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Electrode material

Posted: Wed Aug 16, 2006 10:45 am
by Linus
Hi,
I'm planing to build a Farnsworth-Hirsch-Fusor with two spherical grid electrodes, but I'm still searching for a capable and cheap material for these electrodes. I've been told that stainless steel corrodes very fast under such conditions so I tought about using copper. Is a good material or are there better alternatives?

Re: Electrode material

Posted: Wed Aug 16, 2006 6:35 pm
by Tman
Hi David,
I think you would be better off using stainless grids. The grid tends to heat up and a copper grid could deform from the heat. Stainless's melting point is about 400C higher than copper. It also conducts less of heat so your feedthru wont get as hot.
Tungsten however is one of the best grid materials, It can get extremely hot and won't deform. Its melting point is 2000C higher than copper. Thats why light bulbs use tungsten filaments.

Here's Jon Rosenstiel's post on his inner grid.
viewtopic.php?f=6&t=2484#p11994

An outer grid is not required unless you are using a nonconductive chamber, such as a belljar.
The outer grid(if needed) dosent have to be anything special. Stainless works good.

Hope this helps

-Thiago Olson

Re: Electrode material

Posted: Thu Aug 17, 2006 3:19 pm
by Linus
Thank you very much for your reply, I think I take stainless steel.
I will use a bell jar if possible so the outer grid will be necessary.