
The Fusioneers, who build nuclear reactors in their back yards - Fjolsvith
https://www.washingtonpost.com/news/style/wp/2016/05/26/fusioneers/
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paulsutter
These are Farnswoth Fusors[1], first developed by Philo T Farnsworth, one of
the inventors of television.

The devices use about 100,000x more energy than they produce FROM FUSION
(edit, thanks), but some fusion does occur. An individual ion can be heated by
11,000 kelvins with a single electron volt, so 15,000ev is enough to reach
fusion temperature. The statistical challenge is getting ions to collide -
overcome the (repelling) coulomb force - and fuse.

There are discusson groups online for this topic [2] and there's even a high
school in the Seattle area that has a fusor [3].

[1] [https://en.wikipedia.org/wiki/Fusor](https://en.wikipedia.org/wiki/Fusor)

[2] [http://www.fusor.net/board/](http://www.fusor.net/board/)

[3] [http://www.industrytap.com/overview-
polywell/31940](http://www.industrytap.com/overview-polywell/31940)

~~~
cyanoacry
I've built a fusor[1], and in its simplified form, it's just a large,
negatively charged grid in a vacuum chamber with some hydrogen sitting around.
Nothing to be afraid of!

You're absolutely right that these devices don't produce net energy. I built
mine because I wanted to learn more about all the tech involved (high vacuum,
high voltage, some nuclear physics). They're really good teaching projects for
folks going into experimental physics, since there's a neat outcome without
too much danger.

I assembled a coffee table book with some pretty pictures about it, PDF copy
here:
[http://shia.wsyntax.com/stuff/fusion/fusor_book_web.pdf](http://shia.wsyntax.com/stuff/fusion/fusor_book_web.pdf)

[1] [http://fusion.wsyntax.com/](http://fusion.wsyntax.com/) ,
[http://fusion.wsyntax.com/setup/](http://fusion.wsyntax.com/setup/)

~~~
lawpoop
How much would it cost, roughly, to manufacture helium from one of these?

From what I understand, we are running out of our natural stock.

~~~
GeorgeKangas
It would cost a fuck ton! Here's how I figure it:

Each fusion event makes one He atom and releases about 17 MeV of fusion
energy. Since (one mole) X (one eV) = ~100,000 Joules, fusing one mole (2
grams) of He would produce about 1.7 X 10^12 Joules. That's about 472
megawatt-hours of fusion energy produced.

Another commenter says that the energy INput (to the Farnsworth fusor) is
about 100,000 times the energy OUTput; so fusing that 2 grams of He would
require a 2,000 megawatt power plant to run for 23,600 hours, or 2.7 years.

Readers: please correct any mistakes you find.

~~~
Thorondor
Since a fusor normally runs on deuterium fuel, wouldn't the output be helium-3
with a mass of 3 grams/mole?

Not that it makes a big difference - producing helium with a fusor remains
extremely impractical.

~~~
GeorgeKangas
Oops! I used He's atomic number (2) instead of its atomic mass (usually 4).

I believe deuterium fusion events mostly produce He4, occasionally He3 +
neutron. So we'd actually produce between 3 and 4 grams.

~~~
Thorondor
No, deuterium-deuterium fusion reactions usually produce helium-3 and a
neutron. Due to the conservation of energy, producing helium-4 requires the
emission of a gamma ray. This happens rarely because, since the strong nuclear
force is stronger than the electromagnetic force at small distances, fusion
reactions tend to release energy as protons and neutrons rather than gamma
rays.

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snarfy
I have a hack project like this going in my garage.

I'm trying to build a resonant tuned polywell device. The tldr is polywell +
tesla coil power source + microwave oven = fusion? I have no idea if it will
work but is something I wanted to try.

The original polywell is a steady state device, where this is meant to create
a dynamic system in tune with the power source.

[https://en.wikipedia.org/wiki/Polywell](https://en.wikipedia.org/wiki/Polywell)

[http://2.bp.blogspot.com/-3BPtWiGxd3c/Vj7ecWEoXuI/AAAAAAAAGc...](http://2.bp.blogspot.com/-3BPtWiGxd3c/Vj7ecWEoXuI/AAAAAAAAGcs/ywhNj7we_AU/s1600/4.png)

~~~
mh-cx
> I'm trying to build a resonant tuned polywell device. The tldr is polywell +
> tesla coil power source + microwave oven = fusion? I have no idea if it will
> work but is something I wanted to try.

I hope you thought about all the consequences this may have. See Primer.[1]

[1][https://en.wikipedia.org/wiki/Primer_(film)](https://en.wikipedia.org/wiki/Primer_\(film\))

~~~
pdabbadabba
The sequel is a let down though. Oh well.

~~~
mh-cx
There's a sequel? Or did you mean Upstream Color? It's definitely quite
different and more artistic. But I want to give it a second chance.

~~~
pdabbadabba
Oops! Must have gotten my timelines mixed up. Please don't tell anyone.

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Aelinsaar
Impressive people, but I don't feel that I got a sense of what they were
actually doing. I understand that it's a challenge for a writer who probably
doesn't understand the subject well, to talk to the average read who doesn't
understand it at all. Still, this feels like a wasted opportunity to teach,
and to inform others with more knowledge about what these interesting people
are doing.

~~~
josefresco
Felt like we read just the beginning to a very thorough article. Instead we
just got introduced...

~~~
jloughry
This feels like the introduction to a book. It sounds like an interesting one.

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andrey_utkin
This listing won't be full without David Hahn aka "Nuclear Boy Scout".
[https://en.wikipedia.org/wiki/David_Hahn](https://en.wikipedia.org/wiki/David_Hahn)

~~~
deepnet
Hahn was working with fission not fusion , he was not a 'fusioneer' but
splitting the atom.

Hahn produced amazing amateur nuclear work nonetheless, ( somewhat out of
control when his reactor went critical ).

~~~
arethuza
I wonder if you could use a Farnswoth Fusor as a neutron source to do some
fissioning?

~~~
myrryr
yes you can, and it means you can have a reactor which (when the power to the
fusor fails), it turns off(ish).

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Animats
Lockheed-Martin's Skunk Works is trying to build a useful fusion reactor using
a somewhat similar approach.[1] They announced this a few years ago, and last
fall, their people gave a talk at the Princeton Plasma Physics Laboratory.
(There's video, but it won't play in Firefox on Linux.[2])

It's striking that a very capable organization is working on this.

[1] [http://www.pppl.gov/events/colloquium-lockheed-martin-
compac...](http://www.pppl.gov/events/colloquium-lockheed-martin-compact-
fusion-reactor) [2]
[https://mediacentral.princeton.edu/media/Thursday+Colloquium...](https://mediacentral.princeton.edu/media/Thursday+Colloquium,+August+6,+2015,+%22The+Lockheed+Marin+Compact+Fusion+Reactor%22,+Dr.+Thomas+McGuire,+Lockheed+Martin/1_5j8kix93)

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riprowan
Nice bios. Would rather read about what they're building.

~~~
djaychela
Exactly - this was just the opening page to the article I would have like to
have read; that may be because I did my apprenticeship in the UK Atomic
industry and long for my 20s, but maybe it's because it would be really
interesting to read about this stuff - I had no idea people were doing this
sort of thing as a hobby. I feel an evening's search-and-read activity coming
on!

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nickpsecurity
Let's not forget Doug Coulter:

[http://sploid.gizmodo.com/this-chain-smoking-gun-loving-
guy-...](http://sploid.gizmodo.com/this-chain-smoking-gun-loving-guy-built-a-
nuclear-reac-1536653459)

He has a forum dedicated to all kinds of stuff. He occasionally stopped by
Schneier's blog to deliver insightful posts. I particularly liked his calling
out the Anarchist Cookbook's many ways of killing people... that try to do
what it says. ;)

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cm3
While we're at it, are safety considerations the only problem that prevented
nuclear powered automotive engines? I've always wondered why.

~~~
brandmeyer
Mostly its about size. There is effectively a minimum viable size for a
fission reactor. There are a pinch more than 2 neutrons born from each fission
event. In order to operate at criticality, exactly one of them must go on to
produce another fission. Leakage of neutron radiation from the effective
surface of the core is a major way that neutrons don't make it to cause
another fission event. As the ratio of surface area to volume goes up (because
the core got smaller) it becomes harder and harder to design a core that
doesn't lose neutrons to the other loss mechanisms to keep up with the
increasing loss out the core's surface.

