discharge lamp

n.
A lamp that generates light by means of an internal electrical discharge between electrodes in a gas.

A source of radiant energy excited by a supply of electricity which creates a current of ionized gas between electrodes in an enclosure that contains the arc while permitting transmission of the radiant energy. Gaseous-discharge lamps or vapor lamps are given various names relating to the element responsible for the majority of the radiation (mercury, sodium metal-halide, xenon), to the physical attribute of the lamp (short-arc, high-pressure), or, in the case of fluorescent lamps, to the way a phosphor on the bulb wall fluoresces as a result of the lamp's low-pressure mercury-vapor excitation. See also Arc discharge; Electrical conduction in gases.

Gaseous-discharge lamps are broadly used throughout the world because the conversion of electric energy to radiant energy in a gaseous discharge provides radiation in narrow bands within the range of visible light in which the rods and cones of the eye are most sensitive. These light sources have high efficiency in conversion of electricity to light.

For discussions of common types of vapor lamps See also Fluorescent lamp; Mercury-vapor lamp; Neon glow lamp; Sodium-vapor lamp.

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Any lamp that produces light by means of phosphors as a result of an electrical discharge through one or more gases or vapors within the lamp’s envelope (e.g., see fluorescent lamp).

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