Electric discharge lamp, also called Vapour Lamp, lighting device consisting of a transparent container within which a gas is energized by an applied voltage and thereby made to glow. Although the differential resistance of the discharge is not necessarily negative in the intended operation point, the lamp impedance is a quite variable quantity, and the power supply must somehow stabilize the operation current rather than the applied voltage. When such a lamp is broken, and the mercury content is released into the air, that will usually not lead to acute poisoning. From Simple English Wikipedia, the free encyclopedia, https://simple.wikipedia.org/w/index.php?title=Gas_discharge_lamp&oldid=6744681, Creative Commons Attribution/Share-Alike License. Those lamps are mostly based on metals (e.g. However, a rather compact tube is often desirable for various reasons, such as easier collection of the light output and avoiding dark depositions on the glass for too low operating temperatures. In particular, each electrode has a well defined function (cathode or anode) and can be optimized accordingly. As explained above, low pressure lamps typically emit a line spectrum, while high pressure lamps tend to produce a continuum spectrum. A wide range of gases is used in gas discharge lamps, depending on the required emission spectrum, optical output power and radiance. However, there can also be problems with contamination of the gas filling (e.g. For arc lamps, one often applies a more sophisticated startup method, where one starts with a relatively low energy high-voltage trigger pulse and then applies a lower-voltage higher-energy booster pulse before the main power supply for continuous-wave operation can take over. The continuous emission often leads to the naming as arc lamps even if the physical operation parameters actually indicate the glow discharge regime. The operation temperature of the gas and electrodes usually remains rather small, and the same holds for the applied current densities. Special care is necessary for cooled electrodes, avoiding any insulation problems despite the applied high voltages. mercury or sodium) or metal halides. Subsequently, the excited species emit luminescent light, which is frequently either in the visible spectral range or in the ultraviolet, but sometimes in the infrared. Nevertheless, such mercury exposure should be avoided if at all possible. The electrodes of high-power lamps (particularly anodes) needed to be specially cooled during operation – sometimes even with a water flow. Make sure to use the right socket when changing your Gas Discharge Lamp. In that regime, the discharge exhibits a negative differential resistance: an increase of current does not increase the voltage drop, but rather decreases it because of the increased degree of ionization. With modern electronics, lamp performance can be substantially enhanced. Encyclopedia … combined with a great Buyer's Guide! Various details of electrodes can have a substantial impact on the lamp performance and lifetime. With forced air cooling, one can accelerate the heat transfer. Commonly, we separate them in 3 basic categories: High pressure discharge lamps, Low pressure discharge lamps and High-intensity discharge lamps. Note: the article keyword search field and some other of the site's functionality would require Javascript, which however is turned off in your browser. The operation temperature of the gas (e.g. xenon. Lampu Gas Discharge (Neon, Merkuri dsb.) Also wouldn't want to produce RFI buy using an undisciplined switching supply…. Gas-discharge lamps have a long life and a high efficiency, but they are more complicated to manufacture, which makes them more expensive to buy than incandescent lamps. Due to the relatively small density of the gas, one needs to use a substantial gas volume for obtaining a certain optical power, and the resulting radiance is quite small. Ordinary household fluorescent lamps can also be fairly long-lived, particularly when operated with modern electronic ballasts. The voltage drop is then U = R I = K0 I1/2. The electrical feedthrough can be a critical aspect since the thermal coefficient of expansion is quite different between common wire materials and the glass. In nearly all cases, a gas discharge lamp requires a kind of transparent enclosure for keeping the gas separated from the ambient atmosphere; the only notable exception is the traditional carbon arc lamp, working with air at atmospheric pressure. For applications, there can be a trade-off between high luminous efficacy and high color rendering index; the best choice can depend on how critical accurate color vision is for the specific application. Therefore, one sometimes needs to use different metals for a feedthrough and an electrode, which are soldered together for getting a good electrical contact. One then obtains a much higher current through the filaments of the fluorescent lamp, which prepares the lamp for ignition. with well over 100 W per square centimeter of tube area. For DC operation, i.e., with a constant direction of current, one electrode is the cathode (the negative one, emitting electrons into the gas), and the other one is the anode (collecting electrons). In that regime, the rate of collisions between the atoms, ions or molecules of the gas is relatively low, so that the light emission remains relatively undisturbed by such effects. One therefore often uses tungsten electrodes, being particularly resistant to high temperature, and which are possibly treated for more efficient electronic mission. The luminous efficacy (specified in lm/W) depends very much on the type of lamp, mostly on the used gas, but also on the operation regime. At the end of durability (strong colour changes, difficult to start up or on/off), replace the lamp on time to prevent defects to the ballast. Gas discharge lamp synonyms, Gas discharge lamp pronunciation, Gas discharge lamp translation, English dictionary definition of Gas discharge lamp. This is not always easy, for example due to substantial discrepancies of the thermal expansion coefficients between glass and electrode metals. It is often exploited that the gas tube does not need to be straight, but can be bent to form letters or other symbols. The thermionic emission may be enhanced with a thin oxide coating on the metallic electrode. The discharge is usually in the glow discharge regime. The electrodes are also operated with high current densities, exposed to high temperatures and the bombardment with electrons and/or ions; due to those harsh conditions, the lamp lifetime is often (but not always) not that long – in some cases, only a few tens of hours. In many cases, a gas discharge lamp uses a suitable mixture of different gases which allows one to achieve the desired operation characteristics e.g. by degrading electrodes. Others require substantial time for startup, and some require substantial time thereafter to reach their full specified luminous flux. In a few cases, one uses flicker light bulbs with an orange color tone, which somewhat mimics the emission of candles. In other cases, one uses fused silica (“quartz”) with some dopants for introducing UV absorption, because intense ultraviolet light would be detrimental; it could damage parts of an application setup (e.g. They come in three different forms: high pressure discharge, low pressure discharge and high-intensity discharge. For applications in the area of lighting, one often specifies the luminous flux, which in that case is a better measure, since it takes into account the wavelength-dependent sensitivity of the human eye. Gas discharge lamps are a family of artificial light sources (or lamps).These lamps produce light by sending electricity through an ionized gas.Most of these lamps use a noble gas, or a combination of noble gases, but they often contain other materials, such as mercury, sodium or metal halides.The gases in these lamps are ionized in operation. a U shape, a near circle or a helical shape. They are used in electrical switches, for example, for indicating the “on” state, or elsewhere just to indicate that line voltage is available. That is particularly the case for metal halide lamps, where the elevated operation temperature of gas and electrodes is needed for developing the full operation pressure. For many of those applications, the large emitting volume is not problematic. The French astronomer Jean Picard observed (1675) a faint glow in a mercury-barometer tube when it was agitated, but the cause of the glow (static electricity) was not then understood. in terms of optical spectrum, luminous efficacy, radiance and ease of ignition. The author will decide on acceptance based on certain criteria. for laser pumping, usually require liquid cooling, in most cases with a turbulent flow of demineralized water, e.g. Gas discharge lamp basics The use of electrically excited gas discharges significantly predates the invention of the incandescent lamp. These are old antique bulbs and I wouldn't want to hurt them. Encyclopedia > letter G > gas discharge lamps. What are synonyms for gas-discharge lamp? Further, stronger heating of such a cathode tip for good thermionic emission is generally welcome for arc lamps; note that the power density in continuous-wave operation is not that high. with a UV-absorbing dopant (e.g. For example, illumination of pieces of art is generally more sensitive in that respect than lighting in households or industrial settings. See the article on fluorescent lamps for more details. Therefore, lamp lifetimes of many thousands of hours are often achieved. Therefore, one often uses specially treated metals. Due to their greater efficiency, gas-discharge lamps replacing incandescent light bulbs for many purposes in the late 20th century. Traditional arc lamps have basically always been carbon arc lamps, where graphite electrodes were operated in air. In the following sections, distinctions of lamps according to different criteria are explained. plastics, seals and laser crystals) and could also cause disturbing ozone generation from ambient oxygen. The starter contains a tiny discharge lamp, which in contrast to the fluorescent lamp can start with line voltage. Synonyms for Gas discharge lamp in Free Thesaurus. The noble gas enables the arc's initial strike. That may not only constitute a loss of energy, but also have negative side effects concerning human skin and eyes. plasma. In other cases, one uses much higher pressures, e.g. That is fully acceptable or even advantageous for illumination (lighting) purposes, for signal lights (e.g. The evaporation of the metal or metal halide may be caused by a discharge in an additional starter gas, e.g. Gas discharge lamps are often operated with direct current (DC), which has various advantages over alternating current (AC) mode. Definition: light sources which are based on an electrical discharge in an ionized gas or metal vapor, More specific terms: arc lamps, flash lamps, fluorescent lamps, metal vapor lamps, metal halide lamps, high intensity discharge lamps, spectral lamps, mercury vapor lamps, excimer lamps, neon lamps, krypton lamps, xenon lamps, sodium vapor lamps, How to cite the article; suggest additional literature. This is related to the use technique for producing the electrode feedthrough. Please do not enter personal data here; we would otherwise delete it soon. In the latter case, for example, a thick electrode rod is sealed with glass such that one obtains a tight connection. for projection displays or search lamps, where a well directed light beam needs to be generated. For some applications, bent shapes are required, e.g. As an example, Figure 1 shows a typical electrical circuit used for operating fluorescent lamps, which can be used for some other gas discharge lamps as well. The envelope is usually realized as a sealed glass container (often in the form of a cylindrical glass tube with a bore diameter of a few millimeters) which is penetrated by the electrode wires. Sodium vapor lamps are commonplace as streetlights. The use of gas discharge lamps can involve various safety hazards and environmental burdens: The RP Photonics Buyer's Guide contains 30 suppliers for gas discharge lamps. There are also electrode-less lamps, where the electric energy is introduced in other ways, typically with a radio frequency or microwave field. Most of these lamps use a noble gas, or a combination of noble gases, but they often contain other materials, such as mercury, sodium or metal halides. The power density is also quite high; an electrical power between some tens of watts and many kilowatts is converted in a relatively small volume, leading to a very high operation temperature of the arc and to emission with a relatively high radiance – suitable for high-power projection displays (in cinemas and beamers) and directed search lights, for example. The quasi-monochromatic emission of some low pressure lamps makes them useful as spectral lamps for applications in spectroscopy, for example. End of life may mean that the lamp does not work any more (e.g. due to a too high ignition voltage), or that it produces insufficient light output. Early in the 21st century, light-emitting diodes improved, with even higher efficiency. For higher lamp currents, as usually used in many arc lamps, the differential resistance becomes positive. Some lamps are made for pulsed emission, and many of them can be used only in that operation mode. Some amount of flicker (variations of limited power and its spatial distribution) is frequently observed due to instabilities of the gas discharge. As a result, the optical spectrum of the generated light is usually a line spectrum, i.e., it consists of discrete spectral emission lines (resulting from bound-to-bound transitions) rather than a broad continuum (involving free electrons). Typical glow discharge lamps are tiny low-power signal lamps containing neon or a gas mixture. Antonyms for Gas discharge lamp. gas-discharge lamp synonyms, gas-discharge lamp pronunciation, gas-discharge lamp translation, English dictionary definition of gas-discharge lamp. The handling of such high pressure lamps require special precautions to minimize safety hazards; for high-power versions (e.g. Also, one can produce bent tubes in the forms of letters and other symbols, e.g. Due to the omnidirectional emission, the measurement of output power would be more difficult than for a laser source, for example; one typically uses a integrating sphere. Sorry, we don't have an article for that keyword! Due to the need of triggering, possibly also boosting and because of the negative differential impedance in certain regimes, most gas discharge lamps cannot be operated simply by applying a constant voltage, as one would normally do with an incandescent lamp, for example. Gas Discharge Lamps. For example, pointed cathodes can provide a well defined position of the discharge in the center of the tube; it is important to avoid that the discharge comes too close to the envelope, because that could lead to rapid degradation. 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