LXCat is an open‐access platform (http://www.lxcat.net) for curating data needed for modeling the electron and ion components of technological plasmas. The data types presently supported on LXCat are scattering cross sections and swarm/transport parameters, ion‐neutral interaction potentials, and optical oscillator strengths. Twenty‐four databases contributed by different groups around the world can be accessed on LXCat. New contributors are welcome; the database contributors retain ownership and are responsible for the contents and maintenance of the individual databases. This article summarizes the present status of the project.

Our recently reported fully relativistic distorted-wave electron-impact cross sections from the ground and metastable states of argon to various excited fine-structure levels are incorporated in a collisional-radiative model to obtain the population densities for the 3p54s and 3p54p (1s and 2p) fine-structure manifolds for low temperature argon plasmas. Excitation cross sections from the two 3p54s J = 1 resonance levels, 1s2 and 1s4, to the higher lying 2p fine-structure manifold as well as for transitions among individual levels of the 1s and 2p manifolds are also calculated and included in the present model which were not fully considered in any earlier model. Our results for the population densities of the 1s and 2p levels show good agreement with recent measurements. The variation of population densities of all the 1s and 2p levels with electron temperature and density are presented. We have also calculated and compared the intensities for the 750.38 nm (2p1 → 1s2) and 696.54 nm (2p2 → 1s5) lines with recently reported experimental results. The present work suggests that the inclusion of a complete fine-structure description of the electronic processes occurring in the plasma is important for a collisional radiative model, which includes separate 1s and 2p levels.

Optical emission spectroscopy (OES) measurements coupled with a collisional-radiative model were used to characterize a plane-to-plane dielectric barrier discharge at atmospheric pressure operated in nominally pure helium. The model predicts the population densities for the n = 3 levels of He excited by electron impact processes from either ground or metastable states and takes into account excitation transfer processes between He n = 3 levels as well as all relevant radiative decays and quenching reactions. Time-resolved OES measurements indicate that line ratios from He n = 3 triplet states (for example, 587.5 nm-to-706.5 nm) and singlet states (for example, 667.8 nm-to-728.1 nm) first sharply rise as the discharge ignites and then slowly decrease as it extinguishes. Assuming that n = 3 levels are first populated only by electron impact on ground state He atoms and then only by electron impact on metastable He atoms as the discharge current and thus the metastable number density rise, triplet and singlet line ratios predicted by the model become in each opposite case solely dependent on the electron temperature T e (assuming Maxwellian electron energy distribution function). The values of T e deduced from the analysis of both ratios were relatively high early in the discharge cycle (around 1.0-1.4 eV) and then much lower near discharge extinction (around 0.15 eV). For analysis of time-integrated (or cycle-averaged) OES measurements, the electron temperatures were closer to the 0.15 eV values near the end of the discharge cycle, in good agreement with the values expected from theoretical predictions in the positive columns of He glow discharges at atmospheric pressure.

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Detailed electron-impact excitation cross-section results for xenon in the wide range of incident energy from threshold to 1000 eV are calculated using relativistic distorted wave theory. Various transitions from the ground 5p 6 state to the excited 5p 5 6s, 5p 5 6p, 5p 5 5d, 5p 5 7s and 5p 5 7p as well as among these excited states are considered. The relativistic Dirac-Fock multi-configuration wave functions for the ground and excited states of Xe are obtained and used in the calculations. Where available, our cross-section results are compared with previously reported measurements and calculations. We have also fitted the calculated cross-sections through analytical formulae for plasma modeling purposes. As an application, using the obtained cross-sections, a collisional-radiative (C-R) model coupled with an optical emission measurement from the inductively coupled Xe plasma is developed and the extracted plasma parameters are reported.

A collisional-radiative (C-R) model for krypton plasma using fully relativistic distortedwave cross sections for electron excitations was developed. The model was applied to the characterization of inductively coupled Kr plasma with cylindrical geometry over the pressure regime 1-50 mTorr. Radially averaged emission intensities from transitions of Kr (4p 5 5p → 4p 5 5s) in the range 500-900 nm were recorded at 17 cm from the planar RF-driven coil, with the plasma operated in the inductive regime (H mode). The measured emission intensities were then fitted by varying the electron density, n e , and electron temperature, T e , in the C-R model. At both low and high pressures, variations of the electron density by over two orders of magnitude had only a minor role on the relative emission intensities. On the other hand, T e values deduced from the comparison between experiment and model decreased from 6.7 to 2.6 eV as pressure increased from 1 to 50 mTorr. These results are found to be in good agreement with the effective electron temperature determined from Langmuir probe measurements and the predictions of a model based on the particle balance equation of charged particles.

We have performed relativistic distorted-wave calculations to study the excitation of Kr from its ground 4p 6 configuration to the higher lying fine-structure levels of the 4p 5 4d, 4p 5 5p, and 4p 5 6s manifolds. We have obtained relativistic Dirac-Fock multiconfiguration wave functions for the ground and the excited states. We present results for differential cross section and compare these with the available experimental measurements for energies up to 100 eV. We also report integrated cross sections for incident electron energies up to 300 eV and provide analytic fits for plasma modeling applications.

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