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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I should have foreseen the problems I'm now having - aside from slatternly idleness that is - and have had to construct a 40kV PSU with a stiffer output that isn't so easily pulled down when the 2X2A starts drawing current, which makes trying to draw graphs relating Ia, Va, and Gy rather like playing croquet with a flamingo and a hedgehog that keeps wandering off as the ball.
Registered Member #1938
Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701
Les, did you get your tubes? I've just returned from the post office with my package from Gintaras (KWTubes). Love the radio-id postcards he is sending.
Stella, more problems may also be a premise for more innovative solutions, keep us posted of your progress and good luck with that!
Registered Member #1143
Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721
radhoo wrote ...
Les, did you get your tubes? I've just returned from the post office with my package from Gintaras (KWTubes). Love the radio-id postcards he is sending.
What a small world, i saw Gintaras yesterday Maybe you know which x ray screen is best for experiments ? (most sensitive to x rays and have low cost) Now thinking about this:
Registered Member #1134
Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351
radhoo wrote ...
Les, did you get your tubes? I've just returned from the post office with my package from Gintaras (KWTubes). Love the radio-id postcards he is sending.
No yet, I have heard from him a few days ago though, and they have been posted, so within the week I guess.
The component values and choice of parts reflect what I could find around the house, rather than what might be ideal.
Vpk across the balanced input can be varied across about 2kV - 6.7kV to produce an output of ~12kV - ~40kV NEG. Being a total slut, I'll supply the C&W from a 4kV-0-4kV 50Hz transformer controlled by a Variac, though I shan't be able to exploit the maximum Vpk of 11kV because of the 16kV Vmax limit of the capacitors.
If, in future, I should want more than a few hundred μA for other experiments, I can run the multiplier module at a higher frequency from an inverter, when the large capacitors will really come into their own. I've made it into a HV NEG supply because I mostly work in grounded anode mode, and it makes no difference to the 2X2A tests.
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
Linas wrote ...
radhoo wrote ...
Les, did you get your tubes? I've just returned from the post office with my package from Gintaras (KWTubes). Love the radio-id postcards he is sending.
What a small world, i saw Gintaras yesterday Maybe you know which x ray screen is best for experiments ? (most sensitive to x rays and have low cost) Now thinking about this:
What sort of experiments? If you want max light output and don't care much about resolution, a screen from a fast/rapid x-ray cassette would be ideal. If you want maximum resolution, a screen from a mammography cassette (Agfa Mamoray, Fuji Mammo or Kodak Min-R) would be best. These have much higher resolution than regular x-ray cassettes, but they give a bit less light.
That's some very nice work Stella, looking forward to seeing your results.
And I've said it before, but your results here have been much better than what I thought was possible with these tubes, Radhoo
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
plazmatron wrote ...
OK the intensified pinhole camera works fine.
First off we have an image of the focal spot of a small dental x-ray tube (below). Note, the resolution is good enough that is is obvious the spot is rectangular, corresponding to the spot etched to the anode face
Very interesting experiment. Notice the figure-8 shape of the focal spot, it actually corresponds very well with this drawing.
Do you have any dental x-ray tubes with a biased filament cup you could try this experiment with? It would be very interesting seeing how changing the bias voltage affected the size and shape of the focal spot.
Registered Member #1134
Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351
Anders M. wrote ...
Very interesting experiment. Notice the figure-8 shape of the focal spot, it actually corresponds very well with this drawing.
Do you have any dental x-ray tubes with a biased filament cup you could try this experiment with? It would be very interesting seeing how changing the bias voltage affected the size and shape of the focal spot.
So it does! I have noticed this self same pattern etched into the anodes of x-ray tubes before.
Unfortunately none of the tubes I have has a biased filament cup, but it would make for an interesting future experiment for the vacuum rig
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Vacuum Rectifiers X-rays report
