A start to my first fusion reactor

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Casey Rojas
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A start to my first fusion reactor

Post by Casey Rojas »

Hello everyone! This is my first post on fusor, but i’ve read through a lot of posts about construction and theory on this site. I’m an undergraduate physics major that has been fascinated by fusion, however my university doesn’t have a fusion or plasma laboratory (the departments main focus is particle physics). I’m fortunate enough to work in the particle accelerator laboratory which has a ton of scrap parts and deuterium, everything i need to make a fusor.

I’ve begun collecting pieces for my vacuum chamber, as well as a diffusion pump that is just way too small to be of any use on the accelerator. I also have plenty of roughing pumps to pick from

This is a rough layout of my design so far:
Chamber layout
Chamber layout
To the left will be the line for deuterium gas. The top will be for the high voltage feedthrough (next to it is a bnc feedthrough i may use). To the right has a T for the viewport and TC gauge. At the bottom has a valve that will connect to the diffusion pump.

Ill need to search for some more connectors to finish it up, and try to pull a vacuum on it.

Seeing as I want to achieve fusion and not just a demo fusor, the available high voltage power supplies are bit more limited.

I found this power supply that gets up to 20 kv:
20kv supply
20kv supply
This one may need some repairs

Otherwise, I’ll use this 5 kv one for now which is too low for fusion, but enough to generate plasma:
5kv
5kv
My goal is to eventually get a 40 kv power supply, neutron detector, and integrate it with Arduino Uno and LabView

I’m excited to be part of this community and I’m open to any recommendations and insights you all may have.

-Casey Rojas
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Rich Feldman
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Re: A start to my first fusion reactor

Post by Rich Feldman »

Welcome!
That 0 to 5 kV power supply looks like something for biasing particle detectors.
Not much current for lighting up a fusor-size plasma.
My bias supply has a little voltage multiplier inside, and consequently a very high output impedance. To choose positive or negative output, one needs to open the box and change some jumpers. I think its output connector is a weird variant of BNC.
If yours is like that, then it might safely limit the current instead of being damaged by the load of a plasma.

For demo plasma, you could use a little neon sign transformer and a rectifier from microwave oven.
All models are wrong; some models are useful. -- George Box
Casey Rojas
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Re: A start to my first fusion reactor

Post by Casey Rojas »

Thats what i realized about the 5kv supply after posting. The graph suggests the current goes to zero at 5 kv. Even at 1kv, 2ma doesn’t seem like enough. This one has two BNC outputs on the back for the desired polarity.

My understanding is the grid is like a filament of a light bulb and needs decent current to heat up.

If i can’t repair the 20kv supply, ill have to consider the neon transformer and microwave rectifier.

Thank you!
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Richard Hull
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Re: A start to my first fusion reactor

Post by Richard Hull »

A good usable power supply, 30kv plus, and an ultra sensitive neutron detector, large multi-atmosphere 3He tube, are the most difficult part of making a fusor and convincing yourself it is doing fusion.

You seem off to a good start.

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: A start to my first fusion reactor

Post by Dennis P Brown »

Nice fusor chamber. You can also consider a deuterium ion gun for a demo but that would create some fusion (if high enough voltage.) This requires far less current. As for detectable fusion, others here would have more knowledge on that relative to simple guns.
Ignorance is what we all experience until we make an effort to learn
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Taylor Romain
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Re: A start to my first fusion reactor

Post by Taylor Romain »

Welcome!

I started my fusor project with a 5kV DC power supply, 2mA limited and found at pressures around 3.5E-2 torr that the voltage would not increase past 350V-400V with 2mA output. My fusor did produce a plasma discharge and allow me to "get my feet wet". As I upgraded to a pump capable of 5E-3 torr, the voltage would increase to 5kV with no visible plasma glow as the current was likely at 0mA. None the less, it served as a excellent power supply for proof of concept and finishing the demo design.
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Richard Hull
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Re: A start to my first fusion reactor

Post by Richard Hull »

Learning by doing is the thing. Do it. Learn about it. Own it.
Experiment with it while reading to further your knowledge on the theory.
The above is self-directed learning and the best path to ownership of many concepts related to physics or any scientific endeavor.

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: A start to my first fusion reactor

Post by Dennis P Brown »

Yes, a conductive plasma can cause the voltage to drop - as what often happens in a fusor when operated at its best parameters. As many first time fusor operators discover and experience. The reason many fusors can be difficult to hold a proper plasma in the device.
Ignorance is what we all experience until we make an effort to learn
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Richard Hull
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Re: A start to my first fusion reactor

Post by Richard Hull »

Dennis told you what you have already observed, and assuaged your worries by telling you it is normal, but.....Do you know why? Yes, you have learned by doing, but that is all. A bit of reading regarding gaseous conduction will tell you why. Also learn about different transformer designs.

Work on making yourself wise as well as merely noting something unexpected.

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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