using CRT electron beam for something other then display?

[Gyro]

I imagined like sawing open a television with a diamond saw so you can put the front on a hinge with some kinda vacuum gasket and put stuff in there

The other problem is that the emissive coating on the cathode will be destroyed as soon as it comes into contact with air. In manufacture, it is coated with chemical salts and then the final forming is done under vacuum.

I would imagine so long you keep it dry its OK? Guess you would need a dry box to load this up.
...

Nope, it's contact with atmospheric oxygen, not humidity.

[coppercone2]

that is even harder.

Are there any unique masks or something that need to be exposed with electron beam rather then just UV light? paints?

[David Hess]

CRTs can be used for data storage, where the electron beam writes spots to the phosphor and then can be used to read them back.

https://en.wikipedia.org/wiki/Williams_tube

The bistable storage variation would have allowed the data to be retained without refresh.  I have actually seen this occur on my storage CRT oscilloscopes where the previously stored image returns years later when I first power up the storage mode.

[ikrase]

 You would need to seal the tube to a vacuum manifold (the aperture of this should be a significant percentage of the overall size of the CRT) and pump it down (which means a diffusion or turbo molecular pump, and a rotary vane pump to back it). Vacuum is its own whole (very fascinating, somewhat expensive) thing.

There are some cathode coatings which can withstand air, such as those used on ionization gauges that may be exposed to poor vacuums and won't instantly fail even if briefly turned on at atm. Probably those are not the ones used in CRTs.


For people hacking stuff on their own with a box of scraps, I strongly recommend John Strong's Procedures In Experimental Physics from 1938 -- but I recommend you do not make your own blown-glass mercury diffusion pumps. The Fusor Forums are also a useful place for amateur experiments in this realm, even though they are focused, unsurprisingly, on fusion and fusors. Nowadays you can make some use of purpose-built vacuum hardware from ebay -- purchased new, this is $$$.


If you just want to build your own electron beam, this might be easier to do yourself, inside a large steel, copper, or glass vacuum chamber.



Electron beam lithography is used as a no-tooling-required method of extremely fine integrated circuit patterning. I believe the resists used with this are PMMA-based.

That monster with the carts going through it is firing the E-beam through a window made of very thin material (and also tremendously powerful). This device is used for cross-linking plastics "radiation cross-linked PE" wire insulation is made by this method.

[coppercone2]

is the e-beam in a TV capable of any unique process at its normal power level and resolution for manufacturing anything? I just wanna know , I know its not practical to hack such an apparatus

[BrokenYugo]

An electron beam of around color TV energy demonstrated in air.

[calzap]

If you wanted to go to the effort, you could use the backend of a CRT as the start gun of a high-energy accelerator.  And yeah, you’d have to get it out carefully and keep it in an inert atmosphere or vacuum.  The electrons can be accelerated by EM fields or microwaves.  Then smash the beam into a high-Z target to get all sorts of radiation including high energy bremsstrahlung like used in radiation therapy.  But if you had the expertise and finances to construct such a thing, why would you use part of a CRT rather than a custom gun?

Mike

[David Hess]

If you wanted to go to the effort, you could use the backend of a CRT as the start gun of a high-energy accelerator.  And yeah, you’d have to get it out carefully and keep it in an inert atmosphere or vacuum.  The electrons can be accelerated by EM fields or microwaves.  Then smash the beam into a high-Z target to get all sorts of radiation including high energy bremsstrahlung like used in radiation therapy.  But if you had the expertise and finances to construct such a thing, why would you use part of a CRT rather than a custom gun?

Electron gun construction is pretty finicky.  I have seen several projects that started with an electron gun extracted from a CRT for this reason.

[HarryDoPECC]

Selectron Memory

Very cool I think, arguably a/the pinnacle of tube technology. RCA abandoned it to concentrate on TV stuff, much to von Neumann's disgust.

Great site here http://www.rcaselectron.com/

[SeanB]

How about this CRT, which was used as a medical imager of some sort, dating from around 1975. Used to write an image onto some form of thermal paper, with the screen brightness being used to write on the paper directly. Likely to fade fast, and I only have the one very old roll of the paper that came left in the Medelec unit. Screen has some rather severe burns on it, seeing as it was used at such a high beam current to get the light output.

[Gyro]

Selectron Memory

Very cool I think, arguably a/the pinnacle of tube technology. RCA abandoned it to concentrate on TV stuff, much to von Neumann's disgust.

Great site here http://www.rcaselectron.com/

Wow, looking at the AFCRC (Air Force Cambridge Research Center Memory System), 14ft of rack and 6kW consumption for 5kb of RAM? It's a shame they didn't develop the 4kb part a bit quicker.

[calzap]

The link below is to a video that has a good look at the electron gun of a therapeutic electron linear accelerator.  The spooky parts of these machines are the copper microwave cavities that accelerate the electrons.
Mike