Demo Fusor First Light

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Liam David
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Demo Fusor First Light

Post by Liam David »

I just introduced myself in the introduction section and said that I was going to post pictures of my setup.
Image

The chamber
Image

First Light
Image

"Second light" with a deeper vacuum
Image

I am using an HVAC 2.3 micron 3 CFM 1/3 hp vacuum pump.
A 3kV half-wave rectified NST.
Three way stainless steel ISO-flange vacuum chamber.
Tungsten wire inner grid.
Alumina insulator stalk.
Aluminum 1/8 in "end caps".
Plexiglass viewport.
Automotive gaskets.
12 one inch steel clamps.
Auto spark plug insulator.
Epoxy to seal spark plug and vacuum connection to aluminum plates.
Epoxy for alumina insulator and HV feedthrough.

Any comments/suggestions?
Tom McCarthy
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Re: Demo Fusor First Light

Post by Tom McCarthy »

Hey Liam,

You mentioned that you had a massive leak, I'd say it's probably from where you have the pyrex/glass or whatever you have clamped on to your chamber.

If you have the funds, you should probably get a vacuum rated chamber - Conflat or Kf, you can get fittings along with them and allegedly, they are very good for keeping your vacuum but can be prohibitively expensive in certain cases.

Best of luck,
Tom
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Liam David
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Re: Demo Fusor First Light

Post by Liam David »

Tom,
I've been trying to find a cheap cf flange vacuum chamber, but haven't had any luck. I'll try adding another gasket to the plexiglass viewport.
-Liam
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Rich Feldman
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Re: Demo Fusor First Light

Post by Rich Feldman »

Here's a trick I've used to locate gross leaks.
It depends on having a vacuum gauge.
Your ionization around part of the grid wire would be a good enough indicator of pressure.

Using a small brush, such as an acid brush,
apply vacuum pump oil to the outside of each suspected joint.
When you hit a leaky joint, the oil will make a temporary seal
and the pressure in chamber will drop rapidly.
In the case of your flat glass windows, you could even see whether
the oil is sucked in and if bubbles appear on the vacuum side of the seal.

Good work so far. Good luck.
All models are wrong; some models are useful. -- George Box
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Liam David
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Re: Demo Fusor First Light

Post by Liam David »

Thanks! I'll see if I can find the leak.
-Liam
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Liam David
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Re: Demo Fusor First Light

Post by Liam David »

Also, does anyone know of any 10-15 kV NST sources? I'd like to get a ball of plasma instead of just plasma on the grid wires.
prestonbarrows
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Re: Demo Fusor First Light

Post by prestonbarrows »

Another, less messy, trick is to spray some methanol around on each seal. You will see a large spike in pressure if you hit a leaky joint. It will all evaporate away cleanly so there is nothing to clean up after.

If that 3-way cross has ISO flanges on it, do yourself a favor and buy some real ISO blanks/viewport to seal things up easily. They won't be that expensive from ebay for small sizes like this. Use a proper KF-16 or KF-25 feedthru to mount up the roughing pump to; either find an appropriate ISO to KF adapter or weld a nipple on. If you don't have a welder, JB-weld or torr-seal will work.
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Richard Hull
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Re: Demo Fusor First Light

Post by Richard Hull »

Liam, I have placed you on the Plasma club listing. Good luck with sealing your chamber.

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
ARDYN VAN FOSAAEN
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Re: Demo Fusor First Light

Post by ARDYN VAN FOSAAEN »

Liam If you want to get a good seal on the cheap for a quick demo use teflon pipe dope. It can be picked up at any hardware store for a few bucks. Take off the gaskets and clamps, run a thin bead of pipe dope around the openings and stick your plexiglass view ports to the opening press and slightly twist to get a good seal. You can visually check to see if you have any gaps in your seal. You can use your fingers to spread the dope around if you need to. I use this to seal a 6" x 10" quartz tube with plexiglass end plates, with no clamps standing on end. Also the vacuum will hold end plates / view ports in place.
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