Gas Glow Tube

a high-voltage gas-discharge light source that uses the radiation of a positive column of glow discharge.

Gas glow tubes consist of glass tubes that have the ends sealed with cylindrical steel electrodes (the electrodes are sometimes made of nickel, aluminum, and other metals). The tubes are filled with argon or neon (more rarely with other gases) at a pressure of 400 to 2,100 newtons per sq m (3-16 mm of mercury) and a certain amount of mercury vapor. The lamps are connected to the AC network through a transformer (1.2-13 kilowatts with magnetic dispersion). Gas glow tubes are 10-30 mm in diameter and 0.1-3 in length. In order to broaden the color range of the light emission and to increase the luminescent efficiency, the tubes are coated inside with a phosphor. The luminance of a gas glow tube usually is about 1 kilonit (1 nit = 1 candle per sq m). Gas glow tubes may be twisted and may assume the shape of letters, symbols, and figures for advertising and decorative lighting purposes and also for signaling.