Casting away

Discuss the technical details of an "open source" community-driven design of a polywell reactor.

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JohnSmith
Posts: 161
Joined: Fri Aug 01, 2008 3:04 pm
Location: University

Casting away

Post by JohnSmith »

I've been trying to figure out a good construction project I can put together.
Then I started reading about backyard aluminum casting.
I've read that you can make UHV tanks out of aluminum (not that I'd try), but would aluminum coil casings work?

Or would this at least be a cheap step towards a Fusor?

D Tibbets
Posts: 2775
Joined: Thu Jun 26, 2008 6:52 am

Post by D Tibbets »

Making a vacuum casing is simple with surplus parts- pressure cookers, sause pans, stainless steel salid bowls, even glass jars (watch out for implosions). The problem comes from sealing the containers, finding appropiate gaskets, view ports, feed throughs, etc. If you are interested in a demo fusor ( produce plasma/ glow discharges) with voltages well below 10,000 volts, then gobs of epoxie, rubber gaskets from the hardware store, etc will do. If you are interested in the real thing- deuterium fusion with detectable neutron output, you need to be more concerned with precision, outgassing, materials, valves,and radiation- possible dangerous levels of X- rays if not properly shielded. Not to mention safe and parionoid handling of high voltage.

As far as aluminum casting- I found a cast aluminum plate~3/16 " thick that appeared to have been sand cast from its' grainy surface. It fit well on the concave lip of an aluminum pan. Unfortionatly I found that it leaked air in several places (bubbles when I had a layer of water over it with a vacuum)- it was porous. A thicker/better casting might solve this problem, but it is a concern. It would pump down * to a vacuum level to achieve some glow, but not to the levels where the more interesting action is.

Other concerns of aluminum- Strength is not a majer concern ( especially if you stay in a near spherical shape) unless you are making a Large vacuum chamber. It only needs to resist 15 lbs of pressure, as opposed to over 100 lbs in a typical compresser tank. For outgassing concerns, stainless steel is best (best to use variety that does not contain zinc), then aluminum, and worst is soft iron. Also, outgassing is dependant on surface area, a smaller chamber with sooth walls is better, a rough casting would benifit from polishing the inner surface.

Good nformtion can be found at Fusor.net and Bell Jar.com or net (approx names- Google should find them)

* Even coating the outside with enamel paint didn't help much, though it was probably also leaking at the seams (not enough to produce visible bubbles). I used hot melt glue as the 'weld' between the plate and the pan as I could not find a gasket that fit. The glue must have been leaking and/or outgassing alot (based on some other experements I did).


Dan Tibbets
To error is human... and I'm very human.

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