16 HN users recommended this lecture13 months2017–2023score 15
Years with an HN recommendation, 2007–2026
Recommended again and again as the best accessible overview of fusion physics, useful for judging fusion announcements and understanding why high-temperature superconducting magnets matter.
Zach Hartwig of MIT introduces the key concepts of magnetic fusion energy and the state of fusion research. He then presents MIT's proposed pathway of using high-field superconducting magnets to build smaller, cheaper tokamaks on a climate-relevant timescale.
“This has been by far the most informative source on Fusion I've seen and gives a clear picture on how to evaluate claims like this.” (HN, 2022)
This talk by Zach Hartwig from IAP 2017 "MIT's Pathway to Fusion Energy" is fantastic. Hartwig is an assistant professor in the Nuclear Science & Engineering department at MIT. He presents a straightforward overview of the basic science involved as well as the most promising technologies today. [this video]
Straightforward overview of fusion science and most promising technologies.
As there seems to be quite a lot of confusion in this thread about what this is, here's an excellent video giving an overview of the state of the art in fusion energy research that is understandable by a lay audience: [this video] (somebody posted that video on another recent HN fusion thread)
Excellent lay-accessible overview of state of the art fusion research.
My layman's understanding is that recently available (~last 5 years) industrial scale processes to produce rebco tape[1] is the specific advance in superconductor tech that's specifically enabling higher tesla magnetic field strengths from significantly smaller and lighter and easier to manage magnets, so you can get a system that's "powerful enough" to run net posititve at a size that's small enough to be built by a few universities rather than a few dozen nations (i.e. ITER), so the complexity of the engineering project drops from "unimaginable" to "just very high". 1 - [link] 2 - really great talk from a few years ago about this from MIT's Plasma Science Fusion Centre: [this video] (really, if you like this stuff, give the talk a watch. It's great.)
Great talk on high-field magnets making compact fusion feasible.
This has been by far the most informative source on Fusion I've seen and gives a clear picture on how to evaluate claims like this. MIT's Pathway to Fusion Energy (IAP 2017) - Zach Hartwig [this video]
Most informative fusion source for evaluating breakthrough claims.
Simple: people in the know realize that this technique still needs a bunch of development. This is a good talk about the various variables you need to demonstrate in fusion: [this video]
> Scale is everything for fusion (plasma). No. Q is everything in fusion. Scale is one way to improve Q in a Tokamak. The problem with improving Q by increasing scale is that it makes the reactors uneconomical. A reactor the size of ITER cannot ever be economically viable, even was capable of producing massive amounts of electricity. Luckily, scaling up is not the only way to increase Q. The better way is to use more powerful magnetic fields. Put more eloquently than I can: [this video]
Explains improving Q with stronger magnets rather than scale.
Agreed — the problem is that, from an energy perspective, it "doesn't break even". Zach Hartwig of MIT has an excellent video [0] of how to evaluate announcements of nuclear fusion advances. The big problem is breaking even. There are other problem, too: plasma containment, etc. [0] [this video]
How to evaluate fusion announcements; breaking even is the big problem.
There are a number of interesting companies looking at fusion. High Temperature Superconductors change what you can do for Tokomaks. In the US Commonwealth Fusion Systems are exploring these paths: [link] In the UK Tokomak energy are exploring ideas as well: [link] This video explains why high temperature super conductors can enhance fusion's prospects: [this video]
There's a good talk here about why ITER is so large: [this video] The idea is essentially that to get the parameters needed to make net energy with tokamaks, you need either very strong magnets or a large device. At the time of ITER's design, they used the strongest magnets they could find and then made the thing big enough to get the energy gain they wanted. The speaker of this talk argues that it's size that stalled progress in tokamaks, since they'd become so big that building them became a massive, multinational project.
There's some discussion about this in this[1] presentation which also mentions the SPARC reactor. My main takeaway is basically yes, high-temp superconductors got "mainstream" very quickly. I'd recommend watching the whole thing, I found it quite interesting. [1]: [this video]
Covers high-temperature superconductors and the SPARC reactor.
As a very much non-nuclear engineer, I found this video [1] explaining different fuels, size, magnetic field strength, and the orders of magnitude physics and engineering that goes into current fusion efforts. Curious where Helion would put themselves on the nτE vs ion temperature plot he uses to evaluate how feasible a technology is. [1] [this video] [2] [link]
Explains fuels, size, magnetic field strength and orders of magnitude in fusion.
Small tokamaks are what I think are potentially viable, a la Commonwealth Fusion Systems. Here's a good talk that I think addresses the physics vs engineering approaches to fusion. [this video]
Addresses physics versus engineering approaches to fusion.
Your comment makes it sound like you don't understand the physics of it at all. What does Uranium have to do with this? What does "performance of uranium" means? What do you think will happen when you bombard it with "radiation"? What kind of "radiation"? Uranium is most commonly used in fission devices, not fusion ones. Fusing Uranium would absorb energy, not liberate energy, this is why we split it. [link] For heating, you'd be better off using a heat pump. Or I guess you could take some radioactive material and shield it. Or even a breeder reactor, but that's fission. I do not want to come across as disrespectful, but what you're saying sounds like alchemy, or the kind of "science" they show in superhero movies. I could understand using a layer of metal to produce x-rays, and concentrate these to heat a sample (a bit similar to H-bombs, BTW), but I am not a nuclear physicist either. Real physicists have thought about this much more than we did, and if there was a simple pathway to practical fusion, we'd know about it by now. I think you underestimate the complexity of all this (kind of a "Dunning-Kruger" effect), go watch the "MIT's pathway to fusion[1]" videos for an introduction to the problem and modern approaches :) [1]: [this video]
Introduction to fusion problems and modern approaches.
You might allowed to be much more optimistic. A 50% increase could be much much more significant depending on the parameter optimised. Tokamak magnetic field strength for example has a factor ^4 effect towards net energy. Have a look at [this video] , as previously discussed here: [link] .
Shows magnetic field strength strongly affects net energy.
My first thought was that maybe this would lower the cost of particle accelerators like the LHC, due to more mass production of superconducting magnets. The other consideration is that apparently we now have much more powerful, higher temperature superconductors, at least the talk about MIT's current fusion project says so. [this video] Not sure if they are cheaper, but since there would be less bulk and no need for liquid helium, that would be my guess.
Notes MIT fusion work uses higher-temperature superconductors.
At this point I've got a lot more hope in the MIT/Commonwealth Fusion Systems approach with REBCO magnets: [this video] At this point it looks like ITER is hampered by it's relatively old supeconductor technology (ultra low temp/moderate field strength traditional magnets vs high temp/high field REBCO magnets).
Supports hope in MIT/CFS high-temperature magnet approach.
Someone below mentioned the following link, in which they do a sharp comparison of fusion technologies. I am by no means an expert, but after watching that link, it appears to me that such solutions are probably unproven science: it took over 50 years to get anywhere near a Q-factor of 1 (energy in = energy out), with hundreds of technologies screened, tested and scrapped. [this video]
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