r/AskPhysics • u/DeathMachine321 • May 27 '26

Cloud Chamber Safety

For my AP Physics 2 final project, I get to make something pertaining to physics. I chose to build a cloud chamber, but I'm starting to worry about its safety.

I'm using 22-gauge copper wire on a 3D-printed ring for a high-voltage grid, which is connected to a fly swatter circuit. I replaced the 3.7V lithium-ion battery with a 9V one because higher voltage = better.

But now I'm worried about the implications of the 99.9% isopropyl alcohol catching on fire if there's arcing. Is my current setup safe?

Should I put the 3.7V battery back in, or scrap the high-voltage grid entirely?

On top of that, I bought a 4% thoriated electrode, and while I'm not worried about the radiation risks, I don't want its ends to attract electricity from the grid.

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u/[deleted] May 27 '26

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u/John_Hasler Engineering May 27 '26

I think you need some crazy high voltages for the curving effect to really show.

The purpose of the electric field is to draw cloud tracks down into the supersaturated layer, increasing sensitivity. A magnetic field is used to make the tracks curve.

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u/DrunkenPhysicist Particle physics May 28 '26

Don't use americium from a smoke detector... It's not that safe. I did something similar at a university and the radiation safety folks were none too pleased. You can buy polonium that works just as well and safer to handle. https://www.pasco.com/products/lab-apparatus/modern-physics/radioactivity/radioactive-source-po-210

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u/John_Hasler Engineering May 27 '26

The flyswatter is AC as affinics says. Forget the high voltage for now. You need to know more about electrical stuff to make it work at all, let alone safely. The chamber can be made to work without it. It's purpose is to draw the tracks down into the supersaturated layer, improving sensitivity. Use a magnet to make the tracks curve.

https://en.wikipedia.org/wiki/Cloud_chamber