From CRT to Electron Gun

6 10 2011

This post is dedicated to Steve Jobs. Hero, and inspiration to all.

All photos.

I bought a second CRT; broke the vacuum by drilling an unused pin; scored it and smashed it!

Now we have an electron gun:

I installed it in the chamber and wired it up:

Here you can see down the beam line to the hot cathode.

I taped a piece of broken phosphor screen on the viewport so I can see the electron beam:

But something is not working, no beam.

Time to troubleshoot.




11 responses

6 10 2011

Look up oxide-coated hot cathodes, which are sensitive to being exposed to air.

6 10 2011
Mark Suppes

The cathode was not heated in air.Although it was exposed to air at room temp.

6 10 2011

Taped to the inside or the outside? You sure those electrons are getting through the viewport?

6 10 2011
Mark Suppes

It’s attached so the electrons would directly hit the phosphor powder.

6 10 2011

is the phosphor powder oxygen senstive? This guy uses fluroescent lamp powder:

6 10 2011

oh nm, it’s obvious from the pics.

6 10 2011

You need a positive connection to the phosphor, It has a conductive coating, otherwise the coating / conductor charges negatively and repels the incoming electrons. Perhaps copper tape would make the best connection.

7 10 2011

i always thought the front of the screen ‘pulled’ the electrons to it via a grid once the were focussed by the electron gun.

on the inside of the screen there should be a conductive grid, and the holes in the grid is what you see on a tv screen as ‘pixels’
not 100% sure though

7 10 2011

I was curious about this problem so i did some websurfing. While I didn’t find an answer your quandary, I did find an interesting website, which I am passing along in case you didn’t know about them. No idea of the $ involved in having a electron gun made for your application, but maybe an engineer at the firm would be willing to help you troubleshoot your improvised solution.

13 10 2011
Remy Dyer

Hmm. What vacuum are you getting?

I’m not sure about the exposed insulation and heat shrink – might they outgas enough to add a virtual leak?

5 12 2011
Just Look at this Print « Prometheus Fusion Perfection

[…] I tesed out the electron gun and I didn’t see a beam on the phosphor. I wanted to rule out the possibility that there WAS […]

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