Anton’s fusor

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
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Anton Isaksen
Posts: 7
Joined: Tue Jun 01, 2021 5:53 pm
Real name: Anton Isaksen
Location: Norway

Anton’s fusor

Post by Anton Isaksen »

Hi, I’ve been working on my fusor for around a year now, so I think it’s about time that I start posting something regarding my progress. The fusor is mostly made of kf-parts, with the main chamber being a kf-40 cross. Vacuum is attained using a pfeiffer turbomolecular pump backed by a 2-stage mechanical pump. And like others here, I made a feedthrough consisting of a quartz glass tube and compression fittings. My power supply is a 30kv chinese precipitator supply. The pressure is measured by an inficon triple vacuum gauge, but just the pirani part works, so it only goes down to 0,75 mTorr. I haven’t bothered trying to fix it yet, but any suggestions are welcome.
Admitting deuterium is done through a swagelok needle valve and gate valve, which makes it very sensitive to adjustments, but still doable. And finally, my deuterium is acquired through electrolysis with the horizon PEM cell.

The pictures of my setup are a bit old, since im currently repairing the turbo and a few of the parts have been disassembled.
Bilde 1.jpg
Bilde 4.jpg
I got my first plasma a while back using a crudely made tungsten grid, but I soon moved on to a way more symmetric grid which seems to keep the plasma better contained. What I’m worried about is the placement of the plasma, which seems to be concentrated in the upper part of the grid instead of the middle, resorting in the heating of only certain parts of the grid. I tried moving the grid a little bit further up, but it didn’t help. Is this a problem or is it fine?
Any other criticism is also welcome.
First plasma.
First plasma.
Latest deuterium-plasma at approximately 27mTorr, 30kV and 2mA.
Latest deuterium-plasma at approximately 27mTorr, 30kV and 2mA.
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Richard Hull
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Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Anton’s fusor

Post by Richard Hull »

Welcome to the plasma club, Anton.
I have placed your name on the list.
Images of gear and metering and reported image data on last image.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.
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Liam David
Posts: 367
Joined: Sat Jan 25, 2014 5:30 pm
Real name: Liam David
Location: Arizona

Re: Anton’s fusor

Post by Liam David »

Good job getting a plasma. It looks like all you need is a neutron detector.

Some feedback:

The plasma is pulled towards the feedthrough stalk for a number of reasons. The main cause is that neither of your grids is particularly symmetric or placed symmetrically in the chamber. At the very least, line up one of the "holes" in the grid with the long axis of the chamber. Also, a wire grid design is not the best for this kind of chamber. It works alright for spherical systems, but yours might fare better with a linear cathode. Will your current setup do fusion? Sure, but you will do much better with a newer cathode.

I don't know how you're taking pictures of the plasma, but please use a remote camera and some lead if you're not already. Your last picture was accompanied by lots of x-rays (100s of mRem/hr to >1 rem/hr).

I don't see a gate valve in your setup and one wouldn't typically find one in a gas line. Do you mean a needle valve followed by a shutoff valve? Also, neither valve in the bottom left of your first image is, functionally speaking, a needle valve. You mention that pressure control is difficult; this is because the valve is far too coarse.

I would suggest adding a valve between the turbo and chamber to save deuterium, as well as one between the rough and turbo pumps.

If that's a hard line between your rough and turbo pumps, I would definitely add a bellows for vibration isolation. If you touch the turbo while the rough pump is running, you should not be able to feel any vibrations.

Good work so far and we're looking forward to your new setup.
Anton Isaksen
Posts: 7
Joined: Tue Jun 01, 2021 5:53 pm
Real name: Anton Isaksen
Location: Norway

Re: Anton’s fusor

Post by Anton Isaksen »

Thanks for the tips! I certainly have some improvements to make.

My pictures of the plasma are taken from videos recorded on my phone(for now) up next to the viewport. I also have a piece of lead behind it to block the x-rays. As seen from the quality of the pictures, the whole chamber does vibrate from the mechanical pump. So I’ll try getting a piece of bellows tubing in the foreline to smoothen it out.

Regarding the inlet line, I did mean shutoff valve, not gate valve. My mistake. The other valve is an SS-1RS4 integral bonnet needle valve and I was gifted both of them by Swagelok Norway, as they didn’t have any finer ones in stock. I was however still able to gain a usable amount of control over the chamber pressure by putting the two valves in line and setting the shutoff valve to a position right at the limit of letting gas through.

After I had taken the above pictures of my setup I also acquired a butterfly valve to throttle the turbo. Like the needle valve, it isn’t very easy to use, but i don’t adjust it too often so it’s good enough for me. It’s maybe not too easy to see in the picture, but I’ve also got a ball valve between the turbo and mechanical pump. Though that one is open most of the time.
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