

Machinery of an Energy Dream: How to Keep Fusion Going Long Enough - wikiburner
http://www.nytimes.com/2014/03/18/science/the-challenge-how-to-keep-fusion-going-long-enough.html

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cjslep
The question of sustainable fusion receives a lot of press regardless whether
it is a Tokamak or laser-ignited fuel pellets. However, the question I'd
always love to see get some attention is the engineering required to make it a
successful power plant -- will it use heat transfer and neutron thermalization
like traditional fission reactors to heat a coolant? How will that interface
look, and what kind of maintenance issues are going to go along with that?

I'm waiting especially eagerly in the case of laser-ignited fuel pellets, as
to me it's like harnessing the power of a multitude of miniature discrete
hydrogen bombs.

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Retric
Laser-ignited fuel pellets is all about nuclear weapons testing to validate
computer models not net energy generation. It's even paid for by "the 'Nuclear
Weapons Stockpile Stewardship' program, and the goals of the program are
oriented accordingly" It's possible to scale the idea to the point where it
would generate energy but Tokamak's are far cheaper and much further along. As
in we could build one that generates net energy today it's the material
science stuff as in how long do the wall last under heavy neutron bombardment
there still working out.

"ITER's goal is to produce 10 times as much power as is required for break-
even" but what there going to be doing with it is testing different material
blankets and magnetic control schemes plasma heating methods etc. There is
also some concern about trying to stabilize as self heating plasma. (Of
interest it's supposed go generate 500MW of thermal energy for ~10+ minutes so
dissipating that is rather important.)

After that DEMO is supposed to be a working prototype fusion reactor.

PS: Jet reactor built in 1982 was reasonably close to break even. It was
assumed we could build a working reactor next but it was simpler and cheaper
to scale ITER down as much as possible which removed the energy generating
side of thigns which is both expencive and well understood.
[http://en.wikipedia.org/wiki/Joint_European_Torus](http://en.wikipedia.org/wiki/Joint_European_Torus)

~~~
araes
"we could build one that generates net energy today". That's a pretty broad
claim, considering the article linked itself notes that we've only hit a Q
factor (output/input) of 0.7 with a test reactor measuring all the available
energy. We still need a Q of 5, or a little under a factor of 10 (7.14) jump
to be able to even have sustained fusion, as we specifically need the energy
of the alpha particles, and need an estimated Q of 10 (factor of 14.3 jump,
"Indispensable Truth") to be able to extract useful power. Any engineer will
tell you jumping the efficiency of almost any system enough to get a 14.3x
jump is not trivial.

We are making steady progress, and we're at least getting near break-even, but
we're still a ways from rolling out Tokamak's as the one true solution.
Frankly, I think the final solution may be a combination of strategies
(magnetic confinement, inertial confinement, electrostatic confinement, and /
or maybe one of the other ones, like sonofusion or the z-pinch).

~~~
Retric
Q is only the first problem. Tokamak's are considered the front runner because
they scale ridiculously well so getting something as small as JET to 0.7
briefly means something with 10x the volume is easy to hit a Q of 10. Jet's
was design work started in 1973 we simply have never built another device that
large again.

However, the Tokamack confinement record is only 6 minutes 30 seconds. The
neutron bombardment at scale is insane and grid power needs a steady and
dependable energy supply, nobody has a ready supply of Tritium so they need to
breed it somehow etc etc.

Worse even if we built something that was clean and net energy positive so are
windmills so the reactor also needs to be cheap. Also, while far safer and
cleaner than fission fusion still generates a fair bit of radioactive waste
due to all that neutron bombardment.

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crusso
Nothing to see here. The story is just a "where we are now" update with
nothing new or significant to add for anyone casually following progress on
controlled fusion.

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ZenoArrow
Of all the various fusion approaches out there, I believe that dense plasma
focus fusion (dubbed by one group pursuing it as 'focus fusion') is the most
promising. Considering the ridiculously small budget they've had to work on
it, the Lawrenceville Plasma Physics team has worked wonders. If I had the
money I'd show no hesitation in investing.
[http://www.lawrencevilleplasmaphysics.com/](http://www.lawrencevilleplasmaphysics.com/)

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ihnorton
“Awesome science story, but there’s a zero percent chance that a fusion laser
scientist named Dr. Hurricane isn’t a supervillain”

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rpedela
I got a pay wall...

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dm2
10 free articles per month.

You could either pay or bypass it.
[https://www.google.com/search?q=bypass+nyt+paywall](https://www.google.com/search?q=bypass+nyt+paywall)

