This is a great update! I hope the authors continue publishing new versions of their plots as the community builds up towards facility gain. It's hard to keep track of all the experiments going on around the world, and normalizing all the results into the same plot space (even wrt. just triple product / Lawson criteria) is actually tricky for various reasons and takes dedicated time.
Somewhat relevant, folks here might also be interested in a whitepaper we recently put up on arXiv that describes what we are doing at Pacific Fusion: https://arxiv.org/abs/2504.10680
Section 1 in particular gives some extra high-level context that might be useful to have while reading Sam and Scott's update, and the rest of the paper should also be a good introduction to the various subsystems that make up a high-yield fusion demonstration system (albeit focused on pulser-driven inertial fusion).
CGMthrowaway · 1h ago
I heard that NIF was never intended to be a power plant, not even a prototype of one. It's primarily a nuclear weapon research program. For a power plant you would need much more efficient lasers, you would need a much larger gain in the capsules, you would need lasers that can do many shots per second, some automated reloading system for the capsules, and you would need a heat to electricity conversion system around the fusion spot (which will have an efficiency of ~1/3 or so).
Any truth to that?
DennisP · 1h ago
It's an experimental facility. Yes, a power plant would need much more efficient lasers, but NIF's lasers date back to the 1990s, equivalent modern lasers are about 40X more efficient, and for an experiment it's easy enough to do a multiplication to see what the net result would have been with modern lasers.
Modern lasers can also repeat shots much more quickly. Power gain on the capsules appears to scale faster than linear with the input power, so getting to practical gain might not be as far off as it appears at first glance.
These are some of the reasons that various fusion startups are pursuing laser fusion for power plants.
UltraSane · 32m ago
It was never intended to be a power plant but it was hoped that it would achieve a net gain fusion reaction for the first time. This turned out to be a lot harder than expected.
actinium226 · 3h ago
Why is the last plot basically empty between 2000 and 2020? I understand that NIF was probably being built during that time, but were there no significant tokamak experiments in that time?
sam · 2h ago
Author here - some other posters have touched on the reasons. Much of the focus on high performing tokamaks shifted to ITER in recent decades, though this is now changing as fusion companies are utilizing new enabling technologies like high-temperature superconductors.
Additionally the final plot of scientific gain (Qsci) vs time effectively requires the use of deuterium-tritium fuel to generate the amounts of fusion energy needed for an appreciable level of Qsci. The number of tokamak experiments utilizing deuterium tritium is small.
Companies like Commonwealth Fusion Systems are an example of those utilizing high-temperature superconductors which did not exist commercially when ITER was being designed.
tomnicholas1 · 3h ago
Presumably because everyone in MCF has been waiting for ITER for decades, and JET is being decommissioned after a last gasp. Every other tokamak is considerably smaller (or similar size like DIII-D or JT-60SA).
Much of the interesting tokamak engineering ideas were on small (so low-power) machines or just concepts using high-temperature superconducting magnets.
moffkalast · 2h ago
It's hard to believe that after all of this time, ITER is still almost a decade away from first plasma.
There's the common joke that fusion is always 30 years away, but now with the help of ITER, it's always 10 years away instead.
tomnicholas1 · 2h ago
The really depressing part is if you plot rate of new delays against real time elapsed, the projected finishing date is even further.
This is why much of the fusion research community feel disillusioned with ITER, and so are more interested in these smaller (and supposedly more "agile") machines with high-temperature superconductors instead.
cyberax · 2h ago
The ITER is in development hell.
Mind you, it's not useless! It produced a TON of very useful fusion research: neutral beam injectors, divertors, construction techniques for complex vacuum chambers, etc. At this point, I don't think it's going to be complete by the time its competitors arrive.
One spinoff of this is high-temperature superconductor research that is now close to producing actually usable high-TC flexible tapes. This might make it possible to have cheaper MRI and NMR machines, and probably a lot of other innovations.
pfdietz · 15m ago
ITER doesn't use high temperature superconductors. It uses niobium-tin and niobium-titanium low temperature superconductors in its magnets.
ITER has been criticized since early days as a dead end, for example because of its enormous size relative to the power produced. A commercial follow-on would not be much better by that power density metric, certainly far worse than a fission reactor.
There is basically no chance than a fusion reactor operating in a regime similar to ITER could ever become an economical energy source. And this has been known since the beginning.
I call things like ITER "Blazing Saddles" projects. "We have to protect our phony baloney jobs, gentlemen!"
7thaccount · 3h ago
I imagine a 20 year gap isn't too crazy for a field like fusion, but you've made me curious as well.
UltraSane · 30m ago
The money being spent on fusion should be being spent building next generation fission power plants and liquid salt reactors.
sneak · 22m ago
What's the ROI on that versus current and near-term expected pricing for solar+storage? Is fission getting safer/cheaper at the same rate that solar and batteries are?
UltraSane · 18m ago
Solar + days of storage is far more expensive than fission. Grid scale batteries like California has spent billions on only have 4 hour capacity. Fission can also supply heat that is needed for many industrial processes and chemical reactions.
Calwestjobs · 14m ago
it is not in most us areas. only problem is area covered, NOT price of technology. solar with 12 hour of storage was lower price than fission before covid hit. TCO, not one time nonsense.
fission has relatively low temperature heat, i.e. no metal reduction, no "concrete" production. you can cook hot dogs with it. also electrification of heat can provide lower losses stemming from regulation or lack thereof. with electricity you can say i need 293.5 degrees C and you just type it somewhere and you get it for almost free (regulation).
arghandugh · 2h ago
Maybe someday we’ll finally achieve the ultimate dream: an extremely expensive nuclear power plant that needs vast amounts of coolant water and leaves radioactive waste behind.
thinkingtoilet · 46m ago
If the alternative option is a coal power plant, sign me up!
arghandugh · 35m ago
You will not live long enough to see commercial fusion power, and your children will not live long enough to see a complete end to thermal coal.
sneak · 20m ago
Tossing out your opinions as fact doesn't do much to win hearts and minds, or educate us bystanders to the basis for your point of view.
Presumably your comment is either to persuade or to inform; it does neither. I'm very curious about this field and its future, do you care to try again?
fecal_henge · 1h ago
I see you're in the coolant business
arghandugh · 34m ago
I am in the business of baiting militantly uninformed enthusiasts who form the foundation of the multigenerational grift that is Commercial Fusion Power.
BizarroLand · 1h ago
Real talk, the point is not that whatever system is first past the post for fusion becomes the gold standard and fills the planet.
The issue right now is cracking the code. Once that is done, performance gains and miniaturization can take place.
Fusion can work on lots of things. Its possible that a fusion system the size of a car could be made within 25 years of the code being cracked that would power a house, or the size of a small building that could power a city block.
The waste product of hydrogen fusion is helium, a valuable resource that will always be in high demand, and it will not be radioactive.
And yes, it will need coolant as with hot fusion the system uses the heat to turn a turbine, but that coolant isn't fancy, it's just water.
Fusion has the potential to solve more problems than it causes by every metric as long as it is doable without extremely limited source materials, and this is what these big expensive reactors are trying to solve.
arghandugh · 36m ago
You’ve disputed nothing I’ve said and unless a dramatically higher temperature fusion reaction that does not generate a neutron flux is achieved, it will generate radioactive waste as a matter of factual physics. Thank you though!
Somewhat relevant, folks here might also be interested in a whitepaper we recently put up on arXiv that describes what we are doing at Pacific Fusion: https://arxiv.org/abs/2504.10680
Section 1 in particular gives some extra high-level context that might be useful to have while reading Sam and Scott's update, and the rest of the paper should also be a good introduction to the various subsystems that make up a high-yield fusion demonstration system (albeit focused on pulser-driven inertial fusion).
Any truth to that?
Modern lasers can also repeat shots much more quickly. Power gain on the capsules appears to scale faster than linear with the input power, so getting to practical gain might not be as far off as it appears at first glance.
These are some of the reasons that various fusion startups are pursuing laser fusion for power plants.
Additionally the final plot of scientific gain (Qsci) vs time effectively requires the use of deuterium-tritium fuel to generate the amounts of fusion energy needed for an appreciable level of Qsci. The number of tokamak experiments utilizing deuterium tritium is small.
Much of the interesting tokamak engineering ideas were on small (so low-power) machines or just concepts using high-temperature superconducting magnets.
There's the common joke that fusion is always 30 years away, but now with the help of ITER, it's always 10 years away instead.
This is why much of the fusion research community feel disillusioned with ITER, and so are more interested in these smaller (and supposedly more "agile") machines with high-temperature superconductors instead.
Mind you, it's not useless! It produced a TON of very useful fusion research: neutral beam injectors, divertors, construction techniques for complex vacuum chambers, etc. At this point, I don't think it's going to be complete by the time its competitors arrive.
One spinoff of this is high-temperature superconductor research that is now close to producing actually usable high-TC flexible tapes. This might make it possible to have cheaper MRI and NMR machines, and probably a lot of other innovations.
ITER has been criticized since early days as a dead end, for example because of its enormous size relative to the power produced. A commercial follow-on would not be much better by that power density metric, certainly far worse than a fission reactor.
There is basically no chance than a fusion reactor operating in a regime similar to ITER could ever become an economical energy source. And this has been known since the beginning.
I call things like ITER "Blazing Saddles" projects. "We have to protect our phony baloney jobs, gentlemen!"
fission has relatively low temperature heat, i.e. no metal reduction, no "concrete" production. you can cook hot dogs with it. also electrification of heat can provide lower losses stemming from regulation or lack thereof. with electricity you can say i need 293.5 degrees C and you just type it somewhere and you get it for almost free (regulation).
Presumably your comment is either to persuade or to inform; it does neither. I'm very curious about this field and its future, do you care to try again?
The issue right now is cracking the code. Once that is done, performance gains and miniaturization can take place.
Fusion can work on lots of things. Its possible that a fusion system the size of a car could be made within 25 years of the code being cracked that would power a house, or the size of a small building that could power a city block.
The waste product of hydrogen fusion is helium, a valuable resource that will always be in high demand, and it will not be radioactive.
And yes, it will need coolant as with hot fusion the system uses the heat to turn a turbine, but that coolant isn't fancy, it's just water.
Fusion has the potential to solve more problems than it causes by every metric as long as it is doable without extremely limited source materials, and this is what these big expensive reactors are trying to solve.