The radiation of low-pressure Hg-Ar discharges in tubes of small diameters

Abstract

For low-pressure Hg-Ar discharges line intensities of UV and visible radiation have been measured for tube diameters of 36, 22.8, and 9.5 mm and for different Hg densities and currents. A computer-controlled experiment was used for angularly resolved measurements. For 36-mm tube diameter the measured angular intensity distribution agrees well with published results. For tubes with 9.5-mm diameter the maximum emission of the 254- and 436 nm radiation is reached at a coldest spot temperature of about 45 °C for a lamp current of 200 mA. The ratio of visible to UV radiation becomes larger for smaller diameters which can be important for lamp applications. Increasing the lamp current from 200 to 600 mA leads to saturation effects in the radiation. A further increase to 1 A changes remarkably the measured angular intensity distribution. This indicates that for higher currents a broader radial radiation profile is present and/or an increased trapping especially of the visible radiation. The total radiated power of the discharge column and the intensity normal to the emitting surface are correlated by the Koedam factor β. The investigation shows that this factor is constant within certain parameter ranges but can change drastically, e.g., for tubes having a very small diameter of 2 mm.

UV Radiation of Low Pressure XeCl* and KrCl* Glow Discharges

“…Pb can be deduced from measurements of the total emitted flux using an integrating sphere (Ulbricht sphere) or, as in this experiment, by measuring and integrating the angular intensity distribution of the radiation of a small area of the tube surface (see also, e.g. [22,23]). Fig.…”

“…Denoting the photodiode signal by U ( 0 , @), the Koedam factor p can be defined as [23] n/2 7I n / 2 0 Actually, we measured f3 in the interval1 [0, 71/21 and multiplied the integral with a factor of 2 to obtain p. The signal normal to the lamp surface U(0, 71/2) has been controlled before and after the angularly resolved measurements to correct variations of the UV emission during the measurements. Analogous to [22], for the numerical integration the spherical surface is divided into surfaces A i by n meridians Qi, i = 1n, and j parallels 0 , j = 1 . .…”

Spectral radiance of strong lines in positive column mercury discharges with argon carrier gas

“…Measurements of spectral radiance of Hg-Ar discharges from tubes with diameters of 9.5, 22.8 and 36 mm were reported by Anderer [3]. The results were put on an absolute scale by reference to the results of Koedem for the 36 mm tube.…”

A radiometric investigation of low-pressure rf sulfur discharges

“…The results were then modified by the known non-Lambertian correction factor ␤ϭ0.602 for a Hg-Ar positive column of 36 mm diameter and approximately 400 mA. 11 This measurement yields a total UV efficiency of 62%Ϯ6% which is also in good agreement with the known efficiency of 60%-70% for Hg-Ar positive columns. These tests provide further evidence of the reliability of the absolute radiometric results from the S 2 -Ar and S 2 -Ne discharges.…”