> Then we describe a data-driven method for learning from a dataset of full-orbit α-particle trajectories. We apply this method to the α-particle dynamics shown in Fig. 1 and find the learned non-perturbative guiding center model significantly outperforms the standard guiding center expansion. Our proposed method for learning applies on a per-magnetic field basis; changing requires re-training.

Is this interpolation at its heart? A variable transformation then a data fit?

Anyone know which functionals of these orbits are important? I don't know the space. I am wondering why the orbits with such nuance should be materially important when accessed via lower-order models.

Finding simplified easy to solve solutions and using them to estimate solutions and using adjustments to get closer to the real solution is a baselime technique. That's the core of the pertubative approach in physics which uses : https://en.wikipedia.org/wiki/Perturbation_theory#:~:text=Pe...

However, now it's possible to train AI models to learn much more complex approximations that allow them to run much quicker and more accurately. A prime example is DeepMinds AlphaFold, IMHO.

I haven't read up on the research to much, but I'd place firm bets that AI models will be critical in controlling any viable fusion technology.

for _ in 0..<1000000000000 { do_something_complicated() }

We're not at that point yet with natural gas because a combined cycle turbine is more efficient than a steam turbine.

Another reason is that ̶t̶r̶a̶n̶s̶m̶i̶s̶s̶i̶o̶n̶ distribution costs are half of your energy bill... so even if you could theoretically get fusion energy generation for "free" (which is impossible) you've still only cut your power bill in half.

Edit: I meant to say distribution costs not transmission. Looking at last months bill I paid $66.60 to deliver $51.76 of energy (about 56% of my total bill was delivery). The raw distribution charge was $49.32 or 42% of the bill. I'm not alone in these numbers, but your mileage may vary.

First, actually getting fusion to positive energy ROI. That's step zero and we're not even close.

Second, scaling the production of fusion in an safe and economical way. Given the utter economic failure of fission nuclear power (there has never been a profitable one), my priors are that the fusion advocates are vastly underestimating, if not willfully ignoring, this part.

Finally, even if we do get to "too cheap to meter" energy, what then? Limitless electricity is not the same thing as limitless stored energy. Only 20% of our energy needs are supplied by electricity. To wit, the crucial industrial processes required to build the nuclear power plant in the first place can only be accomplished with combustible carbon. A power plant cannot generate the energy to build another power plant. Please let that sink in.

We're already seeing countries with photovoltaic and wind hitting $0/kW on sunny windy days - the grid is nearly saturated for daytime load. There isn't enough demand! This makes the economic feasibility of fusion even less attractive. No one is going to make money from it.

I’m also skeptical, but I think the emphasis of my skepticism is on “commercially viable” as opposed to an available energy source. That is, I think fusion development will (and should) proceed anyway.

There’s a good argument that nuclear fission is not really commercially viable in its current form. Yet it provides quite a lot of commercially available electricity. And it also powers aircraft carriers and submarines. And similar technology produces plutonium for weapons. In other words, I don’t think fission’s continued availability as a power source is a strictly commercial decision.

I think there’s a quite a lot of technology that is not directly commercially viable, like high energy physics, or the space program. But they remain popular and funded. And they throw off a lot of commercial side benefits.

The growth of solar for domestic consumer power will certainly continue and that is a good thing. But I bet we’ll have fusion too in the long run. There’s no lack of ideas for interesting things to do with extreme amounts of heat and power. For example I’m hopeful that humanity eventually figures out space propulsion powered by fusion.

This is true of Tokamak type designs based around continuous confinement, but perhaps less so with something like Helion's design which is based on magnetically firing plasma blobs at each other and achieving fusion through inertial confinement (cf NIF laser-based fusion), with repeated/pulsed operation rather rather than continuous confinement.

No doubt the containment vessel will still suffer damage, but I guess it's a matter of degree - is it still economically viable to operate or not, which I guess needs to be verified experimentally by scaling up and operating for a sufficiently long period of time. Presumably they at least believe the approach is viable or they'd not be pursuing it (and have an agreement in place with Microsoft to power one of their data centers with one of the early units).

- Lawson criterion is derived with the assumption of equilibrium plasma, which doesn't hold true in any real tokomak/stellarator

- at required temperatures most of the energy would be in photons of thermal radiation, that don't get confined by magnetic field, so when plasma relaxes from high energy beams to thermal equilibrium, it loses all the pumped energy through radiation

- with high energy beams tokomak is essentially a particle accelerator, where electrons get in the way of collision

I see it similarly to the difference between a car with a combustion engine and an electric one. Combustion engines are fully developed. We're reaching the maximum possible performance and utilisation. It's a dead end. However, with electric cars, for example, new battery development is far from over. E.g sodium batteries.

And just off the top of my head, in fusion, the discovery of better electromagnets, as happened a while back, can quadruple energy output.It's not a dead end, and writing it off would be short-sighted.

It can be for deep space propulsion. The Orion project [1] demonstrated that you can power a spaceship so that it has both huge thrust and huge specific impulse with hydrogen bombs. The main issue with this project is the proliferation concerns. However, if you replace the bombs with pellets that are imploded by lasers, like the NIF experiment did [2], then you could get to the point where you can drive a rocket with non-weaponizable fusion explosions.

[1] https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...

[2] https://en.wikipedia.org/wiki/Fusion_ignition#2021_and_2022_...

And before someone chimes in and says Nuclear doesn't make sense - it made sense at plenty of times and in different places.

It doesn't make sense in Western countries that are hell bent on making it as expensive as possible, strictly to ensure it doesn't get built, so we stick on fossil fuels as long as possible.

  * The super conducting metals required for confinement randomly stop superconducting.

  * The fuels produce absurd amounts of radiation and the Helium-3 solution for that might as well be fairy dust, since even if we convert the energy global economy to helium-3 production, we will not have enough by orders of magnitude to power hypothetical fusion reactors that would handle our needs. Strip mining the moon for it is supposedly a way to get it, but defacing the surface of the moon for minuscule amounts of Helium-3 per acre is unlikely to ever be profitable.

  * The amount of radioactive materials produced from the experiments are many times those produced in fission reactors.

I wonder if the only reason countries fund nuclear fusion research is to keep nuclear scientists from finding employment in the production of nuclear weapons.

Depleted uranium is one example but that has terrible implications due to radioactive pollution that would result, disposal costs and risks, etc.

Surprised theres not more research into meta-materials and alloys that are neutron-resistant, neutron-slowing, or neutron-absorbing.

There are interesting small fusion reactors that skip the steam step. They compress plasma magnetically, and when the fusion happens, the expanding plasma in turn expands the magnetic field, and the energy is harvested directly from the field. No steam and turbines.

Here is the video where I learned about it: https://www.youtube.com/watch?v=_bDXXWQxK38

Maybe any physicists in this thread could share insight on how feasible this is?

Your main point stands of course: this is a moonshot project, and solar works TODAY!

The problem(s) of scale are not only those of scaling up, but also scaling down.

One of the best and most unsung benefits of solar is that it is profoundly easy and intuitive to build a very small (ie, vehicle- or house-sized) grid.

In an increasingly decentralized and stateless world, it makes sense to look for these qualities in an energy source.

But so long as there is a boatload of prestige and funding to be harnessed via fusion research, it'll be a Really Big Thing.

Centuries ago, an ambitious and clever alchemist could harness a fair quantity of those things via transmutation research. Vs. these days, we have repeatedly demonstrated the ability to transmute lead into gold. But somehow, there's no big talk about, or prestige in, or funding for scaling that process up to commercial viability.

Kinda. The main catalyst of stellar fusion is quantum tunneling. Temperature and gravity together are not enough to overcome the Coulomb barrier.

Why that last bit? Generic tangents supplant narrower/specific topics with broader/generic ones that people tend to already have opinions about, which they are eager to repeat. Because of this, generic tangents—especially on divisive/indignant topics—end up having two bad effects: (1) they take over the conversation, and (2) they are repetitive.

It's similar to how weeds take over a garden. We want a garden of unusual, interesting plants, not the most common ones that take over everywhere if allowed to.

https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

This work is related to actual genuine nuclear fusion, the kind that occurs at energy scales sufficient to overcome that Coulomb barrier. At those energy scales it becomes very hard to manage the plasma in which fusion occurs. This is a claimed advance in plasma management.

Maybe say which country specifically you mean when you say "dual citizenship" ;)

The LHC uses ~86 megawatts, about the same power as a 747's engine at full throttle. It's about the same as a small natural gas powered turbine. GE builds gas turbines that produce 800+ MW.

The LHC is just a controlled environment to study the kind of particle collisions that are happening all over the earth every day. We live next to a giant fusion reaction, and freak particles come in from outer space all the time. We have detected many particles with millions of times more energy than the particles in the LHC- the Oh-My-God particle had 20 million times more energy.

> Can someone tell me what the likelihood of a humongous explosion from nuclear fusion could be?

Fission self-sustains. Each reaction produces 3 neutrons that can start another reaction. It explodes because the neutrons grow like 3, 9, 27 etc.

Fusion does not. You have a number of atoms, and 2 of those atoms have to find each other to fuse. One reaction does not make any other reactions more likely. Unlike fossil fuels or fission reactions, the fuel cannot be lit. It can only burn when carefully confined. You can only build up enough flame to break the containment vessel, at which point it goes out. Since the inside of the vessel is basically a vacuum, it will implode instead of exploding.

1. High energy particles destroy the container. Alpha particles, which are just Helium nuclei, are quite small and can in between metal atoms. Neutrons too. High energy electrons too; and

2. It's an energy loss for the system to lose particles this way.

Magnetic confinement works for alpha and beta particles because they're electrically charged. Neutrons are a far bigger problem, such that you have fun phrases like "neutron embrittlement".

https://www.jp-petit.org/NUCLEAIRE/ITER/ITER_fusion_non_cont...