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Momentary fusion breakthroughs face hard reality

spectrum.ieee.org

41–50 of 71 posts

Re: Momentary fusion breakthroughs face hard reality

#41

Imagine a second Manhattan Project, except this time, it's to produce fusion energy and try to save the world from climate disasters instead of making a weapon. Who would you tap to participate in/lead this?

Elon Musk and his ability to gather financing and top engineers

Re: Momentary fusion breakthroughs face hard reality

#45

Imagine a second Manhattan Project, except this time, it's to produce fusion energy and try to save the world from climate disasters instead of making a weapon. Who would you tap to participate in/lead this?

Why do you think finishing the fusion research (just another 10 years? again?), and then designing commercial reactors, and then building out all the fusion generation capacity we need, could possibly take less time/money/effort than just building out all the wind/solar/battery capacity instead, which we already know how to make?

Re: Momentary fusion breakthroughs face hard reality

#46
post #31
post #30

Earlier quoted context omitted.

> Why go through the expense of... Good question. I should have asked strictly about fusion bombs. These being a known-working example of energy production by fusion, why not use them when we can't get 'controlled' fusion working?

From my recollection, even in a fusion bomb, most of the energy comes from the fission. I don't fully remember/understand the physics involved. But apparently the fission reaction triggers the fusion reaction (that part I get) and then that fusion reaction in turns boosts the fission reaction. So my takeaway is that fission bombs are not very efficient to begin with. You're after all trying to extract as much energy…

Yes, the gist is that in a fusion device, you've got a chain reaction where the splitting uranium or plutonium is making neutrons, and those neutrons strike other uranium or plutonium, which makes more neutrons, etc. But you have a very short period of time to take advantage of this chain reaction, because before long, your device has blown apart, so a large percentage of the fuel in a conventional fission device never undergoes fission (the device has blown up before it has a chance). The job of the fusion reaction in a fission-fusion-fission device (how "modern" thermonuclear weapons work) is, in addition to producing energy of its own, to rapidly produce lots of lots of neutrons, which can very quickly fission a second quantity of fissile material.

Re: Momentary fusion breakthroughs face hard reality

#47

I don't think fusion will ever be cheaper than solar and wind

No, but it will be more reliable, and potentially portable. Both very important characteristics.

I do agree that distributed solar and wind (with battery storage) can take take care of grid base load, but that doesn't mean fusion is pointless.

Re: Momentary fusion breakthroughs face hard reality

#48
post #18
post #3

> Plenty of other obstacles remain than those noted above, too. Current calculations compare energy generated against the NIF laser’s output, but that brushes over the fact that the lasers draw more than 100 times the power from the grid than any fusion reaction yields. That means either energy gains or laser efficiency would need to improve by two orders of magnitude to break even in any practical sense. The NIF’s f…

This basically the plot of the movie ”Real Genius”

Great film! https://www.youtube.com/watch?v=xuv7SIVNkx8

Re: Momentary fusion breakthroughs face hard reality

#49
post #30

Earlier quoted context omitted.

> Why go through the expense of... Good question. I should have asked strictly about fusion bombs. These being a known-working example of energy production by fusion, why not use them when we can't get 'controlled' fusion working?

One of the biggest challenges is that the fusion reaction can't be fully contained. There are particles without electric charge that simply go through your magnetic containment field and smash into the reactor wall, continuously destroying it. You don't really care about preserving the shell of your bomb. You care about preserving the shell of your reactor.

How do fusion researchers handle that problem?

Re: Momentary fusion breakthroughs face hard reality

#50
post #10
post #3

> Plenty of other obstacles remain than those noted above, too. Current calculations compare energy generated against the NIF laser’s output, but that brushes over the fact that the lasers draw more than 100 times the power from the grid than any fusion reaction yields. That means either energy gains or laser efficiency would need to improve by two orders of magnitude to break even in any practical sense. The NIF’s f…

NIF uses inefficient lasers because they were cheap to build at the time and because NIF is a science experiment. Lasers have gotten better. And lasers aren't the only way ICF fusion could be carried out, it may be possible to use ion beams instead[0]. It does not matter if fusion reactions last microseconds if they generate more energy. Using optimistic, but not unrealistic assumptions, it appears feasible for elect…

NIF exists to research nuclear weapons without breaking the treaties. Their fusion energy research is a nice corollary but it is absolutely not their focus.
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