Review my Fusor Design!

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Nick Babusis
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Review my Fusor Design!

Post by Nick Babusis »

I am about 80% finished with the conceptual design of my fusor and would like to get some expert feedback before I start buying parts and committing to my design. I'm sure there will be lots of mistakes and unanticipated problems once I start construction, but here I am trying to catch anything I'm doing that fundamentally won't work or has an obviously easier solution. Some key components that are still TBD are: He3 detector tube, rotary vane pump, and x-ray transformer. I will be buying most of these components online and plan on posting a full parts list and budget provided I can get this thing to produce and detect neutrons.

Fusor Diagram v3.png
Electrical Feedthrough Diagram.png
HV probe diagram.png
High Voltage Diagram.png
(Apologies for the small text)

So what's the verdict; am I on my way to fusion or back to the drawing board?
John Futter
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Re: Review my Fusor Design!

Post by John Futter »

Nick
The steel bellows tubing is OTT ordinary milking rubber tube is much less expensive and easier to get (farm supply stores)
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Liam David
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Re: Review my Fusor Design!

Post by Liam David »

Things look good for the most part. I don't see any major flaws at a quick glance and just have some non-critical suggestions. We gave you feedback on the feedthrough in your other thread.

Necking down the diff pump to a KF 25 isn't ideal for pumping the chamber. You might consider a rearrangement of the vacuum hub to widen and shorten the connection and perhaps add a gate valve.

Put the TC gauge on the roughing line and find a high-vac gauge to replace it on the chamber. It helps to know whether your pressure is e.g. e-4 torr vs. e-7 torr and knowing the roughing pressure is not unhelpful.

Replace the capillary and needle valve with e.g. 1/4" tubing and a finer needle valve. The capillary will kill conductance and make pumping the air and any contaminants out of the gas line very laborious. Put a shutoff valve on the gas line instead of using a KF 25 ball valve.

Make sure your rectifier diodes have some headroom over the peak voltage of your TBD XRT. I have heard that the open-circuit voltage of some XRTs can be significantly higher than their nameplate voltage.
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Nick Babusis
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Re: Review my Fusor Design!

Post by Nick Babusis »

John: I looked into other forms of tubing for the roughing pump and found that a short length of KF25 SS flex hose can be found for $15-20 on Ebay, making it cheaper than using a polymer hose + adapters.

Liam: Thanks for the advice! I'll look into changing the gauges and capillary as you suggested and use a wide margin for the diode voltage ratings. I don't understand why the chamber to diffusion pump conductance is significant here since I will be choking off that conductance with the throttle during operation. The only benefit I see this having is a faster/more complete evacuation of the chamber before adding deuterium.
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Maxwell_Epstein
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Re: Review my Fusor Design!

Post by Maxwell_Epstein »

Nick,

Your design looks fantastic, but I lack the expertise to comment on it in a substantive way. I am wondering, however, what program you used to create those diagrams. I am looking to move away from hand drawn sketches and your presentation stood out to me.

Thanks!
Max E.
See my needlessly verbose fusor blog here: https://highschool-fusioneer.medium.com/!
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Liam David
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Re: Review my Fusor Design!

Post by Liam David »

Nick, you're correct in that choking the conductance with a valve during operation means that increasing the max conductance isn't important per se. I recommended it only because it quickens the initial pump-down. Generally speaking, the faster you can remove the material that initially outgasses the better, but it's really just a trade-off in time you're willing to spend waiting, especially if you want to achieve higher vacuums.

Max, I'd suggest learning a CAD program as well. It'll serve you well in the long run. You might start with something like Fusion 360, which is relatively straightforward to learn and is free for students.
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Maxwell_Epstein
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Re: Review my Fusor Design!

Post by Maxwell_Epstein »

Thanks for the advice, Liam! I don't mean to take over this thread, but I am already teaching myself fusion 360! Mainly to design supports and such for my fusor project, although my main goal is to fully 3D model my system. Always more to learn!
See my needlessly verbose fusor blog here: https://highschool-fusioneer.medium.com/!
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Nick Babusis
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Re: Review my Fusor Design!

Post by Nick Babusis »

Maxwell_Epstein wrote: Wed Jan 11, 2023 7:56 pm Nick,

Your design looks fantastic, but I lack the expertise to comment on it in a substantive way. I am wondering, however, what program you used to create those diagrams. I am looking to move away from hand drawn sketches and your presentation stood out to me.

Thanks!
Max E.
I used Google Drawings for this, which is great for conceptual diagrams. Visio is better for high quality schematics/plumbing diagrams, and I prefer Solidworks for modeling parts that have to be machined.
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