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Ignition confirmed in a nuclear fusion experiment for the first time
A 2021 experiment achieved the landmark milestone of nuclear fusion ignition, which data analysis has now confirmed – but attempts to recreate it over the last year haven't been able to reach ignition again.
Breakthrough in Nuclear Fusion Energy: Ignition Confirmed in Record 1.3 Megajoule Shot
Exactly one year later, the scientific results of this record experiment have been published in three peer-reviewed papers: one in Physical Review Letters and two in Physical Review E, according to a press release by LLNL.
"The record shot was a major scientific advance in fusion research, which establishes that fusion ignition in the lab is possible at NIF," said Omar Hurricane, chief scientist for LLNL's inertial confinement fusion program.
"Achieving the conditions needed for ignition has been a long-standing goal for all inertial confinement fusion research and opens access to a new experimental regime where alpha-particle self-heating outstrips all the cooling mechanisms in the fusion plasma."
[...] Since their success last August, the researchers have been trying to recreate the record-breaking performance in order to understand its experimental sensitivities.
[...] While the researchers have not been able to recreate the same level of fusion yield as the August 2021 experiment, all of them have showcased capsule gain greater than unity with yields in the 430-700 kJ range, significantly higher than the previous highest yield of 170 kJ from February 2021.
"It is extremely exciting to have an 'existence proof' of ignition in the lab," Hurricane concluded. "We're operating in a regime that no researchers have accessed since the end of nuclear testing, and it's an incredible opportunity to expand our knowledge as we continue to make progress."
Previously: Finally, a Fusion Reaction Has Generated More Energy Than Absorbed by the Fuel
Original Submission #1 Original Submission #2 Original Submission #3
(Score: 1, Flamebait) by HammeredGlass on Wednesday August 17 2022, @12:45AM (13 children)
you haven't recreated it.
see ya all next year
(Score: 0) by Anonymous Coward on Wednesday August 17 2022, @12:50AM (11 children)
Do you have to burn a second house down to confirm the first one burned down? Or did we have to wait for the second person to orbit the Earth before confirming it was done the first time?
(Score: 2, Troll) by HammeredGlass on Wednesday August 17 2022, @12:54AM (3 children)
You're not proving either happened at all without the scientific method which is the slow process of proof by repeatable actions that produce repeatable results.
(Score: 0) by Anonymous Coward on Wednesday August 17 2022, @12:59AM (1 child)
I think you missed this bit at the end of tfs?
> "We're operating in a regime that no researchers have accessed since the end of nuclear testing,...
There is plenty of prior art. It's just that this time they've done it in a tiny way with some additional control over the process, and, most importantly, without blowing up everything.
(Score: 0, Troll) by HammeredGlass on Wednesday August 17 2022, @01:12AM
thanks, that just adds to their shame
(Score: 3, Insightful) by Anonymous Coward on Wednesday August 17 2022, @01:36AM
There are expected signatures when you've crossed the fusion threshold, with input/output energy being an obvious one, so you look for those things to tell if fusion occurred. That's not a repeatable action measurement. Determining how easy/hard it is to reach that state under whatever conditions they are using is one of those kind of things. Like determining whether the first A-bomb worked. They didn't have to blow up a bunch of them to determine whether fusion was going on, they knew from measurements and observations (energy, radioisotope production, etc.) that it occurred. Here they're going to keep beating on it and tweaking their setup and hopefully they get to where they can understand the threshold requirements and optimize on that so that they can do it consistently while probably turning up new and interesting science along the way.
I assume these papers are presenting the observational evidence to justify their claim that fusion occurred, but I haven't looked at them or their abstracts to know what they're saying.
(Score: 1) by khallow on Wednesday August 17 2022, @01:33AM (4 children)
What's the evidence that the first house burned down? How reproducible is that evidence? Now, try the same thing for the above research.
(Score: 0) by Anonymous Coward on Wednesday August 17 2022, @02:21AM (3 children)
I assume that is what the journal paper goes into. For the house, I can show you the temperature measurements made, the videos of flames and smoke, the chemical analysis showing the chemical conversion of elements due to oxidative reactions, cite papers showing the combustion threshold for materials in the house and compare that to the temperature measurements, etc. etc. And we can compare all that to the smoldering rubble and conclude that not only is everything consistent with the house burning down, that is by far the most likely thing that happened under our current understanding of physics and chemistry. What I don't see is what that has to do with the "slow process of proof by repeatable actions" argument here that suggests that you have to keep lighting houses on fire to prove the first one burnt down. Sure, do that if you want to determine how often houses burn down, and maybe it turns out to be really hard to burn them down, but we're talking about whether a threshold was crossed here, not how often it gets crossed. That's the next step.
(Score: 1) by khallow on Wednesday August 17 2022, @02:49AM (2 children)
And we can confirm several of those observations after the fact - until they clean up the burn site. What's the evidence after the fact that you supposedly had nuclear fusion ignition? It doesn't leave a smoldering pile of ashes after all.
(Score: 0) by Anonymous Coward on Wednesday August 17 2022, @02:42PM (1 child)
The whole experiment is, by design, set up and instrumented with the detectors you need to make the measurements to look for the things you expect to see when fusion occurs, so you have all of that data. As for exactly what that evidence is, I suppose you'll have to read their paper to find out because that isn't explained much in the summary, though the LLNL press release [llnl.gov] has a little bit more info, but all of that is a separate issue from how repeatable it is.
(Score: 1) by khallow on Wednesday August 17 2022, @11:12PM
(Score: 2) by Opportunist on Wednesday August 17 2022, @05:40AM (1 child)
No, but you have to burn the second house down to prove that the way you say the first burned down actually was how it burned down. Maybe you just thought that the fire in the basement was the reason the house burned down completely and it was a spark in the gas main that actually caused it, so if you try to burn down the second house by setting the basement ablaze and it doesn't go up in flames ... boy, will you have egg on your face.
(Score: 0) by Anonymous Coward on Wednesday August 17 2022, @02:36PM
But you're getting into the why or how easy is it to burn down questions, not whether it burned down in the first place. The issue we're looking at here is, say, we've been trying to burn down the house for a long time. We've tried holding a match to the garage door, to the box in the basement, to the carpet in the family room, etc., and they don't seem to work because the house, or most of it, is still standing. Then one time we did it and we think the house burned down, and here's why we think so (it isn't standing any more or whatever other reason we think it met our criteria to be classified as "burned down"). If you repeat it by holding the match in the same place as that time and not having it burn down doesn't mean that it didn't burn down the first time, it just means that it doesn't happen all the time, so now maybe you repeat that a bunch of times to see how often it happens under those conditions, or maybe you move the match around in that general area, or you use two matches, etc., but you know it burned down the first time because it met your "burned down" definition, which you of course have written up and explained in a paper to Nature.
In the case of fusion, one is expected to at least meet Lawson's criteria [wikipedia.org] and probably some other things that they describe in their paper. Their paper (presumably) says, "here are our measurements that show that this one shot exceeded the requirements for us to be confident that fusion ignition has been achieved."
(Score: 2) by FatPhil on Friday August 19 2022, @07:25AM
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