Proxima Fusion looks to take stellarators commercial
theengineer.co.uk
theengineer.co.uk
https://www.llnl.gov/article/49301/shot-ages-fusion-ignition...
What do you find misleading? The ability to study self sustaining fusion reactions without nukes certainly does have implications for fusion, which aligns with their stated goals of researching nuclear physics.
1) this research is weapons research (much less primarily weapons over power research)
2) this research does not currently contend a viable avenue towards breakeven power generation
> Following Hruby, NNSA Deputy Administrator for Defense Programs Marvin “Marv” Adams showed a NIF target capsule and explained the science behind fusion reactions. Adams said ignition will enhance national security by helping NNSA maintain confidence in the nuclear deterrent, advance the country’s non-proliferation goals and increase national security.
> “The science and technology challenges on the path to fusion energy are daunting but making the seemingly impossible possible is when we're at our very best,” Budil explained. “Ignition is a first step — a truly monumental one that sets the stage for a transformational decade in high energy density science and fusion research — and I cannot wait to see where it takes us.”
> While optimism reigned for the event, Budil cautioned there are still “significant hurdles” and engineering challenges to solve before the commercialization of fusion energy becomes a reality, such as the ability to reproduce ignition many times per minute and making fusion reactions simpler and more efficient.
> “I think it's moving into the foreground and, probably with concerted effort and investment, a few decades of research on the underlying technologies could put us in a position to build a power plant,” Budil said.
Did anyone seriously believe it was impossible to get "q" > 1 fusion by blasting a pellet of hydrogen hard enough?
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Significant hurdles != "There is not currently a/no known path"
I'm still toning down from "a path is impossible" which ought to be the consensus.
> a few decades of research on the underlying technologies could put us in a position to build a power plant
No.
> Granholm added that the unprecedented accomplishment will strengthen national security and moves the world closer to the possibility of an abundant, carbon-free energy source for the future.
> “It would be like adding a power drill to our toolbox for building a clean-energy economy,” Granholm said. “Today, we tell the world: America has achieved a tremendous scientific breakthrough — one that happened because we invested in our national labs and fundamental research. And tomorrow, we will continue to work toward a future powered in part by fusion energy.”
Since the start of the program they have been promoting ICF as a method of power generation. The very fact that they're crowing about net energy gain is because a minimum requirement for a power plant is that the energy that comes out has to be more than the energy that goes in. This is not a requirement for a fusion research machine.
> MAINTAINING THE NUCLEAR DETERRENT
> Stockpile Stewardship
> NIF is a key element of the National Nuclear Security Administration’s science-based Stockpile Stewardship Program to maintain the reliability, security, and safety of the U.S. nuclear deterrent without full-scale testing.
https://lasers.llnl.gov/about/what-is-nif
> For more than 70 years, Lawrence Livermore National Laboratory has applied science and technology (S&T) to make the world a safer place. While keeping our crucial mission-driven commitments in mind, we apply cutting-edge science and technology to achieve breakthroughs in nuclear deterrence, counterterrorism and nonproliferation, defense and intelligence and energy and environmental security.
It's also intended for energy research, but there's an important distinction between "energy research" and "energy production."
They do weapons. They said they do weapons. What’s the problem.
The general public is not stupid (but they are lazy), when the dust settles and people see that nif never resulted in anything but very tangential results useful for power, they're going to complain about the lack of transparency. Just as they are doing with the whole COVID masking debate. Scientists really dig their own graves sometimes.
There are plenty of other problems to be solved, and a lot of room for higher gain — upgrading the lasers isn't worth caring about until those things have actually been done.
Plus the fuel pellets are too expensive anyway.
NIF's lasers are, I'm told, less than 1% efficient; modern lasers can be 50%-80% if that's what is being optimised for.
There's no reason to bother upgrading those lasers until all the other issues are solved, and even then, as it's an experimental facility not a power station, they may well never bother even if it is the only thing holding them back from a gain of more than 1 as measured wallplug-to-wallplug.
That's kinda promising because the fusion output seems to have nonlinear scaling; they increased laser power 8% and got 230% more output.
This is why there are startups now pursuing laser fusion for commercial energy.
IIRC, thermonuclear bombs are already made with lithium deutride.
Do you mean they're trying to build a thermonuclear bomb without the fission "detonator"? That doesn't make tons of sense to me, since I'd think the test ban treaty would realistically prevent creation of novel types of weapons (because it wouldn't be foolish to rely on a weapon for deterrence that you've never fully tested).
1. Energy loss from neutron loss. So-called "aneutronic fusion" seeks to avoid this problem but requires rare fuels (eg He-3), which kind of defeats the point. Also, it's not neutron free. It's just fewer neutrons;
2. Container destruction from neutrons (ie "neutron embrittlement"); and
3. A superheated plasma (in either a tokamak or stellerator) is fundamentally a turbulent fluid. This is inherently unstable. Any imperfection in the containment could result in significant container damage.
Fusion works for stars because fusion is relatively slow (on a per-unit mass basis, which is why stars can live billions or evne trillions of years) and they have gravity for neutron containment.
More on the difference to tokamaks [1].
[1]: https://www.sciencedirect.com/science/article/pii/S2468080X1...
This is a misunderstanding that conflates multiple concepts: instabilities from toroidal plasma current (unnecessary in stellarators) and edge turbulence (lower confinement time). W7-X has done 30 second shots and are working their way to 30 minute shots. It is their control that has terminated their shots, not the plasma.
Update:
> W7-X has done 30 second shots
They're up to 8 minutes now.
Is it gravity, or is it gigameters of nuclei in every direction?
While it's ridiculously difficult for fusion to go off like that, even spreading that same energy over 2.488 hours (for a nice 1 GW-thermal reactor) leaves you with the problem that it is in the form of high energy radiation that's more than strong enough to knock atoms out of their latices.
One part of it is that the plasma sometimes carries a massive current - like, megaamps - that gets dumped into the wall when the plasma contacts it, melting it. This scenario isn't theoretical - it's a big concern when designing and operating tokamaks.
The speed of the particles themselves is also relevant. They're moving rather fast, so they impart a lot of energy when they hit the wall. It doesn't take very many to melt the wall, actually. If some part of the wall sticks out a bit, particles on what are called "banana orbits" will often melt that part off, which isn't good if it's an important part of the wall (e.g. it had been protecting some sensors).
He3 is rare but deuterium is decidedly not. Fusion deuterium is about as easy as fusing He3, and the waste product of D-D is half He3, and half tritium which decays to He3 with a 12-year half-life.
Fusion company Helion is building a hybrid D-D/D-He3, and says the combination would release only 5% of its energy as neutron radiation, compared to 80% from D-T. The neutrons would also have lower energy, below the activation energy of common reactor materials.
https://en.wikipedia.org/wiki/Stellarator
My understanding is that the different sections of the torus experience different forces (inside vs outside due to the varying radii, top vs bottom due to gravity), which the Stellarator design attempts to compensate for by twisting the plasma so that no particular clump spends all of it's time in the same section.
> The basic concept was a way to modify the torus layout so that it addressed Fermi's concerns though the device's geometry. By twisting one end of the torus compared to the other, forming a figure-8 layout instead of a circle, the magnetic lines no longer travelled around the tube at a constant radius, instead they moved closer and further from the torus' center. A particle orbiting these lines would find itself constantly moving in and out across the minor axis of the torus. The drift upward while it travelled through one section of the reactor would be reversed after half an orbit and it would drift downward again. The cancellation was not perfect, but it appeared this would so greatly reduce the net drift rates that the fuel would remain trapped long enough to heat it to the required temperatures.
Tokamaks are nigh impossible to control.
Stellarators, if you can build them, just hum along.
And Wendelstein-7X proved that, though tricky, we can build them. Oh, and that the humming-along part is actually true.
Last I checked, the maximum time for a Tokamak is 30s so far, Wendelstein has already achieved 8 minutes and they're shooting for 30 minutes.
The release of information on the USSR's [better performing] tokamak design in 1968 indicated a leap in performance. After great debate within the US industry, PPPL converted the Model C stellarator to the Symmetrical Tokamak (ST) as a way to confirm or deny these results. ST confirmed them, and large-scale work on the stellarator concept ended in the US as the tokamak got most of the attention for the next two decades.
I once listened to a fairly long podcast on the history of Wendelstein-7X, and apparently the mathematical/computational modelling required to figure out a decently optimized stellarator simply couldn't be done when the first ones were built, so they were very inefficient and easily beaten by the Tokamaks, and so interest and funding understandably shifted.
That changed when compute became much cheaper, and apparently some researchers created software models that they could run on their PCs and the late 80s, maybe early 90s. This was largely ignored for quite a while, as all the focus was on Tokamaks, for example JET and later ITER.
Having cracked what to build, and somehow gotten funding, the problem was then actually building it. Very, very challenging, and it did take a lot longer to build than even initially planned, and it wasn't clear that they would succeed in building it. But they did.
And ever since then, it's been humming along nicely.
And when you think what it actually does then 50 years ago, back when they were merely a concept, it could have passed as one.
Viewing 3d model of 7-X might be easier to comprehend.
Of course, you could challenge its effectiveness, too. London ended its cholera epidemic by no longer drinking sewer water. We still don't vent our buildings properly.
See production machines like stealth fighters, relay-and-rotor-age pinball machines, military submarines, navigation or gunnery mechanical calculators, large construction projects... Some generations of CPUs are elegant in their return to first principles while others throw in everything but the kitchen sink in an unholy mess; Mainframe manufacturing is a gorgeous history of containing and organizing chaos. Fusion research machines are very complex, yes, but by this point... it's only so much of an obstacle.
We might be tempted to throw in software ... Eh, perhaps we are not all that good with that yet. I mean, plenty of complexity, but not yet all that much "managed complexity".
What I see when I look at it is something where the math is probably quite elegant. Fractals are simple mathematical expressions that generate outputs that appear to have infinite complexity.