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Nuclear fusion reaction releases almost twice the energy put in
(www.newscientist.com)
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this post was submitted on 06 Feb 2024
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I can't read the full article (paywalled for me) but it references the National Ignition Facility so the way it goes is super lasers blast a tiny hydrogen thing and that creates a tiny bit of fusion that releases the energy. The energy of the laser blast is what's being called the input and the fusion energy released the output. What is misleading is that a greater amount of energy was used create the laser blast than the laser blast itself outputs. If you consider the energy that went into creating the laser blast the input (rather than the laser blast itself), then it's usually not a net positive energy release.
Thx. Rip tho
What other energy are you referring to? Like warming up the laser?
Remember when incandescent light bulbs were the norm? They worked by sending full line voltage through a tiny tungsten wire that would get so hot that it glows, making some light, but 95% of the energy that gets consumed is frittered away as heat? The high-power lasers needed to make fusion happen are a lot like that.
I believe all this article is saying is that 15% more energy than what came out of the lasers as useful laser light was liberated in the reaction.This completely ignores the energy it took to power those massively inefficient lasers.
I think it also ignores the fact that the 15% more energy liberated wasn't actually, like, harnessed by a generator. I believe (and I may be wrong) this was testing only the reaction itself. Actually hooking that up to a turbine and using it to create energy that is cost competitive with contemporary sources is still a completely unsolved problem.
pixelscript@lemmy.ml got it, but basically lasers are pretty inefficient. The article I just found said (in a different run of this facility) they put 400MJ into the laser to get 2.5MJ out of it. So that makes the whole firing system what, 0.6% efficient? Your fusion reaction would have to give more than 400MJ to truly be in the positive for this particular setup/method, but again this facility is a research one and not meant to generate power - there isn't even a way to harness/collect it here.
Oh so the laser's generating mostly heat and a little coherent radiation, and they're only referring to the coherent radiation as the "energy input" to the process.
Hmm. Kinda sketch.
Especially because that's not trivial. If we have no way of obtaining laser light other than that process, and the laser is the only way to feed the fusion reactor, then that's 100% on the balance books of this process.