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.<p>> 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.<p>Simply: this is not just some kind of unsupervised ML black-box magic. There is a formal mathematical solution to <i>something</i>, but it has a certain gap, namely precisely what quantity is conserved and how to calculate it.<p>> 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.<p>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.<p>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 <i>g</i> 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.
I remain skeptical that fusion will ever be a commercially viable energy source. I'd love to be wrong.<p>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.<p>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.<p>And stars solve the confinement problem with gravity and by being really, really large.<p>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.<p>And all of this to heat water to create steam and turn a turbine.<p>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).
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.
> high-energy electrons that can punch a hole in the surrounding walls.<p>What does it mean? Beta radiation can cause structural damage? Is it really a problem?
TLDR for the paper and article:<p>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.
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?