Incredible Homemade Plasma Discharge Tube - Part 1

Ask any questions in the comments. This may be considered a "rarified arc in a vacuum" but it still demonstrates some properties of a cathode ray tube.

[ScienceMarshall]

If you’re going to make a comment about this not being an actual CRT or that this is generating X-Rays, please don’t! Those topics have already been thoroughly covered in this comment section. This is not a CRT going by the common definition of what a CRT is. I know that now. I made this video many years ago while I was in middle school and certainly didn’t know everything about these topics. I did make an actual cold cathode CRT with a phosphor screen later, if you’re interested in seeing that just look at my later uploads.

This does not produce X-rays. Neither the vacuum nor the voltage are high enough to do that, and I have confirmed this with a Geiger counter.

[MagmaSloth]

This has got to be one of the coolest videos on youtube. I firmly believe that a passionate DIY attitude and a maker mindset can save the world! I've been looking for a way to build a diy plasma discharge tube for experimentation and you've demonstrated just how simple it can be with a stroke of pure genius oozing with creativity. You're most certainly tapping into infinite intelligence and I'm grateful you've shared this ^^

[gertbenade]

Thanks for a great video. No high-tech equipment needed! Always remember to keep one hand behind you back when working with high voltages!

[robmckennie]

This project is pure awesome. I'm definitely going to have to try this, sorry to disregard your instruction not to. My current long term ambition is to build a SEM in my home machine shop, but I figure this is as good a place as any to start. Thanks for the video!

[OmarTheDeadAziz]

people like u are who understands voltage & currents compressors radiators & transformers, are handy to have around

[Kempmaurice]

I finally have a basic understanding of CRT's. Thanks for posting.

[michaelbuchholz]

There are already some comments, that say, this isn't a CRT. Well.. They are right. A CRT needs more vacuum or else, the flowing electrons will iodise the remaining gas and that will produce light - mostly UV, but also some visible.
An electron ray in an absolute vacuum is invisible. It can only made visible, by putting some phosphor on the glass, which will glow, when hit by electrons.
This effect has been used for decades, to produce TV-Screens.
Also, a real CRT only works, if the electron emitter is hot, or else, no electrons can leave it.
A glowing wire has a tiny cloud of free electrons around, that can be accelerated by high voltage. That's the principle, all CRTs use. Is it a TV-Screen or those smaller amplifier tubes, you find in old radios or TVs. Also in sone shops, that sell beyond-hearable-HiFi amplifiers.

But aside of that - nice experiment. Becareful - this time, you have just been lucky, not to been hit by high voltage. Next time, use a plastic stick for that magnet.
Add a video, that shows us your hair, after been hit :-D

[Strike_Raid]

Agreed, that’s a plasma arc. Cool anyway. The X-Ray warnings are more than just a little overblown for 15 kV and stainless steel target but if you ever see a green or greenish glow inside (usually right at the target), turn it off. Also, don’t make the target wire in a loop like that, make an ‘L’ shape (pointing toward the ‘cathode’ in the center). You don’t want that hot plasma getting near the glass like that, it could easily crack the glass and the whole thing will implode. Be sure to always wear goggles, glass and vacuum equals trouble.

[NerokoMimi]

Although I am really bad at homemade stuff, I'll give it a try!
We made a cathod ray tube in my school chemistry lab but I need one at home, too since its so freaking amazing *^*

[tihzho]

Firstly you DO NOT have a cathode ray tube, you have a glass envelope evacuated to a rough vacuum to allow current to flow between the electrodes.
Atmospheric pressure in millibars is 1015. A refrigerator compressor as a vacuum pump can achieve at best a vacuum (called ultimate vacuum) of 300 to 400mbar which is a low vacuum.

A single stage rotary vacuum pump has an ultimate vacuum of around 1x10-2mbar while a two stage rotary vacuum pump is around 1x10-3mbar.

A cathode ray tube has a vacuum at least 1x10-4mbar which is beyond the range of a rotary pump and operates on high voltage DC.

To achieve higher vacuums a good 2 stage rotary pump backing a diffusion pump or a turbomolecular pump which can be expected to achieve 1x10-6mbar. There is of course outgassing from the vacuum chamber which will degrade the ultimate vacuum.

[Badger]

I am learning about Cathode Ray Tubes, which play a significant part in x-ray machines. Wilhelm Roentgen must have suspected that other things were being emitted from cathode rays so he put a piece of black paper around his CRT and directed the cathode ray towards a photographic plate. He put his hand between the CRT and the photographic plate and saw the bones of his hand; fascinating! That would be a real challenge for a do it yourself physicist - to recreate that event!

[曾俊維-tg]

really cool and useful
I ve never seen the cathode ray tube by AC before.

[BecauseWeCanTheChannel]

Amazing video, as always.  Love this channel.

[straylightOz]

nicely done, really good work. Cunning use of the fridge compressor. I'm guessing a CRT flyback transformer can be used in place of the oil heater explanations and commentary as well. Very impressed. Thanks for making the vid.

[seerlifee]

Omg! This is soo cool. Jeez, made me like studying my chemistry chapter.

[jeewankhanal]

Good ! Easy way to make cathode discharge and effect of a magnet on it.

[gnormhurst]

Cool. I think what you may be seeing is an ion plasma arc due to the remaining gas in the bottle. Very interesting experiment. Y'ALL BE CAREFUL WITH THAT HIGH VOLTAGE. You don't want this to be your last experiment.

[frankpitochelli]

Very good, but, it's more of a high voltage controlled arc, which is basically what a CRT is, it would be cool if you could phosphor the end of the glass and put a signal on a control grid...
But, hats off to you for a very cool experiment.!

[vimalvestron]

in school science class i used to wonder how those rays actually look... well.. they look amazing..

[qwertykeyboard]

Dangerous, in multiple parts, and homemade, perfect for YouTube!