Batch processing of overlapping molecular spectra as a tool for spatio-temporal diagnostics of power modulated microwave plasma jet

Voráč, Jan; Synek, Petr; Potočňáková, Lucia; Hnilica, Jaroslav; Kudrle, Vít

doi:10.1088/1361-6595/aa51f0

Cited by 94 publications

(77 citation statements)

References 67 publications

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“…This window contains the (0,0) band of the N 2 (C 3 Π u → B 3 Π g ) transition. The rotational temperature obtained from this band is believed to reliably reflect the translational temperature of gas [19,29,30,31].…”

Section: Experimental Setup and Data Acquisitionmentioning

confidence: 97%

“…This approach resulted in two massiveOES.MeasuredSpectra() instances, containing spatially resolved spectra of N 2 (C-B) for positive and negative streamer discharges (see section 4.1 for explanation of the labels). These were then processed in the massiveOES programme assuming Boltzmann distribution to obtain the rotational temperatures as in [19].…”

Section: Data Processingmentioning

confidence: 99%

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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: Experimental Setup and Data Acquisitionmentioning

confidence: 97%

Section: Data Processingmentioning

confidence: 99%

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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“…A similar method was used by Yagi et al for spatially resolved measurement of humidity based on quenching of NO radical [57]. For further investigations of gas dynamics in plasma jets, see also [58][59][60].…”

Section: Planar Lif In the Effluent Of A Radio-frequency Plasma Jetmentioning

confidence: 99%

Laser-Induced Fluorescence of Hydroxyl (OH) Radical in Cold Atmospheric Discharges

Voráč¹,

Dvořák²,

Mrkvičková³

2018

Photon Counting - Fundamentals and Applications

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The application of laser-induced fluorescence (LIF) to measurement of absolute concentration of hydroxyl radicals in cold atmospheric discharges is described. Though only the case of OH is presented, the method can be directly applied to other molecules as well. Starting from the rate equations for the LIF process, the main formulas for two-and multilevel excitation scheme are derived. It is also shown how to use partially saturated LIF in practice, enhancing the signal-to-noise ratio. Practical tips for automating the data evaluation are given, allowing processing large data sets, particularly suitable for planar measurements. Gas temperature estimation from fluorescence on different rotational absorption lines is shown as an attractive method for obtaining temperature maps with high spatial resolution. The important aspects of calibration are discussed, particularly the overlap of the laser line with the selected absorption line and the measurement of the Rayleigh scattering for sensitivity calibration, together with the common sources of errors. The application of OH(A, v 0 =0 X, v 00 = 0) excitation scheme to the effluent of atmospheric pressure plasma jet ignited in argon and of OH(A, v 0 =1 X, v 00 = 0) to the plasma of coplanar surface barrier discharge in air and in water vapor is shown.

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“…In recent years, considerable interest has been attracted to the investigations of the low-current atmosphericpressure discharges in gas flow [1][2][3][4][5]. A variety of the discharge types and the electrode configurations are used in the experiments [2,3,[6][7][8][9][10][11][12][13][14][15][16]. The present paper deals with the glow-type discharge in airflow in the electrode system of the classical coaxial plasmatron [3,[17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Nonsteady-state processes in a low-current discharge in airflow and formation of a plasma jet

et al. 2019

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The paper describes the investigations of a low-current discharge in airflow with the electrode configuration of coaxial plasmatron. An inner diameter of the plasmatron nozzle is of 0.5 cm and the mass airflow rate is from 0.1 to 0.3 g s −1 . Typical averaged discharge current is varied from 0.06 to 0.2 A. In these conditions, due to airflow the so-called plasma jet forms in the plasmatron nozzle and at its exit. The total current in plasmatron mainly flows via the constricted plasma column of the glow discharge and only a small fraction of current is carried by the jet. The principal idea of the experiments is to reveal the mechanism of the jet formation and to elucidate how the nonsteady discharge regimes influence on the jet properties. We have proposed the method for the jet diagnostics, which is based on measuring the currents to the additional diagnostic electrodes located outside the nozzle. The obtained data show that the jet current forms due to electrons that are emitted from the boundary of plasma column. The temporal behavior of the jet current is determined by the position of the column inside the plasmatron nozzle, which changes with time. Hence, the term 'plasma jet' has to be used with care, since the charged particles in the jet area are the electrons. The estimated electron density in the jet is of about 10 9 cm -3 .

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Batch processing of overlapping molecular spectra as a tool for spatio-temporal diagnostics of power modulated microwave plasma jet

Cited by 94 publications

References 67 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

Laser-Induced Fluorescence of Hydroxyl (OH) Radical in Cold Atmospheric Discharges

Nonsteady-state processes in a low-current discharge in airflow and formation of a plasma jet

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