DIY Electron Accelerator: A Cathode Ray Tube in a Wine Bottle

Step 10 Fire it Up!

Once you've assembled the vacuum system and connected the high voltage power supply, you're ready for a test.

To begin, simply turn on the power supply and vacuum pump, sit back, and enjoy the show!

At first, a continuous red-purple discharge will appear between the anode and cathode. Then, the two colors will begin to separate until there is a distinctly visible dark space between them called the Crookes dark space. After that, striations in the plasma near the cathode will appear and the colors of the discharge will start to become paler. Finally, the striations and dark space will disappear and the entire tube will be filled with a pale blue/white glow. At this point, you have reached cathode ray tube operation.

Here is a brief document that explains some of the plasma-related phenomena visible inside the tube:
http://www.madsci.org/posts/archives/feb2001/981758142.Ph.r.html

I've included a picture of the tube operating in cathode ray mode and some pictures of what it looks like during the pump down sequence.

Comments

[longwinters]

It would be nice to get rid of the pump, if your seals are good you should be able to pump it down and disconnect it, (unless you like watching the process of pump down,it's quite interesting) You may get a little better vacuum if you warm the bottle to the highest temp. it can tollerate while under vac. then seal it off.

Very nice project being a person who enjoys High Voltage projects this looks like a fun one.

[techno guy]

Is the tube connecting the bottle to the vacuum pump actually glowing or is that a wierd camera illusion?

[Xellers]

Nope, it's not an illusion. I didn't ground the cathode because the NST is already mid-point grounded, so there was a potential difference between the cathode and the vacuum pump. As you might imagine, this isn't too good for the pump, so in later tests, I grounded the cathode and left one side of the NST floating.

[skrubol]

Shouldn't grounding the inlet of the pump take care of any potential damage to the pump?

[Xellers]

The pump is already grounded, so I think that's why the arcing occurred in the first place. I guess there's no real harm done to the pump, but it might cause the vacuum line to weaken. In my original gas discharge tube experiments several months ago, I managed to melt holes in my plastic vacuum chamber multiple times! Of course, that's why I decided to use a wine bottle.

[skrubol]

Ah, hadn't thought about the tubing. Vaporizing/burning too much of whatever polymer that tubing is made of I suppose could be bad for the pump.