Influence of gas temperature on the loss mechanisms of H-atoms in a pulsed microwave discharge identified by time-resolved LIF measurements

Lamara, T.; Hugon, R.; Bougdira, J.

doi:10.1088/0963-0252/15/3/031

Cited by 13 publications

(10 citation statements)

References 44 publications

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“…This kind of study requires a good knowledge and good characterization of the plasma for two main reasons. The first one concerns the measurement of the loss coefficient in itself that can be badly estimated if effects such as gas temperature and neutral density variations are not well managed (Cartry et al 2006, Lamara et al 2006. Second, a key point in surface loss studies is the identification of the parameters playing a role on the surface loss coefficient.…”

Section: Resultsmentioning

confidence: 99%

Diagnostics of low-pressure hydrogen discharge created in a 13.56 MHz RF plasma reactor

Krištof¹,

Annušová²,

Anguš³

et al. 2016

Phys. Scr.

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A 13.56 MHz RF discharge in hydrogen was studied within the pressure range of 1-10 Pa, and at power range of 400 -1000 W. The electron energy distribution function and electron density were measured by a Langmuir probe. The gas temperature was determined by the Fulcher-α system in pure H2, and by the second positive system of nitrogen using N2 as the probing gas. The gas temperature was constant and equal to 450 ± 50 K in the Capacitively Coupled Plasma mode (CCP), and it was increasing with pressure and power in the Inductively Coupled Plasma mode (ICP). Also the vibrational temperature of ground state of hydrogen molecules was determined to be around 3100 and 2000 ± 500 K in ICP and CCP mode, respectively. The concentration of atomic hydrogen was determined by means of actinometry, either by using Ar (5 %) as the probing gas, or by using H2 as the actinometer in pure hydrogen (Q1 rotational line of Fulcher-α system) The concentration of hydrogen density was increasing with pressure in both modes, but with a dissociation degree slightly higher in the ICP mode (a factor 2). Submitted to Physica Scripta

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Section: Resultsmentioning

confidence: 99%

Diagnostics of low-pressure hydrogen discharge created in a 13.56 MHz RF plasma reactor

Krištof¹,

Annušová²,

Anguš³

et al. 2016

Phys. Scr.

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“…Therefore, the H temperature should be in the range between 3.5 eV and T g . Studies in different discharge types (mostly in microwave discharges) at considerably higher pressures (≥ 30 Pa) than in the present study have measured the atomic hydrogen temperature via line broadening in the range between 1000 and 3000 K 37,38,[40][41][42] . The measured atomic hydrogen temperatures were considerably lower than 3.5 eV but higher than the gas temperature.…”

Section: Equationmentioning

confidence: 76%

Surface loss probability of atomic hydrogen for different electrode cover materials investigated in H2-Ar low-pressure plasmas

Sode

Schwarz-Selinger

Jacob

et al. 2014

Journal of Applied Physics

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In an inductively-coupled H 2 -Ar plasma at a total pressure of 1.5 Pa the influence of the electrode cover material on selected line intensities of H, H 2 , and Ar are determined by optical emission spectroscopy and actinometry for the electrode cover materials stainless steel, copper, tungsten, Macor , and aluminum. Hydrogen dissociation degrees for the considered conditions are determined experimentally from the measured emission intensity ratios. The surface loss probability β H of atomic hydrogen is correlated with the measured line intensities and β H values are determined for the considered materials. Without the knowledge of the atomic hydrogen temperature, β H cannot be determined exactly. However, ratios of β H values for different surface materials are in first order approximation independent of the atomic hydrogen temperature. Our results show that β H of copper is equal to the value of stainless steel, β H of Macor and tungsten is about 2 times smaller and β H of aluminum about 5 times smaller compared with stainless steel. The latter ratio is in reasonable agreement with literature. The influence of the atomic hydrogen temperature T H on the absolute value is thoroughly discussed. For our assumption of T H = 600 K we determine a β H for stainless steel of 0.39 ± 0.13.

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“…Many other ns-TALIF measurements of the H atom in plasmas are reported, e.g. in highly diluted SiH 4 -H 2 RF discharges that are used in thin-film deposition [118], in a large-scale microwave plasma reactor [119], in a pulsed microwave discharge [120], in a diamond-depositing DC arcjet [121], in a hydrogen gas flow into a wall-stabilized cascaded arc [122], in helicon plasmas [123], in ns-pulse discharges at a liquidvapor interface [93], in an Ar-O 2 -H 2 mixture excited by nspulse discharges [124], etc. Ns-TALIF suffers from rapid quenching (particularly in higher pressures) and photolytic interferences, as discussed earlier.…”

Section: Atomic Imaging In Low-pressure and Atmospheric-pressure Plasmasmentioning

confidence: 99%

Recent advances in ultrafast-laser-based spectroscopy and imaging for reacting plasmas and flames

Patnaik

Adamovich

Gord

et al. 2017

Plasma Sources Sci. Technol.

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Reacting flows and plasmas are prevalent in a wide array of systems involving defense, commercial, space, energy, medical, and consumer products. Understanding the complex physical and chemical processes involving reacting flows and plasmas requires measurements of key parameters, such as temperature, pressure, electric field, velocity, and number densities of chemical species. Time-resolved measurements of key chemical species and temperature are required to determine kinetics related to the chemical reactions and transient phenomena. Laser-based, noninvasive linear and nonlinear spectroscopic approaches have proved to be very valuable in providing key insights into the physico-chemical processes governing reacting flows and plasmas as well as validating numerical models. The advent of kilohertz rate amplified femtosecond lasers has expanded the multidimensional imaging of key atomic species such as H, O, and N in a significant way, providing unprecedented insight into preferential diffusion and production of these species under chemical reactions or electric-field driven processes. These lasers not only provide 2D imaging of chemical species but have the ability to perform measurements free of various interferences. Moreover, these lasers allow 1D and 2D temperature-field measurements, which were quite unimaginable only a few years ago. The rapid growth of the ultrafast-laser-based spectroscopic measurements has been fueled by the need to achieve the following when measurements are performed in reacting flows and plasmas. They are: (1) interference-free measurements (collision broadening, photolytic dissociation, Stark broadening, etc), (2) timeresolved single-shot measurements at a rate of 1-10 kHz, (3) spatially-resolved measurements, (4) higher dimensionality (line, planar, or volumetric), and (5) simultaneous detection of multiple species. The overarching goal of this article is to review the current state-of-the-art ultrafast-laserbased spectroscopic techniques and their remarkable development in the past two decades in meeting one or all of the above five goals for the spectroscopic measurement of temperature, number density of the atomic and molecular species, and electric field.

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Influence of gas temperature on the loss mechanisms of H-atoms in a pulsed microwave discharge identified by time-resolved LIF measurements

Cited by 13 publications

References 44 publications

Diagnostics of low-pressure hydrogen discharge created in a 13.56 MHz RF plasma reactor

Diagnostics of low-pressure hydrogen discharge created in a 13.56 MHz RF plasma reactor

Surface loss probability of atomic hydrogen for different electrode cover materials investigated in H2-Ar low-pressure plasmas

Recent advances in ultrafast-laser-based spectroscopy and imaging for reacting plasmas and flames

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