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Re:Nuclear physicist explains why fusion ignition is hailed ... by dotancohen on Monday December 19, 2022 @07:37AM (#34051346)
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".
Re:Nuclear physicist explains why fusion ignition is hailed ... by HPsquared on Monday December 19, 2022 @08:54AM (#34052014)
It has always been a matter of building a machine with sufficient performance. That's engineering, by definition.
Re:Nuclear physicist explains why fusion ignition is hailed ... by lazide on Monday December 19, 2022 @09:38AM (#34052516)
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.

Re:Nuclear physicist explains why fusion ignition is hailed ... by Robotbeat on Monday December 19, 2022 @10:16AM (#34053015)
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...
Re:Nuclear physicist explains why fusion ignition is hailed ... by lazide on Monday December 19, 2022 @10:24AM (#34053123)
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 ... by Robotbeat on Monday December 19, 2022 @11:11AM (#34053720)
I would consider the sparking of fire a big step. And that it used inefficient lasers is irrelevant because it wasn’t intended to be anything but a demonstration of ignition and scientific breakeven. The follow-ons which would use modern efficient solid state lasers were delayed because there’s no reason to build a power plant without first having the fire. Funding for them was premature, and it was right to focus on achieving ignition first: https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy

No one needs to talk about delaying solar deployment, obviously that would be stupid. No one should be arguing for that, I certainly am not, and trying to do this whole thing where we attack genuine advances just because they aren’t the thing we prefer is super counterproductive to progress. Shameful to do that, no matter how common it is on social media.

This was built as a machine to test fusion, not to generate electricity. It did that, and doing so is a significant advance.

Re:Nuclear physicist explains why fusion ignition is hailed ... by lazide on Monday December 19, 2022 @12:18PM (#34054659)
This isn’t sparking fire. We already know how to do that. Fusion reactors have been doing that for decades, and we’ve been doing it overall for 80ish years now.

It’s sparking fire in a very specific synthetic scenario which maybe could be useful in making a specific type of fusion reactor.

It’s a critical step, yes, in development of that type of reactor, if we wanted to do so. Currently there is no reason to believe we’d find it worthwhile to do.

But there are literally hundreds more steps just as critical with no known solution, that are likely just as hard before we could actually have net positive energy even in a lab for such a reactor. Even if we found the economics would pan out.

That’s why I’m saying it’s a small step and we’ve got miles to go - because we do.

You’re pointing out some of the next small steps.

But those won’t get us to even having the energy balance positive on paper.

making lasers 100x more efficient for one being a notably hard problem, from a physics perspective. Probably even harder than IC fusion. The planned upgrades to lasers will help, but not enough to be close to a positive energy balance.

If the ‘first 90% takes 90% of the time’, we’re now at 2% of that first 90%. But everyone is hyping it up as we just completed it. Which is not true at all.

Honestly, it sounds like a Hail Mary funding push to try to get a new project funded or stop the lab from being shut down.

Re:Nuclear physicist explains why fusion ignition is hailed ... by candiodari on Monday December 19, 2022 @07:06PM (#34059700)
NO. The lasers are immaterial. You could use a hammer to cause the initial fusion (in fact ... [1]). The point of ignition is to have fusion powered by fusion, NOT by lasers. We want fusion of two atoms cause at least 2.000001 other atoms to fuse, and then raise that number. Not even by much 3 will definitely do it. If Q > 1, then this must have happened, there is no other explanation. That's the big advance. The point is to have the fire burn after we've lit the match.

You want to use lasers to initiate some fusion, you can do that using a tabletop laser lab (although magnetic confinement and big voltages is much simpler).

So this is the first machine where we're sure: it wasn't fusion caused by lasers, it was fusion caused by neutron pressure! Where did that neutron pressure come from? From other atoms fusing!

Note also that the sun does NOT do this. Fusion inside the sun is powered by falling atoms converting their falling energy first into heat then into singular fusion events, which essentially explode and throw a lot of atoms back up. Then the cycle begins again. Fusion inside the sun is a self-limiting reaction, which is why stars don't just blow up once, but "burn" over a long time. All the fusion inside the sun really does is slow down gravity for a little bit, then immediately stop. Gravity is producing the heat from the sun.

[1] https://en.wikipedia.org/wiki/General_Fusion

Re:Nuclear physicist explains why fusion ignition is hailed ... by lazide on Monday December 19, 2022 @09:29PM (#34060793)
The hohlraum is destroyed almost instantly by the reaction.

The reaction is initiated by the lasers.

You can’t actually use a hammer to initiate it at any useful scale because hammers can’t create the appropriate pressures and temperatures to initiate the process at the scale needed to produce a useful energy output. Which is why the lasers.

So no, the lasers are not immaterial at all.

Re:Nuclear physicist explains why fusion ignition is hailed ... by manholio on Monday December 19, 2022 @09:09AM (#34052182)
> 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.

Re:Nuclear physicist explains why fusion ignition is hailed ... by Robotbeat on Monday December 19, 2022 @10:19AM (#34053055)
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 ... by IshKebab on Monday December 19, 2022 @09:35AM (#34052488)
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 don't have a practical way of capturing the energy that's produced at all as far as I understand it.

None of that has changed.

Re:Nuclear physicist explains why fusion ignition is hailed ... by Robotbeat on Monday December 19, 2022 @10:19AM (#34053045)
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.