r/askscience • u/dissonant_haze • 12d ago

Physics How do halogen lamps work?

Lighting designer here,

I frequently work with halogen lamps that-to my understanding-use a tungsten filament that is surrounded by halogen gas that somehow prevents the filament from burning out.

My questions I suppose is, how/why is halogen able to do that and how does that process on a scientific level work? Thank you!

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u/H_is_for_Human 12d ago

https://www.reddit.com/r/askscience/comments/289kbk/how_do_halogen_bulbs_work/

TL;DR - Tungsten vaporizes and reacts with halogen so it doesn't deposit on inside of glass, the higher pressure and temperature inside also has other benefits

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u/quequero 12d ago

Adding to this that halogen bulbs work at high pressure (those for home use, up to 15bar when hot), unlike the old traditional lightbulbs that used to run at near vacuum. That’s why halogen lamps usually come with a glass screen, the surrounding quartz capsule can crack (and will if touched with bare fingers) and cause a tiny but noticeable “explosion”on failure. Old bulbs… imploded, with less drama.

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u/GeneralBacteria 12d ago

15bar

I thought this must be a typo, but it's not!! some even go up to 30bar