"170 kJ. That result suggested NIF was finally creating a “burning plasma,” in which the fusion reactions themselves provide the heat for more fusion—a runaway reaction that is key to getting higher yields. Then, on 8 August, a shot generated the remarkable 1.35 MJ. “It was a surprise to everyone,” Herrmann says. “This is a whole new regime.”"
That is certainly a big jump up and something to be happy about. I have a couple of problems. The first is it is only a single shot, if they could that two shot, three shots and so on then I think this is major. The issue is that this was a single shot, no two samples are the same on the atomic level by definition so it could be some odd property go the surface of the sample, lack of grain boundaries or defects act, not to mention that rare events can arise where by chance some particles just happen to go the right way due to chaotic dynamics. This could be some kind of lucky shot kind of thing where some unknown parameter could be present that could hard to reproduce. Single event discoveries happen all the time that cannot be reproduced, like the magnetic monopole. Perhaps they know a lot more that will be in the paper that shows that this result is repeatable and can be built upon. Let us hope so., I am also a bit leery they that the go from 170 to 1.35 MJ, a rather large jump. It may be possible that the burning phase simply has a long trail distribution with mostly short times but occasionally you get a long time.
On a funny note I was watching popular sci-tech podcast tonight and they talked about the great new laser induced fusion just done at some place in California when someone said you mean UC Berkley National labs to be exact. Ha
4 comments:
I'm a retired LLNL physicist and I tend to disagree with the "it's only one shot" criticism of the 1.35 MJ NIF experiment. If indeed they got solid evidence in support of a +1 MJ experiment (and I would think that a sudden energy release equal to that of a few hundred grams of high explosives would result in unmistakable evidence), then it's a big breakthrough.
The only possible thing that I can see that would ruin the party is this: I see that the energy output of a pulse from NIF's 192 lasers is in the range of 2 MJ, which is comparable to the claimed energy release. There's no way that that laser energy could somehow have been mistaken for actual energy output, is there? I'm not familiar with the NIF diagnostics used to measure energy release, and don't know if it is possible that they could have been somehow fooled.
-Doug
This is a joke, right?
The diagnostics of laser input are not the same as the diagnostics of neutron output.
@6:44
As I wrote, “I’m not familiar with the NIF diagnostics used to measure energy release” and the fact that energy release was based on neutron output. So my next question would be are the neutron detector diagnostics completely reliable for accurately measuring the released energy? I assume that there are multiple neutron detectors and that they’re cross-checked? That the data looks 100% legit and there’s absolutely nothing suspicious about the timing, pulse shapes, amplitudes, etc.? You may think that I’m being nit-picky, but in my +30 year career at LLNL I can recall several major LLNL “scientific breakthroughs” which had to be retracted because diagnostics were either faulty or misinterpreted. “Cold Fusion”-like flubs aren’t something that only happens at other institutions.
-Doug
Well…even Bodner said it worked…
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