Build A Fusion Reactor

Yes, you can build your very own nuclear fusion reactor in your house! But first, a few warnings:

-This project includes lethal voltage levels. Make sure you know your high voltage safety or have a qualified electrical advisor.
-Potentially hazardous levels of x-rays will be produced. Lead shielding of viewports is a must!
-Deuterium, an explosive gas, will be used. Make sure to check for fuel leaks.
-All the other inherent dangers of a home engineering project of this degree (a wide gamut of potential injuries, damage to the checking account, and the loss of general sanity)



Here are the minimum required materials:

-A vacuum chamber, preferably in a spherical shape
-A roughing vacuum pump capable of reaching at least 75 microns vacuum
-A secondary high vacuum pump, either a turbo pump or oil diffusion pump
-A high voltage supply, preferably capable of at least 40kv 10ma - Must be negative polarity
-A high voltage divider probe for use with a digital multimeter
-A thermocouple or baratron (of appropriate scale) vacuum gauge
-A neutron radiation detector, either a proportional He-3 or BF3 tube with counting instrumentation, or a bubble dosimeter
-A Geiger counter, preferably a scintillator type, for x-ray detection and safety
-Deuterium gas (can be purchased as a gas or extracted from D2O through electrolysis - it is much easier and more effective to use compressed gas)
-A large ballast resistor in the range of 50-100k and at least a foot long
-A camera and TV display for viewing the inside of the reactor
-Lead to shield the camera viewport
-General engineering tools, a machine shop if at all possible (although 90% of mine was built with nothing but a dremel and cordless drill, the only thing you really can't build without a shop is scratch building the vacuum chamber)

Step 1: Assemble The Vacuum Chamber

A quality high vacuum chamber is required for the fusor to operate. Sometimes an appropriate chamber can be found on eBay, but generally it is best to make one. Parts can be scrounged for several hundred dollars, or purchased new for $500+.

Get two stainless steel hemispheres, purchase two corresponding conflat-flanges (8" flanges in my case), bore out holes for accessory flanges, and then TIG weld it all together. Flanges are typically either of the KF or the conflat style. Conflat can be seen in the image below as the flanges with bolts, and KF (kwik-flange) are seen as those with only clamps holding an o-ring on the mating surface. Only weld on the inside, never on the outside (since virtual leaks can be formed if both inside and outside are welded). If you've never TIG welded before, it would be wise to have someone with experience do it as the welds must be flawless with no pin-sized holes or porous areas to hold a vacuum.

After machining, thoroughly clean the chamber and avoid getting fingerprints in it since these will outgas, which means at vacuum pressure molecules in the oil of finger prints or machining oil will become vapor and make it hard to maintain plasma stability or reach a good ultimate vacuum level.

Comments

[trosa4]

Hi there mister hmm...may I ask what grade of stainless steel for the hemispheres did you use?
And what thickness was it?
And if you bought it from a manufacturer maybe could you give me the link so I could acquire a similar enough piece of such stainless steel?

[cobra6romeo]

Amazing! When are you planning to build your table top Tokamac?

[jbaker22]

Is it possible for me to hook up high enough voltage and amperage to a deuterium lightbulb to create fusion?

[christensent]

No, the pressure is too high... they sustain plasma at only a few hundred volts.

[jbaker22]

What if I put it in a container filled with pressurized air?

[christensent]

That would accomplish nothing. Read up on the concepts of gas laws and plasma voltage characteristics.

[jbaker22]

How efficient is the reactor? (watts use and watts generated)

[christensent]

Something in the range of a million to a billion times inefficient

[jbaker22]

Did you ever hook this up to a lighting rod for fun?

[nate.2310]

Is it legal to build one of these things?

[antioch]

Probably everywhere but in (post 9/11) USA, haha

[crash landing]

any chance your next project could be a table top model of the hadron collider? I started on mine but my wife wanted her washing machine back so the project is on hold for the moment.

[crash landing]

I was just looking for something to do in my retirement

[munkey906]

oooo yes... table top hadron collider, that would be sweet!

[Higgs Boson]

While that would be very cool, The LHC uses a bunch of pipe shaped superconducting magnets, and these would just not scale down well. The smallest cyclotrons consist of two hollow D shaped electrodes in a vacuum chamber oscillating between positive and negative charges within a very powerful magnetic field. They could maybe fit on a very large and sturdy table but for anything tabletop sized you would need a lower energy linear accelerator.

[crash landing]

I have been working on a variation of the bitsco fignut separator. As you are well aware, this is the integral part of a bowling machine. I currently use it to rotate the stiltson fluid in the turn indicators on my wifes 1937 Packard. The replacement lenses,now being amber, have altered the color spectrum. Do you have any suggestions?

[Higgs Boson]

Nothing you just said makes any sense at all.

[crash landing]

I had the same thoughts listening to the republican convention...

[Higgs Boson]

That's funny.

[Nuclear_Ninja]

Nice Project I would like to give it a try myself. What inspired you to build this?
Can you give me an estimated cost to build what you did?
Also do you have to TIG weld the parts or can another type of welding work?
One last question what type of shielding other than the lead did you use?

[christensent]

I was just looking for a science project online, found it, and it sparked my interest. I spent about $6000 on it, but it could be done for less with better planning. Yes, the parts need to be TIG welded. Other forms of welding are not completely vacuum tight. I used only lead. While it is possible to shield neutrons, it is extremely expensive and bulky, and isn't really necessary for the neutron levels produced by this device.

[AlbinoMoose308]

$6,000?!?! That's half my upcoming mars mission budget!
(I'm planning the launch for ~2015)

[Nuclear_Ninja]

on what scale are you talking like what counts were you getting off the neutron detector?
and thank you for the information

[christensent]

At peak run a typical home built reactor will make one to two million neutrons per second. This may sound like a lot, but it is very few from a biological hazard. You could stand a few feet from it for days with effectively no risk.

[Nuclear_Ninja]

Ok what are you currently using your neutrons for or are you just running it for the sake of running it? and if you dont mind me asking are you in college if so what degree are you working on

[christensent]

I was pretty much running it for the sake of building it, tweaking it, and having fun with it... It is possible for it to be used as a useful neutron source for experimentation, however I lacked sufficient equipment to do that stuff. I no longer run it since I am not at home. I built this in high school, and am now at college at MIT studying electrical engineering and physics.

[Nuclear_Ninja]

ok and congrats on the MIT thing I an studying nuclear engineering at nc state. hints at my intrest in a reactor. thank you for all the information. If I end up building one of my own I will post pics.
Once again thank you for the info

[garagegenius]

(removed by author or community request)

[christensent]

This is inertial electrostatic confinement

[Machine]

These instruments are called Fusor. The American inventor Philo Farnsworth was likely the first to produce one and gave it that name.

[Nuclear Radiator]

Wouldn't a deuterium bulb work if given a few hundred volts for it to sustain plasma.

[Nuclear Radiator]

Where to fit the vacuum gauge ?

[resistanceisfutileiflessthan1ohm]

i've heard of this setup before, if it works it would be awesome. i do not know if it would be easier but couldn't you detect the neutrons using a proton detector of some kind on the other side of a paraffin wax target as james chadwick did when he discovered the neutron.

[Higgs Boson]

Just out of curiosity what was your budget on this?

[christensent]

~$5000, although you could build one for a lot less if you're going for bare minimum proof of fusion with no other goals (and much much less if you're willing to wait years scrounging parts... many of the parts are expensive to buy immediately, but if you sit around on ebay for a year, you might get lucky and find expensive parts for a tiny fraction of what you'd pay new or even common surplus prices)

[Higgs Boson]

Okay thanks. I was just curious because everything seemed pretty expensive. Not having that much money I would probably have to look (or beg for) donations of discarded equipment from local universities. Although it seems that the number one best way to save money on this kind of thing is to improvise.

[agm88]

i have to agree with higgs here this seems a little to expensive for my budget(20 dollars)

[Higgs Boson]

Well, your not going to be able to build anything with only $20. I'm just saying that if you could only invest say $500 in this project, you could easily blow that just getting a diffusion pump (that's a pretty good deal for those by the way). But it would still not be out of your reach if you were to try to borrow some of the really expensive stuff, and/or get creative and improvise with cheaper items to construct what would otherwise be very expensive.

[agm88]

even though i love this project im afraid of it to
never would hav thought of diy nuclear fusion =)

[burpreynolds]

Who are you?