5 ms·

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 tokam

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?

7thaccount 1y ago
I imagine a 20 year gap isn't too crazy for a field like fusion, but you've made me curious as well.
tomnicholas1 1y 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 1y 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 1y 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 1y 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 1y 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!"
  - robocat 1y ago
    > phony baloney jobs I looked hopefully at the HR report https://www.iter.org/sites/default/files/media/2024-11/rh-2023-okweb.pdf https://www.iter.org/sites/default/files/media/2024-11/rh-20... to see if there was some sort of job categorisation - scientist, engineer, management. Disappointingly scant. PhD heavy. Perhaps the budget would be more insightful. "Execution not ideas" is a common refrain for startups. I wonder how much of the real engineering for ITER is occurring in subcontractors?
    - whatshisface 1y ago
      I wonder why a physics research facility would be PhD-heavy. ;-)
  - cyberax 1y ago
    > ITER doesn't use high temperature superconductors. It does, for high-current buses that interface with regular resistive power distribution. They are also planned for some auxiliary components (like the neutral beam injectors). > ITER has been criticized since early days as a dead end, for example because of its enormous size relative to the power produced. ITER is NOT designed for power generation. It's essentially a lab experiment to see how plasma behaves in magnetic confinement and test various technologies. That's why ITER was designed with a very conservative approach to reduce the technical risk. We don't need it to be compact, this can come later. We just need it to work. And yes, it is necessary. Plasma behavior can't be simulated numerically or analytically. It always provides surprises, sometimes even good ones: https://en.wikipedia.org/wiki/High-confinement_mode https://en.wikipedia.org/wiki/High-confinement_mode
sam 1y 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.
- CGMthrowaway 1y ago
  If ITER is where it's at why are we building commercial scale tokamak? https://en.wikipedia.org/wiki/Commonwealth_Fusion_Systems https://en.wikipedia.org/wiki/Commonwealth_Fusion_Systems
  - sam 1y ago
    Companies like Commonwealth Fusion Systems are an example of those utilizing high-temperature superconductors which did not exist commercially when ITER was being designed.
    - twothreeone 1y ago
      ITER uses HTSs, just not for the coils: > The design operating current of the feeders is 68Ka. High temperature superconductor (HTS) current leads transmit the high-power currents from the room-temperature power supplies to the low-temperature superconducting coils 4K (-269°C) with minimum heat load. Source: https://www.iter.org/machine/magnets https://www.iter.org/machine/magnets
      - stshank 1y ago
        HTS current feeds are a good idea (we also use them at CFS, my employer: https://www.instagram.com/p/DJXInDUuDAK/ https://www.instagram.com/p/DJXInDUuDAK/). It's HTS in the coils (electromagnets) that enables higher magnetic fields and thus a more compact tokamak.

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?

7thaccount 1y ago

I imagine a 20 year gap isn't too crazy for a field like fusion, but you've made me curious as well.

tomnicholas1 1y 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 1y 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 1y 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 1y 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 1y 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!"
- robocat 1y ago
  > phony baloney jobs I looked hopefully at the HR report https://www.iter.org/sites/default/files/media/2024-11/rh-2023-okweb.pdf https://www.iter.org/sites/default/files/media/2024-11/rh-20... to see if there was some sort of job categorisation - scientist, engineer, management. Disappointingly scant. PhD heavy. Perhaps the budget would be more insightful. "Execution not ideas" is a common refrain for startups. I wonder how much of the real engineering for ITER is occurring in subcontractors?
  - whatshisface 1y ago
    I wonder why a physics research facility would be PhD-heavy. ;-)
- cyberax 1y ago
  > ITER doesn't use high temperature superconductors. It does, for high-current buses that interface with regular resistive power distribution. They are also planned for some auxiliary components (like the neutral beam injectors). > ITER has been criticized since early days as a dead end, for example because of its enormous size relative to the power produced. ITER is NOT designed for power generation. It's essentially a lab experiment to see how plasma behaves in magnetic confinement and test various technologies. That's why ITER was designed with a very conservative approach to reduce the technical risk. We don't need it to be compact, this can come later. We just need it to work. And yes, it is necessary. Plasma behavior can't be simulated numerically or analytically. It always provides surprises, sometimes even good ones: https://en.wikipedia.org/wiki/High-confinement_mode https://en.wikipedia.org/wiki/High-confinement_mode

sam 1y 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.

CGMthrowaway 1y ago
If ITER is where it's at why are we building commercial scale tokamak? https://en.wikipedia.org/wiki/Commonwealth_Fusion_Systems https://en.wikipedia.org/wiki/Commonwealth_Fusion_Systems
- sam 1y ago
  Companies like Commonwealth Fusion Systems are an example of those utilizing high-temperature superconductors which did not exist commercially when ITER was being designed.
  - twothreeone 1y ago
    ITER uses HTSs, just not for the coils: > The design operating current of the feeders is 68Ka. High temperature superconductor (HTS) current leads transmit the high-power currents from the room-temperature power supplies to the low-temperature superconducting coils 4K (-269°C) with minimum heat load. Source: https://www.iter.org/machine/magnets https://www.iter.org/machine/magnets
    - stshank 1y ago
      HTS current feeds are a good idea (we also use them at CFS, my employer: https://www.instagram.com/p/DJXInDUuDAK/ https://www.instagram.com/p/DJXInDUuDAK/). It's HTS in the coils (electromagnets) that enables higher magnetic fields and thus a more compact tokamak.