Numerical analysis has been made of a fluorescent lamp with an elliptical tube. Radiation transport analysis of the 254 nm mercury resonance line using a Monte-Carlo method is combined with rate equations for production-and-loss of electrons and excited atoms. Calculation is made for an elliptical positive column with a major radius of 16.25 mm and a minor radius of 13.0 mm. Parameters are calculated at a coldest spot temperature of 40°C. The distributions of electron density and 6³P₁ atom density are derived. The effective lifetime of the 6³P₁ level is 4.7×10^-6s and the escape factor for Hg 254 nm is 0.0256. The irradiance for Hg 254 nm at the surface of phosphor layer is approximately 12 % larger than the average value on the minor axis and approximately 11 % smaller on the major axis.

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A capillary discharge tube is very useful for the back light source for a liquid crystal display device. The luminance and the spectral characteristics of the positive column of the capillary discharge tube usually depend on plasma parameters of positive column. Therefore, it is very important to investigate the relation between the spectral characteristics and the plasma parameters in order to increase the spectral luminous efficiency of discharge tubes. In this paper, the luminance and the spectral characteristics were measured for a cylindrical capillary discharge tube. Then the plasma parameters were also measured. The gases used were helium, neon and argon. The tube used for measurement was 1 mm in diameter and the discharge current was 10∼50 mA. The gas pressure was varied from 0.2 to 20 Torr. The luminance and the spectral characteristics were obtained as a function of the gas pressure. The electron temperature and the axial electric field were also measured as a function of the gas pressure. The experimental results were discussed qualitatively.

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