Electron swarms in mixtures of metal vapour and argon gas

Al-Amin, S A J; Lucas, J.

doi:10.1088/0022-3727/21/8/003

Cited by 11 publications

(7 citation statements)

References 23 publications

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“…The left panel shows the elastic momentum transfer (1), total ionization (2), and quantities that are obtained by multiplying the total cross section for superelastic collisions with the corresponding fractional populations of the first excited metastable state at indium vapour temperatures of 1260 K, 3260 K, and 5260 K. The quantities obtained as the product of the total cross section for superelastic collisions and the corresponding fractional populations of the first excited metastable state were subsequently multiplied by factors of 10 9 , 10 3 , and 10 2 , at indium vapour temperatures of 1260, 3260 and 5260, respectively. The left panel also includes the following discrete inelastic transitions: (5s 2 6s) 2 S 1/2 (3), (5s 2 6p) 2 P 1/2 (4), (5s 2 6p) 2 P 3/2 (5), (5s 2 5d) 2 D 3/2 (6), (5s 2 5d) 2 D 5/2 (7), (5s 2 4p) 2 P 1/2 (8), (5s 2 4p) 2 P 3/2 (9), (5s 2 7s) 2 S 1/2 (10), (5s 2 4p) 2 P 5/2 (11) and (5s 2 7s) 2 P 1/2 (12). The right panel includes the following discrete inelastic transitions: (5s 2 7s) 2 P 3/2 (13), (5p 2 6d) 2 D 3/2 (14), (5p 2 6d) 2 D 5/2 (15), (5p 2 4 f ) 2 F 7/2 (16), (5p 2 4 f ) 2 F 5/2 (17), (5p 2 8s) 2 S 1/2 (18), (5p 2 8s) 2 P 1/2 (19), (5s 2 7d) 2 D 3/2 (20), (5s 2 7d) 2 D 5/2 (21) and (5s 2 8p) 2 P 3/2 (22).…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

“…Early studies of electron transport in metal vapours were limited to the vapours of mercury, caesium, and other alkali metals, due to the many technical difficulties associated with the control of high temperatures in swarm experiments. In addition to decades of studying the transport of electrons in mercury vapour [6][7][8][9][10][11], swarm studies were performed in the vapours of sodium, potassium, and caesium [12] while the experimental results of breakdown voltages and V -I characteristics were measured for sodium, potassium, cadmium, and zinc [13]. The primary driving force behind these early studies was the modelling and optimization of light sources containing mercury [8,14,15], sodium [16,17], and zinc [18,19].…”

Section: Introductionmentioning

confidence: 99%

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Transport of electrons and propagation of the negative ionisation fronts in indium vapour

Dujko¹,

Atic²,

Bošnjaković³

et al. 2021

Plasma Sources Sci. Technol.

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We study the transport of electrons and propagation of the negative ionisation fronts in indium vapour. Electron swarm transport properties are calculated using a Monte Carlo simulation technique over a wide range of reduced electric fields E/N (where E is the electric field and N is the gas number density) and indium vapour temperatures in hydrodynamic conditions, and under non-hydrodynamic conditions in an idealised steady-state Townsend (SST) setup. As many indium atoms are in the first ( 5 s 2 5 p ) 2 P 3 / 2 metastable state at vapour temperatures of a few thousand Kelvin, the initial Monte Carlo code was extended and generalized to consider the spatial relaxation and the transport of electrons in an idealised SST experiment, in the presence of thermal motion of the host-gas atoms and superelastic collisions. We observe a significant sensitivity of the spatial relaxation of the electrons on the indium vapour temperature and the initial conditions used to release electrons from the cathode into the space between the electrodes. The calculated electron transport coefficients are used as input for the classical fluid model, to investigate the inception and propagation of negative ionisation fronts in indium vapour at various E/N and vapour temperatures. We calculate the electron density, electric field, and velocity of ionisation fronts as a function of E/N and indium vapour temperature. The presence of indium atoms in the first ( 5 s 2 5 p ) 2 P 3 / 2 metastable state significantly affects the characteristics of the negative ionisation fronts. The transition from an avalanche into a negative ionisation front occurs faster with increasing indium vapour temperature, due to enhanced ionisation and more efficient production of electrons at higher vapour temperatures. For lower values of E/N, the electron density behind the streamer front, where the electric field is screened, does not decay as one might expect for atomic gases, but it could be increased due to the accumulation of low-energy electrons that are capable of initiating ionisation in the streamer interior.

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Section: Monte Carlo Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transport of electrons and propagation of the negative ionisation fronts in indium vapour

Dujko¹,

Atic²,

Bošnjaković³

et al. 2021

Plasma Sources Sci. Technol.

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“…In this case, the electron energy distribution function (EEDF) derived analytically is the main coefficient to calculate the electron swarm parameters, that is. the electron drift velocity v d and the transverse diffusion coefficient D T as follows (Thomson and Smith, 1976;Al-Amin and Lucas, 1988),…”

Section: The Transport Parametersmentioning

confidence: 99%

Boltzmann equation studies on electron swarm parameters for oxygen plasma by using electron collision cross – sections

2020

ZJPAS

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The Boltzmann transport equation has been solved using a two-term approximation method in pure electronegative gas oxygen to evaluate the electron energy distribution function (EEDF) and electron transport parameters for a wide range of E/N varying from 0.1 to 1000 Td (1 Td=10-17 V.cm 2). These parameters, are "electron drift velocity, mean electron energy, characteristic energy, diffusion coefficients, electron mobility, attachment and ionization coefficients, effective ionization coefficient and critical reduced electric field strength (E/N) crt ".. The dependence of second kind collision (super-elastic collision) and electron energy distribution function on E/N are explained (where E is electric field and N is neutral number density). The present calculated results are in good agreements as compared, with the previous experimental and theoretical results. A group of electron/molecule collision (elastic and inelastic) cross-sections are collected for oxygen gas to evaluate transport parameters over the entire E/N range. In addition, the energy lost by different types of electron/molecule collision processes are computed as a function of E/N.

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“…The relation between drift velocity V d and electron energy distribution function is (Al-Amin and Lucas, 1988):…”

Section: Transport Coefficientsmentioning

confidence: 99%

Solving of the Boltzmann transport equation using two - term approximation for pure electronegative gases (SF6, CCl2F2)

2019

ZJPAS

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The Boltzmann transport equation is solved by using two-term approximation for pure electronegative gases (SF 6 , CCl 2 F 2). This method used to calculate the electron energy distribution function (EEDF) and electron swarm parameters in the range of E/N varying from 100 Td to 1000 Td (1 Td=10-17 V.cm 2). Electron swarm parameters have been calculated as a function of E/N namely: drift velocity, mean electron energy, characteristic energy, diffusion coefficients, mobility, and attachment and ionization coefficients also effective ionization coefficient. The results have shown that the calculated swarm parameters were in good agreements with those obtained by experiment and theoretical (Three-term and Monte Carlo Simulation) methods. A set of elastic and inelastic cross-sections have been collected for each gas such that the computed and experimental values gave good agreement for each swarm parameter over the entire E/N range

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Electron swarms in mixtures of metal vapour and argon gas

Cited by 11 publications

References 23 publications

Transport of electrons and propagation of the negative ionisation fronts in indium vapour

Transport of electrons and propagation of the negative ionisation fronts in indium vapour

Boltzmann equation studies on electron swarm parameters for oxygen plasma by using electron collision cross – sections

Solving of the Boltzmann transport equation using two - term approximation for pure electronegative gases (SF6, CCl2F2)

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