Fusor Chamber 101

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George Schmermund
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Fusor Chamber 101

Post by George Schmermund » Fri Jul 29, 2011 1:48 am

Just when I thought that I was going to wrap up the DP project with a few simple tests, I was thrown back into the crucible by another one of my chemically induced visions. This pump went together so easily, with only simple hand tools, that It was hopeless to try and stop there. Why not take it to the next level and build a whole vacuum system using the same parts and methods? The only tools that I've added to the mix are a hand nibbler, hand punch, bench vise, and more beer. They aren't really necessary (well, the beer is), but they save a lot of time that would otherwise be spent with a rat tail file.

The hemispheres are fashioned from the tops of 2 more cocktail shakers. This leaves a pair of SS beakers for the lab or they can be used as alternative vacuum chambers. For those that might want to try and reproduce this style of chamber I'll confess that there is no precision involved when putting it together. Just eyeball where things would go and then get to work.

What's left to do now is braze the hemispheres together and then water cool it the same as the pump. The water cooling will allow high power inputs and long runs without the expense and inconvenience of welding and having to use CF flanges. A useful feature of the KF flange design is that the 'O'ring centering part can shield the Viton 'O'rings from most of the chamber processes. The access ports are KF 16, 25, and 40. I try to buy them in batches on eBay when they're listed too cheap to pass up. Otherwise, I get them at Duniway Stockroom.

For this setup to be useful for fusion there needs to be an adjustable flow restrictor between the pump and chamber. I have a simple butterfly valve in the works and will report on its progress in another thread.

Here's a look at things as they stand now.
Attachments
DSCF1669.jpg
DSCF1671.jpg
DSCF1676.jpg
Anything obvious in high vacuum is probably wrong.

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Carl Willis
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Re: Fusor Chamber 101

Post by Carl Willis » Fri Jul 29, 2011 7:01 am

It's a work of art, George!

I'm just curious if you plan to give the diff pump a trial run before completing the rest of the fusor layout. I'm really curious about that in particular.

-Carl
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Richard Hull
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Re: Fusor Chamber 101

Post by Richard Hull » Fri Jul 29, 2011 2:39 pm

It all really looks amazing and if it fuses, It will be the most kludged up system, yet, in spite of your demonstrating obvious welding and brazing skills well beyond the average DIY yahoo that stumbles in here.

I'm with Carl, lets get some data on that Diff pump's operation.

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.

George Schmermund
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Re: Fusor Chamber 101

Post by George Schmermund » Fri Jul 29, 2011 5:49 pm

O ye of little faith! Of course the pump will work, I designed it myself! There is really no difference between designing with glass or metal. Only the construction material and techniques are different. My history of success with glass pumps is well documented in these forums.

As for rigorous testing, the pump will have to be connected to gauges and flow meters and such. I was going to connect it to a 'plain vanilla' ported manifold, but now have chosen to use the new chamber as the testbed. This of course will require that the chamber be finished to the level where it can be helium leak tested. The cooling coils can be installed after pump testing is finished.
Anything obvious in high vacuum is probably wrong.

Todd Massure
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Re: Fusor Chamber 101

Post by Todd Massure » Fri Jul 29, 2011 6:09 pm

Nice George. What's the inside diameter of the chamber?
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Bruce Meagher
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Re: Fusor Chamber 101

Post by Bruce Meagher » Fri Jul 29, 2011 10:36 pm

Hi George,

Your designs are inspiring! One thing I noticed on your setup is the lack of a roughing line port just below the chamber above some type of butterfly valve. Will you use one of the ports on the chamber for this, or is this a design feature of your super small pump? If you've simplified the operating procedures and valving of a diffusion pump I'd love to understand the details.

Bruce

George Schmermund
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Re: Fusor Chamber 101

Post by George Schmermund » Sat Jul 30, 2011 7:30 pm

Todd - The inside diameter is ~ 3 1/4".

Bruce - The only dedicated ports so far are the main pumping port for the DP and the one opposite it that I envision as the HV port. The other 4 ports are up for grabs. The TC and ion gauges can each have one and the spares could be used for roughing and/or venting and the last one could be used to feed gasses into the chamber. For more complex experiments more ports can be easily added.

The butterfly restrictor wouldn't be a valve as such because it won't have a gasket on it. It's just a way of keeping a large pressure differential between the chamber and the DP when that mode is useful.

I'll cover more about how to use this setup as a valveless system after the testing is done.
Anything obvious in high vacuum is probably wrong.

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Steven Sesselmann
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Re: Fusor Chamber 101

Post by Steven Sesselmann » Sat Jul 30, 2011 9:54 pm

Great work!

Boiler maker or bartender, who cares, it's what you want to be that counts, a great experimental physicist.

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
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