Question about demo fusor

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Julian Stanek
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Question about demo fusor

Post by Julian Stanek »

Hello, I am planning on building a demo fusor, and I already have a good vacuum pump. Could I use a plastic bell jar for a demo fusor? If not are there any alternatives? Also, should I make the base plate out of aluminum and use it as a cathode? Would a sparkplug be good for an anode? Can I seal the threads with Teflon tape, will it outgas? I know that probably most of these questions were already answered but for personal reasons, I need to make the demo fusor fast.
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Richard Hull
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Re: Question about demo fusor

Post by Richard Hull »

How fast is fast? Rushing to a demo fusor is never a good idea.

No, a plastic demo vessel is no good. It outgases and once a plasma is struck it outgasses horribly. You should have a good vacuum in the fusor vessel of 50 microns or below. A spark plug will be fine to hold the cathode grid as the voltage on the central grid will not be over a few thousand volts DC.
It is best to have a nice larger wire spherical grid attached to aluminum base plate as the anode.

See the demo I built in 1997-98 here

viewtopic.php?f=24&t=13052&p=84814#p84814

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Dennis P Brown
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Re: Question about demo fusor

Post by Dennis P Brown »

For a fast, and inexpensive DEMO fusor (a few thousand volts, and very low current), a wine bottle works. Use a bottle cutter to remove the base. Wet some emery paper (auto store) and grid the base of the bottle smooth. Buy a sheet of gasket material (again, auto store) and cut the o-ring flat gasket for the bottle bottom to seal. This mates to the Al plate. Put a rubber cork in the top of the bottle that has a hole for a standard 1/4 inch copper tube. Use this tube to both pump out the bottle and apply voltage. You can attach a wire cage to the tube in the bottle.

By the way, if you can find a junk AC unit or Refrigerator, one can convert the compressor into a vacuum pump. Not great but ok for a demo. See back issues of Scientific American, Amateur Scientist on how to convert those units. Of course, easier to buy someone's unneeded vacuum pump on e-bay.
Matt_Gibson
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Re: Question about demo fusor

Post by Matt_Gibson »

What’s your budget? The more $$$, the easier and faster this can be, but also the least educational.

-Matt
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