US nuclear-fusion lab enters new era: achieving 'ignition' over and over | Hacker News Reader

US nuclear-fusion lab enters new era: achieving 'ignition' over and over

nature.com

194 pointsgoplayoutside175 comments

But not over and over and over again.

"Scientists at the laboratory achieved ignition during two further attempts in October. And the laboratory’s calculations suggest that two others in June and September generated slightly more energy than the lasers provided, but not enough to confirm ignition."

It's not like they're running an engine.

Nobody has claimed that this approach is a useful power source since the 1970s. There was, at one time, talk of systems where pellets are injected, zapped with lasers, some fusion and heat results, and this is cycled at some high rate, maybe a few times per second. But that was really political cover for the National Ignition Facility, which is really for studying what happens in an H-bomb without setting one off.

There's an pulsed fusion startup.[1] This is not laser-triggered fusion with inertial containment; it's a combo of magnetic containment and inertial containment, triggered by a huge electrical pulse applied to a plasma. Like the Z-machine at Sandia.

They were supposed to have a demo by the end of 2023. Press releases stopped in July. Uh oh.

[1] https://www.f.energy/

Ah. Here's why the PR. They previously failed to replicate their earlier success.[1]

[1] https://www.nature.com/articles/d41586-022-02022-1

The startup you link is one of dozens, many of which are pulsed, with several being laser fusion specifically, including Longview, LaserFusionX, Xcimer Energy, Focused Energy, HB11 Energy, and Marvel Fusion.[1]

NIF doesn't need political cover for weapons work. We openly spend a hundred times more on nuclear weapons than on fusion power.

[1] https://www.nytimes.com/2023/11/13/science/laser-fusion-ener...

Here's the archive: https://archive.is/BCsf5

The article also says "A decade ago, a report by the National Academy of Sciences found much to like in the energy potential of laser fusion but recommended that the United States hold off major investments until ignition was achieved. That time is now." Here is the NAS report:

https://nap.nationalacademies.org/read/18289/chapter/1#xv

I'm curious what is even being discovered with H bomb simulation work these days. I thought we figured out already how to glass the earth in 15 minutes by the 1960s.

Maybe they're figuring out how to NOT glass the earth with fusion?

In the 1960s they were testing detonations.

If you were tasked with manufacturing a 1960s car today that had to work without ever actually starting the engine doing so would be a monumental undertaking, involving supercomputers simulating the internal combustion etc.

That's what's happening with nuclear weapons development since the testing ban, and simulating that's a lot more complex.

I guess its like, we already have invented the hammer. It works. The complex stuff honestly seems to be what makes any targeted bomb complex vs the teller-ulam mechanism. What exactly are we simulating?

To be clear, NIF's ignition is getting more energy out of the fuel than the laser they hit it with put in, but there are other energy drains and inefficiencies in the system that make it nowhere close to break-even fusion energy. That requires building a new machine designed for continuous fusion detonations.

So it's a scientific accomplishment, but not that scientific accomplishment.

And they don't have any mechanism to capture the generated energy and convert it to electricity.

What are the chances that will be anything other than the tried and true "boil some water to make steam to turn a turbine"

Fusion produces helium, you fill party balloons with it, they lift an anvil which falls on a pair of scissors that cuts a piece of string in half...

The Incredible Fusion Machine

Phew!

This is like saying "burning gasoline produces CO2, how do you make energy with that?" Literally the quoted energy they use to calculate the ignition criterion for NIF is the neutron yield.

It’s also like saying, “This is kind of an amusing joke for those that enjoy amusing jokes”.

That's exactly what it would be, for any fusion that's not using aneutronic fuel.

That literally is it, just like fission you capture neutrons and heat water. The engineering issue of getting a stream of pellets to shoot is the issue, the "how do you convert neutrons from DT into electricity" just betrays severe ignorance. The engineering issue is a bigger jump.

The issue of capturing power out of the exploding pellet is not at all the same as the issue of capturing neutrons out of a MCF reactor, and neither is the same as the problem of capturing the neutrons from a fission power plant.

The neutrons from fusion reactos are far more powerful, so they punch much more easily through materials you put in the way. Also, the ICF reactor has many moving parts (the pellet needs to be put in a very precise position for the lasers to shoot), so transferring heat from it is not nearly as easy as a much simpler fission reactor (which is mostly just a hunk of uranium which stays hot, and all the complexity comes out of being able to prevent the uranium from getting too hot).

When I first learned how nuclear reactors actually generate power it was a big WTF moment for me. Wait - do they really just heat water? For some reason I thought that there was a more advanced process to extract electricity from the reactor.

Yup. It does seem inefficient.

I assume the cost is “good enough”.

In Back to The Future, Doc Brown not only invented a time machine, but a device that fits into a Delorean that can directly convert plutonium into electricity.

This was announced back in 2008, but it sounds like it didn't go anywhere:

https://www.newscientist.com/article/dn13545-nanomaterial-tu...

“Energy drains and inefficiencies” underplays it. The laser they’re using is, what, 10% efficient? So they’re at least an order of magnitude away from net power. Probably two orders.

0.5% efficient, but they're old lasers. Equivalent modern ones are over 20% efficient.

Also, with their first Q>1 shot they increased the laser power 8% and got 230% more output. They think the nonlinear scaling will continue for a while. If they're right, then they're not actually that far from overall net power, if you correct for the obsolete laser tech.

Whenever anyone brings this up, it's important to remind everyone this is the best in the world to this day, so every time people (namely, people invested in MCF or various private companies) shit talk NIF understand they are saying their schemes per the data are even worse than what is apparently a bad result.

I question your assumption that most people who bring this up are people invested in MCF or various private companies.

I think for most people, the question isn't between this fusion and that fusion, it's about fusion and anything else.

We haven't yet been able to get useable energy out of fusion. It may be wonderful if we could, but at the moment, every dollar spent on fusion is a dollar not spent on building more solar panels and wind turbines.

If it really is the case that it will not be possible to power the world without fusion, then that might be money well invested, but it's quite possible that we should just be putting everything into existing renewable technologies.

>It may be wonderful if we could, but at the moment, every dollar spent on fusion is a dollar not spent on building more solar panels and wind turbines.

You care to back your armchairing with data? I'll bet you 100usd that it's a pittance compared to what goes into solar and wind turbines world wide. This point is not salient.

>I think for most people, the question isn't between this fusion and that fusion, it's about fusion and anything else.

That's a more valid point. The point for ICF is the potential, this is a sure push in the direction of "this actually has potential," justifying more research, not that we'll have a power plant in 5 years. There isn't this antagonism towards other aspirational research like superconductors or quantum computers.

>> every dollar spent on fusion is a dollar not spent on building more solar panels and wind turbines.

> You care to back your armchairing with data?

I'm confused by your confusion. I'm literally saying we could optionally be spending the money we currently spend on fusion on solar panels instead. This isn't a statement that needs data.

The question is simply which is going to go further in decarbonizing our energy: $1 spent on solar or $1 spent on fusion research?

That's an open question, of course, and people don't have the answer, since one is based on probabilities of future success.

Note, though, that even if fusion is successful, it may still be more expensive than solar, and so then would it actually be successful? We would have saved more tons of CO2 by making more solar panels. [1] [2] [3]

1. https://www.wired.com/story/no-fusion-energy-wont-be-limitle...

2. https://futurism.com/elon-musk-fusion-more-expensive-wind-so...

3. https://engineering.princeton.edu/news/2023/03/16/fusions-fu...

> I'm literally saying we could optionally be spending the money we currently spend on fusion on solar panels instead. This isn't a statement that needs data.

We can’t. Who is picking between fusion research and 7% IRR solar projects? Two totally different risk profiles.

> We would have saved more tons of CO2 by making more solar panels.

If that’s your sole metric it’s probably worth thinking a little broader towards a solution. I don’t think Mohammed bin Salman is going to cap Ghawar Field because we put up a bunch of solar panels over here. He’s going to sell to somebody else.

I think it’s better to let the market work towards solutions that compete across all dimensions—density included—and let that drive the energy transition.

So the question is, what is a better energy infrastructure investment—definitely spending a dollar on fusion research, or not spending that dollar on fusion research and instead maybe, in theory, spending it on solar panels. I’ll take the good plan now vs the maybe a better plan later option.

"Solar vs. Fusion" isn't really important as long as trillions of $/€/£/... are sunk into fossil fuel extraction and use ?

There's plenty to reaearch in Solar Panels still as well - Perovskite is hot now, but other material systems, engineering optimisation, inverter efficiencies, BIPV, non-Li-Ion battery systems, all these and then some are actively researched and developed right now. And not all of that will productise. Yet, move money off fossil subsidies to those first ... and only after bash nuclear, whether fission or fusion.

Even if fusion is the energy source of the future and will always be that - fossil fuels are that of the past. They shall be, or remain, buried. This really isn't about renewable vs. renewable.

Comparing basic science research with commercial product research is comparing apples with oranges.

Governments spend research money on space research, particle accelerator, fusion research, basic medical research, and similar that do not intend to turn a profit. National Institutes of Health for example spends more on basic medical research than all of industry combined. The health industry takes that research and uses it to develop products, which combined R&D are several times that of the budget of NiH. $1 of NiH basic medical research is not the same as $1 R&D by a medical company, and especially not the same as $1 going into production. Spending $1 to produce a pill may save a life. $1 of NiH basic medical research may save a population.

We could but it’s a short sighted perspective. It’s like telling someone working on the steam engine to stop spending money because we could buy so many horses instead.

Every dollar we put into fusion could also go into all sorts of things that have nothing to do with renewable energy.

For government funding, the money could go to small fission reactors, some military project unrelated to energy, or just a reduction in the deficit.

For private investment, the sort of investors interested in fusion breakthroughs would probably go for other high-risk, high-reward opportunities rather than switching to a mature industry.

> at the moment, every dollar spent on fusion is a dollar not spent on building more solar panels and wind turbines

You are of course technically correct ("the best way to be correct"), but let's be honest: figuring out the optimal allocation of resources between solar/wind/geothermal and fusion research is unsolved problem. It's probably outright unsolvable.

It's also not a problem of one or the other. We will need both.

Remember that fusion research is not just about fusion. The materials technology advances are almost certainly going to show up elsewhere in various forms. To top it off, the nature of the technology itself requires that a non-trivial fraction of the funds are directed towards fundamental research. We can not know, or even guesstimate where those results end up being used outside of fusion research tracks.

I will not be surprised at all if/when some research done for advancing fusion will be used to improve solar and wind technologies.

> It may be wonderful if we could, but at the moment, every dollar spent on fusion is a dollar not spent on building more solar panels and wind turbines.

That's not how this works. The money that goes to research is very far removed from the money that goes towards utilities' capital investments. To say nothing of the politics involved.

Regardless, we stand to gain more than just a possible energy source from this research.

>“ It may be wonderful if we could, but at the moment, every dollar spent on fusion is a dollar not spent on building more solar panels and wind turbines.”

Every dollar spent on cars and transistors is a dollar not spent buying more horses and vacuum tubes

People shit talk NIF because it's a very expensive machine to calibrate the Fortran code used to test hydrogen bombs without detonating them, in no way meant to advance fusion for power generation, that gets accolades for doing something that will probably not be useful for a useful advance in fusion.

Indeed, in the laser business, during a time period when it seemed like someone was coming up with a new kind of laser every month, the field developed a term, "wall plug efficiency," which meant how much laser power per unit of power drawn from the electrical outlet. It was meant to capture the true energy efficiency of the system, rather than just the efficiency of the lasing process.

Certainly a cool achievement and something to be proud of. Maybe even a very important step towards real usable fusion power plants.

But:

> The facility’s laser system is enormously inefficient, and more than 99% of the energy that goes into a single ignition attempt is lost before it can reach the target.

So it's still two orders of magnitude off hitting break even. And that's without a suitable device to actually capture the released energy and it does not account for pellet production. For all we know, it might very well be three orders of magnitude away from a real powerplant.

That being said, making more efficient lasers and working on capturing energy might be more fruitful than trying to improve a Tokamak design. So it's good to have options.

Far more efficient lasers already exist. Their lasers are old.

Two orders of magnitude more efficient?

From 0.5% to over 20%, for equivalent lasers. So they still have work to do, but not as much you'd think without accounting for the old lasers.

Are modern petawatt class lasers really 20% efficient?

Helion's design seems way more promising than the NIF one which doesn't seem to have any clear path to being a "continuous" operation production design.

Helion's design also works essentially by brief inertial confinement, thereby avoiding the issues of Tomahawk continuous confinement designs. However, in the Helion design rather than having pellets of fuel which would need to be replaced for each shot, it uses injected gaseous fuel (deuterium + He-3) which is heated into two plasma "donuts" which are magnetically fired at each other to (together with brief magnetic compression) achieve fusion conditions.

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

Helion have a contract with Microsoft to build a production model for them (to power a datacenter) by 2028.

https://www.helionenergy.com/articles/helion-announces-world...

By 2028, not 2008.

Enormous amounts of energy needed for the closed timelike curves to generate Kerr singularities with flux stored in a capacitor.

My money is on the technology behind a flux capacitor maturing before Helion’s fusion tech.

Thanks - corrected.

Like all fusion reactors in the world currently, NIF was made for research, not as a prototype for a power plant. As it stands, NIF is the only non-bomb fusion device to reach the fusion breakeven point. If we are ignoring the research angle though, and are appraising the potential for commercial power production, Helion's design has a similar issue to NIF. Where a tokamak and similar designs create constant power, NIF and Helion's design have to generate power from sequential nuclear explosions. However for the purpose of research, NIF is indispensable; We can finally see and measure the behavior of true power positive fusion (without setting off a bomb).

edit: breakeven means the reaction put out more power than the fuel took in. It does not mean the plant as a whole puts out more power than it takes, we aren't even close to that.

Helion’s design doesn’t require constant power, it’s not based on heating water into steam to turn a turbine. Rather, their reactor is the turbine, the sequential plasma ring collision fusion reactions generate a magnetic field that drives a current in wires coiled around the reactor.

It’s rather ingenious and is the first reactor-based power source that generates electricity directly from the reaction itself, rather than from heating water into steam. I hope they’re able to achieve breakeven in their next prototype or two.

I'm excited to see what they can do, but its important to remember they are the only fusion device with a marketing department. Pulsed power generation would be a problem for any power plant, and its viability is predicated on its ability to reset rapidly. Helion needs to demonstrate their 12T compression ignition works, then need to demonstrate the reactor can reset quickly, and they need to demonstrate they can generate enough power from the expanding magnetic field.

Its an awesome design, its just their marketing material has led people into believing we are on the verge of fusion power, which we are not. Also note, I am not against private companies competing, or marketing their product, just remember that it's not quite as great as they claim.

I wish people would stop parroting Helion's obvious lie that they invented direct energy capture. These ideas are more than half a century old and have been tried before.

https://en.m.wikipedia.org/wiki/Direct_energy_conversion

I would have a lot more faith in Helion if they were more upfront instead of playing stupid games. If they're willing to bend the truth on this, I can believe they're lying about all sorts of other things. I suspect Helion will eventually have it's own Theranos moment.

They have to convince senators to invest into their company lol. There is no way they are going to do that with a plasma physics textbook and a white paper on plasma compression ignition. I don't blame them for building hype, and glossing over the technical risks. It's just if you want an informed opinion you have to look past the marketing material.

As devils advocate I will make the counterpoint, the idea of generating steam using heat through the walls of a tokamak is perhaps equally unproven. You need to have intense temperatures right next to supercooled magnets. That seems like a potential dealbreaker too, and everyone glosses over it in the same way.

I've been following them for years and I've never seen them claim they invented DAC in general, just their particular device.

To be fair I’ve never heard Helion explicitly claim they invented direct energy capture, that was my interpretation only, not anything from their PR. I’m not aware of it ever being used in a commercial power reactor design until now.

Eh not really. SNAP10A didn't have a steam turbine. It used thermoelectrics to directly convert heat to electricity.

https://en.wikipedia.org/wiki/SNAP-10A

There's a whole world of direct energy concepts out there: https://www.osti.gov/biblio/1130979

Good to know, thanks. I think that SNAP design is only feasible in space, or maybe the polar regions on Earth, since it requires a cold source on one side of the converter that is cheap or free to produce.

NIF is thinly veiled fusion weapons test research, nothing more. There's no real intention for advances in energy generation research. If it happens it's more an accident or part of the 'cover'.

It isn't even that veiled. The article points out: 'The NIF was designed not as a power plant, but as a facility to recreate and study the reactions that occur during thermonuclear detonations after the United States halted underground weapons testing in 1992. The higher fusion yields are already being used to advance nuclear-weapons research, and have also fuelled enthusiasm about fusion as a limitless source of clean energy.'

However, whatever the situation was before, the DOE recently made fusion power research officially part of their mission.

https://www.ans.org/news/article-5611/three-new-inertial-fus...

Sure, but how does that veil the weapons component, even lightly?

I mean, an early Python conference was held at LLNL (1996?), but surely that didn't veil that LLNL is a nuclear weapons lab.

As you pointed out, it's not veiled at all. And why should it be? We openly spend vast sums on nuclear weapons and people are fine with it.

But also, if they already have a weapons research facility and for a little extra money they can also research power production, why not do that?

Because my response was an objection to sgift's comment "NIF is thinly veiled fusion weapons test research" and I wasn't expecting a change in topic.

It's my fault to have brought up the term "veil". To expand where I'm coming from: I think that they even talk about it in the context of energy research is a veil, cause I don't see any way how this will ever be used for it. IMHO, it's only useful for weapons research. But maybe it's just a lack of fantasy on my part and it is possible (in a useful way, not possible in a "we could do this, but it's so blatantly stupid, why would anyone ever think we'd do it?" way).

I know essentially nothing about the field. I can imagine how it might be used to understand how plasma works, and how to measure plasma activity, specifically in the domain appropriate for fusion reaction instead of thermonuclear weapons, might be relevant.

I conjecture this because I read about how knowledge from thermonuclear weapons development helped inform our understanding about how fusion works in stars, even though the experiments themselves were secret.

The story was of a Soviet astrophysicist visiting the US. He gave a lecture about stellar processes. A US grad student asked him afterward about one step in the process, something like "how do you know the plasma is transparent to X-rays?". The Soviet scientist said simply "it is." The US student, confused about it, asked his US advisor, who informed the student that it meant the Soviets figured it out as part of research for H-bomb development. I don't have a primary source for it though.

As a possible parallel, Shepard's suborbital flight used a Redstone ballistic missile, modified to make it human rated. Space flight and space telescopes are closely intertwined with missile technology and espionage/surveillance.

Here's a NYTimes article about six companies attempting laser fusion for power production. At least two have personnel from NIF. One uses an approach similar to NIF's but with modern lasers, and a couple others use a different type of laser that removes the need for the hohlraum.

https://www.nytimes.com/2023/11/13/science/laser-fusion-ener...

https://archive.is/BCsf5

Also it says "A decade ago, a report by the National Academy of Sciences found much to like in the energy potential of laser fusion but recommended that the United States hold off major investments until ignition was achieved. That time is now." Here is the NAS report:

https://nap.nationalacademies.org/read/18289/chapter/1#xv

Thanks for the links! Seems my pessimism got the better of me. I'll look a bit more into it.

We openly spend a hundred times as much money on nuclear weapons as we do on fusion research. There's no need for a "cover."

> to build a production model for them (to power a datacenter) by 2028.

Helion is known to promise the pie in the sky, and soon. In [1] they tell you (in 2014) that they will have a "pilot plant operation in 2019". One year later, in 2015, they let you know in [2] that they will "start building commercial systems by 2022".

[1] https://www.nextbigfuture.com/2014/07/helion-energy-plans-to...

[2] https://www.nextbigfuture.com/2015/08/helion-energy-raised-1...

Honest question: How much of this is engineering and how much is regulation? Everyone overestimated development cycles but if there was 0 regulation and we lived in Ayn Rands' wet dream, do you think they could be close to delivering, or no?

There's no regulation holding them back. They can do whatever they want.

What regulation can possibly be in the way?

Wow, is this really the case? They could go build a novel reactor without any regulatory oversight? I guess I'll look into this but honestly doesn't seem like it would be true for the US

The situation was unclear for a while, but a few months ago the NRC decided to regulate fusion reactors like particle accelerators and hospital devices, rather than like fission reactors. It was a unanimous decision by the five commissioners.[1]

According to the CEO of Helion, this essentially means they get regulated at the state level, in their case by the WA Department of Health.[2]

A poorly-designed fission reactor can turn into Chernobyl. A poorly-designed fusion reactor just doesn't work. It's not the same level of risk at all.

[1] https://www.fusionindustryassociation.org/nrc-decision-separ...

[2] https://www.reddit.com/r/fusion/comments/18k8roi/age_of_mira...

Thanks for the detailed info!

No. Experimental fusion reactors are not subject to the kind of scrutiny that even a coal plant would be subjected to. (Essentially very little oversight unless you start emitting a lot of ionizing radiation outside of your containment structure) When they outgrow the lab, that will start to change a bit, but we are far from net positive even in a lab environment.

OK, good to know, and I suppose not surprising since this is after all never-been-done-before research as well as engineering.

I guess the big question is how have they been progressing since, say, 2014? Are they making obvious progress and overcoming potential problems, or are new issues being identified as fast as others are being resolved ?

The design itself does seem promising, certainly more so than Tomahawk designs. I remember excitedly following the UK's JET (Joint European Torus) project when in high school in the late 1970's and here we are with ITER still sucking money and not appearing much closer than we were back then!

Those older predictions were based on getting the necessary funding, which they didn't get until years later.

Does anyone know the triple product of their experiments? I've seen values ranging from 10^22 to 10^25.

I was hoping to find an updated chart of the triple product over time but can't find anything more recent than 2019.

See wiki: https://en.m.wikipedia.org/wiki/Lawson_criterion

And this chart: https://www.fusionenergybase.com/article/measuring-progress-...

I'm looking forward to the Boron-11 based ones. Or any of the Aneutronic ones, as they used charged particles directly rather than by heat transfer and electric generation.

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

The article is hinting that there are weapons applications for this. What types of weapons would those be? Bombs? Are there any other countries with research programs similarly far along?

Yes, nuclear bombs/warheads

https://lasers.llnl.gov/science/nif-and-stockpile-stewardshi...

It’s less that this allows new unprecedented weapons, and more that this allows one to validate material properties in similar conditions to a nuclear bomb detonation without actually testing a full scale device. This lets one verify and refine the otherwise “magic number” constants in computer simulation code that were empirically derived 50-80 years ago.

Of course, if you’re a nascent nuclear power along the lines of NK, you just do full scale tests, treaties be damned.

North Korea hasn't signed any treaties abolishing nuclear weapons tests. In point of fact, the USA itself hasn't ratified[0] any treaties prohibiting the type of underground tests the DPRK has conducted. The US chooses not to do those (and has maintained a voluntary moratorium since 1992), but is under no obligations.

[0] https://en.wikipedia.org/wiki/Comprehensive_Nuclear-Test-Ban...

Notwithstanding the US's deeply hypocritical stance on treaties it hasn't ratified but others must follow, North Korea did in 1985 sign the NPT which forbids them even building nuclear weapons, as well as the 1992 "South-North Joint Declaration on the Denuclearization of the Korean Peninsula" where they explicitly pledge not to test nuclear weapons (which they indeed didn't do until 2006).

https://www.armscontrol.org/factsheets/dprkchron

Sure; though to be fair, North Korea withdrew from the NNPT a full three years before its first nuclear test (2003, 2006).

The US walked away from deals with NK[1].

An agreement was made to suspend the nuclear program in 1994, the US then refused to certify it after 9/11 due to NK's transfers of technology to Iran.

Whatever anyone thinks about that, it's got nothing to do with the 1994 agreement (which is easy to read, it's only a few pages).

NK subsequently withdrew from the NPT, and got a nuclear weapon in 2006.

> South-North Joint Declaration on the Denuclearization of the Korean Peninsula" [...]

I believe that NK's stance on the matter is that SK is hosting military bases for a foreign nuclear armed power (the US).

So it's implicitly threatened by a US nuclear attacks, and that threat became explicit under Trump.

1. https://www.cfr.org/timeline/north-korean-nuclear-negotiatio...

You know, the best part is that US is doing this same thing with the incoming president shitting on the work on the previous president for the sake of domestic politics, and not getting a new deal with the belligerent state!

So instead of Clintons deal Bush tore it up, didn't get anything, and now North Korea has nuclear weapons. And instead of Obamas deal Trump tore it up and got nothing. Now Biden also wants a new deal, so we know how this version of story likely ends (especially with Bibi bombing out of control, the pro-nuke factions in Iran have great fuel for winning the go/no-go argument on building a weapon.)

If I'm not mistaken it's used instead of actual nuclear weapons tests. Wikipedia says the following about the NIF

> It supports nuclear weapon maintenance and design by studying the behavior of matter under the conditions found within nuclear explosions.

The mission of NIF is and has always been to subvert the test ban treaties. It is written down in the original proposal, which are available on the web from the agency. NIF has no civilian energy applications, and will never have any.

> to subvert the test ban treaties

How is this subverting the treaties? The test ban is about not detonating nuclear weapons, and the NIF complies with that.

I suppose it depends on how you interpret the intent of the test ban. If the intent was to stop detonations because they are bad in themselves, then it's not subversive. If the intent was to stop detonations in order to curtail further weapons development, then it is.

It's a test ban treaty, not an agreement to stop development of nuclear weapons.

Detonations are bad in of themselves, they cause various items to become contaminated, causing issues for imaging and science applications. Being able to ignite fusion without using a fission bomb to do it lets you prevent the contamination without sacrificing your negotiating position. Remember, the best lie is the truth, your enemy can't figure out your nuclear weapons don't work if they actually work.

Directed high energy weapons, as well as existing nuclear weapons.

H-bombs, the entire thing they do is look at the expansion of plasma that is heated by a thermonuclear reaction. The most prominent application of expansion of a plasma heated by a thermonuclear reaction is the explosion of thermonuclear weapons.

Fission bombs can be tested with subcritical explosions. You have a plutonium core (a sphere the size of a grapefruit) and surround it with high explosives. Not as many as for an actual detonation. You blow them up, create the implosion, and trigger a subcritical fission reaction, or one that is very slightly supercritical. You then take lots of measurements (temperature increase, X and gamma rays, neutrons, etc) and see if they align with your theoretical models. If they do, you have extremely high confidence that the bomb will work as designed.

Now, virtually all nukes in the US arsenal have a fusion bomb stage too. The way that works in practice is this: you first detonate the fission component of the bomb, and that produces a huge amount of X-rays. It's so huge that the wavefront of the X-rays behaves like a solid hammer. That's what produces the compression for the secondary. This design is called the Teller-Ulam design, and it is extremely likely that it was discovered only once (by Ulam and Teller), all other thermonuclear bombs are just the result of successful spying and secret sharing.

This X-ray hammer can't be very easily tested. That's what these guys are doing.

Now, you may wonder if Putin's guys are doing an equally good job at testing their thermonuclear bombs. We don't know, but it doesn't make a difference: the fission part of the bombs is powerful enough to create utter devastation. The fusion part adds some extra punch, but it doesn't change the scale of devastation. And the CIA is highly confident that Russia is properly testing the fission bombs, even undergoing what is called "hydronuclear" tests, which, although not formally banned, other countries don't do.

> This design is called the Teller-Ulam design, and it is extremely likely that it was discovered only once (by Ulam and Teller), all other thermonuclear bombs are just the result of successful spying and secret sharing.

Hans Bethe believed that the Soviets and the British got it by analyzing the fallout from fusion bomb tests. Apparently the high number of heavy elements suggested high rates of compression

Hans Bethe guessed based on the information available to him at the time.

But there was information not available to the West prior to the end of the Cold War.

In December 1991 two US atomic scientists, Danny Stillman and Nerses Krikorian visited the head of the former Soviet nuclear program, Yuliy Khariton [1]. In their discussions, the Americans realized that even Khariton was not aware of the extent of the Soviet spying. In any case, Khariton had a very dubious recollection of who came up with the idea of the radiation implosion (the Teller-Ulam design). This was such an ingenious idea that if it had indeed originated with one of the Soviet scientists, it would have been memorable. By the way, the Soviets did come up with a thermonuclear design, dubbed "layer cake" in the US. But it was an inferior design that resulted in a yield of only 400 kT (the RDS-6 test [2], in August 1953), which was achievable with fission only. In March 54 the US detonated a few hydrogen bombs, and indeed, the Soviets collected radioactive debris. However, Khariton told Stillman that that information was not helpful, aside from the confirmation that higher yields are somehow possible.

Throughout the month of March 1954 the Soviets played with a few ideas, but none was good. Then, miraculously in mid-April 1954, Khariton claims that his deputy Yakov Zeldovich [3] came up with the idea of radiation implosion. But other Soviet nuclear scientists that Stillman and Krikorian interviewed stated that they never heard Zeldovich confirm that story. Moreover, one of these scientists , Lev Feoktistov stated quite candidly "We had neither drawings nor accurate data from the outside, but we were prepared to catch hints and half-hints. I can't shake the feeling that in those times, we were not completely independent"

Stillman put all these things (and quite some more) in a book, The Nuclear Express [4].

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

[2] https://en.wikipedia.org/wiki/Joe_4

[3] https://en.wikipedia.org/wiki/Yakov_Zeldovich

[4] https://www.google.com/books/edition/The_Nuclear_Express/qLT...

We already have fusion bombs. Making a fusion bomb is a lot easier than creating a fusion reactor that can emit energy in a more controlled manner.

France is building a similar facility called "Laser MégaJoule" (LMJ).

https://en.wikipedia.org/wiki/Laser_M%C3%A9gajoule

> Developing more efficient laser systems is one goal of the DOE’s new inertial-fusion-energy research programme. This month, the agency announced US$42 million over four years to establish three new research centres — each involving a mix of national laboratories, university researchers and industry partners — that will work towards this and other advances.

In other words, the government is spending enough to keep the lights on.

It’s a high-flux isotropic neutron source intended for things that have nothing at all to do with power generation, but, possibly great improvements over spallation sources for certain applications.

Or, from the more bureaucratic viewpoint, it’s a successful sale of ‘science’ to the congress for your money. You paid about 0.1% of your gross income for it (ROM).

> a high-flux isotropic neutron source intended for things that have nothing at all to do with power generation

We're still characterising how non-stellar fusion plasmas behave. It's valuable to be able to create that on demand. Also, this research is critical to modelling nuclear weapons without live tests.

Far ahead of you, a lot of the non-stewardship and non-ignition work of NIF is for creating neutrons, although you don't even need ignition levels of energy to make neutrons with lasers. Although the research is premature and the beams aren't as good as spallation sources, tabletop (as in a laser table a few metres across) ultra-intense laser systems have been generating neutron beams in a single room for almost a decade+ now, we just need to improve the beams and get the word out there.

Much in the same way that the “Wright brothers flight has nothing to do with transportation”

Can somebody explain, what exactly is "ignition"? If even a single helium atom is fused you have "more energy than you have put into it". That does not seem impressive.

No, you have more energy than two separate helium atoms.

You haven't counted the energy required to make them fuse in the first place.

There is a nice Sankey diagram at https://en.wikipedia.org/wiki/National_Ignition_Facility#Sys... showing where the energy losses go.

this may help: https://lasers.llnl.gov/science/ignition

Next step: achieving the actual energy break even instead of laser energy break even. That'll require improving it by an order of magnitude.

It's not even laser energy break even if you count the energy used to actually generate the laser. It's only break even if you just count the energy from the laser going into the fuel pellet.

Two orders of magnitude. (Currently they input 300 MJ of electricity and get 4 MJ of fusion.)

The Lawrence Livermore National Laboratory director says it could be done in "probably decades — not six decades, I don’t think, not five decades, which is what we used to say." [https://ww2.aip.org/fyi/2022/national-ignition-facility-achi...]

If you count the efficiency of the steam turbines to actually generate electricity from the fusion thermal energy you'd need something like 750MJ of fusion energy to break even. (assuming your steam turbines are 40% efficient)

Given that you'd want to actually generate electricity rather than just break even we're talking about three orders of magnitude rather than two.

First computer fit in a hangar, consumed enormous amount of energy and provided a tiny fraction of the computing power that you now have in your smartphone.

Just saying.

For computing devices being smaller typically means using less energy as well, so it’s a bit different than a power generation facility where the whole point is power.

a computer simply automates something you can do with your bare hands: calculate. Manipulating the strong nuclear force is not even comparable.

My opinion about fusion is that by the time they figure it out (which I think could eventually be done, if we invest a large portion of humanity's knowledge and wealth), it won't even be worth it. We could have almost-free energy now with fission, and renewables keep getting better. Fusing atoms (and getting more energy back) will be an astonishing feat when we accomplish it, but not offer much benefit over existing power generation. For instance, financially it would take a lifetime to ever recover the costs invested. Even once it's figured out, it will still take decades to build the plants, which will be buggy-first-generation models (that still contain dangerous radiation, just more manageable). I really wanted it to succeed (20 years ago, say), but now I think it's a lost cause.

While you are right, sometimes I can't help but feel like Moore's Law (etc) has done us a disservice by making it so we compare every kind of technological progress to the progress in computer hardware (or I guess electronics more broadly) and expect that kind of progress in other domains. Are there any other fields that have experienced the same sort of staggering, exponential improvement? Off the top of my head, think of say, food/agriculture, biology, aerospace engineering, construction engineering, etc. All have seen steady, impressive improvements, but nothing comparable to the steady (over many decades), yet exponential improvement of Moore's Law - nothing comparable to going from room-sized computers to having 1000x the compute power in a smartphone chip.

(EDIT: This isn't to say that those fields are worse, or the scientists there less skilled, or something. They're just different domains. "Increase transistor density" may simply just be an easier problem to solve - despite being an incredibly difficult problem - than the issues in those fields.)

I'm going off on a tangent a bit, but all I'm trying to say is, I feel like "if electronics manufacturing can improve at X rate, then surely Y field can also improve at that rate" is a bit of a fallacy.

Of course you're right in general but the fusion triple product actually did increase exponentially, at a faster pace than Moore's Law, from 1970 to 2000. Then for a while everybody decided to put most of the money in a giant construction project in France that still isn't finished. Now we're partway back to the system of competing smaller projects that we had during the exponential period.

Lasers have also been improving dramatically. In particular the power of fast lasers has been going up exponentially.

That's a fair point! Didn't look at it that way.

There's also the construction of the pellets[1], which uses deuterium and tritium as fuel, and capturing the released energy.

[1]: https://lasers.llnl.gov/news/papers-presentations/2016/decem...

The article linked says the laser energy is 2 MJ. So even a 100% efficient laser would only have a 2x gain. And some quick googling gets me 80-90% as max feasible laser efficiency.

And you would probably need more like a 10x gain to make it feasible so would need another order of magnitude from something beyond laser efficiency. Can you trigger more fusion with the same laser energy by scaling the system up?

> The article linked says the laser energy is 2 MJ. So even a 100% efficient laser would only have a 2x gain. And some quick googling gets me 80-90% as max feasible laser efficiency.

This doesn't sound right to me. The NIF's laser efficiency is less than 1%, so an 80% efficiency laser would be ~100x gain.

Edit: Actually, I'm not positive I'm reading this right. It says the laser was less than 1% efficient in 1996, there may have been upgrades since then...

Edit 2: There has not been.

https://en.wikipedia.org/wiki/National_Ignition_Facility#:~:....

The point is that the fusion reaction has produced 2x the power that the laser fed into it. So a 100% efficient laser (which is not physically possible) that injected 2MJ of power into the pellet would mean a net 4MJ of generated fusion energy. Then, you need some way to turn that energy into electricity, for which no realistic design exists in the case of ICF, so you'll lose more power.

For what it's worth, the claim that improving laser efficiency should be straightforward sounds right to me. That they ignored laser efficiency to focus on ignition sounds like a principled approach to research: pick a specific target and focus exclusively on that target.

We've already produced lasers with about a 100x efficiency improvement over what the NIF currently uses (65% vs 0.5%). Same wavelength, but obviously very different power levels.

https://www.laserfocusworld.com/lasers-sources/article/16556...

Nice.

You're right, but it's also important to remind everyone that this type of fusion research is only relevant for fundamental physics and for nuclear weapons research. This is not remotely a plausible path to fusion power generation. And, the NIF is part of the branch of the US government that handles nuclear weapons.

Is there a physical law that indicates it's not feasible? Because if not, this is just like saying multiplying a bunch of matrices is not a feasible way to build a machine that speaks English. These things are unpredictable.

I think it'd simply be the fact that the facility isn't aimed at achieving break even, they're mainly interested in performing tests which validate the viability of the nuclear stockpile without having to test the bombs directly.

For example, there isn't really a means to extract the energy released to generate electricity from it in the facility (as the pellet has to be equally compressed from all sides by lasers).

Similarly, the lasers they're using are pretty old and inefficient by modern standards, they're sticking to them because improving electricity-to-laser efficiency is not the bottleneck to their system, it's laser-to-pellet efficiency (along with the stability and accuracy of their optics etc). But if they were concerned about power generation, electricity-to-laser efficiency is obviously important.

Basically, while the general concept of this kind of fusion reactor might be potentially viable, this specific facility likely is not (with its current mandate).

Which isn't a problem anymore because nuclear test ban is over. They are more than welcome to test the bombs directly again.

I don't think it'll be as politically acceptable nowadays to do that.

In any case, once Russia restarts testing, everyone else will have, to, because of tremendous advantage it provides.

I don't think so. The point of these tests is to maintain the deterrent power of nukes by showing that they are still intact.

The West doing this by putting effort into all sorts of extremely advanced machinery like NIF in contrast to Russia having to resort to setting off nukes would be a convenient situation for propaganda, since it only makes Russia look even more like a warmongerer.

As for the advantage provided, IIRC the US has been performing "dry" tests, where a bomb with no nuclear material is detonated to verify the trigger mechanisms. That, combined with the tests at NIF and other facilties to verify the viability of the nuclear material, should be comparable in terms of verifying functionality.

Point of tests is to verify state of the pits after long storage. Plutonium is a bitch to manage because it is alpha-active and alpha particles are in essence, helium atoms, so over time a piece of plutonium gets full of helium caverns and develops internal tension. It's also very complex in terms of crystallic properties (has several stable crystal forms), which are impacted by temperatures and yes, those internal tensions. While it is modelled as much as possible, no one truly knows how good are the pits that were kept in storage for decades, anymore. They certainly still work, but whether they are good enough to properly initiate a secondary, no one really knows. Testing could be very instrumental in finding that out.

Laser efficiency is important if you're actually building a power plant, but for an experimental facility, it's easy enough to correct for the inefficiency of your old lasers. That doesn't make your research inapplicable to power plants.

Well, somewhat. The amount of precision that the physical worlds demand in the construction of the fuel pellets, and the amount of energy involved in using them, guarantee that you need an extremely expensive mechanical process for the fuel. So, while physically you probably can extract energy from the pellets, it'd be like a steam train powered by gold bars instead of coal.

I think someone would've said the same thing about megaflop computers before the IC was invented.

Worth pointing out that "the part of the branch of the US government that handles nuclear weapons" is the Department of Energy, which of course also handles fusion energy research.

> achieving the actual energy break even instead of laser energy break even.

Can someone elaborate on why laser energy break even was even a big deal? Why does that matter? Doesn't only total net energy matter?

The former is a milestone for the latter. In order to demonstrate that net energy for the process is even possible, they have to show that the ignition can be breakeven. By analogy they have to show that combustion is possible before spending even more money on building a giant gas fired power plant.

It's a small milestone, but it's a very important stepping stone if there's going to be any future for it. Getting it to the commercial power plant stage is a much more holistic problem that will probably take 10x more investment which no one wants to spend sight unseen.

While it's true that total net energy is what ultimately matters, the article points out that 99% of the energy that goes towards the lasers is wasted. So it seems like a logical next milestone.

Prior to this, ignition had only been achieved in hydrogen bombs.

Basically, they confirmed that it is possible to have a controlled fusion reaction where the reaction puts out more energy than was put into the reaction, a prerequisite step to being able to put out more energy than was put into the entire machine.

Everyone assumed that controlled ignition was possible, but it's still meaningful to be able to prove it experimentally, particularly since now they can probe the limits and understand how different factors affect the result.

Is a big loss here laser efficiency and cooling issues?

I attended a presentation by the NIF guys earlier this year at a conference, where IIRC one of the bigger challenges was the optics.

Due to the amount of energy being put through them (particularly since it was pulsed), any imperfections would be amplified, quickly rendering the component unusable. They ended up developing an entire automated system for fixing these using an approach I can't recall.

So I guess the losses in terms of reaching break even (which this facility is not specifically aiming for, its main purpose is to ensure our hydrogen bombs still work) are the electricity-to-laser efficiency (IIRC these lasers are pretty old now and less efficient than modern lasers), making optics which can better tolerate the energy, getting the timing right so that the pellet is compressed equally (any imbalances manifest as reduced efficiency) and making better pellets (since of course, this is also an energy intensive process at the moment).

Yup. Also energy recapture. (I suppose you could argue that's included in "cooling issues.")

Thats more like 10 steps away, not really the next step.

I'm generally on team NIF as a laser guy, but my biggest gripe is the calculation for ignition they employ uses the UV light into the hohlraum which ignores the 3-omega frequency tripling as the light (originally IR at 1053nm) enters the main target chamber. That frequency tripling will always rob a lot of energy from the lasers as it does generally for normal laser setups. I feel like loss from other parts of the laser like the amplification and other general losses are understandable because it's a laser and that's unavoidable, but they absolutely should include the loss from the frequency tripling because that seems like an added on thing (this improves penetration into the walls of the hohlraum), even though that will push them below the ignition threshold again.

The loss there is about a factor of 1/2 or so, so they'd have to improve things by that much.

“Ignition” in this sense is interesting physics. But it has absolutely nothing to do with power generation.

Half a dozen commercial laser fusion projects disagree with you.

https://www.nytimes.com/2023/11/13/science/laser-fusion-ener...

Those companies are good at one thing: extracting money from VCs who are bad at math.

The article mentions that the National Academy of Sciences also disagrees with you. Here is their report.

https://nap.nationalacademies.org/read/18289/chapter/1#xv

I’d love to be wrong about this, but I don’t think I am.

Well there's something to be said for confidence I guess.

the end game here is so exciting, getting these news of the steps in the right direction is welcome in my book

Holy shit it's happening...

Yes, but it's not ICF that will make it happen. It's MCF, look to SPARC and ARC being made by MIT & CFS in Massachusetts. Mark these words, by end of this decade we will have Q > 3 in an experimental MCF reactor and it will be SPARC. End of next decade we will have the first fusion power reactors (ARC). Whether they are used as on the grid solutions or instead heat sources for energy intensive processes (think chemical reactions, metal forges, etc ) in the 30's is yet to be determined.

Can someone expand these acronyms for me please?

ICF: Inertial Confinement Fusion

MCF: Magnetic Confinement Fusion

CFS is Commonwealth Fusion Systems - https://cfs.energy/

Q is the ratio between energy in and out in a fusion system. Q > 1 is the holy grail, which implies we have more energy out of the fusion system than in. CFS is aiming for Q 11 in its prototype reactor.

SPARC is the "Smallest Possible" ARC I believe. It's their prototype reactor that they're working on that uses magnetic fields through superconductors to contain Hydrogen as it heats up into plasma and goes through the fusion process.

ARC is the 400MW reactor that will be produced (aimed for within a decade) if SPARC succeeds - it's the scaled-out version of SPARC.

It has an impressive set of people working on it (ex-SpaceX).

And yes, ARC is named after the Iron Man reactor.

It happened in 2013 lol. This is just about how its happening easier. This is a research milestone, it will help us model fusion plasma, but in no way is a prototype for a fusion power plant.

I guess that means we will have another round of "this interesting result in basic research that has no relation to practical use of fusion energy shows that practical and commercially viable fusion energy is basically just around the corner".

The rate of progress is astounding.

If growth is high, you can look nowhere near something, and then without too much time, it actually is right around the corner.

We are probably AT LEAST 50 years away from a near 100% non-nuclear "renewable" world.

That's enough time for the entire lifecycle of nuclear reactors and fusion reactors.

Much of the world doesn't have their own fossil fuels they can rely on, and is definitely interested in alternatives in less than 50 years - even if it means - in ideal conditions - they'd be overpaying for nuclear (or fusion if it becomes viable within 15 years).

It's almost as if all the people working on these projects and funding them aren't complete morons, and the world quite so reductive, like half of hacker news seems to smugly dismiss EVERY time any fusion article is posted.

> Much of the world doesn't have their own fossil fuels they can rely on

For some reason this thought reminded me of the transition from the Bronze Age to the Iron Age.

Iron failed to displace bronze during the Bronze Age for two reasons:

1. It is technologically difficult to make.

2. It is mostly an inferior material.

(Steel is a lot better than bronze, but that wasn't an option.)

But the Bronze Age ended in a near-total collapse of the social order across most of Eurasia. International trade routes dried up. And iron was readily available everywhere in the world, whereas bronze was not even available to regions that mined their own copper, because they didn't have any tin.

Interestingly enough, having your own local supplies of food and energy protects you from suddenly starving and freezing if a war should break out, but it makes everyone else a lot less safe from you, because now you're insulated from the consequences of war.

> We are probably AT LEAST 50 years away from a near 100% non-nuclear "renewable" world.

For electricity (which is the only energy category where nuclear makes sense) I see no reason to be this pessimistic (of course, depending on your definition of near 100%, but let's say 95%). Solar and Wind have strong growth prospects and are very economical, with reason to believe in further price reductions (especially for solar). As we've seen at COP, a lot of countries are planning to strongly build out renewables (a simple tripling, disregarding a lot of factors, leading to 45% share of renewables by 2030) and only a few are planning a much slower expansion of nuclear.

Storage shows a lot of promise and very successful initial deployments for short duration storage and I see no reason to be more (or even as) optimistic about future development of nuclear & fusion reactors than chemical energy storage.

> It's almost as if all the people working on these projects and funding them aren't complete morons, and the world quite so reductive, like half of hacker news seems to smugly dismiss EVERY time any fusion article is posted.

Or there's a reason why this is mostly funded by governments as a foundational work, presumably with hopes that fusion will be largely viable in the long term. If governments funding this work were hopeful that fusion would be economically viable within 15 years, you'd expect very large funding increases (especially from the private sector) and a reduction in investment for transforming the electricity grid away from big central power producers to more geographically diverse renewable supply.

I still don't get why thorium reactors basically don't exist despite on paper being superior for energy generation.

https://en.wikipedia.org/wiki/Thorium-based_nuclear_power

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

I find it frustrating the the US Govt spends > $800B/yr on our "defense" while we run out of basic supplies like ammunition and all of our tanks and ships are falling apart.

Meanwhile, that same Govt spends < $1B on fusion, which could change the course of humanity.

I'm usually the last person to suggest that the govt should spend money on things, but for goodness sake I wish we could at least get our priorities straight as far as what to spend the money on.

If I didn't know better I'd think that the whole point of the defense department was to funnel money to well-connected corporations and execs.

Source on running out of ammunition? I've never heard that about the US military before

I imagine it has a lot to do with oil company lobbying.

> while we run out of basic supplies like ammunition

Because they're actively being used in a war in Ukraine at a prodigious rate? And we're spending money ramping up production.

And we're not "running out" -- we're keeping plenty to defend ourselves, we just want to be able to send Ukraine even more.

> and all of our tanks and ships are falling apart.

Source? This is the first I'm hearing of this.

The US has the most powerful and capable military in the world. You're acting like we're spending money on it but are getting something cut-rate in return. But we're not.

Too much fox/maga media/kremlin propaganda. All the ammo given to Ukraine has been expired and due to be disposed of.

otoh, Its the natural state of ships to be falling apart, they’re very maintenance heavy

What in the world led you to think that? In the real world, solving problems is more than just a function of how far to the right you slide their budget allocation.

In case of fusion I don't think it's a money problem. ITER has funding from a lot of countries and even they have a hard time with it. It could be that fusion is almost impossible with the current state of technology that we have now.

As for govt spending on military vs science almost all govts are like this. I wish it was different. It's almost like a zero sum game when it need not be like that

There's a difference between running out of ammunition and running out of ammunition that can be supplied.

They're running out of ammunition that can be supplied, because the rest is being reserved for if we end up needing it for ourselves.

As for tanks and ships falling apart, I have no idea where you're getting that from.

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