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Sodium-vapor lamp
Type of electric gas-discharge lamp / From Wikipedia, the free encyclopedia
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A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm.
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Two varieties of such lamps exist: low pressure and high pressure. Low-pressure sodium lamps are highly efficient electrical light sources, but their yellow light restricts applications to outdoor lighting, such as street lamps, where they are widely used.[1] High-pressure sodium lamps emit a broader spectrum of light than the low-pressure lamps, but they still have poorer color rendering than other types of lamps.[2] Low-pressure sodium lamps only give monochromatic yellow light and so inhibit color vision at night.
Single ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) and a metal cap.[3][4] They include the sodium-vapor lamp that is the gas-discharge lamp in street lighting.[5][6][3][4]