![]() These areas include gymnasiums, large public areas, warehouses, movie theatres, football stadiums, outdoor activity areas, roadways, parking lots, and pathways. HID lamps are typically used when high levels of light over large areas are required, and when energy efficiency and/or light intensity are desired. The amount of gamma radiation produced by the isotopes that can escape from the lamp is negligible. Moreover, the presence of thorium in electrodes reduces the work function which again results in easier arc starting and sustaining. High ionisation makes arc starting via Townsend avalanche much easier. This radiation causes high ionization inside the lamp without being able to escape from the lamp. These isotopes produce ionizing radiation of alpha and beta type. The thorium, which is a solid, is used in the electrodes. Krypton-85 is a gas and is found mixed in with the argon, which is in the arc tube of the lamp. These isotopes help start the lamps and improve lamp operating characteristics. Some HID lamps make use of radioactive substances such as krypton-85 and thorium. Experiments show promising results and widespread future applications are expected. Replacements for the toxic mercury in the HID lamps have been investigated and are a matter of ongoing research. The method used to initially strike the arc varies: mercury-vapor lamps and some metal-halide lamps are usually started using a third electrode near one of the main electrodes, while other lamp styles are usually started using pulses of high voltage. Like fluorescent lamps, HID lamps require a ballast to start and maintain their arcs. New color-corrected versions producing a whiter light are now available, but some efficiency is sacrificed for the improved color. High-pressure sodium lamps tend to produce a much whiter light, but still with a characteristic orange-pink cast. This makes them particularly effective as photographic safelights. They produce a deep yellow-orange light and have an effective CRI of nearly zero items viewed under their light appear monochromatic. Low-pressure sodium-vapor lamps are extremely efficient. Metal-halide and ceramic metal-halide lamps can be made to give off neutral white light useful for applications where normal color appearance is critical, such as TV and movie production, indoor or nighttime sports games, automotive headlamps, and aquarium lighting. However, mercury-vapor lamps are falling out of favor and being replaced by sodium-vapor and metal-halide lamps. Originally they produced a bluish-green light, but more recent versions can produce light with a less pronounced color tint. ![]() Mercury-vapor lamps were the first commercially available HID lamps. The light-producing element of these lamp types is a well-stabilized arc discharge contained within a refractory envelope arc tube with wall loading in excess of 3 W/cm² (19.4 W/in²). ![]() Various types of chemistry are used in the arc tubes of HID lamps, depending on the desired characteristics of light intensity, correlated color temperature, color rendering index (CRI), energy efficiency, and lifespan. Construction Diagram of a high-pressure sodium lamp A high-pressure sodium lamp, Philips Master SDW-T 100W Many modern vehicles use HID bulbs for the main lighting systems, although some applications are now moving from HID bulbs to LED and laser technology. However, the lumen output of HID lighting can deteriorate by up to 70% over 10,000 burning hours. High-intensity discharge lamps are a type of arc lamp.īrand new high-intensity discharge lamps make more visible light per unit of electric power consumed than fluorescent and incandescent lamps, since a greater proportion of their radiation is visible light in contrast to infrared. Its presence in the arc plasma greatly increases the intensity of visible light produced by the arc for a given power input, as the metals have many emission spectral lines in the visible part of the spectrum. Once the arc is started, it heats and evaporates the metallic admixture. The noble gas enables the arc's initial strike. This tube is filled with noble gas and often also contains suitable metal or metal salts. High-intensity discharge lamps ( HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. Type of electric lamp/bulb 15 kW xenon short-arc lamp used in IMAX projectors
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |