The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hong Qin - One of the best experts on this subject based on the ideXlab platform.
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topological phases and bulk edge correspondence of magnetized Cold Plasmas
Nature Communications, 2021Co-Authors: Hong QinAbstract:Plasmas have been recently studied as topological materials. However, a comprehensive picture of topological phases and topological phase transitions in Cold magnetized Plasmas is still missing. Here we systematically map out all the topological phases and establish the bulk-edge correspondence in Cold magnetized Plasmas. We find that for the linear eigenmodes, there are 10 topological phases in the parameter space of density n, magnetic field B, and parallel wavenumber kz, separated by the surfaces of Langmuir wave-L wave resonance, Langmuir wave-cyclotron wave resonance, and zero magnetic field. For fixed B and kz, only the phase transition at the Langmuir wave-cyclotron wave resonance corresponds to edge modes. A sufficient and necessary condition for the existence of this type of edge modes is given and verified by numerical solutions. We demonstrate that edge modes exist not only on a plasma-vacuum interface but also on more general plasma-plasma interfaces. This finding broadens the possible applications of these exotic excitations in space and laboratory Plasmas. Magnetized plasma can be regarded as topological matter. Here the authors identify a necessary and sufficient condition for the existence of topological edge mode and find that Cold magnetized plasma has ten topological phases in the plasma frequency, cyclotron frequency and wave-vector space.
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topological phases and bulk edge correspondence of magnetized Cold Plasmas
arXiv: Plasma Physics, 2020Co-Authors: Hong QinAbstract:Plasmas have been recently studied as topological materials. However, a comprehensive picture of topological phases and topological phase transitions in Cold magnetized Plasmas is still missing. Here we systematically map out all the topological phases and establish the bulk-edge correspondence in Cold magnetized Plasmas. We find that for the linear eigenmodes, there are 10 topological phases in the parameter space of density $n$, magnetic field $B$, and parallel wavenumber $k_{z}$, separated by the surfaces of Langmuir wave-L wave resonance, Langmuir wave-cyclotron wave resonance, and zero magnetic field. For fixed $B$ and $k_{z}$, only the phase transition at the Langmuir wave-cyclotron wave resonance corresponds to edge modes. A sufficient and necessary condition for the existence of this type of edge modes is given and verified by numerical solutions. We demonstrate that edge modes exist not only on a plasma-vacuum interface but also on more general plasma-plasma interfaces. This finding broadens the possible applications of these exotic excitations in space and laboratory Plasmas.
Francesco Fracassi - One of the best experts on this subject based on the ideXlab platform.
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aerosol assisted atmospheric pressure Cold plasma deposition of organic inorganic nanocomposite coatings
Plasma Chemistry and Plasma Processing, 2014Co-Authors: Fiorenza Fanelli, Francesco FracassiAbstract:Low pressure plasma technologies have been widely and successfully utilized for the production of a large variety of organic–inorganic nanocomposite (NC) thin films consisting of metal or metal oxide nanoparticles embedded in a polymer matrix. Recently, the deposition of this class of coatings has been also accomplished by atmospheric pressure Cold Plasmas using aerosol-assisted processes in which a dispersion containing preformed inorganic nanoparticles and the liquid precursor of the polymeric component is atomized and injected in aerosol form in the atmospheric plasma. This short review is aimed at presenting this approach which is expected to enlarge the range of structures and properties of organic–inorganic NC coatings deposited by Cold plasma technologies.
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gc ms investigation of hexamethyldisiloxane oxygen fed Cold Plasmas low pressure versus atmospheric pressure operation
Plasma Processes and Polymers, 2011Co-Authors: Fiorenza Fanelli, Riccardo Dagostino, Francesco FracassiAbstract:This study deals with the investigation by means of gas chromatography-mass spectrometry (GC-MS) of the exhaust gas of an rf low pressure (LP) glow discharge and of an atmospheric pressure (AP) FDBD fed with hexamethyldisiloxane (HMDSO), O2, and Ar. The influence of feed composition on monomer depletion and on the qualitative‐quantitative distribution of stable by-products formed by recombination of plasma intermediates is investigated. Without O2 addition to the feed almost comparable values of HMDSO depletion are observed both at low and AP. Oxygen addition does not influence the monomer depletion at LP while it induces a slight decrease of the depletion at AP. Whatever the working pressure, O2 controls the overall chemistry of the plasma, since it influences the concentration of by-products (e.g., silanes, silanols, linear, and cyclic methylsiloxanes). At AP evidences of the importance of methyl abstraction from HMDSO molecule have been obtained, whileatLPtheprevalence ofSi‐Obondrupture, of fragmentation, and oligomerization reactions is observed. The comparison of results from the GCMS investigation of the exhaust gas with FT-IR spectra of the deposited coatings allows to enhance hypotheses on the formation of silanols in the gas phase and in the deposit.
K Burnett - One of the best experts on this subject based on the ideXlab platform.
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possible production of Cold Plasmas through optical field induced ionization
Physical Review A, 1992Co-Authors: S C Rae, K BurnettAbstract:A one-dimensional model incorporating Maxwell's equations and tunneling ionization is used to predict the plasma temperature after the passage of an intense femtosecond laser pulse through an atmospheric-density noble gas. These calculations are of relevance to a new class of proposed recombination x-ray lasers that use optical-field-induced ionization to generate an initially Cold plasma. The residual plasma temperature is determined under a range of relevant conditions, and is found to be minimized for short laser pulses, short wavelengths, and the lowest intensity consistent with reaching the desired ionization stage. Even under optimum conditions, the predicted temperature is significantly greater than that required for high efficiency in the transient-gain regime.
Mehmet Mutlu - One of the best experts on this subject based on the ideXlab platform.
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quality changes of hazelnut kernels subjected to different Cold Plasmas and gamma irradiation treatments
Lwt - Food Science and Technology, 2019Co-Authors: Baran Onalulusoy, Yasin Sen, Mehmet MutluAbstract:Abstract In this study, physicochemical parameters of hazelnuts after atmospheric-pressure (AP:air, 3000 L/h, 655 W, 25 kHz, 1.7 min) and low-pressure (LP:air, 25 Pa, 100 W, 13.56 MHz, 30 min) Cold Plasmas, and gamma irradiation (GMI:10 kGy, 10 min) treatments, and untreated and treated hazelnuts after accelerated storage for 30 days(60 °C) were investigated. All treatments significantly reduced moisture (26–47%), aw (16–48%), oil (13–15%), soluble phenolic content (SPC; 26–36%) and total tocopherols (TT; 8–38%) compared to untreated hazelnut (Control-1) while no significant changes determined between treatments and Control-1 in terms of L*a*b*, protein, total sugars (TS) and total phenolic compounds. However, TS of all treatments after storage were significantly increased (3.2–33%) while aw (7–27%) and TT (13–31%) of all treatments were significantly decreased compared to both Control-2 and before storage (p
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detoxification of hazelnuts by different Cold Plasmas and gamma irradiation treatments
Innovative Food Science and Emerging Technologies, 2019Co-Authors: Yasin Sen, Baran Onalulusoy, Mehmet MutluAbstract:Abstract The detoxification effects of Cold atmospheric-pressure (AP,3000 L/h of air, 25 kHz, 655 W-1.7 min) and low-pressure (LP,air-100 W-30 min) Plasmas and gamma irradiation(GMI,10 kGy-10 min) treatments on different concentrations of pure aflatoxin B1(AFB1) and AFB1 + B2 (TotAFs) as well as same toxins spiked on hazelnut were investigated. Both Plasmas reduced 72–73% of AFB1 (3 ppb) spiked on hazelnuts while GMI reduced 47% of AFB1. TotAFs (6 ppb) reductions on hazelnut after both Plasmas were 70–71%, which was also higher than that of GMI (15.5%). However, the reductions in pure AFB1 at 1–50 ppb and TotAFs at 1.03–51.5 ppb after GMI (97–100%) were higher than those of AP (55–75%) and LP (69–90%) Plasmas. AP plasma has the potential to be an alternative to conventional detoxification methods because it is both effective on aflatoxins in foods and maintains the sensory attributes of food evaluated by a sensory panel. Industry relevance The use of plasma technology in foods for detoxification purposes is an economic alternative to conventional and other non-thermal processes as well as meeting the industry's demand for sustainable development. This study showed that different Cold Plasmas are capable of reducing the aflatoxins as pure forms as well as in food. The results contributed to the understanding of Cold plasma detoxification effects on aflatoxins and could be a basis for a possible industrial implementation.
Victor J Herrero - One of the best experts on this subject based on the ideXlab platform.
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ionic polymerization in Cold Plasmas of acetylene with ar and he
Journal of Physical Chemistry A, 2019Co-Authors: Miguel Jimenezredondo, Isabel Tanarro, Ramon J Pelaez, Lidia Diazperez, Victor J HerreroAbstract:The ionic polymerization of acetylene in Cold Plasmas of C2H2/He and C2H2/Ar has been experimentally studied and modeled in radio frequency (rf) discharges with conditions selected to avoid particle formation. Steady-state distributions of positive and negative ions were measured with mass spectrometry. All the measured distributions are dominated by ions with an even number of carbon atoms, reflecting the characteristic polyyne structures typical for the polymerization of acetylene. The distributions show a monotonic decrease in intensity from ions with two carbon atoms until the highest number of atoms detected. For cations, the distributions extend until 12 carbon atoms. The anion distributions extend further, and negative ions with 20 C atoms are observed in the C2H2/Ar plasma. From the measured mass spectra it is not possible to decide on the possible presence of aromatic species in ions with more than six carbon atoms. A simple model assuming a homogeneous discharge was used to describe the plasma k...
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ion kinetics in ar h2 Cold Plasmas the relevance of arh
RSC Advances, 2014Co-Authors: Miguel Jimenezredondo, Isabel Tanarro, Maite Cueto, Jose Luis Domenech, Victor J HerreroAbstract:The recent discovery of ArH+ in the interstellar medium has aroused an interest for this ion in chemistry. In this work, the ion-molecule kinetics of Cold Plasmas of Ar/H2 is investigated in glow discharges spanning the whole range of [H2]/([H2] + [Ar]) proportions for two pressures, 1.5 Pa and 8 Pa. Ion concentrations are determined by mass spectrometry, and electron temperatures and densities, with Langmuir probes. A kinetic model is used for the interpretation of the results. The selection of experimental conditions evinces relevant changes with plasma pressure in the ion distributions dependence with the H2 fraction, particularly for the major ions: Ar+, ArH+ and H3+. At 1.5 Pa, ArH+ prevails for a wide interval of H2 fractions: 0.3 0.1. The analysis of the data with the kinetic model allows for the identification of the sources and sinks of the major ions over the whole range of experimental conditions sampled. Two key factors turn out to be responsible for the different ion distributions observed: the electron temperature, which determines the rate of Ar+ formation and thus of ArH+, and the equilibrium ArH+ + H2 ⇄ H3+ + Ar, which can be strongly dependent of the degree of vibrational excitation of H3+. The results are discussed and compared with previously published data on other Ar/H2 Plasmas.
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proton transfer chains in Cold Plasmas of h2 with small amounts of n2 the prevalence of nh4
Physical Chemistry Chemical Physics, 2013Co-Authors: Esther Carrasco, Isabel Tanarro, Victor J Herrero, J CernicharoAbstract:The ion–molecule chemistry of the astronomically relevant H3+, N2H+, and NH4+ ions has been investigated in the weakly ionized Cold Plasmas formed in glow discharges of H2 with small amounts of nitrogen. The concentrations of neutrals and ions were determined by means of mass spectrometry, and electron temperatures and densities were measured using Langmuir probes. A kinetic model was used for the interpretation of the results. The selection of experimental conditions allowed the generation of ion distributions with different relative weights of the mentioned protonated species and the model calculations showed that the observed ion distributions can be explained by the occurrence of a very efficient H3+ → N2H+ → NH4+ proton transfer chain. The NH4+ ion, which is dominant in most of the cases studied, is ultimately derived from the small amount of NH3 produced at the reactor walls. NH4+ tends to be preponderant in the ion distributions even for NH3 density ratios as low as 1%. Due to the high proton affinity of ammonia, this molecule is readily transformed into NH4+ upon collision with H3+ or N2H+. It is conjectured that these results can be extrapolated to most of the small molecules predominant in the interstellar medium, which also have proton affinities lower than that of NH3. The results support the predictions of astrochemical models indicating that NH4+ could be a preponderant ion in some warm environments like hot cores, where NH3 molecules have desorbed from the grains.
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chemistry in low pressure Cold Plasmas ions of astrophysical interest
Plasma Physics and Controlled Fusion, 2012Co-Authors: Esther Carrasco, Miguel Jimenezredondo, Isabel Tanarro, Victor J HerreroAbstract:The ionic chemistry of various hydrogen mixtures (H2/N2, H2/O2, and H2/air) has been studied in low-pressure hollow cathode discharges. The major ions identified in the different discharges , N2H+, H3O+ and have been also found in astronomical observations or predicted in astrochemical models. The relative stability of the protonated ions in the various mixtures has been investigated in detail. In discharges of H2 with small amounts of N2, O2 and air, appreciable amounts of NH3 and H2O were formed at the reactor walls. The preponderance of the protonated ions in these Plasmas was found to be largely dictated by the proton affinity of their respective molecular precursors. Even for small amounts of water and ammonia, proton transfer reactions tend to concentrate the positive charge in H3O+ and, especially, in ions. These results support the predictions of some astrochemical models indicating that these ions could be dominant in warm astronomical environments where H2O and NH3 molecules evaporate from dust grain mantels.
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isotopic exchange processes in Cold Plasmas of h2 d2 mixtures
Physical Chemistry Chemical Physics, 2011Co-Authors: Miguel Jimenezredondo, Victor J Herrero, Esther Carrasco, Isabel TanarroAbstract:Isotope exchange in low pressure Cold Plasmas of H2/D2 mixtures has been investigated by means of mass spectrometric measurements of neutrals and ions, and kinetic model calculations. The measurements, which include also electron temperatures and densities, were performed in a stainless steel hollow cathode reactor for three discharge pressures: 1, 2 and 8 Pa, and for mixture compositions ranging from 100% H2 to 100% D2. The data are analyzed in the light of the model calculations, which are in good global agreement with the experiments. Isotope selective effects are found both in the surface recombination and in the gas-phase ionic chemistry. The dissociation of the fuel gas molecules is followed by wall recycling, which regenerates H2 and D2 and produces HD. Atomic recombination at the wall is found to proceed through an Eley–Rideal mechanism, with a preference for reaction of the adsorbed atoms with gas phase D atoms. The best fit probabilities for Eley–Rideal abstraction with H and D are: γER H = 1.5 × 10−3, γER D = 2.0 × 10−3. Concerning ions, at 1 Pa the diatomic species H2+, D2+ and HD+, formed directly by electron impact, prevail in the distributions, and at 8 Pa, the triatomic ions H3+, H2D+, HD2+ and D3+, produced primarily in reactions of diatomic ions with molecules, dominate the plasma composition. In this higher pressure regime, the formation of the mixed ions H2D+ and HD2+ is favoured in comparison with that of H3+ and D3+, as expected on statistical grounds. The model results predict a very small preference, undetectable within the precision of the measurements, for the generation of triatomic ions with a higher degree of deuteration, which is probably a residual influence at room temperature of the marked zero point energy effects (ZPE), relevant for deuterium fractionation in interstellar space. In contrast, ZPE effects are found to be decisive for the observed distribution of monoatomic ions H+ and D+, even at room temperature. The final H+/D+ ratio is determined to a great extent by proton (and deuteron) exchange, which favours the enhancement of H+ and the concomitant decrease of D+.