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Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

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Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#171

Post by dghughes »

albertopv wrote: post #22

Real Engineering published a video about Helion Energy company. I don't have the tools to filter out commercial BS, still it seems to me to be most promising effort. The idea to get electricity directly from magnetic fields instead of boiling water is very intriguing.

Everything about that was amazing. The design loos so simple and it's so small. The fuel used and the forward thinking of the fuel availability, separating fuel making from the reactor, how the fuel interacts with the reactor. Harnessing power from the magnetic field not by boiling water.

https://www.youtube.com/watch?v=_bDXXWQxK38

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#172

Post by hilbert42 »

sigmoid10 wrote: post #86
rob74 wrote: post #43

Still unconvinced why this is such a major breakthrough - it may be the first net-positive controlled fusion, but the distinction between controlled and uncontrolled fusion is a bit academic in this case. In uncontrolled fusion ( https://en.wikipedia.org/wiki/Thermonuclear_weapon ), you are using a nuclear fission primary stage to generate enough energy to start the fusion reaction in the secondary stage. In the NIF,…

You greatly underestimate the order of magnitude difference of produced energy in these two examples. You can't contain a bomb's hydrogen fusion reaction in a chamber for the simple reason that you need a nuclear fission warhead just to ignite it. So if you want to produce useful, controlled energy outside of killing things, the lasers are your only shot for inertial confinement fusion. Yes they still get damaged, bu…

"This news shows that practical fusion is now only an engineering problem, not a fundamental physics one..."

Yes, I'd agree with that statement that it's only an engineering problem, but with a laser energy of 2 million joules and a fusion yield of only 3 million joules and an overall input of nearly 300 million joules to produce the lasers then I've no expectation of ever seeing a total net positive output in my lifetime let alone fully established working fusion plants providing power to ordinary customers.

Moreover, compare the overall 'negative' efficiency of this experiment with the actual positive efficiencies of existing generation systems: solar: 20+%, combustion: 20%-40%, mechanical/electrical turbine: >97% and so on and we see there's three or so orders of magnitude to catch up upon.

The task may not be impossible but don't hold your breath.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#173

Post by Robotbeat »

rz2k wrote: post #155
zmgsabst wrote: post #114

Earlier quoted context omitted.

We can debate the importance, but it’s clear that they’ve made a qualitative leap in their technology the past few years — a “breakthrough”. https://en.wikipedia.org/wiki/National_Ignition_Facility#/me...

And that graph does not include the 2022 experiment with 3.15, which also happened to be the first one with net positive output.

Yup, here’s the one: https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121...

Credit: Mark Herrmann/LLNL

From this article: https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121...

Clear qualitative difference.

Additionally, this is laser energy, but the lasers aren’t used directly. They produce X-rays which are the ones that actually drive the ablative implosion of the fuel pellet. If you used X-rays directly, the gain value would be MUCH higher… I think by that measure, they would’ve achieved Q=1 back in 2013?

Note that hey COULD use the lasers directly to drive implosion but haven’t yet. The Hohlraum/X-ray/indirect method I think produces more consistent lighting on the target, and is more analogous to the operation of an H-bomb, which is partly what this entire process is intended to replicate. They may do future experiments to try direct drive, in preparation for actually using this as a power production method and improving the efficiency dramatically… in combination with far higher efficiency modern lasers, this could enable Q high enough for net electricity production.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#174

Post by mikeyouse »

hilbert42 wrote: post #172
sigmoid10 wrote: post #86

Earlier quoted context omitted.

You greatly underestimate the order of magnitude difference of produced energy in these two examples. You can't contain a bomb's hydrogen fusion reaction in a chamber for the simple reason that you need a nuclear fission warhead just to ignite it. So if you want to produce useful, controlled energy outside of killing things, the lasers are your only shot for inertial confinement fusion. Yes they still get damaged, bu…

"This news shows that practical fusion is now only an engineering problem, not a fundamental physics one..." Yes, I'd agree with that statement that it's only an engineering problem, but with a laser energy of 2 million joules and a fusion yield of only 3 million joules and an overall input of nearly 300 million joules to produce the lasers then I've no expectation of ever seeing a total net positive output in my lif…

The 300 million joules to produce 2 million joules was almost entirely due to 2->3” implies.

Some labs are already working with 20% efficient lasers, so hypothetically, Fusion is closer to “10->2->3” which is just amazing.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#175

Post by Robotbeat »

lazide wrote: post #151
HPsquared wrote: post #133

Earlier quoted context omitted.

It has always been a matter of building a machine with sufficient performance. That's engineering, by definition.

What kind of machine though is the point. A bomb? Already done. A fusion reactor? We’re still light years away from anything of the sort. This is only one tiny tiny step there, and we’ve got miles to go.

This is actually a significant step, not a tiny step. Achieving fusion ignition, ie including the 2021 shot, is THE non-linear scaling effect needed to make fusion a viable energy source. The other items needed to make this practical would’ve been premature to fund without this significant advance. https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121...

EDIT: Being down-voted, why? Previous steps to actually develop a power plant around NIF-like inertial fusion were cancelled in order to focus on achieving ignition first: https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#176

Post by graycat »

Ah, maybe there is a point so far not mentioned:

For a hint, the work was at the NIF, National Ignition Facility.

Even to start a wood fire, need an ignition facility. Then the fire continues on its own putting out much more energy than was used with the matches or whatever during the ignition. Then the energy from the fire ignites the wood that is not yet burning.

As we now know, once the nuclear reaction is ignited, the reaction generates more energy than was used with the lasers for the ignition. Then, sure, we can expect that the energy of the reaction should, without more energy from lasers, have the reaction continue.

Right, I'm ignoring a long list of what are sometimes called engineering details, e.g., that this is inertial confinement fusion!

Ah, at one time I worked for KMS, that is the company of Kip M. Siegel, as at Google and Wikipedia:

"KMS Fusion was the first and only private sector company to pursue controlled thermonuclear fusion research through use of laser technology."

https://en.wikipedia.org/wiki/Kip_Siegel

The report at the time was that KMS had achieved fusion neutrons.

Hmm ....

I didn't work on fusion but was hired because I knew quite a lot about the fast Fourier transform (FFT).

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#177

Post by Robotbeat »

IshKebab wrote: post #149
dotancohen wrote: post #108

Earlier quoted context omitted.

As I understand it - correct me if I'm wrong - one of the consequences of the December 5 experiment is that the engineering uncertainty was brought into the realm of "this now fits the progress of engineering, so we expect to be able to engineer the thing given sufficient capital and time", rather than the previous "we have no idea if we'll ever be able to engineer this thing".

Not really because we have known for almost a century that nuclear fusion is a real thing that can release energy. The problem is the engineering of how to actually do it in a useful way. They have made some progress towards that but it's still extremely unlikely that laser based fusion will ever work as a power source because: a) they're still two orders of magnitude from break-even from the input side, and b) they…

All of that has changed, since they’ve achieved ignition in 2021 and then confirmed the result here. https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121...

The way to capture the energy and make it into electricity was studied here: https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy

But it had been premature before they achieved ignition. You don’t build a boiler before you even have been able to spark a flame.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#178

Post by Robotbeat »

manholio wrote: post #140
dotancohen wrote: post #108

Earlier quoted context omitted.

As I understand it - correct me if I'm wrong - one of the consequences of the December 5 experiment is that the engineering uncertainty was brought into the realm of "this now fits the progress of engineering, so we expect to be able to engineer the thing given sufficient capital and time", rather than the previous "we have no idea if we'll ever be able to engineer this thing".

> rather than the previous "we have no idea if we'll ever be able to engineer this thing". We still have no idea if we'll ever be able to engineer this thing to produce commercially useful energy. And we probably never will, for all interesting values of "never", the challenges are simply so massive.

We have some idea, but wasn’t worth pursuing before we had achieved ignition: https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#179

Post by lazide »

Robotbeat wrote: post #175
lazide wrote: post #151

Earlier quoted context omitted.

What kind of machine though is the point. A bomb? Already done. A fusion reactor? We’re still light years away from anything of the sort. This is only one tiny tiny step there, and we’ve got miles to go.

This is actually a significant step, not a tiny step. Achieving fusion ignition, ie including the 2021 shot, is THE non-linear scaling effect needed to make fusion a viable energy source. The other items needed to make this practical would’ve been premature to fund without this significant advance. https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121... EDIT: Being down-voted, why? Previous steps to actually…

Uh no.

For sure, you can’t even consider the possibility of a fusion power plant without the core reaction producing power. That they figured out how to do the energy equivalent of getting the coal to actually light (finally!) in this context, is indeed useful.

But it is a tiny, tiny step towards an actual working fusion power plant.

And it does nothing to fix the economic issues here in competition with all the other energy sources, which matters.

Igniting that bit of ‘coal’ took near 100x the energy we got out of it. It was essentially putting it in a giant blowtorch, and then getting excited when it finally got lit and burned. That we previously only got half smoldering was indeed a problem! And that it finally lit is indeed cool.

it also took an extreme amount of thought, precision, investment, etc. to do it once.

Meanwhile, solar plants in the area were churning out billions of kwh.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#180

Post by woeirua »

jliptzin wrote: post #163
HPsquared wrote: post #97

Earlier quoted context omitted.

Parent was basically saying it has not been a physics problem for decades, it's already an engineering problem and there is no change there. The physics are known to work and have been demonstrated decades ago in a different engineering context (i.e. weapons).

Didn’t we already know it’s just an engineering problem by virtue of the sun existing?

No. Just because the sun exists, does not mean that it is necessarily physically possible to emulate controlled nuclear fusion without an _immense_ gravity well. Ignition in this context is a validation of our understanding of the physics. _Now_ it is just an engineering problem.
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