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Zur Radialstruktur der diffusionsbestimmten positiven Säule der Sauerstoff‐Entladung bei niederen Gasdrucken
Author(s) -
Sabadil Heinz
Publication year - 1973
Publication title -
beiträge aus der plasmaphysik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0005-8025
DOI - 10.1002/ctpp.19730130406
Subject(s) - ion , chemistry , electron , bessel function , atomic physics , diffusion , analytical chemistry (journal) , physics , thermodynamics , quantum mechanics , organic chemistry , chromatography
The radial distribution of the electrons, negative and positive ions in the cylindrical positive column of the direct current discharge in 0 2 has been calculated. The negative ions are formed by dissociative attachment (0 2 + e → − + 0), the destruction of negative ions is effected by the reverse process (0 − + 0 → β0 2 + e ). The pressure is assumed to be low enough that the radial variation of 0‐concentration can be neglected. By use of the condition of the quasineutrality and the ambipolarity for the radial current from the balance equations of the electrons and the negative ions two differential equations of second order are derived, which has been solved numerically for different values of the ratio z j /z a and β[0]. Numerical results show that the radial distributions of the charge carriers are not‐proportional. If z j ≈ z a the radial distribution of the electron density is enlarged, compared to a Bessel distribution. The radial distribution of the negative ions is also enlarged in the centre of the column, but near the wall of the tube a lack in the density exists. The effective diffusion coefficient of the negative ions is negative, i.e., they are moving from the wall of the tube to the centre of the discharge. The enlargement of the radial distributions of the charge carriers, which results in an improvement of the economy of the balance of electrons, increases if z j / z a and β/[0] are decreased.