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We have had obtained the temperature of a cold hollow cathode electric discharge (HCED) plasma by fitting the experimental rotational spectra of the vibrational-rotational N2 first negative system (FNS) and of second positive system (SPS) sequences, with the simulate spectra of the same plasma. With the accordance of the rotational temperature from...
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... the Fig. 1 we can see a nitrogen spectra from the molecular nitrogen HCED, containing the FNS and SPS bands. Because the rotational structure of the vibrational bands in our conditions can't be resolved, the Boltzmann method for temperature determination is not possible. The rotational temperature was determined by the fit of some vibrational ...
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... The dominant N 2 -band spectrum shows that RDBD was mainly discharged by nitrogen molecules. The rotational and vibrational temperatures were calculated via the spectrum-fittin method using the experimental spectrum of nitrogen molecules (337 nm), which was ob tained from a fitted Boltzmann plot [22,23]. The rotational and vibrational temperature were measured to be 342 K and 2860 K, respectively (see Supplementary Figure S1). ...
... Th gas FTIR and 0D chemical simulation results are shown in Figure 3. In the FTIR spectros The rotational and vibrational temperatures were calculated via the spectrum-fitting method using the experimental spectrum of nitrogen molecules (337 nm), which was obtained from a fitted Boltzmann plot [22,23]. The rotational and vibrational temperatures were measured to be 342 K and 2860 K, respectively (see Supplementary Figure S1). ...
We investigated the characteristics of a rollable dielectric barrier discharge (RDBD) and evaluate its effects on seed germination rate and water uptake. The RDBD source was composed of a polyimide substrate and copper electrode, and it was mounted in a rolled-up structure for omnidirectional and uniform treatment of seeds with flowing synthetic air gas. The rotational and vibrational temperatures were measured to be 342 K and 2860 K, respectively, using optical emission spectroscopy. The chemical species analysis via Fourier-transform infrared spectroscopy and 0D chemical simulation showed that O3 production was dominant and NOx production was restrained at the given temperatures. The water uptake and germination rate of spinach seeds by 5 min treatment of RDBD was increased by 10% and 15%, respectively, and the standard error of germination was reduced by 4% in comparison with the controls. RDBD enables an important step forward in non-thermal atmospheric-pressure plasma agriculture for omnidirectional seed treatment.
... In the spectra through water we can observe OH system, argon atomic lines, strong emissions from NH system (A3Π + → X3Σ, 336 nm) and weak bands of second order of OH molecular band (610-630 nm) and Hα line (656 nm), while the OH and NH bands are missing from the spectrum through air. The gas temperature was estimated from the rotational temperature of OH molecular species present in the discharge [39]. The T rot was calculated using the intensities, wavelengths, Honl-London factors and energies of excited states of particular selection of OH lines. ...
New efficient depollution techniques for water decontamination, purification and disinfection are being sought to replace those classic methods (chemical, filtration, ozonisation, photochemical reactions) that have deficiency for some substances. The use of plasma technologies, discharges in, or in contact with, wastewater are promising approaches for the decomposition of pollutants by highly oxidative radicals, charged particles, UV radiation, etc. produced by plasma. In the present study we report on the potential of radiofrequency single and multiple filamentary Dielectric Barrier Discharge (DBD) jets for the decolorization of methylene blue (MB) dye in water solutions. Optical emission spectroscopy (OES) investigations were performed for the characterization of plasma evolving in air, and in liquid. The decolorization process was monitored by absorption spectroscopy. We determined the decolorization time, according to a variety of external parameters. The key parameters for obtaining the maximum decolorization rate were identified as being the discharge tube diameter, tube nature (glass/ceramic), the injected power in the discharge, the type of reactive gas and the number of filamentary plasma jets.
... Die meisten Rotations-und Vibrationstemperaturbestimmungen basieren auf der Intensitätsgleichung, bei der die Besetzung der Energieniveaus über eine Boltzmann-Verteilung beschrieben wird (siehe Gleichung (110)). In vielen Fällen wurden die Spektren auf Grundlage der zuvor genannten Gleichung berechnet [51,55,[119][120][121][122][123][124][125], andere wiederum nutzen das kommerziell erhältliche Programm Specair [20,[126][127][128][129][130] ...
Published in http://hdl.handle.net/11858/00-1735-0000-002E-E553-0;
There are mainly three discharge types known for the treatment of wood and wooden materials with atmosphere pressure plasmas. These differ significantly in their range of applications. The coplanar surface barrier discharge (CSBD) requires very smooth and planar surfaces, to realise the required discharge distance of below 1mm. It is, however, independent of the strength of the material. The direct dielectric barrier discharge (DDBD) works well on uneven surfaces, but is limited to material strengths in the order of a few centimeters, due to the available voltages. The third variant, called Remote-Plasma (RP) or jet system, is universally applicable and independent of material features. For the latter type, the plasma is ignited further away from the surface, and the plasma species are being directed towards it by a gas stream. So far, investigations on wood and wooden surfaces were mostly performed with single plasma sources. Different setups and power supplies make a comparison of the reported studies difficult. The aim of this work was therefore to provide a comparative analysis of the three different discharge types. To this end, all three plasma sources were realised with the same electrodes and power supply. Furthermore, the same power has been used in all cases. The three discharge types were characterised by comparison of plasma temperatures – rotational, gaseous, vibrational and electron temperature – as well as the reduced electrical field strength. Furthermore, the influence on the surfaces of wood and wooden materials were considered. Also, different methods to measure temperatures via optical emission spectroscopy were compared in terms of their applicability within the used plasma discharges. The temperatures did not show any significant differences depending on the discharge type or the treated material. The calculated electron temperatures are between 49 000K and 64 000K, which corresponds to reduced electrical field strengths between 250Td and 390Td. The vibrational temperature was determined to be (2500 ± 300)K. The rotational temperature, which can be used as approximation for the local gas temperature, lies below 400K. There was a good agreement between the rotational temperatures determined by emission spectroscopy and the gas temperatures measured with an optical fibre thermometer. The surface temperature after a 30 s plasma treatment determined by infrared imaging did not exceed 320K. Treatment with RP did not show any surface temperature increase at all (T = 300K). The influence of different plasma treatments on maple, high density fibreboard (HDF) and wood-plastic-composite (WPC) were investigated considering a change of surface energy, pH, and adhesive strength. In general, CSDB and DDBD showed similar plasma-induced increases of the surface energy and the adhesion strength as well as a decrease of the pH. The magnitude of the effect was material-dependent. Treatment with RP showed slightly reduced changes. An exception to this was one kind of WPC, where the increase of adhesion by the RP treatment was higher than the one caused by the CSBD treatment. In summary, a comparison between different discharge types could be achieved. In this framework, based on similar electrodes and power, the same types of temperatures were determined for all three discharge types, including the error measurement. There were no significant differences between CSDB and DBDD in terms of their effect on surfaces. Surface modifications with RP were in general slightly diminished, with exception of one kind of WPC.
... Through the degree of Doppler broadening the translational temperature can be determined [98], [99]. The N 2 s positive system can also be adopted to estimate the gas temperature, according to the study of M. Bazavan et al. [100], the electron temperature is generally much greater than the gas temperature, while the rotational temperature is equal with the gas temperature. Therefore, by modeling the N 2 emission spectra of the molecular rotational bands belong to the N 2s positive system, the rotational temperature in the microplasma can be obtained [100]. ...
... The N 2 s positive system can also be adopted to estimate the gas temperature, according to the study of M. Bazavan et al. [100], the electron temperature is generally much greater than the gas temperature, while the rotational temperature is equal with the gas temperature. Therefore, by modeling the N 2 emission spectra of the molecular rotational bands belong to the N 2s positive system, the rotational temperature in the microplasma can be obtained [100]. ...
Plasma technology has been widely applied in the ozone production, material modification, gas/water cleaning, etc. Various nanomaterials were produced by thermal plasma technology. However, the high temperature process and low uniformity products limit their application for the high value added chemicals synthesis, for example the functional materials or the temperature sensitive materials. Microplasma has attracted significant attentions from various fields owing to its unique characteristics, like the high-pressure operation, non-equilibrium chemistry, continuous-flow, microscale geometry and self-organization phenomenon. Its application on the functional nanomaterial synthesis was elaborately discussed in this review paper. Firstly, the main physical parameters were reviewed, which include the electron temperature, electron energy distribution function, electron density and the gas temperature. Then four representative microplasma configurations were categorized, and the proper selection of configuration was summarized in light of different conditions. Finally the synthesis, mechanism and application of some typical nanomaterials were introduced.
... La raie globale de la planète, obtenue en sommant toutes les contributions des différentes lignes de visée selon la méthode citée précédemment est présentée Fig. 4. 10. On peut voir que la raie est large : ceci est dû au scaling, qui fait que l'on a une quantité totale d'hydrogène très importante dans l'atmosphère. ...
... Concernant le flux EUV, il s'agit de la même paramétrisation que précédemment, à savoir que nous avons utilisé le flux de Torr & Torr (1985) [136] pour un « soleil moyen » caractérisé par un f 10 [145]. La raie Lyman Alpha a été mulitpliée par un facteur 100 (dans le cas de l'atmosphère de CO 2 ) pour tenir compte des variations de l'émission solaire au cours du temps [105]. ...
... Le spectre ainsi obtenu est présenté figure 7. 10. Il s'agit du spectre corrigé uniquement de la réponse du CCD (étant données les incertitudes concernant l'absorption par les éléments optiques). ...
Since the discovery of the first exoplanet in 1995 by Mayor and Queloz, the number of extrasolar planets discovered has continuously grown up, to overtake 1000 planets at the end of 2013. Since the beginning of the 2000's, came with the detection the will to characterize the atmospheres of these exoplanets. Until now, the methods used are the primary transit spectroscopy and the study of the thermal emissions in secondary transit or using phase curves. The purpose of this thesis belongs to that search for characterizing exoplanetary atmospheres, by looking at a method unexplored until now: the study of the thermospheric emissions, i.e. emissions from the upper atmosphere induced by the energetic entries, mainly the extreme UV flux and the electronic precipitations. The first part of this thesis concerns the thermospheric emissions of the primitive Earth with an approach based on modeling. The goal is the determination of the several emissions of the Earth through its history in order to have proxies for the search and the characterization of telluric exoplanets. Initially we calculated the emission of the primary atmosphere of the early Earth under the young Sun in the Lyman Alpha line. We showed that the planetary line in mainly due to coherent diffusion and that the emission ratio between the planet and the Sun in this line is of about 10-8, far from the capabilities of current or next generation instruments. This first result lead us to study the feasibility of an indirect method to infer the presence of dense hydrogen corona surrounding a telluric planet with a CO2-dominated atmosphere, by studying its influence on the emissions of two CO2 by-products. The calculations carried out on the oxygen green line (O1S state) and the UV doublet of CO2+ (B2Σu+ state) showed that theses emissions present contrasts of about 10^-12 with the young Sun in the case of a primitive Earth, and of about 10^-6-10^-8 for a close-in telluric planet around a M dwarf. The general conclusion of the investigations is that the thermospheric emissions of thin (atomic or molecular) lines are too weak to be detected. A possible way could be the study of the molecular bands, of which emissions need to be better understood, especially concerning the intensity distribution of the several bands through the spectrum. This comprehension implies experimental studies of these emissions. The second part of this thesis lies in this scope and concerns the spectroscopic analysis of the Planeterrella, an aurora borealis simulator initially designed for outreach purpose. We made a spectroscopic study at low and high resolution with air, in order to characterize the emissions existing in the experiment, and also to have a reference spectrum which will be a final test for a Monte Carlo code developed to study the experimental device, the characterization of this device being a necessary step for the Planeterrella to become suitable for scientific purpose. Finally, we made a low resolution spectroscopic study of carbon dioxide, with potential applications to Mars.
... were fitted using the procedure discussed at length by Iova [25].Fig. 2 shows an example of experimental (dotted) and synthetic (solid) spectra for the FNS and the SPS systems generated using this procedure. The calculated and experimental spectra are in good agreement with each other. ...
In the present report we compare two types of atmospheric pressure radiofrequency cold plasma sources based on different discharge systems in terms of their spectral properties and the induced modification of the surface properties of various polymeric materials (PET and PE).
Flashover on the surface of dielectric materials often causes extensive damage to the insulation system, resulting in reduced withstand voltage and system downtime as the damaged component is located and replaced. Therefore, understanding the flashover mechanism on dielectrics is of great significance to reduce incidences. In this work, the change in gas temperature in an impulse surface discharge during streamer-to-leader transition was measured in atmospheric air by the spectroscopic method. In the experiment, a quartz glass having a conductive indium tin oxide-coated back-surface was used as an insulation material having a back electrode. As a result, the increase in gas temperature in a discharge channel was confirmed when the discharge phase transformed into a leader.
A reactive nitrogen-aluminum plasma generated by electron cyclotron resonance (ECR) microwave discharge of N2 gas and pulsed laser ablation of an Al target is characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy (OES). The vibrational and rotational temperatures of N2 species are determined by spectral simulation. The generated plasma strongly emits radiation from a variety of excited species including ambient nitrogen and ablated aluminum and exhibits unique features in optical emission and temperature evolution compared with the plasmas generated by a pure ECR discharge or by the expansion of the ablation plume. The working N2 gas is first excited by ECR discharge and the excitation of nitrogen is further enhanced due to the fast expansion of the aluminum plume induced by target ablation, while the excitation of the ablated aluminum is prolonged during the plume expansion in the ECR nitrogen plasma, resulting in the formation of strongly reactive nitrogen-aluminum plasma which contains highly excited species with high vibrational and rotational temperatures. The enhanced intensities and the prolonged duration of the optical emissions of the combined plasma would provide an improved analytical capability for spectrochemical analysis.
Measurements with a rf compensated Langmuir probe and optical emission spectroscopy are carried out in capacitively coupled rf (13.56 MHz) pure nitrogen N 2 discharges at fixed rf voltage over a wide range of pressure, 30 to 400 mTorr. The electron energy probability function (EEPF) measured below 100 mTorr resembles a bi-Maxwellian-type distribution. At pressure range of 100-200 mTorr, the EEPF has non-Maxwellian distribution with a dip near 4.5 eV. At the highest pressure of 400 mTorr, the EEPF evolves into a Druyvestein-like distribution and the dip disappears. The electron density significantly decreases with increase in the N 2 pressure. On the other hand, the electron temperatures gradually decrease with an increase in N 2 pressure, reaching minimum at 150 mTorr, beyond which it abruptly increases. Such evolution of the EEPFs shape with gas pressure has been discussed in terms of non-local electron kinetics and heating mode transition. The emission intensities of nitrogen (0-0) band of second positive system at 337.1 nm and (0-0) band of first negative systems at 391.4 nm are used to determine the dependence of their radiative states N 2 (C 3 u) and N 2 + (B 2 u +) with nitrogen pressure. It is observed that the pressure influences the radiative states differently owing to their different populating mechanisms. The vibrational temperature T ib and rotational temperature T rot are measured for the sequence ( = - 2) of N 2 second positive system (C 3 → B 3 g) using the method of comparing the measured and calculated spectra with a chi-squared minimization procedure. It was found that both T ib and T rot have similar dependences with N 2 pressure; peaked at 100 mTorr beyond which it monotonically decreases with increase in the N 2 pressure. The correlation between the observed maximum value of T ib around 100 mTorr and the detected dip in the EEPF in the same pressure range has been discussed.
