Measurements of the number density of water molecules in plasma by using a combined spectral−probe method

Bernatskiy, A. V.; Очкин, В. Н.; Afonin, Oleg; Antipenkov, A.

doi:10.1134/s1063780x15090032

Cited by 25 publications

(20 citation statements)

References 7 publications

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“…To reliably obtain the rotational temperature of both, we have thus fitted the observed population distribution with a sum of two independent Boltzmann distributions. This is in principal similar to the treatment proposed by Bernatskiy [48]. A few implementation details, however, should be noted here.…”

Section: Oh(a-x) Emission Analysissupporting

confidence: 63%

State-by-state emission spectra fitting for non-equilibrium plasmas: OH spectra of surface barrier discharge at argon/water interface

Voráč¹,

Synek²,

Procházka³

et al. 2017

J. Phys. D: Appl. Phys.

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Abstract. Optical emission spectroscopy applied to non-equilibrium plasmas in molecular gases can give important information on basic plasma parameters, including the rotational, vibrational temperatures and densities of the investigated radiative states. In order to precisely understand the non-equilibrium of rotational-vibrational state distribution from investigated spectra without limiting presumptions, a state-bystate temperature-independent fitting procedure is the ideal approach. In this paper we present a novel software tool developed for this purpose, freely available for scientific community. The introduced tool offers a convenient way to construct Boltzmann plots even from partially overlapping spectra, in user-friendly environment.We apply the novel software to the challenging case of OH spectra in surface streamer discharges generated from the triple-line of argon/water/dielectrics interface. After the barrier discharge is characterised by ICCD and electrical measurements, the spatially and phase resolved rotational temperatures from N 2 (C-B) and OH(A-X) spectra are measured, analysed and compared. The precise analysis shows that OH(A) states with quantum numbers (v = 0, 9 ≤ N ≤ 13) are overpopulated with respect to the found two-Boltzmann distribution. We hypothesise that fast vibrational-energy transfer is responsible for this phenomenon observed here for the first time. Finally, the vibrational temperature of the plasma and the relative populations of hot and cold OH(A) states are quantified spatially and phase resolved.PACS numbers: 52.30.-q, 52.50. Dg,

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Section: Oh(a-x) Emission Analysissupporting

confidence: 63%

State-by-state emission spectra fitting for non-equilibrium plasmas: OH spectra of surface barrier discharge at argon/water interface

Voráč¹,

Synek²,

Procházka³

et al. 2017

J. Phys. D: Appl. Phys.

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“…is provided on the Tech installation [164,167]. The measurement results demonstrated the ability to measure concentrations of water molecules at the level of 10 12 cm -3 .…”

Section: ( )mentioning

confidence: 98%

“…The above-noted problem of ambiguity in correlating the luminescence intensities of water molecules with the H 2 O concentration by means of various calibrations [160,163] was considered in [164] in a fundamentally different way.…”

Section: Measurements Of Absolute Concentrations Of Water Molecules By the Fine Structure Of The Emission Electron Spectrum Of Hydroxylmentioning

confidence: 99%

“…Figure 15 shows a fragment of the rotational structure of the spectrum (0, 0) of the transition band ОН(A 2 Σ-Х 2 П) obtained on the Tech facility [164]. The discharge is in the Н 2 О : Не = 0.075 : 0.925 mixture, at a pressure of 1 mbar, and current of 0.23 А.…”

Section: Measurements Of Absolute Concentrations Of Water Molecules By the Fine Structure Of The Emission Electron Spectrum Of Hydroxylmentioning

confidence: 99%

“…In this case, the presence of the partial temperature is explained by the statistical law of the decay of the excited Н 2 О(В 1 А 1 ) complex [173][174][175][176]. These temperatures varied in experiments [164] with different wet gases: T с ~ 320-500 K and T h ~ 4-7 × 10 3 K, but always sharply differed among themselves that allowed their reliable separation. It follows from the balance condition for concentrations of excited molecules of the hot group under stationary conditions that (32) Here, is the lifetime of the ОН(A 2 Σ) state, to which the rotationally hot molecules belong, are electron velocities, σ de is the cross section of the disso-…”

Section: Measurements Of Absolute Concentrations Of Water Molecules By the Fine Structure Of The Emission Electron Spectrum Of Hydroxylmentioning

confidence: 99%

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Spectral Methods of Control of Impurities, Their Flows and Localization in an Equilibrium Low-Temperature Plasma of Low Pressure

2020

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The state-of-art of studies of processes involving small fractions of particles formed as a result of chemical transformations of the source gas or appearing from the outside as an impurity is discussed. Various high-sensitivity methods for measuring the low concentrations of particles are considered. The main focus is on spectral methods, both classical and laser ones. The main modern fields of the application of non-equilibrium plasma, features, and achievements of the diagnostic tools used in them are highlighted. The emphasis is on spectroscopic studies of plasma purity in the low-temperature near-wall layers of thermonuclear reactors. In this case, the issue of the penetration of water molecules into the plasma chamber from the cooling circuits is of particular importance. In view of the limited accessibility to the reactors, new remote versions of spectral emission methods are being developed that are focused on the diagnostics of the ITER near-wall plasma. A new method of multispectral optical actinometry is discussed, in which intermediate chemically unstable particles can play the role of actinometers. This broadens the range of possibilities for quantitative measurements of concentrations of particles of different kinds, and increases the sensitivity. Effective actinometric pairs were found for the objects under consideration, e.g., hydrogen and deuterium atoms. The schemes are worked out on laboratory facilities, and kinetic models of plasma-chemical processes are developed. Scaling of the results of model experiments makes it possible to predict the measurement of the impurity flows at the level (10–9–10–13) Pa m3 s–1 with the localization of sources determined by the spatial resolution of the optical system.

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Plasma Parameters Near a Hollow Rectangular Cathode

2021

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Measurements of the number density of water molecules in plasma by using a combined spectral−probe method

Cited by 25 publications

References 7 publications

State-by-state emission spectra fitting for non-equilibrium plasmas: OH spectra of surface barrier discharge at argon/water interface

State-by-state emission spectra fitting for non-equilibrium plasmas: OH spectra of surface barrier discharge at argon/water interface

Spectral Methods of Control of Impurities, Their Flows and Localization in an Equilibrium Low-Temperature Plasma of Low Pressure

Plasma Parameters Near a Hollow Rectangular Cathode

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