Krypton Incandescent Lamp

an electric incandescent lamp whose bulb is filled with the inert gas krypton.

At equal temperatures, the rate of vaporization of the tungsten filament in a krypton incandescent lamp is lower than in a lamp filled with the usual mixture of gases (85 percent argon and 15 percent nitrogen) because of the greater atomic mass of krypton. The possibility of increasing the temperature of the filament leads to an increase of 15–20 percent in the luminous efficiency of the krypton incandescent lamp compared with ordinary lamps of the same rating, as well as to a decrease in bulb size. A decrease in bulb size, in turn, reduces the consumption of krypton and increases the pressure within the lamp, which leads to a further decrease in the rate of vaporization of the tungsten filament. To reduce heat loss through the gas, the filament in a krypton incandescent lamp is made in the shape of a double helix. Krypton is also used in other types of incandescent lamps (for example, miners’ and automobile lamps) that require maximum luminous efficiency with minimum size.