![]() ![]() This technology was commercialized by the French engineer Georges Claude in 1910 and became neon lighting, used in neon signs. It was found that inert gases such as the noble gases neon, argon, krypton or xenon, as well as carbon dioxide worked well in tubes. The father of the low-pressure gas discharge tube was German glassblower Heinrich Geissler, who beginning in 1857 constructed colorful artistic cold cathode tubes with different gases in them which glowed with many different colors, called Geissler tubes. Since then, discharge light sources have been researched because they create light from electricity considerably more efficiently than incandescent light bulbs. In 1809, Sir Humphry Davy demonstrated the electric arc at the Royal Institution of Great Britain. The phenomenon of electric arc was first described by Vasily V. He showed that an evacuated or partially evacuated glass globe, in which he placed a small amount of mercury, while charged by static electricity could produce a light bright enough to read by. Hauksbee first demonstrated a gas-discharge lamp in 1705. ![]() Investigators, including Francis Hauksbee, tried to determine the cause of the phenomenon. The history of gas-discharge lamps began in 1675 when the French astronomer Jean Picard observed that the empty space in his mercury barometer glowed as the mercury jiggled while he was carrying the barometer. Still, owing to their greater efficiency, gas-discharge lamps were preferred over incandescent lights in many lighting applications, until recent improvements in LED lamp technology. Some gas-discharge lamps also have a perceivable start-up time to achieve their full light output. Therefore, they usually require auxiliary electronic equipment such as ballasts to control current flow through the gas, preventing current runaway ( arc flash). The fluorescent lamp is perhaps the best known gas-discharge lamp.Ĭompared to incandescent lamps, gas-discharge lamps offer higher efficiency, but are more complicated to manufacture and most exhibit negative resistance, causing the resistance in the plasma to decrease as the current flow increases. Some lamps produce ultraviolet radiation which is converted to visible light by a fluorescent coating on the inside of the lamp's glass surface. Gas discharge lamps can produce a wide range of colors. The color of the light produced depends on the emission spectra of the atoms making up the gas, as well as the pressure of the gas, current density, and other variables. In this way, electrons are relayed through the gas from the cathode to the anode. Light of a characteristic frequency is thus emitted. The atoms which lost an electron during the collisions ionize and speed toward the cathode while the ions which gained an electron during the collisions return to a lower energy state, releasing energy in the form of photons. ![]() The ions typically cover only a very short distance before colliding with neutral gas atoms, which give the ions their electrons. The free electrons thus released flow to the anode, while the cations thus formed are accelerated by the electric field and flow towards the cathode. In operation, some of the electrons are forced to leave the atoms of the gas near the anode by the electric field applied between the two electrodes, leaving these atoms positively ionized. They include the sodium-vapor lamp that is the gas-discharge lamp in street lighting. 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. Some include additional substances, such as mercury, sodium, and metal halides, which are vaporized during start-up to become part of the gas mixture. Noble gas ( argon, neon, krypton, and xenon) or a mixture of these gases. Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Germicidal lamps are simple low-pressure mercury vapor discharges in a fused quartz envelope. ![]()
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