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University of Texas-led team solves a big problem for fusion energy
- perihelions 1y agohttps://arxiv.org/abs/2410.02175v2 https://arxiv.org/abs/2410.02175v2
- RhysU 1y ago> We report on a data-driven method for learning a nonperturbative guiding center model from full-orbit particle simulation data. > 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.
- wizardforhire 1y agoHaven’t read the article yet, yet alone the paper but based on what you’ve quoted these are ongoing challenges with regards to confinement. Think tokamak vs stellarator. Magnetoplasmahydrodynamics is hard because you have all the complexities of the navier-stokes combined with Maxwell and thats just scratching the surface. Sensitive dependence on initial conditions has never been so sinister as in plasma confinement. Orbital perturbations quickly lead to turbulent instabilities which lead to containment breach which can lead to multi-million degree hyper velocity jets tearing a hole through your multi-billion dollar toy in seconds.
- actinium226 1y agoAre these sorts of instabilities harder to control in a tokamak as compared to a stellarator, or did you just bring those up as examples of magnetic confinement?
- wizardforhire 1y agoI’ve since gone back and read the article, haven’t looked for the paper yet. > Are these sorts of instabilities harder to control in a tokamak as compared to a stellarator, or did you just bring those up as examples of magnetic confinement? I was just shooting from the hip in the earlier comment alluding to your question and bringing them up as examples of two different approaches to addressing the said issues with instabilities that lead to the complexities of confinement. I think its just a terribly fun thing to think about because of its complexity. Stellarators are attempting to solve the issues passively through design. Tokamaks on the other hand with active control. Theres trade offs to both and neither has reached break even output yet. I’m personally largely bored with them and think linear is the way to go, even though the laser based inertial confinement reactor at Lawrence is the first to reach breakeven output… experimentally at least.
- xyst 1y agoIs there a collective repository on breakthroughs in energy generation by fusion? Sure, this team solves one "big" problem. But hints there are a plethora of other problems (or technology limitations) in this field.
- DennisP 1y agoPart of the excitement these days is that the general march of technology has removed a lot of those technology limitations, due to advances in superconductors, lasers, supercomputers, fast high-power electronics, etc. (Superconductors and computers would be the ones relevant to stellarators, of course.)
- tiahura 1y agoHow is that different than the excitement 30 years ago?
- lupusreal 1y agoEven with all of these advancements I don't see how you get around fusion reactors still being more complicated and expensive to build as fission reactors, and just as radioactive due to the huge amounts of neutron radiation the "easiest" kinds of fusion produce.
- gnfargbl 1y agoThe difference is that waste from neutron activation is "just" an engineering problem which might have an engineering solution (we hope). Waste in the form of long-lived nuclear fission products is fundamentally an unsolvable issue. Transmutation has been proposed but isn't really practicable, shooting it into the sun isn't really an option either, so the only choice is to confine it for geological timescales somehow. Both options are really much better, in my opinion, than pumping more carbon dioxide into our biosphere.
- pfdietz 1y ago> "just" an engineering problem This is a major fallacy that makes people think DT fusion is more promising than it actually is. Engineering problems are perfectly capable of killing a technology. After all, fission after 1942 was "just an engineering problem". And DT fusion faces very serious engineering problems. I include cost issues as engineering problems, as engineering cannot be divorced from economic considerations. Engineering involves cost optimization.
- tiahura 1y ago[flagged]
- gnfargbl 1y agoNo, this has absolutely nothing to do with so-called "cold" fusion. Cold fusion was a hypothetical type of room-temperature nuclear fusion. It was reported in 1989 but not successfully replicated. It can't possibly work because of the Coulomb repulsion between nuclei is far too strong for them to come into contact at our everyday energy levels. 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.
- pfdietz 1y agoOrdinary fusion doesn't overcome the Coulomb barrier either. In a purely classical sense, fusion wouldn't happen, since the thermal energies are well below the height of the Coulomb barrier. What happens is that thermal energies get high enough that the nuclei get close enough to have a significant rate of tunneling through the barrier. It's a quantum mechanical effect. There is a nonzero rate of tunneling through the barrier even at room temperature -- just extremely low, far lower than putative cold fusion claims.
- Sniffnoy 1y ago> It can't possibly work because of the Coulomb repulsion between nuclei is far too strong for them to come into contact at our everyday energy levels. Worth noting that (while obviously not what is normally meant by "cold fusion") muon-catalyzed fusion is possible and is cold, so the above statement can't be quite right.
- gnfargbl 1y agoTechnically correct, yes, but muonic atoms have a lifetime on the order of microseconds. They aren't really relevant to the everyday-scale physics I was discussing. There is however Lattice Confinement Fusion [1] which claims to overcome the Coulomb barrier through some kind of "screening" from the electron cloud in the lattice. That seems more like it would work on at everyday scales, though I don't understand it nearly enough to offer any opinion on viability. [1] https://www1.grc.nasa.gov/space/science/lattice-confinement-fusion/ https://www1.grc.nasa.gov/space/science/lattice-confinement-...
- scythe 1y agoIt is a little jarring to hear "data-driven" and "nonperturbative" in the same sentence. It sounds a little bit like saying you designed a boat with a better lift-to-drag ratio. "Wait, is it a boat or a plane?". So, I opened the paper fully expecting to not understand anything, and I was pleasantly surprised. > First we deduce formally-exact non-perturbative guiding center equations of motion assuming a hidden symmetry with associated conserved quantity J. We refer to J as the non-perturbative adiabatic invariant. Simply: this is not just some kind of unsupervised ML black-box magic. There is a formal mathematical solution to something, but it has a certain gap, namely precisely what quantity is conserved and how to calculate it. > Then we describe a data-driven method for learning J from a dataset of full-orbit α-particle trajectories. [...] Our proposed method for learning J applies on a per-magnetic field basis; changing B requires re-training. This makes it well-suited to stellarator design assessment tasks, such as α-loss fraction uncertainty quantification. With the formal simplification of the dynamics in hand, the researchers believe that a trained model can then give a useful approximation of the invariant, which allows the formal model, with its unknown parameters now filled in, to be used to model the dynamics. In a crude way, I think I have a napkin-level sketch of what they're doing here. Suppose we are modeling a projectile, and we know nothing of kinematics. They have determined that the projectile has a parabolic trajectory (the formal part) and then they are using data analysis to find the g coefficient that represents gravitational acceleration (the data-driven part). Obviously, you would never need machine learning in such a very simple case as I have described, but I think it approximates the main idea.
- ChrisMarshallNY 1y agoOne of the nice things about LLMs/ML, is that they can pound away at something for a billion cycles, and do exactly the same things that you or I would do. for _ in 0..<1000000000000 { do_something_complicated() }
- kjkjadksj 1y agoIsn’t that one of the nice things of computers in general not a feature of llm?
- red75prime 1y ago> high-energy electrons that can punch a hole in the surrounding walls. What does it mean? Beta radiation can cause structural damage? Is it really a problem?
- regularfry 1y agoThe electrons are high enough energy that they can damage the wall, yes. But also they're simply a route for energy loss from the plasma that you don't want. E.g. https://www.nature.com/articles/s41598-023-48672-7 https://www.nature.com/articles/s41598-023-48672-7
- red75prime 1y agoThanks! It's exactly what I needed, but felt too lazy to look up (which is uncharacteristic of me, but, well, why have forums if you have to look everything up yourself).
- jmyeet 1y agoYes. It's a significant problem for two reasons: 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".
- pfdietz 1y agoIn a disruption in a tokamak, when the plasma collapses, the current in the plasma that goes around the ring decays. This creates an electric field as in a kind of accelerator called a "betatron". The electric field can accelerate runaway electrons to relativistic speeds. This beam can hit surfaces and melt holes, like a giant arc welder. https://www.jp-petit.org/NUCLEAIRE/ITER/ITER_fusion_non_controlee/Wurden_en.pdf https://www.jp-petit.org/NUCLEAIRE/ITER/ITER_fusion_non_cont...
- chiffre01 1y agoTLDR for the paper and article: The paper introduces a new, data-driven method for simulating particle motion in fusion devices that is much more accurate than traditional models, especially for fast particles, and could significantly improve fusion reactor design.
- nk8620 1y agoIs that what the paper is about? I thought there was some heavy physics breakthrough. I wanted to read the paper, but given this TLDR, I'm having second thoughts. I'll probably just use an LLM instead now.
- jmyeet 1y agoI remain skeptical that fusion will ever be a commercially viable energy source. I'd love to be wrong. The engineering challenges are so massive that even if they can be solved, which is far from certain, at what cost? With a dense high-energy plasma, you're dealing with a turbulent fluid where any imperfection in your magnetic confinement will likely dmaage the container. People get caught up on cheap or free fuel and the fact that stars do this. The fuel cost is irrelevant if the capital cost of a plant is billions and billions of dollars. That has to be amortized over the life of the plant. Producing 1GW of power for $100 billion (made up numbers) is not commercially viable. And stars solve the confinement problem with gravity and by being really, really large. Neutron loss remains one of the biggest problems. Not only does this damage the container (ie "neutron embrittlement") but it's a significant energy loss for the system and so-called aneutronic fusion tends to rely on rare fuels like Helium-3. And all of this to heat water to create steam and turn a turbine. I see solar as the future. No moving parts. The only form of direct power generation. Cheap and getting cheaper and there are solutions to no power generation at night (eg batteries, long-distance power transmission).
- lordfrito 1y agoNo one wants to acknowledge that the economics will likely never work out for the reasons you mentioned. Too much maintenance -- and very expensive maintenance at that. It's far cheaper cost per watt to build a traditional fission reactor and run/maintain that. 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.
- cmrdporcupine 1y agoAnd the transmission costs argument is precisely why we'd likely be better off solving the problem of distributing power production across a more decentralized grid with a lot of wind and solar and battery all over the place
- blindriver 1y agoCan someone tell me what the likelihood of a humongous explosion from nuclear fusion could be? All these nuclear physicists dealing with enormous amounts of energy, like the LHC or China with their attempts at nuclear fusion really terrify me that it might provoke a huge reaction that will devastate the planet. Is this possible or do they have a true fail-safe in place that prevents it?
- ahazred8ta 1y agoThere's nothing to 'prevent'. There's not enough energy in the hydrogen in the chamber to cause an explosion. Your high school science teacher could have explained this to you.
- hwillis 1y ago> All these nuclear physicists dealing with enormous amounts of energy, like the LHC 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.
- blindriver 1y agoThank you for the great answer, unlike the other responser.
- munchler 1y ago> This work was supported by the U.S. Department of Energy. Unfortunately, sentences like this are going to be way less common soon.
- libraryatnight 1y agoIt's been sad reading the posts of the various people in the sciences and academics that I follow.
- jimbob45 1y ago[flagged]
- gr_norm 1y agohttps://nces.ed.gov/fastfacts/display.asp?id=73 https://nces.ed.gov/fastfacts/display.asp?id=73 https://en.m.wikipedia.org/wiki/List_of_colleges_and_universities_in_the_United_States_by_endowment https://en.m.wikipedia.org/wiki/List_of_colleges_and_univers... Doesn't seem to be true? The LLM response claims 47.5 billion but I have no idea where it got that number from after looking through its sources. edit: Oh, and if you're talking about the Permanent University Fund that's split between the UT + A&M systems. And the ChatGPT response is way off here as well. And as the others have noted, even if what you said was true it has very little to do with what you're replying to.
- 0_____0 1y agoThis doesn't invalidate the comment you're replying to.
- bix6 1y agoWhat if I told you that an endowment isn’t a pile of cash that should be burned through in 4 years to cover an imbecilic government shortfall?
- RandallBrown 1y agoIf you told me that I would ask for some clarification. The UT system has a very large endowment, (which appears to be a little smaller than Harvard's), but UT Austin is much smaller (but still very large for a public university.) I'd also ask why you included the University of Florida in that list, since it appears their endowment is pretty small (at least compared to the other schools in that list.)
- lifeplusplus 1y agoI think it's time to say nobody in Congress can be older than 65 and has a dual citizenship
- tempaccount420 1y agoThose pesky dual-citizenship Europeans are meddling in US politics! Maybe say which country specifically you mean when you say "dual citizenship" ;)
- hornd 1y agoIs this comment on the right thread?
- curtisszmania 1y ago[dead]
- kristel100 1y ago[dead]
- Aardwolf 1y agoDon't worry, AI might need so much energy in the end that it'll need fusion energy
- Finnucane 1y agoBack in the 1970s we were told fusion was 50 years away. It's always 50 years away.
- theptip 1y agoThis was the joke when I did Physics in the ‘00s too. The hilarious part is that the kids these days misquote it as “fusion is 20 years away and always has been”, or even 10 years. I read that as at least 0.5 years per year of progress against the estimate :)
- Dave_Wishengrad 1y ago[dead]