Improving the efficiency of a fluorescent Xe dielectric barrier light source using short pulse excitation

Beleznai, Sz; Mihajlik, Gábor; Maros, I.; Balázs, László; Richter, Péter

doi:10.1088/0022-3727/41/11/115202

Cited by 24 publications

(5 citation statements)

References 21 publications

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“…Finally, an overall thermalisation time is defined in terms of the time taken for the slowest evolving parameter to reach a satisfactory level of convergence. Xenon was chosen as the target gas for two reasons; firstly, fast-risetime pulsed medium-pressure Xe plasmas have been investigated extensively for use as efficient vacuum-ultraviolet (λ∼172 nm) lamps [22][23][24], and secondly, understanding the time-evolution of the EEDF toward thermalisation in the presence of large variations in the electron momentum transfer cross-section associated with the deep Ramsauer minimum in a heavy raregas [25] is of particular interest [26]. Lastly, fast transient plasmas operating with peak voltages substantially higher than the minimum breakdown voltage may utilise very high electric fields E/N=10 3 -10 4 Td [27], and an additional manifestation of non-equilibrium type behaviour will be associated with the production of high-energy runaway or ballistic electrons in the bulk plasma [18,28].…”

Section: Introductionmentioning

confidence: 99%

Thermalisation time of electron swarms in xenon for uniform electric fields

Boyle

Casey

Cocks

et al. 2019

Plasma Sources Sci. Technol.

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We have calculated the thermalisation time for an electron swarm in gaseous xenon using a multi-term time-dependent Boltzmann equation (BE), for a range of instantaneously applied reduced electric fields 1 Td<E/N< 1000 Td. Starting from a Maxwellian electron energy distribution function (EEDF) at room temperature for a given E/N, the time-evolution of the EEDF and associated electron swarm parameters (drift velocity W e , mean energy 〈ε〉, ionisation coefficient k i , excitation coefficient k ex ) are followed as they converge to steady-state values. For all values of E/N considered, the individual swarm parameters are found to converge at different rates. For E/N>5 Td, they converge in order W e (fastest), 〈ε〉, k ex , and k i (slowest). The time taken for the slowest swarm parameter to converge to an acceptable level (e.g. to within 10% of its steady-state value) is used universally as the benchmark for evaluating the thermalisation time τ th . This time is found to be strongly dependent on the value of the reduced electric field E/N, dropping by almost 5 orders of magnitude for increasing E/N fields 1 Td<E/N< 1000 Td. As a key outcome from this work, the calculated thermalisation times τ th •p are expressed as a general formula, as a function of both the reduced electric field E/N and a user defined convergence level between 1% and 20%. We show that ballpark estimates of thermalisation times, based on the inverse of the collision frequency for energy dissipation 1/ν e (ε) at typical average electron energies, are likely to be unreliable if applied to the heating phase. We also undertake a brief analysis of the cooling phase when the electric field is instantaneously removed from the plasma (i.e. field-free) after it evolves to steady-state conditions during the previous heating phase. Finally, we compare calculated thermalisation times with the typical risetimes of the voltage pulse waveforms for several experimental 'nanosecond' pulse excited plasma discharge devices.

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Section: Introductionmentioning

confidence: 99%

Thermalisation time of electron swarms in xenon for uniform electric fields

Boyle

Casey

Cocks

et al. 2019

Plasma Sources Sci. Technol.

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“…Many investigations about the VUV generation process were published before, [23][24][25] and our research focuses on the mechanism of excimer VUV generation in case of the high Xe partial pressure.…”

Section: B 2d Simulationsmentioning

confidence: 99%

“…10 shows the most important energy levels and transitions for Xe. The generation of the Xe excitation states Xe*(1s 4 ) and Xe*(1s 5 ) include three kinds of processes: 21,25 (1) electron impact excitation directly from the ground state (shown by the gray arrows); (2) heavy body collisions with Xe**(2p 5-10 ), Xe*(1s 2 ), or Xe*(1s 3 ) by the Ne or Xe atoms (shown by the magenta arrows); (3) radiative processes by Xe**(2p [1][2][3][4] or Xe**(2p 5-10 ) (shown by the green arrows). The processes related to NIR and VUV radiation, which are concerned with in this section, are marked in the diagram.…”

Section: B 2d Simulationsmentioning

confidence: 99%

“…12(b) gives the total density of Xe 2 *( 1 R u þ ) and Xe 2 *( 3 R u þ ) during one full sustain pulse. Because Xe 2 *( 1 R u þ ) and Xe 2 *( 3 R u þ ) cannot be stepwise-excited or stepwise-ionized, 18,25,27 these Xe excimer excitation states are proportional to the excimer VUV emission. Therefore, we conclude that with the increase of Xe partial pressure, not only the time averaged excimer VUV intensity is increased but also the peak intensity.…”

Section: B 2d Simulationsmentioning

confidence: 99%

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Impact of Xe partial pressure on the production of excimer vacuum ultraviolet emission for plasma display panels

Zhu

Zhang

Kajiyama

2012

Journal of Applied Physics

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In this work, the effect of the Xe partial pressure on the excimer vacuum ultraviolet (VUV) emission intensity of the plasma display panels is investigated, both by measuring the spectral emission directly and by two-dimensional simulations. Experimentally, we find that at the high Xe partial pressure levels, there is an supra-linear increase of excimer VUV radiation and that determines the strong increase of luminance at the high pressures and high voltage. Due to the increase of the luminance and the almost unchanged discharge current, the luminous efficacy strongly increases with the Xe partial pressure. In addition, we also investigated the dynamics of the VUV generation, by measuring the decay time of the excimer VUV light as a function of the gas pressure. It is found that the decay time decreases with the increase of gas pressure. The spatial characteristics of the excimer VUV emission are also discussed. Different from the Ne and near-infrared emission, the excimer VUV emission is generated near the surface of the electrodes and increases uniformly on both sides of the anode and cathode (i.e., the bulk plasma region). Most importantly, it is found that the VUV production occurs during the afterglow period, while it is almost zero at the moment of the discharge itself. From the simulations, it can be seen that the Xe2*(3Σu+) excimer species, which are generated from Xe*(1s5), play a dominant role in the excimer VUV emission output at the high Xe partial pressure. The two-dimensional simulations also show that the strong increase of Xe excimer excitation states in the case of high pressure is mainly the result of the high conversion efficiency of the Xe excimer states, especially in the afterglow period. Due to the high conversion efficiency of Xe excitation species to Xe excimer species by the high collision rate in the case of high pressure, there is a strong increase of excimer VUV production, especially from the cathode.

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“…A homogeneous glow mode can be achieved by a sinusoidal source with the merits of a low working temperature and easy control, but it has a low power conversion efficiency and a low density of chemically active species [12]. In contrast, high-density plasmas can be produced quickly by a short-pulse source, but the high density of active species cannot last long [13]. The RF source can generate high-activity and high-density plasmas, but its power conversion efficiency is lower [14].…”

Section: Introductionmentioning

confidence: 99%

Investigation of NO removal using a pulse-assisted RF discharge

Wang

et al. 2017

Plasma Sci. Technol.

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In this paper, removal of nitrogen oxide (NO) is investigated in capacitive atmospheric pressure discharges driven by both radio-frequency (RF) and trapezoidal pulsed power with a onedimensional self-consistent fluid model. The results show that the number density of NO could be reduced significantly once a short pulse of low duty ratio is additionally applied to the RF power. It is found that the process of NO removal by the pulse-modulated RF discharge could be divided into three stages: the quick reaction stage, the NO removal stage, and the sustaining stage. Furthermore, the temporal evolution of particle densities is analyzed, and the key reactions in each stage are discovered. Finally, the influence on the removal efficiency of the voltage amplitude of the pulse and the RF voltage amplitude is investigated.

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Improving the efficiency of a fluorescent Xe dielectric barrier light source using short pulse excitation

Cited by 24 publications

References 21 publications

Thermalisation time of electron swarms in xenon for uniform electric fields

Thermalisation time of electron swarms in xenon for uniform electric fields

Impact of Xe partial pressure on the production of excimer vacuum ultraviolet emission for plasma display panels

Investigation of NO removal using a pulse-assisted RF discharge

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