I have this idea in my head so i woul'd like to know if you think its possible / good idea.

What about use clear fluorescent tube, like UV germical, and use a fixture with the front glass cover of phosphor.

Adventage ? I principally use fluorescent for lighting movie shooting, so we often change tube for change the color temperature, so just change a glass could be faster, and don't need to carry many tube all the time.
We also use tube with good CRI, so that expensive, by keeping the phosphor we can keep the CRI and the possibility of a good CRI for tube who don't have more than 80 (like for induction, i'm shure a chinese company can make me a without coated tube)

This is only phosphor who make the cri or the gas inside import ?
The light decrease come from gas/electrode or from phosphor ?
What is the lifespan of a <90 phosphor ?
The glass of the tube will not stop UV ?
What kind of glue can be use for put phosphore on glass ?

There would be three major problems:
- The short wave UV emitted by the discharge is blocked by the air (more accurately the oxygen in the air), so the efficacy of the system would be poor...
- You would need a material transparent for these short wave UV for the discharge tube wall, what is everything, but cheap and mechanically robust...
- The short wave UV blocked by the oxygen break oxygen molecules and let them form an ozone, what is quite poisonous...

And others: I'm not sure, how stable are the available phosphors in the presence of oxygen, moreover in the way more aggressive single atomic and ozone form...

In the bottom line, such setup would be at least way less practical then few separate fluorescent tube sets...

Wow so that clearly not possibly !

Thanks, i don't know that uv in fluorescent was so low, and the air can block UV...
It was nice in my head

I think it can be mae like this :

Use a germ lamp as the arc tube

Add sleeve like the fridge lamps in the supermarket that has 2 walls and contains the phosphor between them



Now either :

Make it all of quartz (probably very expensive and fragile)

Make seal beteen the inner quartz tube and the outer glass tube, which i dont know whether is possible

Apply the phosphor the outside of the inner tube, instead of the inside of the outer tube, so that oxygen between them won;t be between the UV and the phosphor, and seal with cheap epoxy / silicone resin / etc just to prevent deterioration of the phosphor and not to prevent oxygen



Now either :

Make the sleeve and germ tube tight fit together to minimize the amount of oxygen between them

Add gaskets to the caps so that you can seal the space between the tubes (not for long, but just for long enough), and add small hole with valve on either end. When the tube is assembled, you hold it vertically, and connect a CO2 refill can from a soda machine to the bottom end, and press the valve on the top end, to evacuate the oxygen and fill with CO2 instead (assuming that CO2 i not problem for the UV, it is just arbitrary gas i thought of that is widely available and not explosive)

@Ash: But the requirement was to have a setup, where the phosphor coated part would be readily replaceable like regular color "gels", so any sealing is out...

The tube containing the phosphor is made of 2 walls, and the phosphor is sealed between them. Then the germ lamp is inserted into the tube
(much same as the old LPS lamps where the arc tube can be removed and replaced, now imagine the outer 2-wall tube containing phosphor inside it)

Sealing between the germ lamp and the tube does not have to be perfect (as in glass fusing) - a gasket would be enough, and filling the atmosphere is as easy as filling gas into a lighter and can be done in seconds by the user, but with non-explosive gas like CO2. When the tube is to be replaced, the end cap is pulled off and CO2 released (no implosion since it is in 1atm pressure anyway)

But then for each color you would need separate sleeve tube - not much help from having separate complete fluorescent lamp.
The idea was about using flat glass, what you may store many pieces in one small stack (like the gels)...

Instead of tube, seal it as a flat panel (like monochrome LCD)

The light fixture is a floodight containing the germ lamp, the front glass of the floodlight is quartz, and is filled with CO2, or he entire rectangular optic unit is a sealed lamp with "proper" lamp atmosphere in it

The filters are attached to the front glass so that they lay flat against the glass, with minimum air between them

And over all this, a glass shield is closed which blocks any remaining UV

the phosphor must be very close to the discharge to work well.
all around best bet is several sets of tubes in the needed color temp/cri.

I've actually been going to try Ash's idea for a while now. With the rare earth phosphor shortage, manufacturers might need to find some way to reuse the expensive phosphor, and applying it to a separate tube is one option I am exploring.

Hum, so as you say Ash, it's seem possible, but more expensive and complicated than just buyng regular tube and change it...

I've actually been going to try Ash's idea for a while now. With the rare earth phosphor shortage, manufacturers might need to find some way to reuse the expensive phosphor, and applying it to a separate tube is one option I am exploring.

I think it would make ANY lamp expensive, so it would force makers for longer life, so less amount of lamps needed...
Second step would be consistently and thoroughly recycle spent lamps - they would become valuable secondary raw material...
But that may bring effect appearing with metals: Thefts of things made of something, what could be sold to scrapyard...

Why not add a "lamp return value" cost to the lamp : You pay it when you buy the lamp, and get it back when you return it EOL

Why not add a "lamp return value" cost to the lamp : You pay it when you buy the lamp, and get it back when you return it EOL

We use that system for pop cans here in Michigan and it works very well! A simple deposit is a good idea if you had a good reason for consumers to return spent lamps. This might be a good way to encourage lamp recycling as well as phosphor recovery.

You can recover everything from the lamps, since the materials are in high concentration, just filter : Phosphors, mercury, filling gasses, glass, electronics . . .

And speaking of electronics, i think an end must be put to self ballasted CFLs where you have to throw away the entire lamp instead of replacing just the tube