Laser-induced fluorescence measurements of a

Excitation of carbon monoxide molecules has been carried out in a cold cell and in a low-pressure plasma jet using an ArF narrow-band excimer laser. The different excitation models are discussed and the relevance of atomic carbon absorption into the laser cavities is pointed out. Excitation spectra of Cameron bands have been obtained in a room-temperature cell and compared with calculated spectra. A value of the constant σ related to the interaction strength between $a^3\Pi (v=2)$ state and its neighbouring singlet states is derived: $0\le \sigma \le 0.05$. The fluorescence spectrum following broad band excitation of CO has been observed both in UV and visible. Similar experiments carried out in a high enthalpy flow have allowed to point out the presence of $a^3\Pi$ metastable carbon monoxide. A method for relative measurements of this species concentration is proposed

CN spectroscopy and physico–chemistry in the boundary layer of a C/SiC tile in a low pressure nitrogen/carbon dioxide plasma flow

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Laser-induced fluorescence measurements of a3Π metastable carbon monoxide in a high enthalpy flow

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NO excitation and thermal non-equilibrium within a flat plate boundary layer in an air plasma

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Demonstration of NO production in air plasmametallic surface interaction by broadband laser-induced fluorescence

International audienceThis paper deals high temperature chemistry of air in interaction with a metallic surface. A subsonic air plasma is created with an inductive torch and is investigated using broadband KrF laser-induced fluorescence. Nitrogen monoxide fluorescence spectra are recorded in the free subsonic plasma jet as well as within the boundary layer above a stainless steel flat plate water-cooled to 300 K. The comparison between calculated and experimental calibrated fluorescence spectra allows the determination of rotational and vibrational temperatures as well as densities of NO ground state. The results demonstrates a strong non-equilibrium between rotational and vibrational temperatures in both the free jet and the boundary layer including very close to the wall. Density determinations show that nitrogen monoxide is in chemical equilibrium on the axis of the free jet but not on its boundaries. The NO results are analyzed together with previous O 2 and N 2 results obtained by Raman spectrosocpy in order to explain the increasing NO densities observed within the boundary layer. The discussion highlights a double production of NO due to catalytic reactions at the wall and to the exothermic reaction N + O 2 −→ NO +O within the boundary layer following O 2 recombination at the wall

Quenching of NO(A Σ2+) state in a nonequilibrium air plasma

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Space and time analysis of the nanosecond scale discharges in atmospheric pressure air: I. Gas temperature and vibrational distribution function of N-2 and O-2

WOS:000332761800005International audienceReliable experimental data on nanosecond discharge plasmas in air become more and more crucial considering their interest in a wide field of applications. However, the investigations on such nonequilibrium plasmas are made difficult by the spatial non-homogeneities, in particular under atmospheric pressure, the wide range of time scales, and the complexity of multi-physics processes involved therein. In this study, we report spatiotemporal experimental analysis on the gas temperature and the vibrational excitation of N-2 and O-2 in their ground electronic state during the post-discharge of an overvoltage nanosecond-pulsed discharge generated in a pin-to-plane gap of air at atmospheric pressure. The gas temperature during the pulsed discharge is measured by optical emission spectroscopy related to the rotational bands of the 0-0 vibrational transition N-2(C-3 Pi(u), nu = 0) -\textgreater N-2 (B-3 Pi(g), nu = 0) of nitrogen. The results show a rapid gas heating up to 700 K in tens of nanoseconds after the current rise. This fast gas heating leads to a high gas temperature up to 1000 K measured at 150 ns in the first stages of the post-discharge using spontaneous Raman scattering (SRS). The spatiotemporal measurements of the gas temperature and the vibrational distribution function of N-2 and O-2, also obtained by SRS, over the post-discharge show the spatial expansion of the high vibrational excitation of N-2, and the gas heating during the post-discharge. The present measurements, focused on thermal and energetic aspect of the discharge, provide a base for spatiotemporal analysis of gas number densities of N-2, O-2 and O atoms and hydrodynamic effects achieved during the post-discharge in part II of this investigation. All these results provide space and time database for the validation of plasma chemical models for nanosecond-pulsed discharges at atmospheric pressure air

Recombination coefficient of atomic oxygen on ceramic materials in a CO2 plasma flow for the simulation of a Martian entry

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Recombination of atomic oxygen on α-Al2O3 at high temperature under air microwave-induced plasma

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