Archived - The Five Minute Fusor

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Mark Rowley
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Archived - The Five Minute Fusor

Post by Mark Rowley »

Several days ago I had a bit of spare time and decided to build an extremely low budget demo fusor. The below pictured effort utilized a 2" x 3" piece of heavy walled borosilicate tubing, stainless tig wire (for grid and HV feedthru), a scrap piece of alumina tubing, two brass discs, vacuum nipple, and Loctite 5 minute epoxy.

After all is said and done, the demo unit operates quite well. With a properly ballasted NST, it barely gets warm. However, I am still careful with those nasty electron beams.

Total cost was $0.00. Since everything was leftover scrap. However, I suspect the assembled chamber would cost about $30 if everything was to be bought.

I would like to add that I am quite impressed with cheap hardware store epoxy. I have no doubt that one could easily attain pressures suitable for fusion using this method. As stated earlier by someone else, the epoxy must not be anywhere near the plasma region or striking distance of an electron beam.

Lastly, I would like to strongly suggest an implosion shield for anyone who should try to attempt this build. I am fairly confident of the strength of my heavy walled borosilicate, however, Murphys Law will always win in the end.

Mark Rowley
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Tyler Christensen
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Re: The Five Minute Fusor

Post by Tyler Christensen »

Looks like a new "smallest operational fusor" competition might be started here...
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Steven Sesselmann
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Re: The Five Minute Fusor

Post by Steven Sesselmann »

Nice, how many volts can you push it to?

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
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Re: The Five Minute Fusor

Post by DaveC »

Hi Mark -

Very nicely done. Certainly shows that a spherical outer electrode is not needed, to make a nice apparently symmetric central focus.

And... the price is right, too. Would be really surprised if it didn't put out some neutrons, when the fill gas is Deuterium.

Dave Cooper
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Mark Rowley
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Re: The Five Minute Fusor

Post by Mark Rowley »

Hi Steve,
Due to the quick nature of this project, I have yet to put much more than 7.5 kV into the unit. After the chamber was complete, I just pulled the nearest NST off the shelf and hooked it up. I would bet 20 kV would be the upper limit.

Last night I modified the chamber by removing the hose adapter and replacing it with a threaded gas flange. This should make Star Mode conditions appear quite fast.

Mark Rowley
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Re: The Five Minute Fusor

Post by Wilfried Heil »

Nice. Be careful with the star mode though. When the beams hit the glass, it can crack very quickly.
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Re: The Five Minute Fusor

Post by adrian.f.h »

Hello
Nice effort.
Im still busy with laser-stuff but something about the fusor-work will come soon. I'm sure.

If you plan to make such a competition please tell me. The first Poisor I achieved was in a 8mm borosilika-tube.
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Richard Hull
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Re: Archived - The Five Minute Fusor

Post by Richard Hull »

Nice little piece of work. Archived for its novelty.

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
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Doug Coulter
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Re: Archived - The Five Minute Fusor

Post by Doug Coulter »

Very nice indeed!

I too have found epoxy better than most think. The key seems to be proper mixing -- un mixed resin or hardener is a nightmare that never stops outgassing at good vacuums.
So, mix it good, and don't use the stuff from the fringes of the mix puddle.
It's also good to keep it warm during cure, and baking a bit after that before it sees vacuum.
The temperature for this would be epoxy formulation dependent, I use about 120c for most with good results, but I don't trust my oven thermostat, I measure.

I use Hysol 1-C here a lot (heard about it here on an older thread). McMaster has it, it's mostly silica filler. Good if you don't get it *too* hot. 24 hour epoxy is next-good, followed by the faster ones. Seems those are hard to get mixed as well before they start to thicken or something like that. But Hysol is the overall winner for low vapor pressure and inertness (but not strength), I've used it to glue a ceramic tube through a CF flange and taken it to better than e-8 mbar, and no epoxy signature on my mass spec after a couple of days. It's darn good stuff, should be in everyone's tool kit.

I'd second the implosion shield. I've made pyrex shatter with localized fast heating. Though this volume wouldn't do much damage -- goggles would do to make you mostly safe. I hate to say this, but you'll grow back, your vacuum pump won't, so make sure *that's* safe from eating glass bits in case the worst happens.
Why guess when you can know? Measure!
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Re: Archived - The Five Minute Fusor

Post by Quantum »

EYES DON'T GROW BACK.....BE CAREFUL...

The longer setting epoxies are easier to mix....have a longer working time.....and, once you finished, can be warmed to obtain a faster 'cure time'....fast epoxiies are (generally) not as good as the slower ones.
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Mark Rowley
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Re: Archived - The Five Minute Fusor

Post by Mark Rowley »

Ash,
Thank you for emphasizing my advisment. The more the merrier !

Mark Rowley
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Re: Archived - The Five Minute Fusor

Post by Legoleech »

Mr. Rowley,
I am an aspiring seventh grade middle school student whom is currently working to build an IEC for the year's upcoming science fair.
I have had little experience in the field of fusion, but have done extensive research on the subject. Upon seeing your post on how easily a small-scale fusor can be built ("The Five Minute Fusor"), I have finally been able to create realistic construction parameters.
I have already bought the basic components, including a 3-inch thick plexiglass wall for safety, but I am unsure of the vacuum pump and power supply.
Fortunately, my parents are very considerate of my interest in the field of science and are willing to buy me whatever equipment I need in order to proceed.
Being the creator of this groundbreaking miniaturized fusor design, I thought that you would perhaps check my selected pieces of equipment for viability before I buy them.
My fusor is nearly identical to yours-- so would a 10kv voltage and my chosen vacuum pump be acceptable?

Power Supply:
http://firehouseneon.biz/items/neon-pow ... detail.htm

Vacuum Pump:
http://www.ecrater.com/product.php?pid=5457323#

Many thanks,
Marcus
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Re: Archived - The Five Minute Fusor

Post by Tyler Christensen »

Read through the archives, you'll quickly learn that both the pump and supply you listed are both completely insufficient to hit fusion levels. Might work to make plasma but not a chance of fusion.
Legoleech
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Re: Archived - The Five Minute Fusor

Post by Legoleech »

I see-- even so, will it be enough to create a measurable amount of plasma?
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Re: Archived - The Five Minute Fusor

Post by Tyler Christensen »

The power supply is questionable, if it works it will make plasma but most likely it will shut off almost immediately since it will seem like it's overloaded or a ground failure.

It would be better to get one of the old tar filled transformer core NST's if possible, call around local neon sign companies and see if they have any extra old ones, I was given access to their junk lot which had lots of good transformers in it.

The pump will work to get to some form of plasma, but your $100 could be much better spent on a used pump if you shop around, I managed to get a decent Welch 1400 for less than $100 and that is worlds better than the pump you listed. It's usually better to go used than new for stuff like this in my experience. You get a lot more for your dollar.
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Re: Archived - The Five Minute Fusor

Post by benbartlett »

Hello Marcus,

The vacuum pump will work for plasma levels if you can seal the threads well, (don't use npt tape - that just makes a mess; use some liquid sealant), and the neon sign transformer you have will probably work, but it seems a little underrated.

I would suggest something along the lines of 15kV, 30-60ma (http://cgi.ebay.com/neon-transformer-ne ... 500wt_1182)

^^^That one would work; it's probably also tar-filled.^^^ (A bit pricey, though...)


By the way, even building a plasma fusor would be a very impressive feat for a seventh grader!

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Re: Archived - The Five Minute Fusor

Post by Legoleech »

Thank you so much for your support.
However, I have one last question; Where did you get your heavy walled pyrex?
I've only been able to find one suitable online resource, as 2-inch diameter borosilicate tubing with 5-7mm wall width is quite rare to find.
Did you order yours online our purchase it locally?

Many thanks,
Marcus.
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Mark Rowley
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Re: Archived - The Five Minute Fusor

Post by Mark Rowley »

The glass was ordered online from:

http://www.sundanceglass.com

Please keep in mind, this is NOT scientific glass nor is it Pyrex. Its heavy borosilicate tubing specific for glassblowing applications. With this in mind, I can say that it is fairly clean with very few (if any) imperfections. Out of almost 20 three foot tubes purchased over the years, only one had a small bubble. Was'nt a big deal as it was at the end. That reminds me, these tubes are rough cut so the ends will need finishing buy the purchaser. Also, they will not custom cut special lengths for you. Its either 3 or 6 foot lengths (or there abouts). Very good prices and fair shipping.

Hope this helps

Mark Rowley
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Re: Archived - The Five Minute Fusor

Post by Richard Hester »

Thanks for the link - it's nice to have a source for thick-wall pyrex. The prices aren't too bad, either.
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Re: Archived - The Five Minute Fusor

Post by Doug Coulter »

I don't know about this particular source, but the borosilicate stuff I got from glass blowers suppliers was kimble K-33 which IS 7740 pyrex in every respect (lousy insulator and all, compared to a lot of other glass alloys I've measured here -- sometimes a good thing as it equalizes potential drops across it like a resistor chain would). I now get all this from www.quartz.com since I'm using a lot of quartz now too, and that stuff is guaranteed to be what it says it is (they are a great outfit to deal with). No troubles at any point with any of it, other than hey, you have to learn how to work with it, whatever you have.
Why guess when you can know? Measure!
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Re: Archived - The Five Minute Fusor

Post by Richard Hester »

Cheap thick wall pyrex stuff is ok for general purpose vacuum applications. I have a couple of boxes of quartz for more serious applications, the first on my mind being a copper halide laser. In that case the power supply is a gating item, as I want to try and do a laser sans thyratron as the Bulgarians claim to have done.
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Re: Archived - The Five Minute Fusor

Post by adrian.f.h »

Ah a copper halide laser.
Please report about this project. I build a metal vapour laser (lead, manganese and a few other metals) on my own but it's not yet finished as can be seen on the first picture.
I also got two BeO tubes (the milky stuff on picture 2). I will use at least one of them in a copper vapour laser. These tubes can be found in RF excited CO2 lasers.
Also on the picture are a few borosilicate tubes for other types of lasers like a N+ laser as well as a quartz tube for the metal vapour laser.

To keep this thread fusor related I also added a photo of a poisor in a 8mm (inner diameter) borosilicate tube. It's in the left electrode.

Adrian
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