Rippey574
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Still have that 'scope? edit
I'm wondering if you still have a working analog oscilloscope? I'd love it if you could turn one on in X-Y mode and turn the intensity all the way up until the spot defocusses. This is a good illustration of secondary emission. Thanks! Maury Markowitz (talk) 22:50, 28 January 2013 (UTC)
Yes I still have it! edit
I need you to specify X-Y mode.. Envelope? Channel AB? I also have inputs in the back I can't remember off hand what they all where. If you let me know what you want, I will upload them so you can link the up or use them as you wish. Rippey574 (talk) 12:39, 29 January 2013 (UTC)
- Hey Rippey, I failed to check back. I'm trying to illustrate secondary emission, which is REALLY easy. Set the scope to X-Y mode with NO input. Now turn up the intensity until you can just see the dot. Take a picture. Now keep turning up the intensity until you see the spot in the middle really bright and then a diffuse disk of light around it. Take another shot. That's it!
- If you're curious, what's happening is that when electrons above a certain threshold energy hit the phosphor, it starts giving off new electrons in all directions. That's the secondary emission. Some of those are released travelling into the face of the tube and get collected, like any other electron coming from the gun. But the ones that are released back into the tube see the accelerating voltage and get pulled back to the face. But they're moving in all sorts of directions, so they spread out and light up a disk.
- Storage tubes used this effect. They added another accelerating grid just behind the screen and trapped the secondary electrons there, holding the image in place.
:Maury Markowitz (talk) 18:59, 8 April 2013 (UTC)
- Let me know if these will work for you, if you need more or different just let me know. I also have a vector scope that's phosphor screen, this one is harder to photograph tho, since the screen does not have a high intensity light.I have always called it over-driving the tube, not secondary emissions; but I do see the secondary emissions as the correct term for this. They showed up darker then what I was expecting, let me know if you need retakes for them. Rippey574 (talk) 09:44, 9 April 2013 (UTC)
These are prefect!. Out of curiosity, what is causing the line to extend to the right? Maury Markowitz (talk) 12:22, 9 April 2013 (UTC)
The east line is just the zero line, the scope does not allow XY, from what I saw. Its a late 80's-early 90's military surplus scope I got at an auction; with a boat load of setting, but I can't get the manual for it. The south east line is just a lens flare. Rippey574 (talk) 18:39, 9 April 2013 (UTC)