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Registered Member #1938
Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 699
Your idea is interesting and it makes sense, of course there are a few limitations given the different purpose of the valves we find (eg. fragility of the 2X2, improper electrode placement in most tubes, etc), but these are of secondary importance.
Personally I don't know much about magnetic acceleration of the electrons, just the basic theory, but from that to an actual working prototype there is a path of trial and error that is yet unknown to me. I would use an electromagnet, and not a permanent magnet, but I have no clue on what the field parameters should look like, nor the driving signal. Any ideas?
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
radhoo wrote ...
Your idea is interesting and it makes sense, of course there are a few limitations given the different purpose of the valves we find (eg. fragility of the 2X2, improper electrode placement in most tubes, etc), but these are of secondary importance.
Personally I don't know much about magnetic acceleration of the electrons, just the basic theory, but from that to an actual working prototype there is a path of trial and error that is yet unknown to me. I would use an electromagnet, and not a permanent magnet, but I have no clue on what the field parameters should look like, nor the driving signal. Any ideas?
Yes, I do! We both know the electrode architecture of the Russian 2X2A very well, and I think it is a very good place to start because
(a) there is a big space between cathode and anode.
(b) the valve will still operate for our purpose with the normal polarity reversed, so the anode bell is now the field emission source.
If you think of the edge of the anode bell - a sharp edge - the field emission from here will be completely exposed to an external magnetic field.
I am thinking of using two large, strong neodymium magnets because they are very compact with intense fields on very small pole surface areas, and come with M8 screw threads already tapped into them for easy mounting on to a frame - an aluminium frame would perhaps be good.
Initial tests could be
(1) change of relative fluence (GM or ion counter etc)
(2) Change of anode current. If the electron path length is curved by the field, it will be longer, so the anode impedance will rise. This effect (if it exists at all! :) ) might be too small to detect with my simple equipment. If it is a few μA out of a standing anode current that wanders around 200 μA it might be possible to detect it by statistical means with enough samples. We shall see!
(3) A radiation pattern test, with the 2X2A inside a Gd2O2S cylinder.
If it works, then we can develop a theory of operation, expressions, to predict how it would change if we changed the magnetic field.
Registered Member #1938
Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 699
Sounds great.
My only ion chamber is a CDV717 unit: I'll need something more sensitive to get a clue on what the 2X2 outputs. And a ion chamber seems to be the perfect candidate for getting an idea on the dose for making comparisons between the various setups, even if not calibrated in standard units.
My geiger counters are getting easily saturated even at 1 meter away from the 2x2 (showing >999uSv/h, etc). Can't use them for this purpose. Good that all my related tests, without exception, have been performed remotely, and the camera was the only observer exposed.
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Vacuum Rectifiers X-rays report
