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Author: Subject: Radioactive lightning rods
Ormarion
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[*] posted on 5-5-2021 at 23:20
Radioactive lightning rods


Hi, i hope everybody is doing ok. Today i wanted to share something i learnt about some years ago that i believe to be pretty interesting.

I believe when we ear about americium we all think about those smoke detector ion chamber but from what i saw at this time they also made some lightnings rod holding quite significant sources on them (sometime they also used radium).

Have any of you ever handle or saw such things ? And how much did you measured out of it ?

Finally is the ionisation created by the rod really enough to potentially attract lightnings to it ?

PS: I am not especially planning to get one, first because no one would ever sell such thing for the purpose of it being radioactive, second because i already have big enough sources of those isotopes.

Anyway have a great day then ;)
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Jenks
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[*] posted on 6-5-2021 at 07:28


Americium is an alpha emitter. The Wikipedia page on the alpha particle says that although this ionized, and ionizing, helium nucleus is typically emitted at around 4% the speed of light (5 MeV), it can only penetrate a few centimeters of air. Since ionizing air makes it relatively conducting, this should make sparks attempting to reach it only a few cm longer. Maybe a neat demo with a high voltage generator, but in the case of the lightning rod it seems like the same result could be obtained by making the rod a few cm longer.
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Ormarion
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[*] posted on 6-5-2021 at 09:42


Ok interesting, in this case as radium is a alpha and gamma emitter i believe it would be a bit more efficient even if i am not sure if it worth it in both cases. I wouldn't test myself to just strike a radioactive sources like this with a HV electrical spark lol.
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Jenks
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[*] posted on 6-5-2021 at 12:16


Now that you mention it, I suppose vaporizing spots of an americium surface with sparks isn't such a good idea. As far as radium being more efficient (as a lightning attractor?), if this is to be due to the gamma radiation - while gamma rays go much further through air, I think they do this by having much less interaction. So unlike leaving a conductive, unbroken ionized trail as visualized in a cloud chamber, a gamma ray would leave a trail of isolated gas atoms too far apart to leave a conductive path. But it is all a matter of amount, right? And this reminds me of a thread I once saw on the topic of summoning lightning either by launching a small rocket with conductive smoke into a cloud (which can work) or by firing a laser beam of ionizing radiation into it. The problem with the lightning rod, with radiation going in all directions, is that the intensity of that radiation is proportional to the cube root of the distance from the rod. Unlike alpha particles, gamma ray photons diverge.

[Edited on 6-5-2021 by Jenks]
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[*] posted on 6-5-2021 at 17:01


Cube root? Why not squate root?
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Jenks
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[*] posted on 6-5-2021 at 18:44


You're right - square root of the distance.
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[*] posted on 6-5-2021 at 23:06


Jenks, interesting for the conductive smoke in rockets, i was thinking it would be some kind of thin wire instead but it seem more logical. If any of you find one of those rods a day please share it under this post !
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