29 Sep
2012
29 Sep
'12
12:39 p.m.
I don't remember how the halogen cycle works in
those bulbs...you
probably do; would that not address the corrosion issue in that case?
My understanding is that te the tempearture of the envelope, the halogen
reacts with any tungsten that may have evaporated there and forms a
volatile tungsten halide. This then ends up on the filalend where it is
decomposed by the heighter temperature there and the tungsten metal
re-depositied o nthe filament.
That's why a quartz envelope is used. It has to get hot.
Surely there is another
element that will emit mostly in the green part of the spectrum?
Neon itself has several green spectral emission lines, hence the
existence of "GreNe" lasers, but they are of far lower in intensity than
the red/orange lines.
Every green gas-discharge bulb I've seen has had a phosphor coating
somewhere, so my assumption (and that's all this is) is that there's not
enough intensity there to be useful.
Yes. Green neons are common, but have phosphor-coated envelopes. I;ve
also seen blue ones, made similarly. There are gasses with strong blue
emission lines, but I guess they're more expensive and/or need a higher
voltage to ionise them than neon.
If there is a gas that will glow green, I guess it's something that's
either exotic, or somethign that attacks the electrodes far too fast.
I've never seen a true green gas discharge lamp.
-tony