Oakland University Low Powered Fusor Update

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Aaron Garofalo
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Joined: Wed Jan 28, 2015 6:08 pm
Real name: Aaron Garofalo

Re: Oakland University Low Powered Fusor Update

Post by Aaron Garofalo » Wed Mar 30, 2016 3:51 am

Hi everyone,

We tested the vacuum pumps by directly connecting them individually to the vacuum gauge. Much better results this time. Our newer high-vacuum, high-speed pump (rated for 50 mTorr) measured in around 100 mTorr (close to 1/10 the original pressure). The older low-vacuum, low-speed pump (rated for 1 mTorr) measured around 200 mTorr. We have since flushed it out and changed oil an are still seeing the same results. Our next step for this pump is to look at the seals and whatnot inside, since it is an older pump and hopefully get closer to the 1 mTorr this pump is supposedly capable of.

We changed out the rubber hoses and hard-plumbed everything (vacuum gauge and vacuum pump). After doing this we ended up finally achieving star mode! (I will upload pictures later unless someone else on my team beats me to it). We still need to do more research on throughput and vacuum conductance to find the right material for the plumbing. For this most recent test we just used what we had on hand (brass and copper nipples and elbows) (I know, I know. Mixing metals for fittings isn't exactly the best, but it's what we had at the moment and it got the job done for the day). In response to a previous question on this post, yes, we have been using teflon tape for all appropriate connections. Our pump has a flanged fitting which we adapted to NPT; therefore, the flanged fittings do not have teflon tape, whereas the NPT fittings do.

In response to another question, our chamber is glass. It is borosilicate glass, and we ran the calculations and simulations to ensure it would be able to withstand atmospheric pressure while holding a vacuum without imploding. All good on that front! I should also mention that this will not be our chamber for fusion. We are currently looking into ordering a stainless steel vacuum chamber from a few different companies in our area. We just got our first quote back at $900 and are currently waiting on the rest.

Our HV feed through is a female threaded aluminum rod which is sealed in the center. The aluminum pass through is insulated by a hollow ceramic tube and sealed with JB Weld. We don't see any leaks here.

Lastly, our lab shares a common ground for all the outlets, so the gauge plugged into the wall and everything else into the e-stop shouldn't cause any anomalies. Just to be sure, we did plug everything into our e-stop. We still saw the glow in both the vacuum pump and vacuum gauge ports in the upper grounded plate. Any other advice/comments/thoughts on this would be very much appreciated.

Again, thank you to everybody who has commented on this for your help, and we hope to continue our progress and make our way to the Neutron Club this year!

-Aaron Garofalo
Oakland University HC/SD Fusor Group

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Dennis P Brown
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Joined: Sun May 20, 2012 2:46 pm
Real name: Dennis P Brown
Location: Glen Arm, MD

Re: Oakland University Low Powered Fusor Update

Post by Dennis P Brown » Wed Mar 30, 2016 6:07 pm

Very glad your vacuum is improving! thanks for the update.

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