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The sulfur lamp (also sulphur lamp) is a highly efficient full-spectrum electrodeless lighting system whose light is generated by sulfur plasma that has been excited by microwave radiation. They are a particular type of plasma lamp, one of the most modern. The technology was developed in the early 1990s, but, although it appeared initially to be very promising, sulfur lighting was a commercial failure by the late 1990s. Since 2005, lamps are again being manufactured for commercial use. ==Mechanism== The sulfur lamp consists of a golf ball-sized (30 mm) fused-quartz bulb containing several milligrams of sulfur powder and argon gas at the end of a thin glass spindle. The bulb is enclosed in a microwave-resonant wire-mesh cage. A magnetron, much like the ones in home microwave ovens, bombards the bulb, via a waveguide, with 2.45 GHz microwaves. The microwave energy excites the gas to five atmospheres pressure, which in turn heats the sulfur to an extreme degree forming a brightly glowing plasma capable of illuminating a large area. Because the bulb heats considerably, it is necessary to provide forced air cooling to prevent it from melting. The bulb is usually placed at the focus of a parabolic reflector to direct all the light in one direction. It would be impossible to excite the sulfur using traditional electrodes since the sulfur would quickly react with and destroy any metallic electrode. A patent pending to employ coated electrodes is discussed in Future prospects below. The absence of electrodes allows for a much greater variety of light-generating substances to be used than those used in traditional lamps. The design life of the bulb is approximately 60,000 hours. The design life of the magnetron has been improved by the Germany/England based Plasma International so it can also last for that same period. The warm-up time of the sulfur lamp is notably shorter than for other gas discharge lamps, with the exception of fluorescent lamps, even at low ambient temperatures. It reaches 80% of its final luminous flux within 20 seconds, and the lamp can be restarted approximately five minutes after a power cut. The first prototype lamps were 5.9 kW units, with a system efficiency of 80 lumens per watt.〔Compare this to 12–18 lumens per watt for conventional tungsten incandescent light bulbs.〕 The first production models were 96.4 lumens per watt. Later models were able to eliminate the cooling fan and improve luminous efficacy to 100 lumens per watt. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「sulfur lamp」の詳細全文を読む スポンサード リンク
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