Progresses in Experimental Study of N2 Plasma Diagnostics by Optical Emission Spectroscopy

Akatsuka, Hiroshi

doi:10.5772/36512

Cited by 17 publications

(16 citation statements)

References 20 publications

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“…The second positive system (SPS) is often used to measure vibrational and rotational temperatures in air discharge plasma [24,25]. The spectrum is emitted as transitions from an electronic state C 3 Πu to an electronic state B 3 Πg and the transitions appear in the ultraviolet region: 300 nm-450 nm.…”

Section: Measurement Of Vibrational and Rotational Temperatures By Th...mentioning

confidence: 99%

“…In this study, vibrational transitions of the second positive system Δv = −2 and −3 were employed for determining vibrational and rotational temperatures, which respectively appear in the wavelength regions: 370-382 nm and 392-410 nm. According to an earlier report [24], the wavelength that those transitions appear can be determined by the energy difference between electronic states C 3 Πu (v', J') and B 3 Πg (v", J"). Here, v and J respectively denote vibrational and rotational quantum numbers.…”

Section: Measurement Of Vibrational and Rotational Temperatures By Th...mentioning

confidence: 99%

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Optical emission spectroscopy of non-equilibrium microwave plasma torch sustained by focused radiation of gyrotron at 24 GHz

Sintsov

Tabata

Mansfeld

et al. 2020

J. Phys. D: Appl. Phys.

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The electron and gas temperature of non-equilibrium argon plasma torch sustained by a focused 24 GHz microwave beam in the external atmosphere of air was measured by optical emission spectroscopy. The excitation temperature of argon atoms was found about 5000 K, while the vibrational and rotational temperatures of ambient nitrogen molecules were respectively estimated at 3000 K and 2000 K. The effective mixing of the external gas atmosphere into the plasma torch is experimentally demonstrated. The vibrational and rotational temperatures of nitrogen molecules slightly increased with the distance from the nozzle exit. Experimental results demonstrate that microwave discharge at atmospheric pressure may be relevant for the decomposition of highly stable molecules, e.g. carbon dioxide, in non-equilibrium conditions.

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Section: Measurement Of Vibrational and Rotational Temperatures By Th...mentioning

confidence: 99%

Section: Measurement Of Vibrational and Rotational Temperatures By Th...mentioning

confidence: 99%

Optical emission spectroscopy of non-equilibrium microwave plasma torch sustained by focused radiation of gyrotron at 24 GHz

Sintsov

Tabata

Mansfeld

et al. 2020

J. Phys. D: Appl. Phys.

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“…On the basis of the observations of N 2 + (391.4 nm), N + (NII) ions, and N atoms (NI, 742–747 nm), the following reactions are likely: ,,,,− …”

Section: Resultsmentioning

confidence: 99%

Formation of CN Radical from Nitrogen and Carbon Condensation and from Photodissociation in Femtosecond Laser-Induced Plasmas: Time-Resolved FT-UV–Vis Spectroscopic Study of the Violet Emission of CN Radical

et al. 2020

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Exploring the formation of diatomic radicals in femtosecond plasmas is important to establish the most dominant kinetic pathways following ionization and dissociation of small molecules. In this work, cyano radical formation has been studied from bromoform, acetonitrile, and methanol in nitrogen and argon plasmas created with a focused femtosecond laser beam operating at 100 kHz repetition rate and 1030 nm wavelength with 43 fs pulse length and 250 μJ pulse energy. Time-resolved Fourier transform fluorescence spectroscopy was applied in the ultraviolet−visible (UV−vis) spectral range for the characterization of the rotational and vibrational temperatures of the CN(B) radicals via fitting the experimental data. The high repetition rate of the laser allows efficient coupling with the step-scan Fourier transform spectroscopy method. Coulomb explosion at the very high intensity (∼10 16 W/cm 2 ) resulted in the formation of nascent atoms, ions, and electrons. The condensation reactions of carbon and reactive nitrogen species resulted in the formation of CN(B 2 Σ + ) radicals and C 2 (d 3 Π g ) dicarbon molecules/radicals. The CN(B) radicals were formed at the highest concentration in the case of bromoform because the weak carbon−bromine bonds resulted in reactive carbon atoms and CH radicals, which are reactive precursors for the CN(B) radical formation. In the case of acetonitrile, immediate production of CN(B) is observed with nanosecond resolution, which suggests that the CN is formed either via photodetachment or via roaming reaction associated with the Coulomb explosion of the parent molecule. The nascent rotational temperature was very high (∼6000−8500 K) and rapidly decreased in all instances within 40 ns with bromoform and acetonitrile. The highest vibrational temperature (∼7800 K) was observed in an acetonitrile/Ar mixture that decreased in about 30 ns and then increased in the observed time window. The vibrational temperature increased in all samples between 30 and 200 ns. The time dependence of fluorescence is described with a monoexponential decay in the case of acetonitrile/Ar and with biexponential decays in all other instances in the 0−250 mbar total pressure range. The shorter time constant is close to the radiative lifetime of CN(B) emission (∼60−80 ns), which can be attributed to the CN(B) radicals produced in the first few collisions at lower pressures. The longer CN(B) emission is from CN(B) created by slower chemical reactions involving carbon atoms, C 2 radicals, and reactive nitrogen-containing species.

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“…Like calculations of rate coefficients of electron collision processes, the reactions with bidirectional arrows are treated not only with the forward reaction but also with the reversal one, whose rate coefficient is calculated with the equation of the detailed balance [5]. The reversal rate coefficient can be calculated with the equilibrium constant of the reaction, which is obtained from the partition function of the molecules involved [5,10]. Table 2: List of atomic and molecular collision processes considered in the calculation of number densities of excited states in Eq.…”

Section: Numerical Modeling Of Chemical Kinetics Of Excited Species Imentioning

confidence: 99%

“…6), we considered the collisions described in Table 3. When we solve the Boltzmann equation for the oxygen plasma, we do not include the superelastic collisions with vibrationally excited species of O 2 molecule, which is quite different from the analysis of nitrogen plasma [5,6,[10][11][12], because vibrational kinetics of O 2 molecules is not so essential for the formation of EEPF of the O 2 plasma [4]. …”

Section: No Heavy Species Collision Reactions Referencementioning

confidence: 99%

Excitation Kinetics of Oxygen O(1D) State in Low-Pressure Oxygen Plasma and the Effect of Electron Energy Distribution Function

Konno

Nezu

Matsuura

et al. 2017

Journal of Advanced Oxidation Technologies

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Abstract:We develop numerical model to discuss the number density and excitation kinetics of O( 1 D) state in lowpressure discharge oxygen plasma. The governing equations are the Boltzmann equation to describe the electron energy distribution function and the rate equations of the relevant excited states. We have calculated them back and forth until self-consistent solution is obtained. When the rate coefficient of the electron impact dissociation of O 2 to O( 3 P) and O( 1 D) atoms is assumed to be functions of electron temperature T e with Maxwellian electron energy distribution, the obtained results are found to be inappropriate. When the rate coefficients are written as functions of electron energy distribution function, satisfactory results are obtained as number density distribution of excited states. We also experimentally examined and confirmed the validity of the model by actinometry measurement for number density of the O( 3 P) state. It is found that we should consider the electron energy distribution function in describing the excitation kinetics of O( 1 D) state in low-pressure oxygen plasma.

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Progresses in Experimental Study of N2 Plasma Diagnostics by Optical Emission Spectroscopy

Cited by 17 publications

References 20 publications

Optical emission spectroscopy of non-equilibrium microwave plasma torch sustained by focused radiation of gyrotron at 24 GHz

Optical emission spectroscopy of non-equilibrium microwave plasma torch sustained by focused radiation of gyrotron at 24 GHz

Formation of CN Radical from Nitrogen and Carbon Condensation and from Photodissociation in Femtosecond Laser-Induced Plasmas: Time-Resolved FT-UV–Vis Spectroscopic Study of the Violet Emission of CN Radical

Excitation Kinetics of Oxygen O(1D) State in Low-Pressure Oxygen Plasma and the Effect of Electron Energy Distribution Function

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