Hi guys,
Im looking for a little advice and direction.

Im trying to put together some element samples to display to my students on a bit of a budget. Spectral tubes are far to expensive for what i want to accomplish

I want some lamps that can show the inert gas colours (al-la 'neon' signs) but with lamps/bulbs/tubes no bigger than 3 - 5 cm. Ideally the same size and shape with neon, argon, krypton and xenon (i know helium is pretty unlikely) ive seen ne-2 neon lamps and these are an ideal form factor.

Do such lamps exist? And can you make any suggestions of where to get them (i am in the UK)

This is the ideal, if not i know i can get a xenon flash tube and ne-2 neon glow lamp, but im a bit stuck on for argon and krypton (and helium).

You guys seem like experts so i would really appreciate any help!

I'm guessing you want to make your students look at these light sources through a spectroscope. I've done it in the past with my students using standard metal halide lamps, during the warmup. In my case, it was the sports hall lighting that I turned on after they had settled and aimed their spectroscopes at unlit fixtures.

If you have such fixtures in your building, you could try that. Otherwise, you can get a protected metal halide lamp and a ballast and you could do it in the laboratory. This works for identifying the light emitted from different ions, not really from different gases, though. Armed with a cheat sheet of the wavelengths of different substances, they should be able to identify them as they appear during the warmup of the lamp.

I'm afraid that what you're looking for is expensive no matter how you look at it.

Fluorescent starters. Take a lot of them (new ones so they are not blackened) from different manufacturers and power ratings, both from your local shops and from Ebay

From what i observed, the brand name ones tend to use Krypton mixes - sometimes with more stuff inside, with exception of Philips S10 which look like Neon with something else added in it. The cheapies from China with Cylinder shaped lamp sometimes Krypton mixes and sometimes quite clean Argon that glows really nice Blue. The older and lower quality cheapies with "random blob" shaped lamp are virtually all Neon. Osram "St111 Basic" (a cheap starter made in Russia for the Russian market, not the European St111) is Neon

They light up nicely in series with a few 10's kOhm resistor on 240V. Pick a resistor with power rating such that it would handle direct connection on 240V

If they start flashing after a few seconds, try a higher value resistor or try to add a 1N4007 diode in series to limit the discharge to the non Bimetal electrode

They don't even need to do that this is more of a matter of fact, "this is interesting that they have different colours" quick demo (hence the very low cost part)

I was hoping for some small bulbs or tubes that could be put ontop of a plasma ball and they would glow or attach to a HT supply so they glow.

The fluorescent starter tubes look an ideal size but I'm after a more guaranteed pure gas fill than the trial and error method that looks like being.

Krypton mixes of varying purity exist in most starters. Just try a few

Argon exists in many Chinese cylinder shaped lamp starters. Basically get a haul of cheap starters from your local cheap stuff supplier and Ebay and test them all, you'll find an Argon one soon

Neon exists in some starters, flicker flame lamps with screw base, and indicators (very small, probably too small for what you want ?)

Xenon exists in Photo Flash tubes and in high pressure Sodium lamps. Both of them will glow in Xenon color when supplied with high voltage at very low currents such as from a Plasma ball. If you are careful to only supply tiny current, you may be able to run the High Pressure Sodium lamp at low enough power to not vaporize any of the Mercury or the Sodium, so get fair enough Xenon color

Helium exists in Helium baloons... Perhaps you can make a short lived lamp by plugging some Helium in a test tube and sucking it to near Vacuum with a syringe. Have not tried and i dont know how clean of Helium discharge you gonna get, but it probably will get contaminated with air and stop working very soon. So if this even works, fill up this lamp right before the presentation

For the argon, you can get Argon indicators, but they are pricey, but a dekatron in violet can be got for a few bucks on ebay and they are argon filled and fairly simple to wire up, with just a handful of parts you can even get them to count..

And depending on how your able to power things up, if you have a small telsa coil you can light up krypton filled bulbs, and lots of cheap bulbs are argon filed. But just throwing it out there I would go and talk real nice to neon shop and see what they would charge for a short tube filled with the gases of your choice,they might not be as much as you think, the real money in neon tubing is when you have to do bending and joining tubes...