Were practically implemented dented lamp (also tested and helical), providing sufficient mechanical strength of the structure. Dents have been made as a tube with one hand and alternately from opposite sides. Dents on the part of the discharge are the projections included in the plasma. In such a tube is lengthened effective way to discharge (approximately 20%), increases the ratio of perimeter to cross section and decreases the average path of photons in the plasma. Thanks to obtain higher values of E and T and improved yield of UV radiation. Welts (edge) of dents due to the lower current density of these zones are less heated and cold zones. With proper selection of the form they have a temperature optimum in terms of mercury vapor pressure.
The initial light output of these lamps was 5-10% higher than comparable round tubes. However, the decline in flux with time is much faster, so that the average light output fluorescent tubes with dents are noticeably lower. Rapid decline in flow was due to a very large non-uniformity of the density of irradiation, ion bombardment and heating of the cross section. In the center of the projections (dents) density is ten times higher than the average density in the tube with a circular cross section, which led to the rapid growth processes of destruction of the phosphor. This, as well as a substantial complexity of manufacturing led to These lamps do not have distribution. Methods for maintaining optimum mercury vapor pressure at high w. In the lamps operating at temperatures above the flask 50-60 C, the optimum mercury vapor pressure can be achieved r0pt by maintaining a small area of the bulb at a lower temperature corresponding to r0t, or by the use of mercury amalgams, have a lower vapor pressure of mercury. Cold spots can be obtained by increasing the heat from the outer surface of the lamp, or by reducing the flow of heat to a small section of the bulb inside, or both one and the other way.