Their "goal" is an order of magnitude improvement on existing stellarators, that sounds to me like it will want billions rather than millions. It's also doesn't seem to meet the "triple product Lawson criterion" for useful fusion (achieved recently at NIF, expected for ITER). This is cool, but I'm always skeptical of the viability of fusion startups. I won't name names, but there's already a couple out there that seem to me to be vapourware but are dragging in big funding based on the dream of fusion.
NIF is doing weapons research, what they achieved is essentially irrelevant for electricity production as there is no plausible route towards a power plant. And if you take the overall energy balance, they did not even break even.
I'm freaking tired of this line. NIF has an actual break even result which is greater than the results of any mcf experiment. If the NIF result is shit that whole field's result is then below shit.
NIF's result is significant milestone in the same sense that the invention of the airplane was a significant milestone in the field of space travel. It matters, but we're still a very, very long way from landing on the moon (a fusion-powered electric grid).
That doesn't address their point. It doesn't matter how good the result is if the entire research direction is a dead end, which it is, being practically impossible to convert into a power plant.
And the Navy puts money into fusion research for that reason, including a bit into cold fusion just in case. But that's not what their doing at NIF, those guys are trying to figure out if you can make a thermonuclear bomb with just cheap lithium deutride and not the expensive plutonium/enriched uranium.
> But that's not what their doing at NIF, those guys are trying to figure out if you can make a thermonuclear bomb with just cheap lithium deutride and not the expensive plutonium/enriched uranium.
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).
The one that the United States signed but never ratified? Just as China, Egypt, Iran and Israel. And that India, North Korea and Pakistan never signed to begin with? And that will enter into force only after all those countries have signed at ratified it?
Triple product is necessary and partially sufficient. One of those products is "confinement time". Longer confinement times with lower density make for machines that are closer to steady state rather than pulsed, greatly reducing engineering challenges. Stellarators are on the far end of the "steady state" spectrum while NIF is on the far end of the "high density" spectrum.
Since we're on the topic of "dragging in big funding based on the dream of fusion", can you point to a press release where they explicitly mention that this research is for weapons research and not for power research?
> 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.
> 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.
At this point the claim seems to be but I think that some people think it is all about energy, as if your random interpretation of other peoples’ belief is relevant.
They do weapons. They said they do weapons. What’s the problem.
They don't say that in their press releases. None of the popular media coverage talks about the weapons aspect, much less that it's primary. I challenge you to prove me wrong.
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.
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.
> 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.
> DOE Under Secretary for Nuclear Security and NNSA Administrator Jill Hruby said in achieving ignition, LLNL researchers have “opened a new chapter in NNSA’s science-based Stockpile Stewardship Program,” one that enables scientists to modernize nuclear weapons and explore new avenues of research in nuclear science.
> 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.
They lose so much in the lasers because they're using lasers from the 1990s, which are only 0.5% efficient. Equivalent modern lasers are over 20% efficient. From the input power being 130X more than the fusion output, modern lasers would turn that into about 3X.
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, that specific issue is merely an implementation detail, much more efficient lasers already exist.
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.
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.
True. But if you replace the Hohlraum with dilithium and find an anti-matter supply you can power a warm drive for FTL travel. Just need to kick it now and then.
I fully support more research into commercial fusion power eneration. I really hope it becomes economical. That being said, I'm not convinced this will ever happen for these reasons:
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.
>This is inherently unstable. Any imperfection in the containment could result in significant container damage.
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.
You're trying to contain something at ~100 million degrees when the result of that process is destroying the container. It's not an exaggeration to say the engineering challenges are... significant.
The temperature is high but the amount of heat isn't unusual. The atoms are moving fast but there aren't many of them. For a 500MW plant you're containing about the same amount of energy whether it's fusion or coal.
In a D-T reactor you're not losing energy from neutrons, you're using the neutrons to heat a coolant and turn a turbine. (And also to breed more tritium, but that still generates heat.)
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.
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.
Hm, the fusion plasma would rapidly cool and stop fusing as soon as containment fails. I don't see how a few grams of very hot gas can do more that a little scratch to a reactor wall that is designed to be bombarded by radiation and carry off megawatts of power to a steam turbine.
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).
I suspect there are multiple PhDs each focussed entirely on one aspect of the problem of damage from the fusion plasma. The example I gave, of atoms being knocked from their lattices? I only know about that because of meeting someone in an infamous Cambridge geek pub who was working on it.
Stellarators are one of those things where the visual complexity tells some basic part of my brain that 'this can't be the real thing'. Simplicity bias, I guess.
Got it. Yeah, some intuition would make you think that the problem is somehow symmetrical, since other electromagnetic systems don’t have this ‚organic‘ kind of shape.
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.
Symmetrical except for gravity that always points downwards. I wonder if it's easier to pull off fusion in a (close to) zero gravity environment because the plasma doesn't budge by other effects than the container's.
As I wrote: the tradeoff is the complexity of the device.
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.
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 haven’t been there, yet. A friend recommended it, though. Besides a look at the machine, there seem to be a bunch of stories about things they had to solve along the way to build it, e.g. to achieve the precise 3D positioning of the parts.
I think humans have very limited capacity for reconstruction of 3d object from 2d image for anything beyond basic shapes or something they encountered extensively in real world.
Viewing 3d model of 7-X might be easier to comprehend.
It’s a trade off. Crazy geometry to try and make the physics of the plasma less crazy. At least that’s my understanding from my friends who study plasma physics
Yeah it almost looks like something where the geometry is the result of trial and error rather than first principles design. Like ‘whoops hit the side again lemme put a magnet there’ x 10e4
Especially when you consider that the image is a top-down view of dozens of layers and contains billions of connections. Amazing it works at all. And then consider it can be yours for something on the order of between an hour's and a day's income. Or, for one a few years old, practically free.
Elegance is an engineering trope. But perhaps by now, it's just convenient. Engineering has gotten very good at managing complexity.
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.
How about the visual complexity of the coronavirus?
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.
Quickly skimming over the links from your profile, I‘m surprised that the non-reality of things might be a challenge to your brain. Cool stuff, will check it out more deeply.
Not close. This amount of money will get you some theoretical modelling at best, which is still nice because stellarators are infinitely more complex than tokamaks. The real hope here is that they might solve the plasma instability problem of tokamaks, but the full picture isn't out yet. In any case, we're very far from a commercial stellarator.
Er, they've solved the instability problem of tokamaks. They've already run it for 8 minutes, target is 30 and there don't seem to be any fundamental hurdles, just stuff to do to get there.
No they haven't. The thing is you need to keep it hot enough and confine it long enough to produce a Q factor large enough for an economically practicable application. We are like one or two orders of magnitude away from that. No magnetic confinement scheme has even reached Q>1 so far, so we're a long way from any useful power plant design.
(Some in) the Greifswald team seem to estimate that it takes ~€20bn for a commercial deployment based on Wendelstein 7-X (according to a blogger who went there to ask: https://blog.fefe.de/?ts=9a9561ab)
Once, when I was a schoolboy, I walked along this thingy: https://www.inp.nsk.su/~dep_plasma/img/GOL3.jpg and the guide told us that a couple of millions USD would let them build a working commercial fusion machine. I've heard many news like that since then, so I'm extremely skeptic.
