Increased Power Concentration and its Effect on the Discharge Parameters of the Low Pressure Hg‐rare Gas Positive Column I. Variation of Current

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The reduction of the tube radius is an effective technique for enhancing power concentration. The increased wall losses are compensated by larger field strengths, which counteract the decrease in radiation efficiency with rising current density. The causal relationships are investigated for tube radii of 18-4 mm a t constant discharge current 1 = 200 mA and constant current density j = 1.2 mA/mm2 and for parameter variation of the field strength only. The measured efficiencies of the Hg-resonance lines 254 and 185 nm and the electron energy distribution functions agree well with the calculated values. Moreover, the results of the model calculations provide information on the elementary processes involved, such as elastic losses, collisions of second kind, stepwise processes and Coulomb interaction. The results show that Hg-rare gas discharge with tube radii R = 5-10 mm are no less suitable for light production than those with radii between 13 and 18 mm.

Increased Power Concentration and its Effects on the Discharge Parameters of the Low Pressure Hg‐rare Gas Positive Column. II. Variation of Tube Radius

Kreher

Steern

1989

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Radiation Efficiency and Kinetic Calculations for the Positive Column in Hg/Ar Mixtures. I. Thg Variation

Kreher¹,

Bartolomäs²,

Wilhelm³

et al. 1990

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Properties of the positive column of low pressure Hg/Ar discharge have been investigated from the point of view of its application in fluorescent lamps. The results obtained are based on experimental methods to determine both UV redonance radiation fluxes of the 63P, and 6IPI Hg levels and t o measure the electron distribution function by probes; in addition a kinetic model is applied for the theoretical interpretation of the experimental results and to give a deeper insight into the particle and energy budget. I n the present first part of the paper the effects of recently determined Teff-values on radiation, net collision rates, power transfer nnd the electron energy distribution for extended parameter values are investigated especially in dependence on mercury partial pressure.

Radiation Efficiency and Kinetic Calculations for the Positive Column in Hg/Ar Mixtures II. Impact of Tube Radius and Current Density

Kreher¹,

Bartolomäus²,

Wilhelm³

et al. 1991

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In a preceding part of the paper, based on experimentid methods and on a corresponding kinetic model, especially the impact of the effective life times of the 63P1 and 61P1 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 applicnt.ion 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 t o 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 nre 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 partizrl pressure when reducing the discharge tube radius for constant discharge current i and argon pressure P,,~. Starting from the electron distribution function thc particle and energy budget will be studied in detail, especially of course the change of the ultraviolet radiation output from both Hg resonmce levels 63P, and 61P1 and, in addition, of visible radiation. Then, to understand the effect of the discharge current density, as a reprcsentntive example two cases with different v i h e s of R, i and pAr but with equal current density have been investigated and discussed.Altogether the investigations made will shed light upon the complex relntions in the mentioned mixture plasma and give hints to select suitable pnrnmetcr values which can be usefill to irnprovc light soiirccs.