I want to characterize an electron beam using something like a CMOS-camera or a scintillator and some light optics or maybe just a Faraday cup. The electron energy is between 1 and 10 keV and the expected total current around 10 microA for 1 keV electrons. Essentially I want to see whether the beam diameter is around 1 micrometer (or smaller) or much bigger than that, so I would need a resolution or pixel size around 1 micrometer. The detector should also be reasonably cheap and should last maybe 100 hours. Does anybody have a suggestion?
Try to get your hands on a cathode ray tube from an oscilloscope (these still are sold new "from old stock"). The inside is nicely coated with a phosphor mix that will nicely light up when the beam hits it, and through the glass you can directly view this with a microscope equipped with a camera. The trick is to first carve the glass of the tube (but not cut through yet) then place the tube in a vacuum chamber with the screen facing upward to avoid scratches of particles, and (once pumped down) hit the pre-carved line with a manipulator. The glass then will break with equal pressure inside and out. After you can harvest your coated CRT screen, e.g. with a dremel and diamond cutter disk. I used this trick several times.
Thanks, that sounds interesting.
I'll have to look into it in more detail.
In nanostructures the have turnstile devices where the see electrons pass one by one, through a circuit. Look into that.
Sometimes electron patters can be built up on cathode ray tube screens
gradually as points.
I'm wondering a bit about the resolution one could get with a cathode ray tube. Isn't the phosphor quite thick?
What kind of resolution did you get, Fokko?
On another forum someone suggested a very thin phosphor on a metal surface.
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