Picture of 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)
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HaydenS315 days ago

I have a quick question, what are the best cf flanges to use? The hemisphere's diameter is six inches. Are rotatable cfs fine? Thanks

Is there a way to set it up were after everything is powered up the plasma powers a different output?
What was the total cost of building this?
oliverg523 days ago

How long did it take you to finich the projekt. Then i mean with reserch and building. apoxemetly how manny hours did you put down?

christensent (author)  oliverg523 days ago
I don't know, maybe 5000 hours or so as a rough estimate... it was my life outside of school for about two years.
RaccoonI29 days ago

could you posibly use hydrogen

christensent (author)  RaccoonI28 days ago
Not if you care about producing neutrons, otherwise you can use any gas to make a "demo fusor" which still visually produces a star of plasma in the chamber.

Would There Be A Chance Of It Working, If It Was Built On A Bigger Scale, And Would It Be Able To Power A Ship That Has A Maximum Speed Of 5000 MPH.

It works, it creates fusion, but it does not output more power than it draws. Its use is more likely to be found as a neutron radiation source. Scientists with much bigger, much more sophisticated equipment have yet to run a fusion experiment in a lab that produces more power than the electricity put into it. So far the sun is the only fusion reactor we can get significant amounts of power from.

As to powering a ship capable of going 5000mph, in the water that's basically impossible so far, as you run into the problem of cavitation behind the boat. The technique for going faster has always been to make a boat that has a smaller water profile to make cavitation smaller, and the fastest they've ever gotten was around 320MPH. A more reasonable and usable boat likely has a physical speed limit of around 50MPH before cavitation presents a hard limit to the speed. The problem isn't getting MOAR POWER, it's mostly solving hydrodynamic problems.

SteveM10 JakeV5 months ago

i dont think the intended medium is water, but near space

less than 3 light years

jbonner2 SteveM104 months ago
Space is the only real practical application of tritium deuterium reactors. The reason is deceptively simple. That is because the raw materials require a ton of energy to make in a fission reactor. But a laser fusion drive spitting 30 one mm pellets of tritium fuel into a rocket bell could sustain a 1g acceleration for a year.. in sci-fi terms .. hyperdrive.

you don't need constant acceleration because it traveling through space has no resistance to slow you down

thought you might light to know: your information regarding scientists with better equipment is outdated. Granted, it's not a LOT of power, but it's a start, and what's more: Lockheed Martin is hoping to make fusion power viable in the next decade.

Cavitation has nothing to do with hull speed limits. Cavitation is cold water boiling and occurs when the water pressure on the back side of a propeller (benoulli effect) gets so low that the water boils. Hull speed in a displacement boat is limited to 1.4 time the square root of the water line length, in meters, and expressed in knots. Faster then that and the boat is planning, much faster the boat is flying. As water resistance is an exponential of speed, there is currently no material in existence that could withstand the pressure created on the hull at 5000 mph, and no portable power source capable of driving said hull.

it is not possible to make a ship go that fast due to the fact it would need to be 10618870.404976288 ft long and the earth is only has a 126720 foot circumfrance

but the DD fusion have two posible out come,3He+n or T+p anyway to detect netron?also the DT fusion is easier to triggle, so any posiblity to get Trituriume?

but the DD fusion have two posible out come,3He+n or T+p anyway to detect netron, also the DT fusion is easier to triggle, so any posiblity to get Trituriume?

NiTaLuH7 months ago

I was looking for spherical vacuum chambers and I couldn't find any to fit the purpose... does it need to be spherical?

jbonner2 NiTaLuH4 months ago
It doesn't need to be spherical. It doesn't even have to be big. A glass tube or even a wine bottle will do fine.
jbonner24 months ago
Some of the steps seems unnecessarily complicated. In my evil lair I have a 100kv Van De Graaff and a 400 kv Tesla coil. But for my fusion reactor I just use a salvaged television fly back. For vacuum a mercury diffusion pump is best but an old refrigerator compressor and a dry ice bucket works pretty good. I cripple evacuate and flush with helium. I think it helps the reaction. Why is a trade secret but if you have read this far you are smart enough to figure it out. OBTW , that vacuum chamber is overkill. You can find a surplus vacuum deposition bell for $100 .. I did. I will post a video soon.
RoanM4 months ago

so all of this so far is just building the vacuum, yes?

SpencerF7 months ago

Can some one please post how to get the 40,000 volts.

I suggest you look up the circuit for a voltage multiplier known as a Cockcroft Walton

Capacitors and diodes in a ladder formation. Feed it with AC and you will get a huge DC voltage out depending on the number of stages you have. There were use originally to power a lot of nuclear reactors

dimu5 SpencerF7 months ago

You can use old TV's transformer in order to achieve very high voltages (and use condensator and diode to double the output up to ~40k), but the current can be quite small, I think it won't go over 2-3mA. Or plug serially 10 MOT's and also double the voltage using diode and condensator. You will get extremely overpowered killer source that might shut the whole street down :). Notice, that both sources can be absolutely lethal, and this voltage can also skip over few centimeters. Also, in both cases you will get direct current as output, because of use of voltage doubler. (sorry for my spelling :/ )

Iflscience7 months ago

This is really cool, what is it for? Just sitting around and being awesome?

I want to know at what pressure in the chamber is needed before and after filling deuterium for fusion.

and how much tritium this device produces.

Plzz reply fast

NiTaLuH7 months ago

so, I'm gonna try building this as a base for Nuclear Reactor experiments... I have a couple of questions.

1. How much does a good Vacuum Chamber go for?

2. Where can I find a High Voltage Power supply, and how much will it cost?

3. what's the approximate ratio for energy going in to energy coming out... in other words, how inefficient is this reactor?

JoshWolff711 months ago

I am really interested in this and would love to build it. Is it possible to hook this up with thorium instead of deuterium? How can I simplify this project? Is this fusion reactor hooked up to a capacitor or something of the like that it charges - how is the power harnessed?



Thorium is a fuel used in a fission reactor. It is essentially a replacement fuel for Uranium 232. Thorium is transformed into Uranium 232 after being bombarded by neutrons traveling close to the speed of light so you need a small cyclonic particle accelerator (think tiny CERN) to make it work.
So no Thorium will not work.

Thorium is much more stable so it is harder to fuse. At this scale probably not.

Would would also need to pump in even more power than the deuterium would need in order to get a reaction if it were even possible.

JakeV JoshWolff79 months ago

How is the power harnessed?

The most likely way you would harness the power would be to use the heat coming off the reactor to drive a thermal process, probably with water becoming superheated steam to turn a generator turbine.

SobhanB JakeV8 months ago

Can you please explain what's the point? I don't think the efficiency of all this is 100%. So aren't we just using a lot of voltage to produce less voltage?

JakeV SobhanB8 months ago

Ultimately the idea would eventually be to use a fusion reactor to produce more power than it requires to run, but that's not what it's capable of right now.

Why bother doing this at all?

Even if it's not producing more power than it takes in, it still has its uses. I don't know about how useful it would be for home projects, but it does make a powerful neutron source for various kinds of analysis.

For examples of neutron spectroscopy, see

JakeV JoshWolff79 months ago

You're talking about a very different nuclear reaction. Deuterium is hydrogen with an extra neutron attached to it, and you get two Deuterium atoms colliding with each other to create heavier Helium atoms, releasing lots of energy in the process. This process is called nuclear fusion.

For Thorium, the reaction is nuclear fission. Take Thorium, bombard it with neutrons to turn it into radioactive Uranium, and the Uranium undergoes a chain reaction dropping off Helium nuclei and eventually leaving you with lighter lead.

Fusion creates heavier elements, fission destroys them.

JoshWolff7 JakeV9 months ago

Oh ok! I got it! Thank you for taking your time to explain that.

christensent (author)  JoshWolff711 months ago

No thorium, can't really be simplified much, no capacitor, and no power harnessing

can we set it up to use ( I hope I spell it right ) helium ( my spelling sucks )?

christensent (author)  ElectricBlue12310 months ago

No, deuterium and tritium are the only gasses that will produce fusion in a DIY fusor. Deuterium is the only one that is legal to use.

Can the valve be manual ones? I prefer to use manual (for simplicity) but can high voltage be dangerous that I shouldn't use a manual valve? I'm not familiar with pneumatic valves or other type of valves.Thanks in advance.

ty by the way

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