Essay by Eric Worrall
No doubt nuclear fusion is just 20 years away, just like last time…
New Record: Reactor Crosses ‘Crucial Milestone’ in Achieving Nuclear Fusion
TECH 22 February 2025
French scientists on Tuesday announced that they had reached a “crucial milestone” in the long road towards nuclear fusion by managing to maintain raging-hot plasma for a record 22 minutes.
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The WEST tokamak machine in southern France managed to maintain plasma for 1,337 seconds on February 12, France’s Atomic Energy Commission (CEA) said in a statement.
This “smashed” the previous record set in China last month by 25 percent, said the CEA, which runs the tokamak machine.
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The goal is to prepare the ground for the International Thermonuclear Experimental Reactor (ITER) being built in France, she added.
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It had been scheduled to go online this year, but repeated setbacks, delays and spiralling costs have postponed operations until at least 2033.
Read more: https://www.sciencealert.com/new-record-reactor-crosses-crucial-milestone-in-achieving-nuclear-fusion
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What is missing from this French announcement is how long that plasma would have to burn to produce a true return on energy.
The big problem with fusion plasmas, aside from stability, is something heated to millions of degrees really wants to radiate its heat. ITER is an attempt to keep the plasma hot by making the plasma really big – taking advantage of the improved surface area to volume ratio of larger objects. Heat generation is governed by volume, while heat radiation is governed by temperature and surface area.
There is also a rarely mentioned problem that the radiation from fusion plasmas tends to destroy its containment vessel. The radiation is so intense a sustained plasma, even if contained, would cause mechanical damage to the containment vessel, leading to rapid structural failure. Solving that may require exotic self healing ceramic alloys or technologies not yet invented.
One government at least is not allowing such obstacles to dent their optimism. They are so confident, in 2023 they started construction on the first commercial British fusion reactor, promising local voters the fusion reactor would be providing jobs and economic prosperity by 2040.
I’m sure construction of a commercial nuclear fusion reactor isn’t just a cynical ploy to win votes from people politicians have no intention of helping. I mean, British politicians wouldn’t do that, would they?
Update (EW): I’m not a total pessimist when it comes to nuclear fusion, because a viable path to producing electricity from nuclear fusion has already been discovered and tested.
https://en.wikipedia.org/wiki/Project_Gnome_(nuclear_test)
Project Gnome was an awful way of solving the problem, about as far from commercially viable and politically acceptable as you can get. But where one viable path exists, other better paths likely also exist, we just need to figure them out.
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Another factor is that this plasma was a long way short of the temperature and density required for fusion, making containment much easier. Still a way to go in research. China now probably in the lead.
In 1997 JET set the record for the closest approach to scientific breakeven, reaching Q = 0.67 in 1997, producing 16 MW of fusion power while injecting 24 MW of thermal power to heat the fuel.
Where do these stand on the Lawson criterion?
You have made a strong argument that the pessimists are wrong. We appear to be on the threshold of stable, confined ignition, unlike 20 years ago.
Fluorescent and neon lights are both plasmas. Some have even broken the 22 minute French record.
55 years ago I did a graduate project at a plasma physics lab in a team working on hot plasmas in a pinched arc discharge. There was a big celebration when the machinery managed a million degrees for almost one second. Not only that, there were neutrons measured which meant that actually a few fusions had taken place.
20 minutes at 100 million degrees is big progress, but of course it takes time. Why anyone would think that mastering the workings of the Sun itself could be done just like that is somewhat beyond me. It will take many decades but in the end we will get there.
We don’t need 100 million degrees to boil water.
If I remember correctly, the original estimate during the time of Project Sherwood, was 40 years, not 20. In the beginning, there was a lot of preliminary work to test the various kinds of potential confinement designs. That work was essentially completed years ago.
The concern about the container walls has always been there, despite the designs attempting to avoid having the plasma touch the walls. If the heat can be conducted away as fast as it arrives, then the heat alone is not a problem. In fact, for most designs, heat is essential to create steam to drive a turbine. A recent upgrade from ceramic to tungsten seems to have solved the problem of plasma erosion and improved heat conduction.
Moving from confinement for milliseconds to thousands of seconds (6 orders of magnitude) is not a trivial accomplishment. It would not be prudent to bet that progress will continue to be as slow as the preliminary investigations were, with low funding levels and little incentive to solve the problem before running out of economic fossil fuels. Ignition has been demonstrated and break even for the energy to power the lasers at Livermore has been reported, albeit the apparent efficiency was inflated by ignoring the energy necessary to construct the facility and manufacture the pellets.
It makes for a good laugh among those who are all-knowing to ridicule the progress. But, remember what the Manhattan Project accomplished when money was not a concern and some of the best minds were tasked with solving a problem with existential consequences. Personally, I think that the progress has been reasonable considering the low level of funding and low priority. It is, hopefully, avoiding the same mistake that solar farms and wind turbines have been, pushing something into use, with tax subsidies, before the technologies were mature enough to compete on its own.
Can neutrons produced by fusion be used to recharge fuel spent in fission?
Fusion requires a rare isotope…it would have to be a huge complex machine that would put millions in the dark when it broke…Dick Nixon shut down the test thorium reactor in favor of a breeder reactor in Callyfornia….it was a $5 billion project for his home state ….where is it today? Where is that elusive breeder? Imagine 1/2 the planet being powered by uranium…..the remaining supply would be like 50 years…..thorium would provide 2 centuries.
We know fission works, let’s get busy building what we know works. When better stuff comes our way we can start building them.
From the above article:
“Heat generation is governed by volume, while heat radiation is governed by temperature and surface area.”
That statement is generally NOT TRUE for plasmas at the low densities used in Tokamaks or other magnetic-confinement fusion devices and in commercial inertial electrostatic confinement, IEC, devices that can positively produce nuclear fusion for hours upon hours . . . as commonly used for portable neutron sources.
Low density plasmas do not have a distinguishable “surface” that radiates. Rather the whole volume of the plasma radiates through the mostly-radiation-transparent volume. The best natural example of this is the low density plasma comprising the Sun’s corona, at a “temperature” of 1-2 million K and thickness of millions of kilometers, but which is so transparent that astronomers can easily view details of sunspots on the “surface” of the Sun’s photosphere.
The other thing missing from the extracted announcement is how they achieved their 22 minute record… They injected 2MW of heat into the process to help stabilise the plasma. I’m not a physicist, so I can’t explain or understand the workings of this, but I can, with absolute certainty, say that all the energy you add requires a bigger payback for net gain.
So what did they prove here? With current technology and this approach, fusion is even less practical as a source of power generation than we thought.
interesting but I’ve been convinced by Helion that sustaining the reaction is the wrong approach
keep an eye on their pulsed Polaris reactor, should produce net electric power via an inductively recovered D-He3 reaction by this summer
because there are no steam turbines involved, this tech could potentially be cheaper than even hydropower
and it could be on the grid by 2028
I’ll bet you $1000 that it will NOT!
Love the terms “should produce”, “could potentially be” and “could be”. I’ve seen them an uncountable number of times previously.
And if they can time it so that each fusion takes place at 16.67 millisecond intervals, it solves the problem of synchronization with existing generators.
The Mr Fusion has already been invented. It is called a Fusor. They are dead simple in comparison, needing only a few tens of thousands of volts to achieve fusion using tech not much different than an old style CRT. Solve the ion beam focus problem and every household could have one.
Dead simple, but has been researched for use in a commercially viable power plant since the 1960’s, akin to the rate of “development” of Tokamak power technology.
“Philo Farnsworth was the father of the true fusor concept and the first fusor fusion occurred in the early 1960’s at the ITT labs in Fort Wayne, Indiana.”
— https://fusor.net/board/viewtopic.php?t=7580
In all fairness, however, inertial electrostatic confinement (IEC), the general scientific term covering fusor physics, has been developed to the point of being used in commercially-available, portable devices for continuously producing neutrons.
— https://asmedigitalcollection.asme.org/gasturbinespower/article-abstract/133/12/124502/466199/Cylindrical-IEC-Fusion-Neutron-Source-for-Broad
— https://www-pub.iaea.org/MTCD/Publications/PDF/P1535_web.pdf
Fission reactors are inherently simple because sold fuel density leads to high reaction rates and thus achieve break even easily.
Fusion reactors with low density fuel in a vacuum are fighting the vacuum while trying to achieve high density and temperature. This is proving to be a non trivial problem.
See my above comment to ferdberple re: IEC devices which use a low density plasma yet still achieve continuous fusion.
So, my clarification to your comment is: The non-trivial problem is producing a fusion device that can exceed “breakeven” in terms of usable output power versus required total input power.