Halogen, Xenon, how do they work?

georget98

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How do these technologies work?

I think I read that the halogen (a gas?) causes the tungsten that boils off the filament to redeposit so the bulb can run hotter/brighter. Is that right?

How about xenon. That's usually a gas discharge lamp like a camera flash. But the bulb in my Legend LX appears to have a filament.

Are there any other tricks to getting a brighter filament lamp?
 

CNC Dan

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You have the halogen thing just about right. At some temp. the gas will absorb the boiled off tungsten from the glass envelope. At a higher temp. still the gas will give up the tungsten. Usualy at the hottest part of the filiment. So if a weak spot develops in the filament it will have the highest resistance, be hotter, and have the most tungsten returned to it.

I'm not sure about xenon.
 

Monsters_Inc

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Halogen refers to a group of elements Chlorine, Bromine, Iodine, etc. in the periodic table. I'm sure these elements play the main part in the tungsten cycle.

Xenon is a usually unreactive "noble" gas, so I'm guessing it requires much higher temps to make it react to do its work - and it's evident that xenon bulbs burn much hotter than their halogen or krypton equivalent.
 

Jonathan

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Actually, the Xenon doesn't react at all; the halogen is takes part in the tungsten cycle. The issue is that you can't just have halogen gas; you need an inert fill gas to make up most of the volume and bring the pressure up.

Any of the inert gasses would do the job of taking up space and keeping the pressure up. However the heavier the gas, the lower its thermal conductivity, and thus the more efficient the lamp.

So a halogen lamp is one that has halogen mixed with an inert gas to make the fill. The cheapest inert gas to use would be Argon. Then a Krypton lamp a halogen lamp where the inert part of the mix is Krypton, and a Xenon lamp is a halogen lamp where the inert part of the gas mix is Xenon.

-Jon
 

Marshall Johnson

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Also, a lot of shady companies are just using Xenon as the inert gas simply for marketing reasons.

HID's use Xenon, and many incandescent manufacturers wants to ride HID's coat tails by claiming they sell "Xenon" lights.
 
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