
First amateur polywell fusion reactor, in a Brooklyn apt - joewadcan
http://prometheusfusionperfection.com/2011/08/02/sydney-experiment-we-have-electron-confinement/
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sbierwagen
There was no actual fusion reaction occurring in this test. He just confined
electrons in an air plasma. No hydrogen was injected.

And, of course, it didn't take place in an apartment.

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VladRussian
well, starting from 20-30KV the plasma may start radiating X-rays
(bremsstrahlung).

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endian
Nitpick: It's not an apartment, it's a shared lab space near the Marcy
Projects. I visited a while back and it was cool.

Awesome work, Mark!

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emeltzer
Haha, I interviewed this guy for a position a while ago and saw his reactor
and workshop. It's totally boss but it wasn't in an apartment but rather in a
huge warehouse workshop space.

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rubyrescue
what are the implications of this?

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hugh3
None. It's just a cool amateur electronics project. Energy in >> energy out.

In fact, I'm _assuming_ and _hoping_ for the sake of his neighbours that he's
not _actually_ attempting fusion. If I recall correctly, doing _actual_ fusion
with one of these requires deuterium and tritium and produces a crapload of
neutrons for which I really doubt he has adequate shielding.

I'm pretty sure the experiment which he's attempting to replicate was never
done with deuterium-tritium either, for similar reasons.

~~~
sbierwagen

      In fact, I'm assuming and hoping for the sake of his neighbours that 
      he's not actually attempting fusion. If I recall correctly, doing 
      actual fusion with one of these requires deuterium and tritium and 
      produces a crapload of neutrons for which I really doubt he has 
      adequate shielding.
    

Yes and no.

The very lowest-energy-threshold fusion reaction _is_ deuterium-tritium, so
must research tokamak reactors use that. The JET[1], ITER[2], et al.

But tritium is both expensive and excitingly dangerous, (It's an alpha
emitter, which is ordinarily harmless, since the alpha particles aren't
energetic enough to penetrate skin; but it's a radioactive _gas_ , not a
solid, so you can inhale it and get all sorts of amusing cancers) so real
amateurs prefer Deuterium-Deuterium fusion, and the kind of fusion reactor
that that produce the higher energies needed to accomplish it, known as
fusors[3].

D-D fusion _does_ produce neutrons, you are correct. But the PF reactor is a
pulsed device, with a tiny coil size: it doesn't make many neutrons, and it
produces them for seconds at a time. This guy has been checked out by the
NYFD, and they've signed off on the project. If it was a power reactor,
neutron emission would be a problem, but it's not, so it ain't.

1: <http://en.wikipedia.org/wiki/Joint_European_Torus> 2:
<http://en.wikipedia.org/wiki/ITER> 3: <http://en.wikipedia.org/wiki/Fusor>

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cperciva
_tritium is both expensive and excitingly dangerous, (It's an alpha
emitter..._

Err... you sure about that? Must be some interesting physics going on for a
p-n-n to emit a p-p-n-n. ;-)

I'm guessing you meant beta emitter?

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sbierwagen
Whoops! You are correct.

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WordSkill
To be remembered down through the ages as the Great Vaporization of Brooklyn,
August 3rd, 2011.

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sbierwagen
Nope.

Fusion reactors are fundamentally different from fission reactors. You have to
get a tenuous wisp of hydrogen (the reactor in this particular experiment was
running at 10 mTorr, or 0.0013% atmospheric pressure) very, very hot, and keep
it away from solid matter, which is millions of degrees of colder than the
fuel plasma, and will suck all of the energy out of the reaction.

You shut off the containment coils, and tremendously hot plasma ions leap away
from each other, instantly stopping the reaction. If the reaction somehow
"runs away", which it absolutely can't, then it brushes the walls of the
vacuum chamber, poisoning it with cold metal ions, like injecting lead
shavings that have been chilled to absolute zero directly into your heart.

If our magical "runaway reaction" somehow overcomes this, and melts a hole in
the vacuum chamber, then the atmosphere rushes in, both freezing cold and at
intolerably high pressure, like the North Sea flooding into the hull of a
submarine resting on the ocean floor.

Fusion reactors don't melt down, or explode. At all. It just can't happen,
much like how a Yugo rear-ending a garbage truck in Brooklyn doesn't instantly
consume all of New York City in a gasoline fireball.

It is indicative of the great difficulty of both starting and sustaining a
fusion reaction that the only fusion reactions which produced more energy than
they consumed, that have _ever_ taken place on Earth were powered by _atomic
bombs,_ and still only ran for fractions of a second.

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jcrites
It's worth calling out that a cubic meter of the sun's fusion reaction
generates about the same power as an active compost heap.
<http://en.wikipedia.org/wiki/Sun#Core> \- the huge energy output is due to
the huge volume

~~~
Eliezer
That really surprised me until I looked it up, and read in Wikipedia that "At
the center of the Sun, theoretical models estimate it to be approximately
276.5 watts/m3, a power production density that more nearly approximates
reptile metabolism than a thermonuclear bomb" and realized a few seconds later
that an object with a thermonuclear bomb's power generation density, _the size
of the Sun_ , would not look like a thumb-sized blazing ball of fire from 93
million miles away. It would look like a supernova, and explode around as
fast.

