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Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
My guess would be that charged particles in the air collect on the surface of the glass, (which is an insulator) until such point as surface tracking occurs and the charge is dissipated to the surrounding metal.
Registered Member #350
Joined: Mon Mar 27 2006, 05:14PM
Location:
Posts: 106
My guess is I couldn't detect any current because it was less then 0.1 nA. I read a helicopter needs a while to get charged. So the charging current is quite low. If you consider the much smaller surface and the much smaller air speed in my experiment the current was probably only a few pA.
Dave Marshall wrote ...
Perhaps one of the simplest and easiest (precautions must be taken) involves coating a razor blade with a mildly radioactive material like Thorium ash from lantern mantles (or Americium-231 *if precautions are taken*). The physics of this are somewhat vague to me but my understanding is you create a small area of ionized air around the razor blade's edge, which increases the effective aperture size. Sort of inflating the razor blade to extend across a more substantial bit of the electrical gradient.
If I lived in the US I would just get some polonium 210 from amazon (search for "staticmaster" to find it). This stuff is extremely radioactive. But it's just alpha radiation so it's relatively harmless. You get 500 microcuries for 20$. The americium from a smoke detector is only 0.9 microcuries
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
The classical way of getting charge from the atmosphere is by using flames. This is being done since the 1700´s. There is no need of radioactive materials. Instead of trying to measure tiny currents, use a sensitive electroscope and see the accumulated charge on it. Interesting the comments about helicopters becoming charged. Note that helicopters are sometimes used in the maintenance of live high-voltage transmission lines, and in this case they are directly connected to several hundreds of kV, and surely get a very significant charge.
Registered Member #902
Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042
DrZoidberg wrote ...
My guess is I couldn't detect any current because it was less then 0.1 nA. I read a helicopter needs a while to get charged. So the charging current is quite low. If you consider the much smaller surface and the much smaller air speed in my experiment the current was probably only a few pA.
Dave Marshall wrote ...
Perhaps one of the simplest and easiest (precautions must be taken) involves coating a razor blade with a mildly radioactive material like Thorium ash from lantern mantles (or Americium-231 *if precautions are taken*). The physics of this are somewhat vague to me but my understanding is you create a small area of ionized air around the razor blade's edge, which increases the effective aperture size. Sort of inflating the razor blade to extend across a more substantial bit of the electrical gradient.
If I lived in the US I would just get some polonium 210 from amazon (search for "staticmaster" to find it). This stuff is extremely radioactive. But it's just alpha radiation so it's relatively harmless. You get 500 microcuries for 20$. The americium from a smoke detector is only 0.9 microcuries
it is very difficult however to get any where the radiation has not gone away (polonium has a VERY short half life
also, the lantern mantles method works, but not well as the blade can pick up the charge from the alpha, to an extent that is... I have a thread on something similar in chemistry...
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helicopter static charge
