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Radiation Efficiency and Kinetic Calculations for the Positive Column in Hg/Ar Mixtures II. Impact of Tube Radius and Current Density
Author(s) -
Kreher J.,
Bartolomäus G.,
Wilhelm J.,
Stern W.
Publication year - 1991
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.2150310304
Subject(s) - radius , atomic physics , radiation , kinetic energy , materials science , plasma , argon , gas filled tube , current (fluid) , tube (container) , electron density , optics , chemistry , physics , thermodynamics , computer security , quantum mechanics , computer science , composite material
In a preceding part of the paper, based on experimental methods and on a corresponding kinetic model, especially the impact of the effective life times of the 6 3 P 1 and 6 1 P 1 Hg resonance levels on the main properties of the low pressure Hg‐–Ar positive column has been studied. In the presented second part these investigations, which have been performed under the aspect of their application in fluorescent lamps, will be continued. They are related to the effects of tube radius and discharge current density. New fluorescent lamps have reduced tube radii from R = 18 to 13 mm and compact lamps down to R = 5 mm. Thus it is of interest to study the electron distribution function and main macroscopic properties of such low pressure discharge plasmas, where the latter properties are obtained by adequate energy space averaging. At first, results are reported and discussed which are related to the dependence of main plasma parameters on the Hg partial pressure when reducing the discharge tube radius for constant discharge current i and argon pressure p A r. Starting from the electron distribution function the particle and energy budget will be studied in detail, especially of course the change of the ultraviolet radiation output from both Hg resonance levels 6 3 P 1 and 6 1 P 1 and, in addition, of visible radiation. Then, to understand the effect of the discharge current density, as a representative example two cases with different values of R , i and P Ar but with equal current density have been investigated and discussed. Altogether the investigations made will shed light upon the complex relations in the mentioned mixture plasma and give hints to select suitable parameter values which can be useful to improve light sources.