Nitric oxide kinetics in the afterglow of a diffuse plasma filament

Burnette, David; Montello, Aaron; Adamovich, Igor V.; Lempert, Walter R.

doi:10.1088/0963-0252/23/4/045007

Cited by 42 publications

(100 citation statements)

References 29 publications

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“…Time-resolved rotational-translational temperature after the discharge pulse in nitrogen and in 10% CO 2 -N 2 mixture at 100 Torr, inferred from the CARS spectra. vibrational level populations measured in our previous work [21], providing confidence in the model predictions. Adding 10% CO 2 to air results in rapid N 2 relaxation, on the time scale t = 50-200 µs (see figure 10), similar to the results in CO 2 -N 2 plotted in figure 8.…”

Section: Diffuse Filament Nanosecond Pulse Dischargesupporting

confidence: 73%

Control of vibrational distribution functions in nonequilibrium molecular plasmas and high-speed flows

Frederickson

Hung

Lempert

et al. 2016

Plasma Sources Sci. Technol.

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The control of the vibrational distribution of nitrogen by energy transfer to CO 2 is studied in two closely related experiments. In the first experiment, the time-resolved N 2 (v = 0-3) vibrational level populations and temperature in the afterglow of a diffuse filament nanosecond pulse discharge are measured using broadband coherent anti-Stokes Raman spectroscopy. The rotational-translational temperature in the afterglow is inferred from the partially rotationally resolved structure of the N 2 (v = 0) band. The measurements are performed in nitrogen, dry air, and their mixtures with CO 2. N 2 vibrational excitation in the discharge occurs by electron impact, with subsequent vibration-vibration (V-V) energy transfer within the N 2 vibrational manifold, vibration-translation (V-T) relaxation, and near-resonance V-V′ energy transfer from the N 2 to CO 2 asymmetric stretch vibrational mode. The results show that rapid V-V′ energy transfer to CO 2 , followed by collisional intramolecular energy redistribution to the symmetric stretch and bending modes of CO 2 and their V-T relaxation, accelerate the net rate of energy thermalization and temperature increase in the afterglow. In the second experiment, injection of CO 2 into a supersonic flow of vibrationally excited nitrogen demonstrates the effect of accelerated vibrational relaxation on a supersonic shear layer. The nitrogen flow is vibrationally excited in a repetitive nanosecond pulse/DC sustainer electric discharge in the plenum of a nonequilibrium flow supersonic wind tunnel. A transient pressure increase as well as an upward displacement of the shear layer between the supersonic N 2 flow and the subsonic CO 2 injection flow are detected when the source of N 2 vibrational excitation is turned on. CO 2 injection leads to the reduction of the N 2 vibrational temperature in the shear layer, demonstrating that its displacement is caused by accelerated N 2 vibrational relaxation by CO 2 , which produces a static temperature and a pressure increase in the test section. This demonstrates the significant potential of accelerated vibrational relaxation for nonequilibrium flow control, by injection of rapid 'relaxer' species at a desired location, resulting in the rapid thermalization of vibrational energy in nitrogen and air flows, and producing a significant effect on the flow field.

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Section: Diffuse Filament Nanosecond Pulse Dischargesupporting

confidence: 73%

Control of vibrational distribution functions in nonequilibrium molecular plasmas and high-speed flows

Frederickson

Hung

Lempert

et al. 2016

Plasma Sources Sci. Technol.

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“…Development of this mechanism has been made possible by measurements of time-resolved temperature, N 2 vibrational temperature, N 2 vibrational level populations, absolute number densities of key atomic and radical species, N, O, NO and OH, and ignition temperature in plane-to-plane and point-to-point nanosecond pulse discharges in air, H 2 -air and hydrocarbon-air mixtures [3][4][5][6][7][8][9][10][11][12][13]. The present kinetic mechanism is intended as a starting point for its further development and validation, and expanding the range of its applicability, as additional experimental results become available.…”

Section: Introductionmentioning

confidence: 99%

Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas

Adamovich

Lempert

2015

Phil. Trans. R. Soc. A.

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This work describes the kinetic mechanism of coupled molecular energy transfer and chemical reactions in low-temperature air, H 2 –air and hydrocarbon–air plasmas sustained by nanosecond pulse discharges (single-pulse or repetitive pulse burst). The model incorporates electron impact processes, state-specific N 2 vibrational energy transfer, reactions of excited electronic species of N 2 , O 2 , N and O, and ‘conventional’ chemical reactions (Konnov mechanism). Effects of diffusion and conduction heat transfer, energy coupled to the cathode layer and gasdynamic compression/expansion are incorporated as quasi-zero-dimensional corrections. The model is exercised using a combination of freeware (Bolsig+) and commercial software (ChemKin-Pro). The model predictions are validated using time-resolved measurements of temperature and N 2 vibrational level populations in nanosecond pulse discharges in air in plane-to-plane and sphere-to-sphere geometry; temperature and OH number density after nanosecond pulse burst discharges in lean H 2 –air, CH 4 –air and C 2 H 4 –air mixtures; and temperature after the nanosecond pulse discharge burst during plasma-assisted ignition of lean H 2 -mixtures, showing good agreement with the data. The model predictions for OH number density in lean C 3 H 8 –air mixtures differ from the experimental results, over-predicting its absolute value and failing to predict transient OH rise and decay after the discharge burst. The agreement with the data for C 3 H 8 –air is improved considerably if a different conventional hydrocarbon chemistry reaction set (LLNL methane– n -butane flame mechanism) is used. The results of mechanism validation demonstrate its applicability for analysis of plasma chemical oxidation and ignition of low-temperature H 2 –air, CH 4 –air and C 2 H 4 –air mixtures using nanosecond pulse discharges. Kinetic modelling of low-temperature plasma excited propane–air mixtures demonstrates the need for development of a more accurate ‘conventional’ chemistry mechanism.

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“…To characterize the ensuing plasma and chemical processes in repetitively pulsed nanosecond discharges (for example, the radicals [5] and excited species [6] production, energy deposition and gas heating) [7,8], it is important to understand the initial breakdown process [9] which, at moderate pressures, is usually in the form of a fast ionization wave (FIW) [10]. FIWs are produced and propagate when the discharge is over-voltaged by hundreds of percent.…”

Section: Introductionmentioning

confidence: 99%

Investigation of capillary nanosecond discharges in air at moderate pressure: comparison of experiments and 2D numerical modelling

Klochko¹,

Starikovskaia²,

Xiong³

et al. 2014

J. Phys. D: Appl. Phys.

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Nanosecond electrical discharges in the form of ionization waves are of interest for rapidly ionizing and exciting complex gas mixtures to initiate chemical reactions. Operating with a small discharge tube diameter can significantly increase the specific energy deposition and so enable optimization of the initiation process. Analysis of the uniformity of energy release in small diameter capillary tubes will aid in this optimization. In this paper, results for the experimentally derived characteristics of nanosecond capillary discharges in air at moderate pressure are presented and compared with results from a two-dimensional model. The quartz capillary tube, having inner and outer diameters of 1.5 and 3.4 mm, is about 80 mm long and filled with synthetic dry air at 27 mbar. The capillary tube with two electrodes at the ends is inserted into a break of the central wire of a long coaxial cable. A metal screen around the tube is connected to the cable ground shield. The discharge is driven by a 19 kV 35 ns voltage pulse applied to the powered electrode. The experimental measurements are conducted primarily by using a calibrated capacitive probe and back current shunts. The numerical modelling focuses on the fast ionization wave (FIW) and the plasma properties in the immediate afterglow after the conductive plasma channel has been established between the two electrodes. The FIW produces a highly focused region of electric field on the tube axis that sustains the ionization wave that eventually bridges the electrode gap. Results from the model predict FIW propagation speed and current rise time that agree with the experiment.

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Nitric oxide kinetics in the afterglow of a diffuse plasma filament

Cited by 42 publications

References 29 publications

Control of vibrational distribution functions in nonequilibrium molecular plasmas and high-speed flows

Control of vibrational distribution functions in nonequilibrium molecular plasmas and high-speed flows

Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas

Investigation of capillary nanosecond discharges in air at moderate pressure: comparison of experiments and 2D numerical modelling

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