Here 6000/6500K is the most common everywhere - Homes, businesses, etc. Seems that outdoor lighting is the biggest exception, there the most common is 4000

It does make sense that for people who generally prefer the 6000K-colors, to give them some fine tuning option around that spot, and not far off color options which they won't use. If you want 3000/4000K you'll just get the other tube with the other set of colors



Personally for me :

I use 6500K Halophosphor Fluorescents throughout my workshop and they are great, even when i am there for very extended periods

At the same time i think LEDs of any color temp are plain unfit for purpose (all of them by awful spectrum, >3000K additionally by amount of blue light, and <3000K by color temperature)



The extreme edges of available LED colors ("white" temperatures) - <2000K and >7000K are a bit of special cases :

6000K is a pretend white light. It is white enough in appearance to make us think it is normal light, while in reality it is anything but. Blue light aside, it lacks the central band of spectrum that we are the most sensitive to - Green. My understanding is that looking at things under the light, some things will appear off, and our vision intuitively will feel stuck, unable to figure out why nothing looks right, despite it being white and apparently all colors are there. This may not be too critical in some applications, but probably not good long term in most places

7000K is so far off the scale that the vision easily writes off everything it misunderstands to the lighting and isn't bothered with it. The only problem with it is then the blue light

2000K is "not white" enough that we don't put high expectations for color rendering with it either, and in 2000K the amount of blue light is low. This may actually be one LED color with no significant drawbacks, except it is not appropriate for a lot of places

You can get an idea of the spectrum of different materials by burning them in fire. That's how it's been done in spectral sources for centuries before electrical lighting became a thing



Arc confinement does not equal vapor confinement. The vapor will still be all over the place :

 - You got to have enough supply of the material so there is enough of it where the arc is supposed to go, despite the material continually getting away from there. That's basically how a carbon arc lamp as well as several welding processes work - There is no confinement at all, the arc medium is a consumable

 - If there is confinement, you got to do something with the material (especially metals) which will tend to concentrate and condense in the colder areas, so it doesn't coat the insides of the confinement and obstruct the light, drown and short circuit the electrodes, do unwanted chemical reactions and so on



The thick quartz wall proposed in itself is a problem. The quartz will expand. If it is thick enough, there will be significant differences in expansion between the inside and outside regions of the quartz block, which will build very high strain

It will probably be able to explode through even massive solid blocks of quartz (in a similar way to how huge rocks are blown up with fairly small explosives placed in a small drilled hole). I wonder if the end result (when such massive block explodes) will have enough force to obliterate lanterns completely

If not, then at some point i think it will start cracking and breaking parts of the quartz wall inside the arc volume, creating a network of new cracks and voids which essentially become the new arc volume. The new volume may deviate enough from the electrodes to make the arc extinguish, but if it doesnt, it will continue the same process from the new position (and probably faster, with radial cracks propagating to the depth of the quartz from where it happened)

6000k is a temp you will rarely see used in homes and businesses, but rather primarily out in street lighting, and even then, thankfully, we are seeing many realize the error in their ways and cutting back to less bluish colors such as 4000k, and in the case of the local municipality here, going to 3000K in the residential areas which looks great with the right lumen selection. I myself have replaced a number of 5000 and 6000k parking lot fixtures due to the complaint of too much blue, or from complaints from residents nearby and also staff.  Same goes for inside the buildings, when initial Fluorescent to LED upgrades were made, they (the facilities managers and lighting contractors) went with 5000K "daylight" as it was used commonly thought that was going to be great for brightening things up, but resulted in complaints of eye strain and headaches from employees/owners and what not. Apparently even a few employees would wear some form of sunglasses it got to be so bad for them-  When I installed 3500K (and in some cases even 3000k) higher lumen LED to replace those 5000K in the office areas, the feedback was always good, and I would put a higher lumen 4000K in the warehouses and again, "much better!" "It doesn't hurt my eyes anymore" responses from employees and management.  The right color temp for the environment and the right lumens matter.   

As for the color selectable tubes/bulb-  My argument was for having the more commonly used colors more. such as 3000, 3500, and 4000.  You will see warm colors in homes, and rightfully so - most folks prefer a warm welcoming and relaxing colortone in their homes. 

We are now seeing more of these color select bulbs offering more options including the most important colors, 3000, 3500, 4000. (and perhaps 5000)  and a few now with 6500 included as technology has improved. Take the link from the place I get bulbs from as example.  Hopefully the big box stores will provide lamps with more selections soon, instead of just 4000, 5000, and 6500.  Some stores will have 3000, 4000, and 5000.  Some will have 3000, 3500, 4000, 5000.  But those are rare.  Hopefully getting to be more common.  Back in the days of the T12, 3500k was a color that was extremely rare and we never saw a lot of, but when T8s came out, the popularity of the 3500 really spiked and was favorable. Especially when the color correction 900 series came out.  I'd still be using those today if fluorescents were not banned in Colorado, forcing my clients to have to do an initial costly upgrade to LED (extra labor to eliminate the ballasts/ballast bypass as plug and play is not a good idea for most applications due to the ballast being a future failure point)

https://www.1000bulbs.com/product/224832/PLT-50305.html

It looks like an overgrown Sunflower seed.

I know for a fact that we can get to at least the boiling point of thallium metal (in Tl spectral lamps), which is 1500C at atmospheric pressure. But even metals like tin and lead have higher boiling points than that, 2600C and 1750C respectively. Zinc has been used in spectral lamps, and you would think that it's boiling point would be higher than tin and lead but it is only 900C. Even gallium has a boiling point of around 2400C. Anything higher than 1600C will soften quartz, anything above 1750C will soften alumina (so lead is probably excluded). Making the metals into iodides makes them boil at lower temperatures, but that's just a MH lamp, not very original. But:

What I would love to see is a potassium SOX lamp (POX?). The boiling point of potassium is a little lower than sodium, and the same two-ply glass would probably be able to work for it. Maybe even having a mixture of potassium and sodium in the lamp, because potassium makes purple and sodium makes yellow and yellow+purple might equal white-ish. Or maybe you can just add a small amount to increase CRI a little. I think this would be very interesting to see.

As to the colors produced by the metals, I have had an okay amount of luck using ChatGPT to generate HEX codes for different metal plasmas, but I doubt that is very accurate. I really don't know how else you would tell, because just looking at a spectrum distribution is not so easy.

As to electromagnetic arc confinement, I would think it would still rely on the coldest spot temperature of the arc tube, but I am unfamiliar with that concept so I don't really know. I would think that for a few seconds you can vaporize almost anything (before the arc tube explodes), but I could be wrong.

My understanding is that not a lot of substances are suitable for arc lamps, and we tried most of them. The only seemingly practical idea that I have come up with has been potassium, but I can't say I have been trying super hard to come up with one. I am sure there are some things that we haven't tried yet. Look into it more, I would like to hear more ideas. I might make them into drawings if they are very unique.

There have been a few already installed around in France and visible in google maps' streetview, i'll send a few links as examples.

Bois-Colombes, France

Eaubonne, France

Eaubonne, France (again)

Mercury and sodium have higher vapor pressure and low vaporizing temperatures. Other metals have lower vapor pressure and higher vaporizing temperatures.

So we have sodium and mercury lamps. Which heat up a vaporize said metals to form plasma arcs.

What is stopping us from upping the heat and vaporizing say... copper, iron, tin, maybe even uranium, gold, lead, Into a plasma arc?

What colors would be produced by such vaporized metals?

I am sure there is alot of fundamental knowledge I am missing. But from my understanding with a thick enough quartz wall and large enough electrodes or electromagnet, it maybe possible to vaporize anything into a plasma state for atleast a short while yes?

I am assuming this has been done somewhere. But I am having trouble finding examples on the web. And finding pictures of said discharges is hard because alot of the search engines also pull up pictures from movies/news articles/market listings for unrelated stuff.

The most important thing in light color/temperature (and light source technology !) is diversity. You may not like 6000K..6500K lights, but the fact they exist and are installed somewhere, make 2700/3000/4000K lighting in other places not be taken for granted, which is an important part of the lighting looking good

I’ve found they only tend to stay white longer as they age?
When new all sizes to me have the same ‘white’ time when running up.

That is correct.  Especially for high pressure sodium. 
Some brands will start up and warm up quicker as well.  Sylvania would warm up fairly quickly versus GE which wasn't bad.  Philips seemed to take a little longer.