Electron and gas temperature dependences of the dissociative recombination coefficient of molecular ions {\rm Ar}_2^+ with electrons

Lukáč, Peter; Mikuš, O.; Morva, I.; Zábudlá, Zuzana; Trnovec, J.; Morvová, Marcela

doi:10.1088/0963-0252/20/5/055012

Cited by 23 publications

(20 citation statements)

References 33 publications

(65 reference statements)

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“…Since it is a very efficient process, it is usually the main channel of charge destruction. Although the rate coefficients have been studied experimentally by many authors [46,53], there is no reliable information concerning its branching ratio. It has been experimentally shown that two dissociation paths are possible: the formation of an atom in ground state and another atom in one of the four states in the 4s electronic configuration or the formation of two atoms in the ground state [54].…”

Section: Dissociative Recombinationmentioning

confidence: 99%

Causes of plasma column contraction in surface-wave-driven discharges in argon at atmospheric pressure

et al. 2018

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In this work we compute the main features of a surface-wave-driven plasma in argon at atmospheric pressure in view of a better understanding of the contraction phenomenon. We include the detailed chemical kinetics dynamics of Ar and solve the mass conservation equations of the relevant neutral excited and charged species. The gas temperature radial profile is calculated by means of the thermal diffusion equation. The electric field radial profile is calculated directly from the numerical solution of the Maxwell equations assuming the surface wave to be propagating in the TM_{00} mode. The problem is considered to be radially symmetrical, the axial variations are neglected, and the equations are solved in a self-consistent fashion. We probe the model results considering three scenarios: (i) the electron energy distribution function (EEDF) is calculated by means of the Boltzmann equation; (ii) the EEDF is considered to be Maxwellian; (iii) the dissociative recombination is excluded from the chemical kinetics dynamics, but the nonequilibrium EEDF is preserved. From this analysis, the dissociative recombination is shown to be the leading mechanism in the constriction of surface-wave plasmas. The results are compared with mass spectrometry measurements of the radial density profile of the ions Ar^{+} and Ar_{2}^{+}. An explanation is proposed for the trends seen by Thomson scattering diagnostics that shows a substantial increase of electron temperature towards the plasma borders where the electron density is small.

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Section: Dissociative Recombinationmentioning

confidence: 99%

Causes of plasma column contraction in surface-wave-driven discharges in argon at atmospheric pressure

et al. 2018

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“…23) Finally, the spatial profile of the total ion density n p ðz; rÞ in Fig. 2 is controlled by the dissociative recombination with the rate constant 5 Â 10 À7 cm 3 s ¹1 , 24) Ar…”

Section: Resultsmentioning

confidence: 99%

Effect of local gas heating on a plasma structure driven at radio frequency in a microcell in Ar at atmospheric pressure

Yamasaki

Yagisawa

Makabe

2014

Jpn. J. Appl. Phys.

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In a microplasma in Ar confined at atmospheric pressure, driven at 13.56 MHz, we theoretically investigate the whole structure of a low-temperature plasma including the local distribution in gas temperature inside and outside a microcell. The governing equation of gas and wall temperature is combined with our original relaxation continuum model of an rf plasma. We demonstrate that electrons with intermediate energy play an important role in plasma production through stepwise ionization and metastable pooling in the presence of high-density metastables. Next, we examine the enhancement of the net ionization rate through the increase in the local reduced field under a broad minimum of the heated gas density. The atmospheric-pressure microcell plasma will be classified into a new spatiotemporal sustaining mechanism in the capacitively coupled plasma at 13.56 MHz. This work predicts the presence of a nonequilibrium, steady plasma in a microcell even at atmospheric pressure in Ar under appropriate conditions.

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“…It is infered that at a low temperature and in the low electron number density region of the arc, molecular ion recombination plays an important role, which leads to the rapid loss of electrons. It is worth noting that the effects of argon molecular ions on the constriction of argon microwavesustained plasma jets have been investigated experimentally [68,69]. It was concluded that the generation and loss of molecular ions have a great influence on the contraction of the discharge.…”

Section: The Chemical Kinetic Processesmentioning

confidence: 99%

Numerical simulation of constricted and diffusive arc–anode attachments in wall-stabilized transferred argon arcs

Zhu

Wang

Sun

et al. 2019

Plasma Sci. Technol.

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A numerical simulation is conducted to investigate arc-anode attachment behavior, especially the formation mechanism of the constricted arc attachment mode for the water-cooled anode of wall-stabilized transferred argon arcs. Argon molecular ions and the corresponding kinetic processes are included to the finite-rate chemistry model in order to capture the chemical nonequilibrium characteristics of the arc near the anode region. Modeling results show that constricted and diffusive arc-anode attachments can be self-consistently obtained at different arc currents while keeping other parameters unchanged. The dominant kinetic processes contributing to ionization and recombination in the arc center and fringes are presented. The results show that in arc fringes and the arc attachment region, molecular ion recombination plays an important role which leads to the rapid loss of electrons. The radial evolution of the production, loss and transport processes of electrons is further analyzed. It is found that for the constricted arc attachment mode, both the recombination and convection transport caused by the anode jet result in the loss of electrons at the arc fringes, which leads to the shrinkage of the arc column at the anode. The formation of the anode jet is due to the combined action of radial and axial Lorentz forces in the anode region.

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Electron and gas temperature dependences of the dissociative recombination coefficient of molecular ions {\rm Ar}_2^+ with electrons

Cited by 23 publications

References 33 publications

Causes of plasma column contraction in surface-wave-driven discharges in argon at atmospheric pressure

Causes of plasma column contraction in surface-wave-driven discharges in argon at atmospheric pressure

Effect of local gas heating on a plasma structure driven at radio frequency in a microcell in Ar at atmospheric pressure

Numerical simulation of constricted and diffusive arc–anode attachments in wall-stabilized transferred argon arcs

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