Archived - Plasma pic
- Doug Coulter
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- Joined: Sun May 27, 2007 3:18 pm
- Real name: Doug Coulter
- Location: Floyd, VA, USA
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Archived - Plasma pic
Here's a rather unconventional cylindrical fusor running a plasma of an argon/neon/air leak mix at about 50 ma at about 1.3 kv -- it heats the tank nicely. The grid is made from ni cr wire, the supports are cut from an old propane tank. I can also get bugles etc at different pressures and power feeds, but now to go fix the doggone leak in the system and protect that nice window! Also shown in the tank are a halogen source I use to help outgass, and a support for some Ti wire to be used as a getter. The thing sticking down from the top is a modified 6sj7 I plan to use as an electron source once I fix the leak.
Why guess when you can know? Measure!
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Re: Plasma pic
That is a very nice window, what's it made from? (The rest of the pic is nice too btw)
- Mike Beauford
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- Location: Morton Grove, IL
Re: Plasma pic
Hi Doug - Looks very nice. Your setup is very similar to one I am eventually going to build. I'm looking forward to your results when you crank-er up for a full D-D run.
Mike Beauford
- Doug Coulter
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- Joined: Sun May 27, 2007 3:18 pm
- Real name: Doug Coulter
- Location: Floyd, VA, USA
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Re: Plasma pic
Just 1/4" pyrex, I didn't spec anything better when I bought the system parts, mainly from Pfeiffer, at the start of this -- and at that it was very pricey (Quartz would have added about a K$ to the window price). Lesker provided most of the rest, but they're not the place to buy pumps from (50% markup vs direct from vendor prices). I bought another thicker piece of pyrex to put in front of that window (cheap) from McMaster-Carr, which does the job of mostly stopping X-rays. But I fear stray electron/ion beams may shatter this thing -- it gets pretty hot sometimes, and has a viton gasket to boot. So I plan to put a mica window inside the tank and cover it with ITO (making it conductive and grounded while still fairly transparent) to take the beatings from this and other projects. If I ruin that I'm only out about 20 bucks, vs half a K+ for the nice window.
I did my own (mostly lousy, but I'm learning) welding on this to save at least a few bucks, buying the mechanical parts from various vendors (www.mcmaster.com), and making quite a few here in the shop downstairs.
In my wine-jug bell jar system where I do lots of sputtering and evaporation, loss of the jug is not a big deal, and there I can just dunk a coated jug in acid to clean it. Not so in this system! I also use this at the HV to UHV range for other toys, and one fingerprint or contaminant in there really makes for heartburn.
I plan to try a pinch on this setup once I get my hands on a big enough energy storage cap. Let the Farnsworth part get all the ions in there, then use an arc (and enourmous magnetic field) to compress the mess down to about a micron in diameter so as to get a real reaction rate. Can't figure a way to do that in a spherical plasma, so I built a cylinder instead.
I did my own (mostly lousy, but I'm learning) welding on this to save at least a few bucks, buying the mechanical parts from various vendors (www.mcmaster.com), and making quite a few here in the shop downstairs.
In my wine-jug bell jar system where I do lots of sputtering and evaporation, loss of the jug is not a big deal, and there I can just dunk a coated jug in acid to clean it. Not so in this system! I also use this at the HV to UHV range for other toys, and one fingerprint or contaminant in there really makes for heartburn.
I plan to try a pinch on this setup once I get my hands on a big enough energy storage cap. Let the Farnsworth part get all the ions in there, then use an arc (and enourmous magnetic field) to compress the mess down to about a micron in diameter so as to get a real reaction rate. Can't figure a way to do that in a spherical plasma, so I built a cylinder instead.
Why guess when you can know? Measure!
- Doug Coulter
- Posts: 1312
- Joined: Sun May 27, 2007 3:18 pm
- Real name: Doug Coulter
- Location: Floyd, VA, USA
- Contact:
Re: Plasma pic
The vacuum setup is as follows:
Economy turbo pumping station from Pfeiffer (about 4.5k). Then the usual cross for gages and side arms -- the little tube coming to the front of the bench has adapters for hanging glass tubing on there to make gas and vacuum tubes, for example. I also sprung for a mass spectrometer, which cost more than the pump station, but was worth it for troubleshooting stuff and seeing gas purity and the like. There is also one of my cheap pirani gages on there and a "real" one from Pfeiffer to calibrate my cheapies with. The bellows-sealed valves were a major outlay, and hard to outgass, but also worth it.
I built the 6" diameter chamber from tubing and flanges, some of which were made here on the lathe once I saw how easy it could be.
That's genuine Glyptal on the tank which hides scars and seals leaks to a nicety (Caswell plating has this) -- and it also tells me right now when some part of the tank gets very hot. This was a lot cheaper than having someone else build my tank, even including the price of the TIG welder and the lathe, etc. In fact, doing some of this homebrew has paid for the building this is in, so to speak (see www.coultersmithing.com), the building was pretty cheap.
The needle valves I use in the gas manifold and the gage there were bought very cheaply from McMaster-Carr. Go look at the Lesker catalog, then see a $7 gage and <$20 valves at McMaster! These are leak free in the bargain and need no separate shutoff valve if the operator is careful to tighten them just so.
Economy turbo pumping station from Pfeiffer (about 4.5k). Then the usual cross for gages and side arms -- the little tube coming to the front of the bench has adapters for hanging glass tubing on there to make gas and vacuum tubes, for example. I also sprung for a mass spectrometer, which cost more than the pump station, but was worth it for troubleshooting stuff and seeing gas purity and the like. There is also one of my cheap pirani gages on there and a "real" one from Pfeiffer to calibrate my cheapies with. The bellows-sealed valves were a major outlay, and hard to outgass, but also worth it.
I built the 6" diameter chamber from tubing and flanges, some of which were made here on the lathe once I saw how easy it could be.
That's genuine Glyptal on the tank which hides scars and seals leaks to a nicety (Caswell plating has this) -- and it also tells me right now when some part of the tank gets very hot. This was a lot cheaper than having someone else build my tank, even including the price of the TIG welder and the lathe, etc. In fact, doing some of this homebrew has paid for the building this is in, so to speak (see www.coultersmithing.com), the building was pretty cheap.
The needle valves I use in the gas manifold and the gage there were bought very cheaply from McMaster-Carr. Go look at the Lesker catalog, then see a $7 gage and <$20 valves at McMaster! These are leak free in the bargain and need no separate shutoff valve if the operator is careful to tighten them just so.
Why guess when you can know? Measure!
- Richard Hull
- Moderator
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- Joined: Fri Jun 15, 2001 9:44 am
- Real name: Richard Hull
Re: Plasma pic
Doug, I have added your name to the Plasma list. Good work.
Richard Hull
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
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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Re: Plasma pic
That definitely looks like work on your table and it's good to see that you are trying a different approach. Good luck!
Wilfried Heil
Wilfried Heil