Information AboutDischarge Lamp |
| CATEGORIES ABOUT GAS-DISCHARGE LAMP | |
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Gas discharge lamps are a family of artificial light sources that generate light by sending an . Typically, such lamps use a Noble Gas ( Argon , Neon , Krypton and Xenon ) or a mixture of these gases. Most lamps are filled with additional materials, like Mercury , Sodium , and/or Metal Halide s. In operation the gas is ionized, and free electrons, accelerated by the Electrical Field in the tube, collide with gas and metal atoms. Some electrons circling around the gas and metal atoms are Excited by these collisions, bringing them to a higher energy state. When the electron falls back to its original state, it emits a Photon , resulting in visible light or Ultraviolet radiation. Ultraviolet radiation is converted to visible light by a Fluorescent coating on the inside of the lamp's glass surface for some lamp types. The Fluorescent Lamp is perhaps the best known gas discharge lamp. Gas discharge lamps offer long life and high light efficiency, but are more complicated to manufacture, and they require electronics to provide the correct current flow through the gas. HISTORY Francis Hauksbee first demonstrated a gas discharge lamp in 1705. He showed that an evacuated or partially evacuated glass globe, while charged by static electricity could produce a light bright enough to read by. Sir Humphry Davy demonstrated in 1802 the first Electric Arc at the Royal Institution of Great Britain. Since then, discharge light sources have been researched because they create light from electricity considerably more efficiently than Incandescent Light Bulb s. Later it was discovered that the arc discharge could be optimized by using an inert gas instead of air as a medium. Therefore Noble Gas es neon, argon, krypton or xenon were used, as well as Carbon Dioxide historically. The introduction of the metal vapor lamp, including various metals within the discharge tube, was a later advance. The heat of the gas discharge vaporized some of the metal and the discharge is then produced almost exclusively by the metal vapor. The usual metals are Sodium and Mercury owing to their high Vapor Pressure s that increase efficiency of visible spectrum emission. One hundred years of research later led to lamps without electrodes which are instead energized by microwave or radio frequency sources. In addition, light sources of much lower output have been created, extending the applications of discharge lighting to home or indoor use. COLOR Each gas, depending on its Atomic Structure emits certain wavelengths which translates in different colors of the lamp. As a way of evaluating the ability of a light source to reproduce the colors of various objects being lit by the source, the International Commission On Illumination ( CIE ) introduced the Color Rendering Index . Some of gas discharge lamps exhibit indexes below 100 which means that the colors appear completely different from, for instance with sun-light illumination. Some people are unconsciously aware of this phenomenon and when buying clothes, they try to illuminate them with sun-light in order to know the "''real''" color. MOST COMMON GAS DISCHARGE LAMPS Low pressure discharge lamps
High pressure discharge lamps
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