BobD1001
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Nuclear Fusion Milestone Achieved
Well I know this is a chemistry forum, but I suppose this is technically nuclear chemistry... Anyways, scientists have now achieved a massive
milestone: A nuclear fusion reaction which produced more energy than it consumed! I figured many of you may enjoy the read so I hope this post is
appropriate. I for one, am very excited about this huge milestone!
http://www.bbc.co.uk/news/science-environment-24429621
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: replaced
"Self Sustaining Nuclear Fusion Achieved" subject]
[Edited on 9.10.13 by bfesser]
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Metacelsus
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Great news! I wonder when the output will exceed the energy required to run the lasers (if ever  ).
(This thread should probably be moved to Miscellaneous or maybe Technochemistry.)
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elementcollector1
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Bloody finally! Hopefully we're a few steps away from internally-powered homes!
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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BobD1001
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Quote: Originally posted by Cheddite Cheese  | Great news! I wonder when the output will exceed the energy required to run the lasers (if ever ).
(This thread should probably be moved to Miscellaneous or maybe Technochemistry.) |
Cheddite, It would seem that the reaction may have in fact surpassed the energy output of the lasers. As stated "The amount of energy released through
the fusion reaction exceeded the amount of energy being absorbed by the fuel - the first time this had been achieved at any fusion facility in the
world."
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Metacelsus
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Nope. The amount of energy being absorbed by the fuel is not the same as the amount required to run the lasers -- the system is not 100% efficient.
Still, it is a great milestone.
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gregxy
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Efficiency:
Heat to electricity => 40%
Electricity to laser energy => 1% ??
(The lasers are pumped with big flash lamps, using diodes would help a lot).
Still a long long way to go.
There is also the "neutron economy" these fusion reactors burn tritium, which requires neutrons to produce. Neutrons are produced by the fusion
reaction, but some are lost, captured by structural elements of the reactor etc. So additional neutrons must be supplied, by a fission reactor. In
addition the "lost" neutrons activate components of the fusion reactor, creating lots of low level radioactive waste. So fusion is not as clean as
one would wish.
[Edited on 8-10-2013 by gregxy]
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bismuthate
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If they have trouble with nuclear waste I'm sure this forum would be more than happy to take it of their hands.
(kidding.......or am I?)
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bfesser
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While this is an impressive milestone—not one I had expected from the NIF—it's not a self-sustaining reaction. I've modified the
subject on the first post.
[edit] A slightly better news article:
<a href="http://www.cbsnews.com/8301-205_162-57606588/apparent-breakthrough-in-nuclear-fusion-silenced-by-shutdown/" target="_blank">Apparent
breakthrough in nuclear fusion silenced by shutdown</a> <img src="../scipics/_ext.png" /> (CBS News)
Official NIF news release:
<a href="https://www.llnl.gov/news/newsreleases/2013/Aug/NR-13-08-04.html" target="_blank">Laser fusion experiment yields record energy at
Lawrence Livermore's National Ignition Facility</a> <img src="../scipics/_ext.png" /> (Lawrence Livermore National Laboratory)
Other resources:
<a href="https://lasers.llnl.gov/" target="_blank">National Ignition Facility & Photon Science</a> <img src="../scipics/_ext.png"
/> (LLNL)
<a href="https://en.wikipedia.org/wiki/National_Ignition_Facility" target="_blank">National Ignition Facility</a> <img
src="../scipics/_wiki.png" />
[Edited on 9.10.13 by bfesser]
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bfesser
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Thread Bumped
9-10-2013 at 08:44 |
BobD1001
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Thank you for the edit and additional info and links Bfesser and gregxy. Hopefully this small stepping stone twoards a self sustaining nuclear fusion
reaction opens some new insight as to how we can sucessfully bring such fusion a bit closer to reality in the not so distant future.
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gregxy
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Looking at the articles, in a bit more detail:
8000 J of Neutron energy were produced. I assume that most of the fusion energy is released in the form of neutron energy. This is converted to heat
when the neutrons are
absorbed.
The laser pulse was 1.7 MJ (optical energy), it appears that most of (1-8000/1.7M = 99.5%) the optical energy misses or is reflected by the target,
but at least it should possible to recapture it since it is at a very high effective temperature.
The laser efficiency (electrical to optical) is probably 1%,
maybe 10% is possible in the future? The 90% that is
wasted would be difficult to recover since the lasers must
operate at close to room temperature.
Thermal to electrical conversion is 30-60% these days, assume 40%.
The "loop gain", which must be > 1 to produce energy is
0.4 * 0.1 * (0.005*G + 0.995) = 1
where G is the gain due to fusion.
Solving gives G=4800 to produce net energy and G is currently 1. So there is a very long way to go
Rats! if it wasn't for that aweful government shut down we could have free fusion energy!!
Note NIF is a "dual use" facility, for nuclear weapons test & development and future energy sources. I suspect the first is the main reason it is
funded.
https://lasers.llnl.gov/about/missions/national_security/
Still it is cool science.
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jock88
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Another milestone?
http://www.bbc.com/news/uk-england-lancashire-26450512
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Metacelsus
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Not really. That kind of fusion has been known since the 1960s and is far from being able to generate energy. It is useful for neutron sources,
though.
https://en.wikipedia.org/wiki/Inertial_electrostatic_confine...
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