Getting a significant energy return from tokamak-based nuclear fusion reactors depends for a large part on plasma density, but increasing said density is tricky, as beyond a certain point the plasma transitions back from the much more stable high-confinement mode (H-mode) into L-mode. Recently Chinese researchers have reported that they managed to increase the plasma density in the EAST tokamak beyond the previously known upper Greenwald Density Limit (GDL), as this phenomenon is known.
We covered these details with nuclear fusion reactors in great detail last year, noting the importance of plasma edge stability, as this causes tokamak wall erosion as well as loss of energy. The EAST tokamak (HT-7U) is a superconducting tokamak that was upgraded and resumed operations in 2014, featuring a 1.85 meter major radius and 7.5 MW heating power. As a tokamak the issue of plasma and edge stability are major concerns, even in H-mode, requiring constant intervention.
In the recent EAST findings, the real news appears to be more confirmation of the plasma-wall self-organization (PWSO) theory that postulates that one of the causes behind plasma wall (edge) instability is due to the interaction between plasma dynamics and wall conditions through impurity radiation. By using electron cyclotron resonance heating (ECRH) and/or pre-filled gas pressure this impurity level might be reduced, enabling higher densities and thus exceeding the empirical GDL.
What’s interesting is that the paper also compares EAST and the Wendelstein 7-X (W7-X) stellarator, making the argument that tokamaks can operate in a way that’s more similar to stellarators, though W7-X is of course gifted with the same advantages as every current stellarator, such as no real GDL or the necessity of dealing with H- or L-mode. It’s therefore not surprising that W7-X is so far the most efficient fusion reactor to achieve the highest triple product.
Thanks ChatGPT, still I don’t have a clue what are H-mode and L-modes though.
Anyway, I’m sure that in 10 to 30 years from now we’ll have cheap fusion energry, as promised in early 1990s pop sci articles.
always ten years away…
Looking at the rate at which news of new achievements comes out these days, it does look like it 10 years is a reasonable time scale for the technology to be viable.
You forgot /s bro
(;
Wait for replication…
The number of examples of “Wait for replication” are enourmous.
Its always exciting to read about any pushing past any limit. Its usually an error, its sometimes dishonesty, its sometimes a dishonestly hiding behind an “error”, then there are the few cases (the few part is what makes us cynical) where replication is easy, and it becomes part of the body of knowledge of science.
So in short, wait for replication.
The second link in this article, the one that says “we covered these details”, covers those details.
I do love me some Free Energy.
Fission was supposed to be free. See how that worked out.
Who promised you it would be free? Pretty silly to expect that to be true.
It was expected to be “too cheap to meter”, but we never deployed enough reactors for that. That doesn’t cover infra and delivery costs of course.
Anti-nuclear activists who take the words of a single guy, who once said it could be “too cheap to meter”, and use that to argue that the entire industry is lying.
But that’s not even saying it would be free – just cheap enough that you don’t have to bother metering it. That is actually true. I’ve lived in apartments where the electricity was not metered and you just paid a flat fee, and it just so happened to come from a nuclear power plant – so it is true that fission power can be too cheap to meter.
The landlord paid the metered bill.
Divided the bill by half the number of apartments and wrapped that in the rent.
Meters cost money and don’t make a ROI for landlords, especially compared to just charging everybody double the average cost.
To be fair, that ‘single guy’ was an industry spokesman and advocate.
It’s not like using the words of some rando hippie to impeach climate alarmism.
It’s like using the words of Al Gore.
True, and irrelevant to the point.
That is the point. If they had put a meter on every apartment, they couldn’t have justified charging as much because people would know how much they’re actually using and paying. The electricity was too cheap to meter.
And it was cheap. Roughly half of what I’m paying now that my contract says solar and wind power. They’re not offering the nuclear option anymore.
Also true, but the actual words were “It is not too much to expect that our children will enjoy in their homes electrical energy too cheap to meter”, and then the NYT switched it into “It will be too cheap for our children to meter”.
Expectation is hope, not certainty. Dropping that one word distorted the statement into a promise.
Yeah, the idea was that once we stop burning enormous volumes of fuel, the marginal cost of energy will be so low that it’s pointless to meter it – you would presumably just pay a flat fee for the “size” of your electrical supply.
It was, and is, 100% true that the cost of running power infrastructure other than fossil fuel plants does not depend on how much power is used. It should be billed like broadband, instead of like old-timey phone service. It’s not nuclear that has failed on this point (or hydro or solar or wind) – the failure is that we still have a crappy system built for coal and gas generators’ business model.
I still see little explanation of where all the tritium needed to fuel these things is supposed to come from.
The Tri Alpha Energy fusion reactor approach is more interesting for actual energy generation as it isn’t a tokomak, uses Boron and hydrogen as fuel, and doesn’t produce any nuclear waste.
I’d love to see an article on that machine in hackaday.
I’ve heard about TAE’s too, but this tidbit about describes what probably happens next: “…TAE Technologies, a private company, has received significant funding and is merging with Trump Media…”. I am afraid it still will be 25+ years away for the average Sam :[
Except that to reach any useful efficiency, the plasma needs to get 2x hotter than for Tritium/Hydrogen based fusion reactor, which is already a challenge for hydrogen reactor and an currently inaccessible technical step for boron.
We’re sitting on top of a giant fission reactor and there’s a giant fusion reactor in the sky and both will last longer than we will.