: Microsoft Excel and ASCII. The SLS software is AI-optimized, runs natively on Windows, and supports multi-core CPU processing (distributed up to all cores of AMD 64-core processors as needed).

The SLS tools enable researchers and engineers to conduct theoretical and computational studies of laboratory and astrophysical plasmas and to develop new or improved spectroscopy-based plasma diagnostics for the characterization and optimization of laboratory and industrial plasma applications. Typical applications are the industrial plasma processes, laboratory plasma sources created by electric discharge (zeta-pinch, theta-pinch), microwaves (Microwave Induced Plasma / MIP), and lasers (Laser-Induced Plasma / LIP, Laser-Induced Breakdown Spectroscopy / LIBS). The SLS tools can be applied to atoms and atomic ions found in a laboratory, naturally occurring, and astrophysical plasmas. The spectral line profiles originating from atomic transitions in plasma can be simultaneously modeled using the SLS tools for neutral, singly, and multiply charged atomic emitters as a function of the plasma parameters. The computed spectral line parameters are also important input parameters for the plasma radiation codes.

The SLS computational algorithms for major spectral line broadening and shifting mechanisms are vectorized and parallelized for fast execution on multi-core CPUs. They address Natural, Doppler, Van der Waals, Resonant, and Stark spectral-line broadening and shifting.

Computationally most demanding calculations of the Stark spectral line parameters are balanced between the accuracy and the computing time by the implementation of several theoretical approaches in the SLS: Semi-Empirical Formula (SE), Modified Semi-Empirical Formula (MSE), Simplified Semi-Classical Formula of Griem (SSC), and Semi-Classical Method of Griem (SCG). The SE, MSE, and SSC approaches are optimized with respect to computing time, whereas the SCG method prioritizes solution accuracy over computing time.

The SLS software enables the user to compute the exact solution of the Plasma Composition in Local Thermodynamic Equilibrium (LTE). This tool estimates the particle densities of all plasma constituents for pairs of input plasma parameters: (Ne, T), (Ne, P), and (P, T), where Ne, P, and T denote the electron density, pressure, and temperature, respectively. The LTE Plasma Composition Solver is a helpful tool for designing and optimizing plasma sources.

The transition probability calculator for the electric and magnetic dipole and quadrupole transitions is part of the SLS package. The atomic transition probabilities can be calculated between the electronic configurations of the same or different coupling schemes. The coupling schemes include LS, LK, J1K, J1j, and jj couplings. Computational routines for the Coefficients of Fractional Parentage (CFP) are integrated into the transition probability calculator.

The SLS tools use atomic data from the National Institute of Standards and Technology (NIST) Atomic Spectra Database (ASD), comprised of over 7000 files. The initial SLS configuration requires downloading the ASD to the local computer. The ASD is not distributed with the SLS package, as it belongs to the U.S. Government. The SLS user can update the local copy of ASD at any time by downloading its current version from the NIST server. Consequently, the SLS-calculated spectral line profiles and plasma composition parameters would be computed with NIST's most recent atomic data.

The SLS's key features and capabilities are:

User-friendly Interface: The software provides a graphical user interface (GUI) for selecting atomic transitions and plasma parameters. This simplifies visualizing spectral line profiles and makes it accessible for researchers at different levels, including graduate and undergraduate students.
Versatile Applications: SLS can be used for laboratory and astrophysical plasma studies as well as in industrial settings. It supports various plasma sources, including electric discharge, microwave-induced plasma, and laser-induced plasma.
Atomic Transitions Modeling: Researchers can model spectral line profiles for neutral, singly, and multiply charged atomic emitters. This enables the study of a wide range of plasma conditions and compositions.
Broadening and Shifting Mechanisms: The software incorporates computational algorithms for major spectral line broadening and shifting mechanisms, including Natural, Doppler, Van der Waals, Resonant, and Stark effects.
Stark Spectral Line Parameters: Complex calculations related to Stark spectral line parameters are optimized for accuracy and efficiency using different theoretical approaches such as Semi-Empirical, Modified Semi-Empirical, and Semi-Classical methods.
Plasma Composition Solver: SLS provides tools for computing the exact solution of plasma composition in Local Thermodynamic Equilibrium (LTE). This is useful for estimating particle densities of plasma constituents under different conditions.
Transition Probability Calculator: The software includes a calculator for determining transition probabilities between electronic configurations using various coupling schemes, including LS, LK, J1K, J1j, and jj couplings. Computational routines for Coefficients of Fractional Parentage (CFP) are integrated into this feature.
Data Source: SLS utilizes atomic data from the National Institute of Standards and Technology (NIST) Atomic Spectra Database (ASD). Users can update their local copy of ASD from the NIST server to ensure calculations are based on the most recent atomic data.

For more information about the SLS software, please request the SLS demo software and the User Manual.

Examples

Example 1: The spectral line of Ar I 1048.2199 A 3s2.3p6 1S - 3s2.3p5.(2Po<1/2>).4s 2[1/2]o, calculated in Semi-Classical impact approximation of Griem (SCG). The perturbing levels of the upper level of the transition have J1K rather than LS coupling. The Debye shielding correction on the line width and shift reveals the significant influence to the line shift of Ar I 1048.2199 A. The SLS calculates the correction to Debye shielding for the spectral line profiles originated from neutral atoms.

Example 2: The width and shift of Mg II 2796.3518 A calculated in the Semiclassical Impact Approximation of Griem (SCG). The temperature dependences of spectral linewidth and shift are normalized to the plasma electron density of 1E17 cm^-3.

Example 3: The width and shift of Ar VII 3s.4s 1S - 3s.4p 1Po 2445.7652 A, calculated in Modified Semi-Empirical approximation (MSE). The temperature dependences of spectral linewidth and shift are normalized to the plasma electron density of 1E17 cm^-3.

Example 4: Calculated Mg II 2796.3518 A spectral line width and shift parameters vs. the plasma temperature, for several line broadening and shifting mechanisms: Doppler, resonant, Van der Waals and natural. The Doppler shift is calculated for predefined emitter velocity (equal to zero in this example).

Example 5: The LTE Plasma Solver solution for inductively coupled Argon plasma (ICP) mixed with CF4 at 6000 K plasma temperature and 1E15 cm^-3. The concentration of singly charged Fluorine ions is predicted to be lower than the concentrations of singly charged Argon and Carbon ions.

Example 6: LTE Plasma Solver solution for pure Uranium plasma. U XXVII and U XXVIII ions are dominant emitters at T=1,E6 K plasma temperature and Ne=1E20 cm^-3 electron density. Low Uranium ion densities are not listed, but rather displayed as the numerical error of LTE solution.

Example 7: Comparison of the line strengths calculated by the enhanced Bates-Damgaard (BD) method used in the SLS vs. NIST ASD tabulated values for the transitions between the perturbing levels of the upper and lower level in B III 1s2.3s 2S 1/2 - 1s2.3p 2P0 3/2 7839.4583 A.

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