Progress toward fusion energy gain as measured against the Lawson criteria
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Progress toward fusion energy gain as measured against the Lawson criteria
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Re: Progress toward fusion energy gain as measured against the Lawson criteria
#2Why 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?
Re: Progress toward fusion energy gain as measured against the Lawson criteria
#3Why 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?
I imagine a 20 year gap isn't too crazy for a field like fusion, but you've made me curious as well.
Re: Progress toward fusion energy gain as measured against the Lawson criteria
#4Why 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?
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.
Re: Progress toward fusion energy gain as measured against the Lawson criteria
#5This 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).
Re: Progress toward fusion energy gain as measured against the Lawson criteria
#6Why 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?
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.
Re: Progress toward fusion energy gain as measured against the Lawson criteria
#7[flagged]
Re: Progress toward fusion energy gain as measured against the Lawson criteria
#8Why 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?
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.
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.
Re: Progress toward fusion energy gain as measured against the Lawson criteria
#9Why 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?
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.
Re: Progress toward fusion energy gain as measured against the Lawson criteria
#10Earlier quoted context omitted.
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.
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.
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.