The Theory of the Positive Column at Low Pressures Including Space‐Charge Effects, the Radial Variation of the Ion Temperature, and the Charge Exchange

Valentini, H.-B.

doi:10.1002/ctpp.19810210104

Cited by 8 publications

(1 citation statement)

References 7 publications

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“…According to [26] HOLSTEIN proposed a simple model for the charge transfer process. If the prime refers to the situation before the collision the Holstein model gives (8)…”

Section: Ion-neu Tral-collisionsmentioning

confidence: 99%

KInetic Description of the Positive Column for Medium Knudsen‐Numbers

Wallschlager

1990

Contrib. Plasma Phys.

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We analyze the influence of collisions on a plasma column with cylindrical symmetry in the pressure regime between the collision-dominated and the free-fall case. A model is investipted which can handle arbitrary contributions from ion-neutral-collisions. One finds a n analytic solution for the ion-distribution-function which depends functionally on the potential. This electrical potential is calculated numerically -with consideration of the space-charge-layer near the walland selfconsistently from the Poisson-equation. From the calculation of the ion-distributionfunction, of density, flux and temperature of the ions as well as of the potential variation, we discuss the influence of the model parameters. The results are compared with corresponding hydrodynamic calculations.

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“…According to [26] HOLSTEIN proposed a simple model for the charge transfer process. If the prime refers to the situation before the collision the Holstein model gives (8)…”

Section: Ion-neu Tral-collisionsmentioning

confidence: 99%

KInetic Description of the Positive Column for Medium Knudsen‐Numbers

Wallschlager

1990

Contrib. Plasma Phys.

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The Construction of Systems of Equations Describing Gas Discharges Containing Several Species of Atoms and Ions, Including Stepwise Processes, Negative Ions, and the Spatial Variation of the Temperatures

Valentini

1983

Contrib Plasma Phys

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The sets of differential equations usually used for the description of the low pressure discharges are underconstrained if several species of atoms and of ions and stepwise procesaes are taken into consideration. Using the equations of continuity, of momentum transfer, and of energy transfer for each species it is shown that, besides known closing statements for these sets of differential equations, additional conditions are necessary. It is found that the following relatively simple condition is sufficient for positive ions. The radial pressure gradient hns to be asaumed to vanish a t least with the third order as the dietance from the axis approaches zero. Various simpler and also more accurate and cumbersome approximations describing non-excited atoms, positive and negative ions are investigated. Under some conditions one can formulate additional boundary conditions a t the wall instead of additional conditions on the axis.

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Geschwindigkeitsverteilungsfunktionen von Atomen und Ionen in verschiedenen Anregungs‐ und Ionisationsstufen in Niederdruck‐Entladungen bei hohem Ionisationsgrad

Valentini

1984

Contrib Plasma Phys

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Supposing free-fall conditions the velocity distribution functions of atoms and ions in various levels in gas discharges a t low pressures are calculated. In particular, plasmas a t high degrees of ionization are considered. Solving the Boltzmann equation for the motions transverse to the wall of the discharge tube it is shown that the velocity distribution functions can considerably deviate from the Maxwellian and become non-isotropic. Inelastic collisions with electrons and the ionization by electron impacts considerably determine the velocity distribution function of the neutral atoms. The velocity dist,ribution function of the ions is also essentially determined by the electric field within the plasma. For the motions transverse to the wall the half widths of the velocity distribution functions do not only depend on the temperature of the wall, but on the electron density and on the electron temperature as well. At small electron densities the half widths for excited atoms and for ions can be narrower than the one for the ground state atoms. The charge exchange between atoms and ions is shortly taken into consideration.

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The Theory of the Positive Column at Low Pressures Including Space‐Charge Effects, the Radial Variation of the Ion Temperature, and the Charge Exchange

Cited by 8 publications

References 7 publications

KInetic Description of the Positive Column for Medium Knudsen‐Numbers

KInetic Description of the Positive Column for Medium Knudsen‐Numbers

The Construction of Systems of Equations Describing Gas Discharges Containing Several Species of Atoms and Ions, Including Stepwise Processes, Negative Ions, and the Spatial Variation of the Temperatures

Geschwindigkeitsverteilungsfunktionen von Atomen und Ionen in verschiedenen Anregungs‐ und Ionisationsstufen in Niederdruck‐Entladungen bei hohem Ionisationsgrad

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