gas discharge lamp

For many purposes, a long lifetime is not only desirable due to the lamp cost, but also because exchanging lamps requires additional efforts, and sometimes because lamp failures cause safety hazards. Often it is recommended to avoid frequent switching, because that can degrade their lifetime. Gas discharge lamps are often operated with direct current (DC), which has various advantages over alternating current (AC) mode. Most lamps are filled with additional materials, like mercury, sodium, and/or metal halides. In a few cases, one uses flicker light bulbs with an orange color tone, which somewhat mimics the emission of candles. 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. Lampen worden onderverdeeld in families op basis van de druk van het gas, en of de kathode verhit. This is not always easy, for example due to substantial discrepancies of the thermal expansion coefficients between glass and electrode metals. Before ignition, i.e., without any significant ionization, the impedance of such a lamp is extremely high, leading to a negligible electric current when simply applying the voltage which would be sufficient during operation. Typical glow discharge lamps are tiny low-power signal lamps containing neon or a gas mixture. 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. One sometimes needs to use a softer special seal glass which itself needs to be fused with the actual envelope glass (and may unfortunately make the device less temperature-resistant). While some gas discharge lamps are specifically made for emitting mostly ultraviolet light, others produce some unwanted ultraviolet light in addition to the actually used visible light. Their disadvantage in terms of power conversion efficiency is not always very relevant in such cases. The naming is sometimes misleading; for example, some cars are said to be equipped with xenon lamps, although in reality they are actually metal halide lamps also containing some xenon as starter gas, which also provides some light output before the full luminous flux from the halides is reached. 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. with krypton or xenon at multiple atmospheres) are also used for pumping of continuous-wave or pulsed (free-running or Q-switched) solid-state lasers (→ lamp-pumped lasers), where the light output of low pressure lamps would normally be insufficient. Discharge lamps often require quite high operation voltages, which may cause severe electric shocks if someone touches a wire. Its presence in the arc plasmagreatly increases the intensity of visibl… Some gas discharge lamps (hot cathode lamps) require high temperatures of the electrodes, at least of the cathode (for operation with DC current), because only then one obtains sufficiently strong thermionic emission of electrons into the gas. Unfortunately, long lamp lifetimes are much more difficult to achieve for lamps where a high power density is required, e.g. 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. 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. Envelopes for low pressure lamps often have a simple cylindrical form. Note that the operation pressure can significantly exceed the fill pressure, because the temperature may rise substantially due to the intense discharge. First of all, what is a gas discharge lamp? (For high fill pressures, triggering can be a challenge.) The technology has in some areas been substantially developed further in recent decades. The resulting voltage peak is normally sufficient for ignition, unless the opening of the starter comes at an inconvenient time during the AC cycle; the process may then have to be repeated. With preview image (see the box just above): For Wikipedia, e.g. The handling of such high pressure lamps require special precautions to minimize safety hazards; for high-power versions (e.g. Here, the arc is very hot (with temperatures of thousands of degrees Celsius), and rather bright white light is generated with a substantial power density. Most frequently, one uses ultraviolet light from a low-pressure mercury discharge for generating white fluorescence in a phosphor layer on the inner side of a glass tube. Also wouldn't want to produce RFI buy using an undisciplined switching supply…. They began to replace some gas discharge lamps. Nevertheless, such mercury exposure should be avoided if at all possible. Instead, they require a more or less sophisticated kind of electrical circuit for triggering and current control. Also, one avoids the risk of using the ionization in the times where the AC current changes its sign. Verhitte kathode lampen hebben elektroden die werken bij een hoge temperatuur en wordt verhit door de boogstroom in de lamp. "The current worldwide trend of replacing gas discharge lamps with solid state lighting, such as LEDs, will affect the radiance and spectrum of urban skyglow," he said. 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. Note: this box searches only for keywords in the titles of encyclopedia articles. For more details, see the article on arc lamps. Low pressure mercury vapor lamps are widely used for generating ultraviolet light, for example for industrial processes with UV curing or UV lithography, or for the sterilization of water. It is often exploited that the gas tube does not need to be straight, but can be bent to form letters or other symbols. There is now a very wide range of discharge lamps available, with essential parameters like output power and pulse durations varying by orders of magnitude. In some cases, e.g. For example, one may exploit energy transfer processes between different species. plasma. Commonly, we separate them in 3 basic categories: High pressure discharge lamps, Low pressure discharge lamps and High-intensity discharge lamps. 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 high operation pressure has two particularly important consequences for the performance: Further consequences are a high operation temperature of the discharge, which together with the high density implies that one is operating in the arc 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. By submitting the information, you give your consent to the potential publication of your inputs on our website according to our rules. A problematic aspect is the substantial content of the poisonous mercury, which is sometimes released into the environment when a lamp explodes – which is not a rare event due to the harsh operation conditions with high temperature and pressure. The discharge is usually in the glow discharge regime. However, there can also be problems with contamination of the gas filling (e.g. The history of gas-discharge lamps began in 1675 when French astronomer Jean-Felix Picard observed that the empty space in his mercury barometer glowed as the mercury jiggled while he was carrying the barometer. Physics labs of yesteryear as well as today have use of a variety of gas filled tubes used for numerous purposes involving light generation including spectroscopy, materials analysis, studies of gas dynamics, and laser pumping. That can be achieved in high pressure lamps (see below) by operation with high enough power density. Upon startup, that must be achieved by applying an electrical voltage which is sufficiently high for ignition, often using an auxiliary electrical circuit. For example, illumination of pieces of art is generally more sensitive in that respect than lighting in households or industrial settings. That is fully acceptable or even advantageous for illumination (lighting) purposes, for signal lights (e.g. At Gas discharge lampsare the lamps for disco, photo, film and theatre. Since 2015, more and more of them have been phased out due to the harmful substances they contain as … Please do not enter personal data here; we would otherwise delete it soon. Somewhat surprisingly, the ignition electrode (trigger electrode) may even be placed outside the glass envelope. 1 synonym for gas-discharge lamp: electric-discharge lamp. in cinema projectors), one may require a full body protection. Some auxiliary gasses, used to improve the performance in some respect, may not be mentioned by suppliers, perhaps even kept secret. If you like this page, please share the link with your friends and colleagues, e.g. 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. Some gas discharge lamps can have very long lifetimes of thousands of hours or millions of flashes in case of flash lamps. Traditionally, gas-discharge lamps are used in industrial settings as well as retail. for laser pumping, usually require liquid cooling, in most cases with a turbulent flow of demineralized water, e.g. Due to their relatively poor luminous efficacy and short lifetime of the graphite electrodes, and also because of the rapid contamination of nearby optical elements, carbon arc lamps have become largely obsolete. My friend wants to power one with some battery arrangement, but it normally just plugs into a socket with 120 V 60 Hz. for advertising signs. On this page you can find a variety of Gas Discharge Lamps. 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. It addresses many questions: © RP Photonics Consulting GmbH      All rights reserved worldwide. Sorry, we don't have an article for that keyword! When the electrodes establish a potential difference, the gas gets ionized. With forced air cooling, one can accelerate the heat transfer. The quasi-monochromatic emission of some low pressure lamps makes them useful as spectral lamps for applications in spectroscopy, for example. Gas discharge lamp basics The use of electrically excited gas discharges significantly predates the invention of the incandescent lamp. While that effect can be minimal for modern fluorescent lamps, allowing many thousands of switching cycles during the lifetime, it can be serious for metal halide lamps, for example. That is most problematic for inefficient lamps, but gas discharge lamps actually often belong to the most efficient light sources available. One may then reach only a few hundred hours, or even only tens of hours. These lamps contain noble gases like: argon, neon, krypton and xenon. The glass may also reach temperatures around 900 °C. Lampu Gas Discharge (Neon, Merkuri dsb.) That works only for high enough current densities, which implies that gas discharge lamps can generally be dimmed only to a limited extent, if at all. The fluorescent lamp is probably the best known gas discharge lamp. See the article on fluorescent lamps for more details. Gas-discharge lamps are a family of artificial light sources that generate light by sending an electrical discharge through an ionized gas. Traditional arc lamps have basically always been carbon arc lamps, where graphite electrodes were operated in air. 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. During the lifetime, there is often a significant gradual loss of radiant flux. In other cases, one uses much higher pressures, e.g. Therefore, one sometimes needs to use different metals for a feedthrough and an electrode, which are soldered together for getting a good electrical contact. These lamps work in combination with a ballast, therefore it is not possible to exchange power. Some of them contain poisonous materials such as mercury. A wide variety of gas discharge lamps options are available to you, such as base type, bulb type, and power. That includes noble gases like neon, helium, argon, krypton and xenon as well as various molecular gases like hydrogen, deuterium, nitrogen, oxygen or carbon diode. Some amount of flicker (variations of limited power and its spatial distribution) is frequently observed due to instabilities of the gas discharge. for producing high-radiance light. Many lamps can simply be operated in air, with no special cooling of the lamp envelope. There are also cold cathode lamps where the electrodes can be relatively cool, and field emission is exploited. In high pressure discharge lamps, the applied gas pressure may still be below atmospheric pressure, e.g. It is often unwanted and minimized through proper design. xenon) one obtains a wide range of lines throughout the visible region and including the ultraviolet. That works particularly for flash lamps which are operated with low repetition rates. Therefore, they are often based on simple gases like xenon. There are also high pressure mercury lamps generating ultraviolet light for applications like photolithography. 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. Although lamp-pump lasers have been replaced with diode-pumped lasers in many areas, they remain superior, at least in terms of cost, particularly for some applications requiring high pulse energies in combination with moderate pulse repetition rates. Without the booster, the impedance would not have been sufficiently reduced. They are used in electrical switches, for example, for indicating the “on” state, or elsewhere just to indicate that line voltage is available. If you wish to receive personal feedback or consultancy from the author, please contact him e.g. There is a wide range of different sockets, adapted to different operation voltages and powers. Unfortunately, I do not know what kind of circuits they used. For operation with a constant drive voltage, that behavior would be potentially catastrophic, since the lamp current could rapidly and strongly grow. for high pressure sodium vapor lamps, special envelope materials are required which can withstand the extreme chemical reactivity of the used vapor. As explained above, low pressure lamps typically emit a line spectrum, while high pressure lamps tend to produce a continuum spectrum. Gas Discharge Lamps. Of course, those categories are overlapping. When such a lamp is broken, and the mercury content is released into the air, that will usually not lead to acute poisoning. Gas discharge lamps are a family of artificial light sources (or lamps). Italian: All italiano: Luci al neon e altre lampade a scarica : Japanese: All 日本語: ネオンサインと放電ランプ: Kazakh: All Kazakh: Неон жарықтар және басқалары разрядтық жарықтар: Korean These, however, are not called lamps. See also: arc lamps, flash lamps, metal vapor lamps, metal halide lamps, high intensity discharge lamps, xenon lamps, spectral lamps, fluorescent lamps, signal lamps, lamp power supplies, color rendering indexand other articles in the category non-laser light sources. The excitation current through the gas is in most cases applied with two electrodes, which are typically placed at two opposite ends of a glass tube containing the gas. 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 an electric current is sent through the gas, electrons collide with atoms of the gas and the metals. 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. They require a substantial operation voltage (tens to hundreds of volts), but only a rather small current, and are reasonably efficient. Particularly some low pressure lamps, emitting only a few such lines, are relatively poor in terms of color rendering. (Please enter the sum of thirteen and three in the form of digits!). With modern electronics, lamp performance can be substantially enhanced. Therefore, lamp lifetimes of many thousands of hours are often achieved. RF interference is another matter – it just depends on the used device. For startup, one generally requires a high-voltage trigger pulse, and sometimes an additional booster pulse. In the context of lighting, the quality of color rendering is often of interest. For some applications, bent shapes are required, e.g. A lamp envelope should be well transparent for the emitted light, mechanically sufficiently stable for high reliability and resistant to the experienced temperature changes, the gas pressure and to the applied gases or vapors. Typically, such lamps use a noble gas (argon, neon, krypton and xenon) or a mixture of these gases. One therefore often uses tungsten electrodes, being particularly resistant to high temperature, and which are possibly treated for more efficient electronic mission.

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