Investigation of a low-pressure He–Xe discharge in spot mode

Porokhova, I. A.; Winter, J.; Sigeneger, F.; Loffhagen, Detlef; Lange, Hartmut

doi:10.1088/0963-0252/18/1/015013

Cited by 7 publications

(5 citation statements)

References 30 publications

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“…(The values of the mean energies are shown in figure 9.) We refer to this approach as the local-mean-energy approximation (LMEA) because it is somewhat similar to the local-mean-energy approximation widely used for the hydrodynamic description of electrons [46][47][48][49][50]. In this approximation, solving the nonstationary, spatially inhomogeneous Boltzmann equation for electrons is replaced by solving the stationary, spatially homogeneous equation.…”

Section: Calculated Results For Non-stationary Electric Field and Dis...mentioning

confidence: 99%

“…The electron characteristics are assumed to be functions of the electron mean energy that is determined from the energy balance equation, taking into account nonlocal effects. This approach is much simpler than a direct numerical solution of the nonstationary, spatially inhomogeneous Boltzmann equation and allows adequate hydrodynamic description of unsteady non-uniform discharge plasmas [46][47][48][49][50]. The main difference between the approach used in this work for the description of ion properties and the local-mean-energy approximation for electrons is that the mean ion energy is calculated by the Monte Carlo technique rather than by solving the electron energy balance equation.…”

Section: Calculated Results For Non-stationary Electric Field and Dis...mentioning

confidence: 99%

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Monte Carlo simulation of negative ion kinetics in air plasmas in a time-varying electric field

Пономарев¹,

Aleksandrov²

2019

J. Phys. D: Appl. Phys.

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The kinetics of and O− ions was addressed in air plasma in a rapidly time-varying electric field that is typical for nanosecond pulsed surface dielectric barrier discharges. Self-consistent sets of cross-sections for these ions in collisions with O2 and N2 molecules were developed. The Monte Carlo technique was used to calculate ion energy distribution, mean ion energy and reaction rate coefficients in a time-varying electric field at air pressures from 0.1 to 1 atm. Simulations showed that the ion characteristics followed the instantaneous values of the electric field at atmospheric pressure, whereas these characteristics evolved with a noticeable delay at lower pressures. As a result, the rates of electron detachment and ion charge exchange were much lower than those corresponding to the instantaneous values of the electric field at the leading edge of the voltage pulse. The reverse effect was observed for the rates of ion–molecule reactions at the trailing edge of the voltage pulse. Here, the reaction rates decreased with some delay in comparison with electric field variation. An approach was suggested to describe ion rate coefficients in time-varying electric fields on the basis of the Monte Carlo calculation of these coefficients under steady electric field conditions, and the calculation of the mean ion energy in unsteady electric fields.

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Section: Calculated Results For Non-stationary Electric Field and Dis...mentioning

confidence: 99%

Section: Calculated Results For Non-stationary Electric Field and Dis...mentioning

confidence: 99%

Monte Carlo simulation of negative ion kinetics in air plasmas in a time-varying electric field

Пономарев¹,

Aleksandrov²

2019

J. Phys. D: Appl. Phys.

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“…The influence of these processes can be taken into account similar to e.g. [74]. Furthermore, it should be mentioned that the present model does not couple self-consistently the timedependent, spatially one-dimensional fluid-Poisson equations with the solution of the time-and space-dependent electron Boltzmann equation because of the large complexity of that approach and the expected enormous computational expenditure.…”

Section: Basic Relationsmentioning

confidence: 99%

Extended reaction kinetics model for non-thermal argon plasmas and its test against experimental data

Stankov

Becker²,

Hoder³

et al. 2022

Plasma Sources Sci. Technol.

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An extended reaction kinetics model (RKM) suitable for the analysis of weakly ionised, non-thermal argon plasmas with gas temperatures around 300K at sub-atmospheric and atmospheric pressures is presented. It considers 23 different species including electrons as well as the ground state atom, an atomic and molecular ion, four excited molecular states, and 15 excited atomic states of argon, where all individual 1s and 2p states (in Paschen notation) are included as a separate species. This 23-species RKM involves 409 collision processes and radiative transitions and recent electron collision cross section data. It is evaluated by means of results of time- and space-dependent fluid modelling of argon discharges and their comparison with measured data for two different dielectric barrier discharge configurations as well as a micro-scaled atmospheric-pressure plasma jet setup. The results are also compared with those obtained by use of a previously established 15-species RKM involving only the two lumped 2p states 2p10...5 and 2p'4...1. It is found that the 23-species RKM shows generally better agreement with experimental data and provides more options for direct comparison with measurements than the frequently used 15-species RKM.

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“…Furthermore, the dependence of the temperature on the distance z from the cathode is corrected by a formalism described in detail in [6]. In an additional experiment, where the laser wavelength is held at a constant value λ 0 , the 2-D optical depth τ (r, z) of the whole spot region is ascertained [7].…”

Section: Jörn Winter and Hartmut Langementioning

confidence: 99%

Spot Mode Operation of a Low-Pressure Helium–Xenon Glow Discharge

Winter

Lange

2011

IEEE Trans. Plasma Sci.

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The cathode region (CR) of a low-pressure He-Xe discharge with a flat thermionic emitting cathode in spot mode has been experimentally investigated by means of tunable diode laser absorption spectroscopy. Due to the strong inhomogeneity of the spot plasma, a multidimensional consideration of the CR is necessary to obtain correct results. This was achieved by an experimental setup, which provides a space-resolved measurement of the absorption signal. Furthermore, the plasma inhomogeneity was considered in the subsequent analysis of the obtained data too. The gas temperature in the surrounding volume was determined. Furthermore, the spatial density profile of the xenon 6s[3/2] 2 metastable atoms was measured in the vicinity of the spot.Index Terms-Atom number density, gas temperature, helium, LAAS, mercury-free low pressure discharge lamp, spot mode, xenon.L OW-PRESSURE glow discharges in He-Xe mixtures can be used for lighting purposes in mercury-free fluorescent lamps [1]. During the last years, investigations have been accomplished on their output characteristics and efficiency in dependence on parameters such as mixture composition, pressure, discharge current, and operation mode [2]. However, the lifetime of this type of fluorescent lamps is too low and will mainly be limited by the performance of the electrodes and their interaction with the surrounding plasma. Therefore, the physical processes in the cathode region (CR) play an important role in mercury-free fluorescent lamps on the basis of xenon low-pressure glow discharges. The extensive literature that exists on this subject is concerned with theoretical and experimental studies on the CR in low-pressure gas discharge lamps with mercury as carrier gas [3] and on Grimm-type glow discharges in argon [4] and helium [5]. Only a limited number of investigations studied hot cathode glow discharges and, particularly, the gas temperature and the atom number density in the vicinity of the cathode.In this paper, measurements of the spatial gas temperature and the optical depth of the 823.16-nm Xe transition, which is correlated to the atom number densities of the lowest excited metastable Xe state in the vicinity of a cathode with a hot spot, are presented. Both are yielded using diode laser absorption technique.The line profile of the Xe-transition 6p[3/2] 2 −6s[3/2] 2 at the center wavelength of 823.16 nm, respectively, was as-

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Investigation of a low-pressure He–Xe discharge in spot mode

Cited by 7 publications

References 30 publications

Monte Carlo simulation of negative ion kinetics in air plasmas in a time-varying electric field

Monte Carlo simulation of negative ion kinetics in air plasmas in a time-varying electric field

Extended reaction kinetics model for non-thermal argon plasmas and its test against experimental data

Spot Mode Operation of a Low-Pressure Helium–Xenon Glow Discharge

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