> 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.
> What if I told you UT has a higher endowment than any other school in the US including Harvard?
I would ask your data source, because Wikipedia has 2024 stats indicating Harvard’s endowment is ~$4.5 billion greater than the UT system’s ($52B vs $47.5B).
I’d also point out that the UT system has almost 9 times the student body size as Harvard (250k+ vs 30k) spread among 14 campuses.
If 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.)
I'm guessing they relied on an LLM response. That was my thought, and having tried it they indeed generate lots of garbage for this topic. I got a ChatGPT A/B test for this and both options were incorrect (one obviously and the other subtly, due to misinterpreting a bond rating page's discussion of the PUF and just blindly regurgitating the number from there).
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.
I 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).
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.
Where did you get the data that there has never been a profitable one? Not calling you out, but curious of where you are getting this data.
I would expect that there have been multiple nuclear power plants that provide a net positive return, specially on countries like France where 70% of their energy is nuclear.
France lost an incredible amount of money on nuclear through capacity factor issues. The numbers are so bad they don’t want to admit what they are.
However a reasonable argument can be made the public benefited from externalities like lower pollution and subsidized electricity prices even if it was a money pit and much of the benefit was exported to other countries via cheap off peak prices while France was forced to import at peak rates.
Regulatory burdens on fission account for negative externalities to an arguably overzealous degree, whereas fossil fuel energy has been until recently allowed to completely ignore them. Doesn't seem like a fair comparison.
I won't dispute that fission power has enormous capital costs. But how much of its alleged "failure" has been the utter FUD that's been pushed for the past 50+ years about how we'd all be glowing if nuclear power was widespread?
I mean sure, waste disposal is a serious issue that deserves serious consideration. But fission waste contaminates a discrete area. Fossil fuels at scale cause climate change that contaminates the entire freaking planet. It's a travesty we haven't had a nuclearized grid for 20-30 years at this point.
We're at a point where even "free hot water" is not competitive with solar for power generation. It costs more to build a 1GW coal power plant than it does to build a 3GW solar power plant (the 3X is capacity factor compensation). And most of the cost of that coal power plant is the steam turbine and its infrastructure.
We're not at that point yet with natural gas because a combined cycle turbine is more efficient than a steam turbine.
We're talking about electricity generation here, not heat generation. People have tried generating electricity using solar heat, but we've stopped doing that because it's too expensive.
> We're talking about electricity generation here, not heat generation
As a peer post noted (without back it up but seems reasonable):
> Only 20% of our energy needs are supplied by electricity.
It is a fair viewpoint to talk about energy instead of only electricity. For exemple the current EV are build using charcoal (steel and cement for the infrastructure) and parts/final product are moved around continent with oil (ships). Same for solar panels and their underlying steel structure. Same for the road were using those EV, etc… there’s technical solutions for those, but they didn’t prove to be economically competitive yet. So I’ll happily take that 80% efficiency when we need relatively low heat : domestic and commercial AC and water heating. Those are by far the most energy intensive usage in the residential sector when there isn’t an electric vehicle and are most needs in pick time (mornings, evening at winter). We better take that +60%.
People really don’t understand how huge that is. There is no way to make the math on nuclear or fusion work when the power extraction portion of the plant costs more than solar even if you zero out the generation costs
I see this is fallacy, there are a ton of industrial processes that use a ton of power just to produce heat. A great early use case for fusion will directly use the heat for these industrial processes. For example, aluminum requires ~14-17MWh to produce 1 ton... If you use the heat directly you reduce your processes inefficiency by removing the conversions: heat to steam to electric to heat.
Yeah, next 50 years you might not see coal/nat gas being replaced by fusion. But you will see fusion displacing chunks of what those powerplants will be powering
> A great early use case for fusion will directly use the heat for these industrial processes.
There is no chance that early fusion plants will be small enough to justify building them in the same building as a factory. They will start large.
> For example, aluminum requires ~14-17MWh to produce 1 ton
The Hall–Héroult process runs at 950 C, just below the melting point of copper. It is close to twice the temperature of steam entering the turbines. It is not something that can be piped around casually- as a gas it will always be at very high pressure because lowering the pressure cools it down. Molten salt or similar is required to transport that much heat as a liquid. Every pipe glows orange. Any industrial process will effectively be a part of the power plant because of how difficult it is to transport that heat away.
Also NB that the Hall–Héroult process is for creating aluminum from ore, and recycling aluminum is the primary way we make aluminum.
To take advantage of this you would need to build an integrated power/manufacturing hub. The project would be extremely expensive and difficult to finance in places that don’t have strong central planning.
> We're at a point where even "free hot water" is not competitive with solar for power generation.
You're making the obvious mistake here of equating 1 GW solar with 1 GW of any other source with a 95-99% baseload capacity. To achieve the equivalent result, you'll need to have at least >2 GW actual solar power to equally compare the two.
Granted, in most developed places, solar still beats coal, but this is why in many developing economies with ample coal resources, it makes more sense economically to go with the coal plants.
Take any other resource, say hydel or geothermal - solar and wind quickly go down in economic efficiency terms compared to these, in most cases almost doubling or tripling in costs.
I can’t really imagine how the person who responded to you managed to miss that, it was like the middle 1/5’th of your post. Oh well, I guess it is impossible to write a post well enough that somebody won’t jump in with a correction… right or wrong!
40% of US corn acreage is used for something like 10% of gasoline. This is an unfathomable amount of land. Solar yields 20x the amount of energy per acre. On top of that many are finding efficiencies of colocating solar with agricultural activities (agrivoltaics). And there's also replacing agricultural activities on marginal or water stressed land.
Conclusion, land isn't really a constraint in the US.
I don’t have any reason to doubt it, but it seems like a basically easy computation to verify or for the AI to show its work.
Anyway, the area issue seems not too bad. In the US as least, we have places like the Dakotas which we could turn like 70% of into a solar farm and nobody would really notice.
> It costs more to build a 1GW coal power plant than it does to build a 3GW solar power plant (the 3X is capacity factor compensation)
That “3X” figure assumes a high‐insolation region (CF ~25 %). In Central Europe, where solar CF is only ~12 %, you’d need about 5x the PV capacity to equal a 1 GW coal plant’s annual generation. How does scaling up to 5 GW of PV change the cost comparison vs a coal plant?
Solar caused problems in Spain because it was misconfigured. AC inverters are a fabulous source of power stabilization; many grids choose to install batteries and inverters for grid stabilization.
The article mentions that largish batteries are needed for synthetic inertia, which I am guessing use A/C inverters. Spain appeared to lack sufficient batteries.
Obviously, this configuration of solar and battery banks will work more optimally when they are closer to the equator.
Will different types of power grids be required for areas further away, or is it practical to ship power long distances to far Northern/Southern areas?
Nobody knows the cause of the energy outage in Spain, Portugal and France... except the U.S. Energy Secretary Chris Wright, a chill for the oil and fracking industry.
> 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.
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).
There are serious theoretical objections to Helion approach so I am very sceptical to their approach. Stellarators on other hand do not have any known theoretical obstacles and avoid the problem of plasma instabilities.
What are the theoretical problems? Aren't they already achieving fusion with their test reactors, so what's the problem with scaling up and producing net energy?
OK, and hobby rocketists have nailed a SpaceX style landing too, but so what?
Have you seen the videos of Helion's reactor - hardly a basement project. Sam Altman (OpenAI) also has personally invested hundreds of millions of dollars into Helion, presumably after some due diligence!
No 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.
> Long-distance transmission (hundreds of kilometers) is cheap and efficient, with costs of US$0.005–0.02 per kWh, compared to annual averaged large producer costs of US$0.01–0.025 per kWh
Do you maybe mean that half electrical energy dissipate between production plant and consummer? But that figure seems quite large compared to what I can find online, and this would not be a problem with "free fusion".
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 alone was $49.32 or 42% of the bill. I'm not alone in these numbers, but your mileage may vary.
My point is that the infrastructure related to the delivery of energy to a physical location is a non trivial part of an energy bill, and that this part doesn't go away magically because "fusion".
Where I live I pay about $0.09 per kWh for generation and about that much for transmission as well. I think that's what they're referring to, the literal bill they get from their current provider.
Transmission is a really interesting problem that creates all kinds of distortions.
Say a house uses 10,000kWh per year at $0.10/kWH so $1000/year electrcitiy bill. Now say you get a solar system that produces 5,000kWh per year, focused in the summer months (where your power bill tends to be higher anyway). You may even export some of that power back to the grid. Have you cut your power bill in half? No. It's probably down ~20-25%.
Why? Because regardless of how much power you use (within limits) you still need a connection to the power grid and that needs to be maintained. You'll often even see this on the electricity bill: fixed charges like "access charge" per month.
We benefit from being on a connected grid. Your own power generation might be insufficient or need maintenance. It's inefficient if everyone is storing their own power. So it's unclaer what the future of the power grid is. Should there be large grids, small grids or no grid?
There also resilience. Having small to medium local storage increases the stability of the grid.
Renewables and something like Iron-Salt battery containers, would be pretty efficient over all. Easy to roll-out, very safe.
We'll still need some sort of base load somewhere and backup to restart everything obviously. But the big giant power plants (with the huge capital costs, delays and NIMBY headaches) might become less necessary.
And 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
Problem: the capital & maintenance costs of the grid vary very little with its utilization %.
So if you build loads of wind & solar & battery all over - either (1) you've got to build so much battery capacity, all over, that you'll never need the grid, or (2) you've still got to build the grid to get you through occasional "calm & dark" periods.
Either way, you're looking at vastly higher capital expenses.
You realize this is what people said about solar energy and nuclear energy at one point, right
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.
Nobody is building commercial plants any time soon; it's still in the experimental phase, with new discoveries happening almost every month.
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.
The steam reactor I guess you might be describing is tokamak, which i agree will be a dead end technology.
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.
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.
There are a couple of factors in play with any research, including fusion. If there's money to be had for funding then somebody will research it.
But another more nefarious factor is the nexus of fusion energy research and nuclear weapons research [1]. To build and maintain a stockpile of nuclear weapons (specificially thermonuclear weapons) you need appropriate trained nuclear energy physicists.
It 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.
One 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()
}
Is 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.
Part 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.)
Even 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.
The 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.
Storing fission waste products is a solved problem. You can either reprocess them as is done in France. Or you can store them forever. Neither approach is difficult or poorly understood. We can store an infinite amount of fission waste products in the ocean, underground or in the mantle.
Nuclear waste isn't an engineering problem at all, it's a social problem. Objectively, dropping it all into a deep ocean crevice is utterly safe and effective but you'll never get the ignorant public who go off feelings to buy into it.
Fusion is only better insofar as the public don't yet understand how radioactive the reactor will become, but counting on that ignorance is a bad long term strategy.
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.
True. Launch loops are "just" an engineering problem which could be built with known materials but in reality the engineering problems are so huge it's hardly any better than space elevators which call for undiscovered materials.
You also have the associated economic problems; the up-front cost of a launch loop would be so huge that you could never convince anybody to build it instead of using rockets. Fusion has the same problem; even if you can design a fusion power plant that produces net power, it needs to produce net power by a massive margin to have any chance of being economically competitive with fission let alone solar.
And fusion reactors cannot end up like a Chernobyl disaster.
That's a huge safety plus and one of the major concerns many countries are phasing out fission reactors.
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.
Is 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.
No, 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.
> 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.
Technically 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.
True...but without an extremely cheap source of muons (half-life: 2 microseconds), muon-catalyzed fusion will forever be condemned to "in theory, you could..." purgatory.
Ordinary 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.
Can 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?
> 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.
There'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.
The 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
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://arxiv.org/abs/2410.02175v2
> 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.
> This work was supported by the U.S. Department of Energy.
Unfortunately, sentences like this are going to be way less common soon.
It's been sad reading the posts of the various people in the sciences and academics that I follow.
What if I told you UT has a higher endowment than any other school in the US including Harvard, Yale, Stanford, and the University of Florida?
> What if I told you UT has a higher endowment than any other school in the US including Harvard?
I would ask your data source, because Wikipedia has 2024 stats indicating Harvard’s endowment is ~$4.5 billion greater than the UT system’s ($52B vs $47.5B).
I’d also point out that the UT system has almost 9 times the student body size as Harvard (250k+ vs 30k) spread among 14 campuses.
If 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.)
I'm guessing they relied on an LLM response. That was my thought, and having tried it they indeed generate lots of garbage for this topic. I got a ChatGPT A/B test for this and both options were incorrect (one obviously and the other subtly, due to misinterpreting a bond rating page's discussion of the PUF and just blindly regurgitating the number from there).
https://nces.ed.gov/fastfacts/display.asp?id=73
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.
This doesn't invalidate the comment you're replying to.
What 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?
I 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).
There are three main hurdles here
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.
Where did you get the data that there has never been a profitable one? Not calling you out, but curious of where you are getting this data.
I would expect that there have been multiple nuclear power plants that provide a net positive return, specially on countries like France where 70% of their energy is nuclear.
France lost an incredible amount of money on nuclear through capacity factor issues. The numbers are so bad they don’t want to admit what they are.
However a reasonable argument can be made the public benefited from externalities like lower pollution and subsidized electricity prices even if it was a money pit and much of the benefit was exported to other countries via cheap off peak prices while France was forced to import at peak rates.
Regulatory burdens on fission account for negative externalities to an arguably overzealous degree, whereas fossil fuel energy has been until recently allowed to completely ignore them. Doesn't seem like a fair comparison.
I won't dispute that fission power has enormous capital costs. But how much of its alleged "failure" has been the utter FUD that's been pushed for the past 50+ years about how we'd all be glowing if nuclear power was widespread?
I mean sure, waste disposal is a serious issue that deserves serious consideration. But fission waste contaminates a discrete area. Fossil fuels at scale cause climate change that contaminates the entire freaking planet. It's a travesty we haven't had a nuclearized grid for 20-30 years at this point.
We're at a point where even "free hot water" is not competitive with solar for power generation. It costs more to build a 1GW coal power plant than it does to build a 3GW solar power plant (the 3X is capacity factor compensation). And most of the cost of that coal power plant is the steam turbine and its infrastructure.
We're not at that point yet with natural gas because a combined cycle turbine is more efficient than a steam turbine.
Comparing solar power generation to solar hot water seems wrong to me because there is solar hot water:
https://www.energy.gov/energysaver/solar-water-heaters
I recall hearing that they are 80% efficient while photovoltaics tend to be around 20% efficient.
We're talking about electricity generation here, not heat generation. People have tried generating electricity using solar heat, but we've stopped doing that because it's too expensive.
https://en.wikipedia.org/wiki/Solar_power_tower
> We're talking about electricity generation here, not heat generation
As a peer post noted (without back it up but seems reasonable):
> Only 20% of our energy needs are supplied by electricity.
It is a fair viewpoint to talk about energy instead of only electricity. For exemple the current EV are build using charcoal (steel and cement for the infrastructure) and parts/final product are moved around continent with oil (ships). Same for solar panels and their underlying steel structure. Same for the road were using those EV, etc… there’s technical solutions for those, but they didn’t prove to be economically competitive yet. So I’ll happily take that 80% efficiency when we need relatively low heat : domestic and commercial AC and water heating. Those are by far the most energy intensive usage in the residential sector when there isn’t an electric vehicle and are most needs in pick time (mornings, evening at winter). We better take that +60%.
People really don’t understand how huge that is. There is no way to make the math on nuclear or fusion work when the power extraction portion of the plant costs more than solar even if you zero out the generation costs
I see this is fallacy, there are a ton of industrial processes that use a ton of power just to produce heat. A great early use case for fusion will directly use the heat for these industrial processes. For example, aluminum requires ~14-17MWh to produce 1 ton... If you use the heat directly you reduce your processes inefficiency by removing the conversions: heat to steam to electric to heat.
Yeah, next 50 years you might not see coal/nat gas being replaced by fusion. But you will see fusion displacing chunks of what those powerplants will be powering
> A great early use case for fusion will directly use the heat for these industrial processes.
There is no chance that early fusion plants will be small enough to justify building them in the same building as a factory. They will start large.
> For example, aluminum requires ~14-17MWh to produce 1 ton
The Hall–Héroult process runs at 950 C, just below the melting point of copper. It is close to twice the temperature of steam entering the turbines. It is not something that can be piped around casually- as a gas it will always be at very high pressure because lowering the pressure cools it down. Molten salt or similar is required to transport that much heat as a liquid. Every pipe glows orange. Any industrial process will effectively be a part of the power plant because of how difficult it is to transport that heat away.
Also NB that the Hall–Héroult process is for creating aluminum from ore, and recycling aluminum is the primary way we make aluminum.
To take advantage of this you would need to build an integrated power/manufacturing hub. The project would be extremely expensive and difficult to finance in places that don’t have strong central planning.
Agreed, fusion is a cool physics problem for now. In the far futrue, if it can scale down, it my have applications in shipping or space.
> We're at a point where even "free hot water" is not competitive with solar for power generation.
You're making the obvious mistake here of equating 1 GW solar with 1 GW of any other source with a 95-99% baseload capacity. To achieve the equivalent result, you'll need to have at least >2 GW actual solar power to equally compare the two.
Granted, in most developed places, solar still beats coal, but this is why in many developing economies with ample coal resources, it makes more sense economically to go with the coal plants.
Take any other resource, say hydel or geothermal - solar and wind quickly go down in economic efficiency terms compared to these, in most cases almost doubling or tripling in costs.
> To achieve the equivalent result, you'll need to have at least >2 GW actual solar power to equally compare the two.
Which is why I compared 1GW of coal power to 3GW of solar power.
I can’t really imagine how the person who responded to you managed to miss that, it was like the middle 1/5’th of your post. Oh well, I guess it is impossible to write a post well enough that somebody won’t jump in with a correction… right or wrong!
A 3GW solar power plant takes up a lot of land. Around 360km² of land according to my AI, FWIW.
We can live with huge land areas converted to power generation, but more space efficient alternatives will be a big improvement.
40% of US corn acreage is used for something like 10% of gasoline. This is an unfathomable amount of land. Solar yields 20x the amount of energy per acre. On top of that many are finding efficiencies of colocating solar with agricultural activities (agrivoltaics). And there's also replacing agricultural activities on marginal or water stressed land.
Conclusion, land isn't really a constraint in the US.
I don’t have any reason to doubt it, but it seems like a basically easy computation to verify or for the AI to show its work.
Anyway, the area issue seems not too bad. In the US as least, we have places like the Dakotas which we could turn like 70% of into a solar farm and nobody would really notice.
> It costs more to build a 1GW coal power plant than it does to build a 3GW solar power plant (the 3X is capacity factor compensation)
That “3X” figure assumes a high‐insolation region (CF ~25 %). In Central Europe, where solar CF is only ~12 %, you’d need about 5x the PV capacity to equal a 1 GW coal plant’s annual generation. How does scaling up to 5 GW of PV change the cost comparison vs a coal plant?
However, solar caused problems in Spain recently due to its lack of mechanical inertia, which brought their grid down due to frequency instability.
Fusion would use a conventional turbine with boiling water. Is this a better source of mechanical inertia than hydropower or fission?
Is there a better way to solve the problem of frequency instability?
Why is this fact downvoted? This article mentions "synthetic inertia;" what are its drawbacks?
https://www.bloomberg.com/news/articles/2025-05-09/spain-bla...
https://archive.ph/VI32e
Solar caused problems in Spain because it was misconfigured. AC inverters are a fabulous source of power stabilization; many grids choose to install batteries and inverters for grid stabilization.
The article mentions that largish batteries are needed for synthetic inertia, which I am guessing use A/C inverters. Spain appeared to lack sufficient batteries.
Obviously, this configuration of solar and battery banks will work more optimally when they are closer to the equator.
Will different types of power grids be required for areas further away, or is it practical to ship power long distances to far Northern/Southern areas?
Synthetic inertia needs a large DC source. At the time of the outage, solar power was a large DC source.
Nobody knows the cause of the energy outage in Spain, Portugal and France... except the U.S. Energy Secretary Chris Wright, a chill for the oil and fracking industry.
Could you point to the outage conclusion report?
> 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.
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).
There are serious theoretical objections to Helion approach so I am very sceptical to their approach. Stellarators on other hand do not have any known theoretical obstacles and avoid the problem of plasma instabilities.
What are the theoretical problems? Aren't they already achieving fusion with their test reactors, so what's the problem with scaling up and producing net energy?
A 12 year old achieved fusion with a test reactor he built himself: https://www.npr.org/2020/10/09/922065766/tennessee-teen-beco...
OK, and hobby rocketists have nailed a SpaceX style landing too, but so what?
Have you seen the videos of Helion's reactor - hardly a basement project. Sam Altman (OpenAI) also has personally invested hundreds of millions of dollars into Helion, presumably after some due diligence!
IMO Helion should not be taken seriously: https://www.youtube.com/watch?v=3vUPhsFoniw
No 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.
Excellent points.
One wonders if this is why Lockheed-Martin dropped their effort:
https://www.lockheedmartin.com/en-us/products/compact-fusion...
(that page is still up, but news reporting indicates it has been dropped)
> transmission costs are half of your energy bill
Wait, what?
Wikipedia[0] seems to disagree:
> Long-distance transmission (hundreds of kilometers) is cheap and efficient, with costs of US$0.005–0.02 per kWh, compared to annual averaged large producer costs of US$0.01–0.025 per kWh
Do you maybe mean that half electrical energy dissipate between production plant and consummer? But that figure seems quite large compared to what I can find online, and this would not be a problem with "free fusion".
Care to explain?
[0]: https://en.wikipedia.org/wiki/Electric_power_transmission
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 alone was $49.32 or 42% of the bill. I'm not alone in these numbers, but your mileage may vary.
My point is that the infrastructure related to the delivery of energy to a physical location is a non trivial part of an energy bill, and that this part doesn't go away magically because "fusion".
Where I live I pay about $0.09 per kWh for generation and about that much for transmission as well. I think that's what they're referring to, the literal bill they get from their current provider.
Transmission is a really interesting problem that creates all kinds of distortions.
Say a house uses 10,000kWh per year at $0.10/kWH so $1000/year electrcitiy bill. Now say you get a solar system that produces 5,000kWh per year, focused in the summer months (where your power bill tends to be higher anyway). You may even export some of that power back to the grid. Have you cut your power bill in half? No. It's probably down ~20-25%.
Why? Because regardless of how much power you use (within limits) you still need a connection to the power grid and that needs to be maintained. You'll often even see this on the electricity bill: fixed charges like "access charge" per month.
We benefit from being on a connected grid. Your own power generation might be insufficient or need maintenance. It's inefficient if everyone is storing their own power. So it's unclaer what the future of the power grid is. Should there be large grids, small grids or no grid?
There also resilience. Having small to medium local storage increases the stability of the grid.
Renewables and something like Iron-Salt battery containers, would be pretty efficient over all. Easy to roll-out, very safe.
We'll still need some sort of base load somewhere and backup to restart everything obviously. But the big giant power plants (with the huge capital costs, delays and NIMBY headaches) might become less necessary.
> the summer months (where your power bill tends to be higher anyway)
This depends on where you live!
And 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
Problem: the capital & maintenance costs of the grid vary very little with its utilization %.
So if you build loads of wind & solar & battery all over - either (1) you've got to build so much battery capacity, all over, that you'll never need the grid, or (2) you've still got to build the grid to get you through occasional "calm & dark" periods.
Either way, you're looking at vastly higher capital expenses.
You realize this is what people said about solar energy and nuclear energy at one point, right
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.
Nobody is building commercial plants any time soon; it's still in the experimental phase, with new discoveries happening almost every month.
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.
They are building a commercial plant right now, and it will come online in the next 10 years. https://news.mit.edu/2024/commonwealth-fusion-systems-unveil...
Unless I missed something they haven’t even completed their technology demonstrator (planned for 2026). No construction has taken place in 2025.
>And stars solve the confinement problem with gravity and by being really, really large.
Kinda. The main catalyst of stellar fusion is quantum tunneling. Temperature and gravity together are not enough to overcome the Coulomb barrier.
The steam reactor I guess you might be describing is tokamak, which i agree will be a dead end technology.
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!
Agreed.
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.
Yep.
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.
There are a couple of factors in play with any research, including fusion. If there's money to be had for funding then somebody will research it.
But another more nefarious factor is the nexus of fusion energy research and nuclear weapons research [1]. To build and maintain a stockpile of nuclear weapons (specificially thermonuclear weapons) you need appropriate trained nuclear energy physicists.
[1]: https://thebulletin.org/premium/2024-11/the-entanglement-of-...
It 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.
One 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() }
Isn’t that one of the nice things of computers in general not a feature of llm?
The difference is the complexity of the repeated task
Is 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.
Part 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.)
Even 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.
The 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.
Storing fission waste products is a solved problem. You can either reprocess them as is done in France. Or you can store them forever. Neither approach is difficult or poorly understood. We can store an infinite amount of fission waste products in the ocean, underground or in the mantle.
Nuclear waste isn't an engineering problem at all, it's a social problem. Objectively, dropping it all into a deep ocean crevice is utterly safe and effective but you'll never get the ignorant public who go off feelings to buy into it.
Fusion is only better insofar as the public don't yet understand how radioactive the reactor will become, but counting on that ignorance is a bad long term strategy.
> "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.
True. Launch loops are "just" an engineering problem which could be built with known materials but in reality the engineering problems are so huge it's hardly any better than space elevators which call for undiscovered materials.
You also have the associated economic problems; the up-front cost of a launch loop would be so huge that you could never convince anybody to build it instead of using rockets. Fusion has the same problem; even if you can design a fusion power plant that produces net power, it needs to produce net power by a massive margin to have any chance of being economically competitive with fission let alone solar.
And fusion reactors cannot end up like a Chernobyl disaster. That's a huge safety plus and one of the major concerns many countries are phasing out fission reactors.
Safe (!) fission reactors are simple? Ok.
Never mind what's required to deal with the fuel & waste products.
They're a hell of a lot simpler than fusion reactors.
How is that different than the excitement 30 years ago?
TLDR 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.
Is 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.
Is this a variation of the Fleischmann-Pons method?
No, 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.
> 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.
Technically 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-...
True...but without an extremely cheap source of muons (half-life: 2 microseconds), muon-catalyzed fusion will forever be condemned to "in theory, you could..." purgatory.
Ordinary 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.
Can 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?
> 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.
There'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.
> 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?
The 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
Yes. 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".