Thermodynamic and transport properties in equilibrium air plasmas in a wide pressure and temperature range

D’Angola, A.; Colonna, G.; Gorse, C.; Capitelli, M.

doi:10.1140/epjd/e2007-00305-4

Cited by 193 publications

(109 citation statements)

References 56 publications

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“…In a more general case, the contribution for Ä T , coming from the chemical reactions in the plasma, depends on pressure and gas composition. The general description of all components of the thermal conductivity in the nonequilibrium case [e.g., Chen and Li, 2003;Nemchinsky, 2005;D'Angola et al, 2008] is beyond the scope of the present work. We also introduce a simplified version of the thermal conductivity Ä ** T = 19k B v /4m air , where m air = amb /N amb is the average mass of an air molecule.…”

Section: Gas Dynamicsmentioning

confidence: 99%

Dynamics of streamer‐to‐leader transition at reduced air densities and its implications for propagation of lightning leaders and gigantic jets

2013

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[1] In this paper we present modeling studies of air heating by electrical discharges in a wide range of pressures. The developed model is capable of quantifying the different contributions for heating of air at the particle level and rigorously accounts for the vibration-dissociation-vibration coupling. The model is validated by calculating the breakdown times of short air gaps and comparing to available experimental data. Detailed discussion on the role of electron detachment in the development of the thermal-ionizational instability that triggers the spark development in short air gaps is presented. The dynamics of fast heating by quenching of excited electronic states is discussed and the scaling of its main channels with ambient air density is quantified. The developed model is employed to study the streamer-to-leader transition process and to obtain its scaling with ambient air density. Streamer-to-leader transition is the name given to a sequence of events occurring in a thin plasma channel through which a relatively strong current is forced through, culminating in heating of ambient gas and increase of the electrical conductivity of the channel. This process occurs during the inception of leaders (from sharp metallic structures, from hydrometeors inside the thundercloud, or in virgin air) and during their propagation (at the leader head or during the growth of a space leader). The development of a thermal-ionizational instability that culminates in the leader formation and propagation is characterized by a change in air ionization mechanism from electron impact to associative ionization and by contraction of the plasma channel. The introduced methodology for estimation of leader speeds shows that the propagation of a leader is limited by the air heating of every newly formed leader section. It is demonstrated that the streamer-to-leader transition time has an inverse-squared dependence on the ambient air density at near-ground pressures, in agreement with similarity laws for Joule heating in a streamer channel. Model results indicate that a deviation from this similarity scaling occurs at very low air densities, where the rate of electronic power deposition is balanced by the channel expansion, and air heating from quenching of excited electronic states is very inefficient. These findings place a limit on the maximum altitude at which a hot and highly conducting lightning leader channel can be formed in the Earth's atmosphere, result which is important for understating of the gigantic jet (GJ) discharges between thundercloud tops and the lower ionosphere. Simulations of leader speeds at GJ altitudes demonstrate that initial speeds of GJs are consistent with the leader propagation mechanism. The simulation of a GJ, escaping upward from a thundercloud top, shows that the lengthening of the leader streamer zone, in a medium of exponentially decreasing air density, determines the existence of an altitude at which the streamer zones of GJs become so long that they dynamically extend (jump) all the way to th...

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Section: Gas Dynamicsmentioning

confidence: 99%

Dynamics of streamer‐to‐leader transition at reduced air densities and its implications for propagation of lightning leaders and gigantic jets

2013

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“…The study was carried out for an arc discharge operating with air. The properties data have been taken from [35] for enthalpy, density, specific heat, electrical conductivity, dynamic viscosity and thermal conductivity. For the source radiation, the net emission coefficients have been taken from [36].…”

Section: B Governing Equationsmentioning

confidence: 99%

Three-Dimensional Unsteady MHD Modeling of a Low-Current High-Voltage Nontransferred DC Plasma Torch Operating With Air

Lebouvier

Delalondre²,

Fresnet

et al. 2011

IEEE Trans. Plasma Sci.

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“…The effects of non-ideality on transport properties have been investigated in the frame of the Chapman-Enskog theory [70,71], assuming the collision integrals for e-H interaction unaffected, while charged-particle interactions modeled with accurate Debye-length-dependent collision integrals by Mason [72,73], recently fitted in a wide temperature range in [74]. The electrical conductivity of Debye plasma (Figure 10c) exhibits a dependence on the total electron density that is affected by the pressure ionization, i.e., the minimum behavior of the conductivity and the Mott transition, merging to the fully-ionized regime.…”

Section: Thermodynamic and Transport Of High-density Hydrogen Plasmamentioning

confidence: 99%

Elementary Processes and Kinetic Modeling for Hydrogen and Helium Plasmas

Celiberto

Capitelli

Colonna

et al. 2017

Atoms

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Abstract:We report cross-sections and rate coefficients for excited states colliding with electrons, heavy particles and walls useful for the description of H 2 /He plasma kinetics under different conditions. In particular, the role of the rotational states in resonant vibrational excitations of the H 2 molecule by electron impact and the calculation of the related cross-sections are illustrated. The theoretical determination of the cross-section for the rovibrational energy exchange and dissociation of H 2 molecule, induced by He atom impact, by using the quasi-classical trajectory method is discussed. Recombination probabilities of H atoms on tungsten and graphite, relevant for the determination of the nascent vibrational distribution, are also presented. An example of a state-to-state plasma kinetic model for the description of shock waves operating in H 2 and He-H 2 mixtures is presented, emphasizing also the role of electronically-excited states in affecting the electron energy distribution function of free electrons. Finally, the thermodynamic properties and the electrical conductivity of non-ideal, high-density hydrogen plasma are finally discussed, in particular focusing on the pressure ionization phenomenon in high-pressure high-temperature plasmas.

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Thermodynamic and transport properties in equilibrium air plasmas in a wide pressure and temperature range

Cited by 193 publications

References 56 publications

Dynamics of streamer‐to‐leader transition at reduced air densities and its implications for propagation of lightning leaders and gigantic jets

Dynamics of streamer‐to‐leader transition at reduced air densities and its implications for propagation of lightning leaders and gigantic jets

Three-Dimensional Unsteady MHD Modeling of a Low-Current High-Voltage Nontransferred DC Plasma Torch Operating With Air

Elementary Processes and Kinetic Modeling for Hydrogen and Helium Plasmas

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