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 International Journal of Aerospace Engineering , 2011, DOI: 10.1155/2011/896836 Abstract: Evaluated atomic data concerning the 4s and 4p configurations of Ar I are averaged in order to simplify their use in various cases of Ar plasma modeling and diagnostics. These data are used here to model a low-power arcjet, running with Argon at low pressure. In so doing, they are explicitly introduced in the chemical processes included in a fluid Navier-Stokes type code, allowing for evaluation of the spectroscopically measurable level populations and of the electronic temperatures. The characteristics of the model are described and the main processes are discussed in view of the results of the calculations. 1. Introduction We address the important problem of the presence of species in excited states in plasmas frequently studied in aerospace engineering. This fact contributes significantly to the overall plasma properties and therefore it has to be considered in the corresponding modeling and diagnostics. Indeed, due to the available energy, the different species are not expected to be in their ground state only; many excited levels of neutral and ionized species are definitely present in the plasma. The analysis of the population of the various excited species reveals a great interest for several domains. Mainly, excited levels of a neutral species, atom or molecule, can play an important role in the ionization process. Moreover, calculation of the different levels population is necessary to evaluate the emission spectra and to allow a spectroscopic validation of the model. Besides, inclusion of a few molecular levels can be used to estimate a “pseudo” vibrational temperature generally obtained by the ground state and the first level. The level of coupling between microscopic and macroscopic description has to be examined for each case. Here, in order to illustrate the importance of the excited states, a first study has been carried out with Argon as feeding gas for a D.C. low-pressure arcjet. The production rates (mainly electron collision excitation and ionization) and the transition probabilities leading to de-excitation of the main excited levels have been evaluated by the GAPHYOR team, using a big number of theoretical codes and also experimental data, as described in Section 3, after a description of the neutral Argon structure in Section 2. Note that these data can be useful for diagnostics of various plasmas, after adding a small quantity of Ar as a tracer gas. The study of arcjets is selected here to illustrate the use of the Ar I atomic data, because of their importance in many aerospace applications. Space missions aiming at the
 Physics , 2010, DOI: 10.1063/1.2390631 Abstract: A simple model and method is proposed here to determine argon metastable number densities and electron temperature with the assumption of a Maxwell-Boltzmann electron energy distribution. This method is based on the availability of experimental relative emission intensities of only four argon lines that originate from any of the 4p argon levels. The proposed model has a relatively wide range of validity for laboratory plasmas that contain argon gas and can be a valuable tool for the emerging field of atmospheric microplasmas, for which diagnostics is still limited.
 Physics , 2015, DOI: 10.1088/0031-8949/90/3/035401 Abstract: The ab initio quasirelativistic Hartree-Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions is used to derive spectral data for the 4s$^2$4p$^5$, 4s$^2$4p$^4$4d and 4s4p$^6$ configurations of the multicharged tungsten ion W$^{39+}$. The relativistic effects are taken into account in the Breit-Pauli approximation for the quasirelativistic Hartree-Fock radial orbitals. The configuration interaction method is applied to include the electron correlation effects. Produced data are compared with existing experimental measurements and theoretical calculations.
 Physics , 2015, Abstract: We report on improved isotope shift measurements of the isotopes $^{40,42,44,48}$Ca in the $4s\,^2 \rm{S}_{\frac{1}{2}} \rightarrow 4p\,^2\rm{P}_{\frac{3}{2}}$ (D2) transition using collinear laser spectroscopy. Accurately known isotope shifts in the $4s\,^2 \rm{S}_{\frac{1}{2}} \rightarrow 4p\,^2\rm{P}_{\frac{1}{2}}$ (D1) transition were used to calibrate the ion beam energy with an uncertainty of $\Delta U \approx \pm 0.25$ V. The accuracy in the D2 transition was improved by a factor of $5 - 10$. A King-plot analysis of the two transitions revealed that the field shift factor in the D2 line is about 1.8(13) % larger than in the D1 transition which is ascribed to relativistic contributions of the $4p_{1/2}$ wave function.
 Physics , 2008, DOI: 10.1103/PhysRevA.78.032511 Abstract: High accuracy frequency metrology on the 4s 2S1/2 - 4p 2P1/2 transition in calcium ions is performed using laser cooled and crystallized ions in a linear Paul trap. Calibration is performed with a frequency comb laser, resulting in a transition frequency of f=755222766.2(1.7) MHz. The accuracy presents an improvement of more than one order of magnitude, and will facilitate a comparison with quasar data in a search for a possible change of the fine structure constant on a cosmological time scale.
 Brazilian Journal of Physics , 2000, DOI: 10.1590/S0103-97332000000200020 Abstract: we present new experimental atomic transition values for the atomic emission spectrum of doubly ionized argon, ar iii. in this work we studied 3s2 3p4 - 3s2 3p3 3d, 3s2 3p4 - 3s2 3p3 4s, 3s2 3p4 - 3s2 3p3 4d, 3s2 3p4 - 3s2 3p3 5s, 3s2 3p3 4p, and 3s2 3p3 4p transition arrays and 196 lines were identified as new atomic transitions between levels of these configurations. the experimental data were obtained from a capillary-discharge tube. the identifications are supported by multiconfiguration hartree-fock relativistic calculations.
 Brazilian Journal of Physics , 2000, Abstract: We present new experimental atomic transition values for the atomic emission spectrum of doubly ionized argon, Ar III. In this work we studied 3s2 3p4 - 3s2 3p3 3d, 3s2 3p4 - 3s2 3p3 4s, 3s2 3p4 - 3s2 3p3 4d, 3s2 3p4 - 3s2 3p3 5s, 3s2 3p3 4p, and 3s2 3p3 4p transition arrays and 196 lines were identified as new atomic transitions between levels of these configurations. The experimental data were obtained from a capillary-discharge tube. The identifications are supported by multiconfiguration Hartree-Fock relativistic calculations.
 Brazilian Journal of Physics , 2010, DOI: 10.1590/S0103-97332010000400018 Abstract: microdischarges at moderate to high pressure in argon were investigated. a hole opening diameter of 500 μm direct current (dc) microhollow cathode discharges (mhcd) were characterized by electrical measurements and optical emission spectroscopy (oes) for pressures ranging between 90 and 800 torr and current from 5 to 20 ma. current-voltage characteristic curves were obtained as a function of the pressure for this hole diameter. mhcd enables stable dc discharges for molybdenum electrodes material at constant ar + 2%h2 flow of 0.03 l/min. optical emission spectroscopy and analysis of the spectral line broadening of plasma line emissions were performed in order to measure gas discharge parameters. electron number densities were obtained from hβ balmer line ( ~ 1014 cm-3). for the above mentioned discharge conditions, gas temperature was estimated to be 550 - 850 k from oh rotational bands. excitation temperature was measured based on two lines method (from atomic mo lines) and from 4p - 4s and 5p - 4s ar radiative transitions. hydrogen atom temperature was measured for 800 torr ( ~ 12000 k).
 科技进步与对策 , 2004, Abstract: 传统的4P组合已不适用于电子商务的互联网营销。通过详细介绍电子商务网络营销的4S组合模型,具体分析了其中每个S的含义及其实施途径。网络营销组合模型的4S要素,是设计、开展BtoC模式电子商务的基本框架。电子商务网络营销组合4S模型
 International Journal of Soft Computing & Engineering , 2011, Abstract: Step and touch voltages play an importantrole when designing high voltage substation. Step and touchpotentials near high voltage substation due to severe ground faultspresent a hazard to anyone in proximity to substation when a faultoccurs. A primary issue of concern is hazardous step and touchvoltage is that arise during fault situations, hence a reliable andefficient solution to the problem is essential. Although personnelsafety is of primary concern, effect of electric current, resistanceof the human body and tolerable voltage criteria considerationsare also essential in the design system to ensure the protection ofpersonnel and equipment. This study will briefly explain thesignificance of step and touch voltages.
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