OSU Fusor Update

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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Logan Holler
Posts: 15
Joined: Tue Apr 05, 2022 3:30 pm
Real name: Logan Holler

OSU Fusor Update

Post by Logan Holler »

Hello from the Oregon State team!

It has been awhile since Phia and I last said something but we have been making good progress and figured it is time for an update. We have completely welded our primary plate and have tested out our systems and was able to generate some plasmas (through clearly not where we want them to be as seen in the images). When we return from winter break we are hoping some parts will be delivered/printed that we can then use to get a better looking result.

For our systems we are using an AIDA camera for remote viewing and recording, a Pfeiffer HiCUBE 80 ECO turbo pump with matching PKR-360 Pirani/Cold Cathode gauge, a FRANCE step-up transformer with 15 kV output which we are only half wave rectifying our negative output of, and a Variac VVR to control the transformer. We were able to get to 1E-6 torr (maybe even down to -7 if we do a better bake out).

It is worth noting that our system is a complete demo fusor yet, our vacuum line is still missing a valve to close off (so during these tests their was a leak coming back in through the pump which could be a reason plasma formed there). Our stalk base also needs to be redesigned as it is not strong enough and is dropping the grid close to the edge of the chamber. When we get back at the start of January we should be able to fix these issues and run it again to see if that is the fix we need. It is also worth noting that the stalk base is currently 3d printed plastic for the demo fusor but we will change it with a ceramic mold of it in the future.

In our first image we had the plasma form around our feedthrough as well as in the piping to the vacuum pump. We can understand it forming around the feedthrough since it carries the voltage but are not too sure why it was forming in vacuum line. If someone else knows then we would appreciate the knowledge in the off chance it happens in the future.

For our second image we have the plasma starting to form in more of the right section of the fusor. We are assuming the grid is drooping too close to the edge of the chamber for us to get a good result out of it which we should hopefully be able to fix with the new stalk. However, it does look much more in line for what we are expecting as a result. Overall we are happy with the progress and are excited to move forward into developing a deuterium feedthrough and finding a fusion capable power supply as well as creating a LabVIEW script to operate the whole system remotely while getting data out of it. Also the images of the setup are after we ran the tests and took it a part, it was clear when we ran it :).
(Sorry if the images come across incorrectly, this is my first time uploading images on a post)
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Liam David
Posts: 509
Joined: Sat Jan 25, 2014 5:30 pm
Real name: Liam David
Location: Arizona

Re: OSU Fusor Update

Post by Liam David »

Nice work!

Plasma is forming in the vacuum line because you have a grounding problem. Make sure the chamber, positive terminal of the transformer, and pumping station are all grounded.

What pressure are you striking plasma at? It looks to be too high, especially for that size chamber, to get the plasma concentrated in the grid rather than on all HV surfaces.
Logan Holler
Posts: 15
Joined: Tue Apr 05, 2022 3:30 pm
Real name: Logan Holler

Re: OSU Fusor Update

Post by Logan Holler »

Thanks for the reply, Liam!

The grounding for the chamber is pretty primitive right now, just a copper wire pressed against the chamber connected to our grounding metal. The pump does have a grounding port that we are going to connect when we get back. As for grounding the positive terminal, in our first testing's we connected the positive terminal to true ground and then tested with case ground but in both instances the transformer tripped some ground protection and restarted, any suggestions on how to get around that (our only thought was to chip away at the asphalt in the case and alter the ground trip which is less than ideal).

As for the pressure, I am away from my lab notebook so I cannot give specific values but we were able to achieve this result along E-2 to E0 torr. Not having the valve meant that the pressure was always increasing. For the second image I think that section of video was taken closer to E0 torr which is high. I do have an mp4 video of it if that would be good to upload as well (if it is possible to) but that mostly shows the variation from 1kV to about 5kV.
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