Sodium Vapor Lamp

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Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A Sodium vapor lamp is a gas discharge lamp which uses sodium in an excited state to produce light. There are two varieties of such lamps: low pressure and high pressure. Because sodium vapor lamps cause less light pollution than mercury-vapor lamps, many cities that have large astronomical observatories employ them. Low-pressure sodium (LPS) lamps consist of an outer vacuum envelope of glass coated with an infrared reflecting layer of indium tin oxide, a semiconductor material which allows visible light wavelengths to pass and reflects infrared back, keeping it from escaping. It has an inner borosilicate glass U-pipe (arc tube) containing solid sodium and a small amount of neon and argon gas Penning mixture to start the gas discharge, so when the lamp is turned on it emits a dim red/pink light to warm the sodium metal and within a few minutes it turns into the common bright yellow as the sodium metal vaporizes.

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Pagina's: 80, Paperback, Betascript Publishers