Sounds like a "sulphur" lamp from before 1994. They used a microwave source to excite the sulphur bit (turned into a vapor) in a low pressure argon atmosphere. This is a 1960's (discovery) lamp that had a lot of problems containing and exciting the plasma.
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"In this new light bulb, sulfur excited by microwaves emits a bright white light. At the DOE's headquarters, a sulfur bulb at each end of one 240-foot-long light pipe replaced 240 individual 175-watt high-intensity lamps. One Tootsie-Pop-size lamp gives off the same light as more than 250 standard 100 watt incandescent bulbs."
Downside was the cost of the excitation gear - a magnetron and large wattage lamps they were making - the smallest was 1,000 watts and way more light than any single source could use - so they resorted to light pipes and optics to distribute the light and that was too costly for most applications.
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A Tic-Tac-sized lightbulb that gives off as much light as a streetlamp may offer a peek at the ultra-efficient lighting of the future. The bulb, developed by Luxim of Sunnyvale, California, uses plasma technology to achieve its brightness.
The tiny bulb contains an argon gas in the middle, as well as a component called a "puck." The bulb is partially embedded in a dielectric material. When electrical energy is delivered to the puck, the puck acts like an electrical lens. It heats up the argon to a temperature of 6000 degrees Kelvin, and turns the gas into a plasma that gives off light.
The plasma, whose 6000-degree temperature is similar to that of the surface of the sun, also emits a spectrum that looks very similar to the spectrum of sunlight.
The plasma bulb uses 250 watts, and achieves around 140 lumens per watt, making it very bright and highly efficient. By comparison, conventional lightbulbs and high-end LEDs get around 15 and 70 lumens per watt, respectively.
It could be true, but most of the time low voltage products are the winners in such applications even if inferior in efficiency. Low voltage products in general are more reliable. I'd bet on LED technology.
That "puck" bit sounds like a Dielectric Resonant Oscillator. When I google on "DRO Luxim" I get this job add. The bit at the end about Dielectric Resonant Cavities seems to be a tip off. Given that it might not be that high a voltage and/or entirely self contained.
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8/30/2006 RF Engineer
. Design and development of novel resonant cavity structures and circuits including EM simulation and optimization. . Working with a cross functional team to develop RF/Microwave circuits to drive electrodeless lamp systems. . Assist applications engineering in the integration of light sources into Televisions. . Will assist manufacturing in the development of processes for building RF Electrodeless lamps. Required skills and experience: . A solid understanding of RF/Microwave circuit fundamentals. . A good understanding of Electromagnetic theory. . A familiarity with general RF test equipment. . Experience with CAD tools such as Microwave Office or ADS as well as electromagnetic simulation tools such as HFSS or Sonnet. . Knowledge of EMI reduction and FCC testing a plus . Knowledge of resonant structures including dielectric resonant cavities a plus . Effective verbal and written communications and interpersonal skills.
"Greg Neill" wrote in news:47e34a2b$0$7025$ snipped-for-privacy@news.newshosting.com:
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It's a quartz bulb (really more of a thick-walled capsule) embedded in a dielectric which acts as a waveguide for the RF amplifier that energizes it. A similar device using sodium or sulfur has been around for a few years. Doesn't say what the dielectric is made of.
All arc lamps contain an area within the bulb where the gas temperature reach 6000 degrees Kelvin.
There's always a steep thermal gradient in the gas which means that quartz bulb itself doesn't get anything like as hot, and in an electrodeless lamp like this one, there aren't any relatively conductive electrodes close to the arc to conduct heat out to the surface of the bulb.
The efficiency of the lamp isn't going to be all that great - the 6000 degree arc is a black body radiator, so a lot of the radiated enegy is in the near infra-red, and the electroncis to generate the RF that excites the arc isn't going to be 100% efficient either. It would be going to do as well as a conventional fluorescent lamp, but it's probably pretty good as point sources go.
Several years ago there was an article in Scientific American on a company that sells a 1MW xenon lamp. IIRC, it relied on water cooling of parts of it, and would be high overhead to set up and run. The report said that there aren't many takers for that much light, and the main market for it has been sources of radiant energy, eg. for testing spacecraft.
Meanwhile, xenon lamps are the standard light source in movie projectors these days. (very) forced air cooled.
I'll bet that if you read it again, there is another material in it. Neither the arc nor the inert gas sound like an efficient way to go. A low pressure of inert gas and some metal that has a strong radiation line near the blue sounds more likely.
There was a similar microwave excited lamp designed some years back. I think it contained sulphur. I was at the SMUD (power utility) offices in Sacramento about 3 years ago and there were lamps in the lobby using the technology.
Their website doesn't provide much information. However, in their project TV app, they indicate the "lamp" needs 28V. The trouble is that could be just the input voltage to a module, which in turn boosts the voltage.
In technology, evolution generally wins over revolution. Remember how the world was supposed to be all gasfet. Not going to happen. I just don't see RF excited plasma winning out over LEDs.
Sulfur lamps consist of a golf-ball-sized sphere filled with sulfur, quartz, and argon. It is energized by a 5900-watt magnetron similar to that on a kitchen microwave oven. The spherical lamp is constantly rotated at about
600 rpm on a glass spindle surrounded by a jet of compressed air. If the lamp were ever to stop rotating, it would melt within two seconds. The technology is quite similar to a UV light source that Fusion Systems has been selling to chip manufacturers and printers for 15 years. Fusion is planning to release more efficient, smaller models by early 1996, roughly
1000 watts and 140,000 lumens. Lawrence Berkeley Labs is working on a
75-watt version of this for interior lighting. They are also working on making the magnetron smaller by using more solid state electronics. The smaller models will not use cooling air and would spin about 1000 rpm. The technology has the environmental advantage of using no mercury.
The light emitted is reflected by a parabolic reflector into a 10" light pipe made of acrylic, prismatic film. This pipe is almost opaque on top.
The bottom is made of many parallel, curved, reflective grates which catch some of the light and reflect in down and out to the sides. The ration of how much light goes down and how much out to the sides can be varied to meet design needs. How much light goes out altogether varies along the length, with more allowed to pass through farther from the light source and less near the light source, to create more uniform luminance along the length.
The light pipe would therefore need to be purchased in sections, each with specific characteristics. A mirror at the far end of the pipe reflects back any light traveling that far. Smaller models may not use light pipe, either using a more standard fixture or possibly fiber optics. One such application being considered is to install the light on a 7' tall pedestal in an office cubicle area creating a powerful indirect lighting system.
Light output:
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Considering that I know of a CO2 LASER that used microwave RF to excite the gas in the cavity into lasing. Total output power for the IR LASER was 150W and I believe the input was about 10 times that.
It needed a water cooled jacket around the cavity to keep it from self- destructing.
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