11 ms·

The simple answer is that the surface only goes up a factor of 4 if you increase the radius by a factor of 2, but the volume goes up by a factor of 8. So the ra

The simple answer is that the surface only goes up a factor of 4 if you increase the radius by a factor of 2, but the volume goes up by a factor of 8. So the ratio of (energy containing) volume to surface (where energy get's lost) if getting better with increasing size. There is of course much more complicated answers, all the way up to full-device simulations using gyrokinetic codes like Gene or Gkeyll that take millions of core hours and predict that ITER will work (and that predict performance of existing devices correctly).

ArtWomb 6y ago
Good answer. It's referred to as the Lawson criterion for those wishing a deeper dive: https://en.wikipedia.org/wiki/Lawson_criterion https://en.wikipedia.org/wiki/Lawson_criterion Regarding simulations, plasma physics can in a very real sense be viewed as the predominant driver for supercomputing research and funding. Ratio of fusion budget allocations to total global energy demand remains woefully pitiful. On order of something like 30B / 100T or 0.03%.
godelski 6y ago
This is the main issue and I don't want to make it any more complicated. But I do want to explain something because people hear arguments between fusion scientists. Within the field no one really doubts that ITER is going to work (there's a few, of course, but the majority don't doubt). The thing they are arguing over is if it is needed. The big reason for ITER is not to generate power but to demonstrate that sustainable fusion is achievable. The idea is that if there is a demonstration people will stop shying away from it and investing would skyrocket (a government would have to be dumb not to substantially invest in PROVEN fusion devices). The counter argument is that there is enough funding and that they will beat ITER to the punch with small scale reactors (much closer to the path for devices that would provide actual energy to our grid). My take is "don't put all your eggs in one basket."
- ArtWomb 6y ago
  >>> small scale reactors I believe this is the DoE position. Leverage AI/ML to design smaller magnetic confinement. With the goal toward commercialized products and partnerships. JET was on track to breakeven. And I think most of the researchers involved believe they would have gotten there if the funding hadn't been cut. I think what they want is simply long term commitments. The sort of thing that is risky in fiscal budgets that can change year to year ;) Final Report of the Committee on a Strategic Plan for U.S.Burning Plasma Research (2018) http://brookhaventech.com/wp-content/uploads/2018/12/Burning-Plasma-Fusion-Plan.pdf http://brookhaventech.com/wp-content/uploads/2018/12/Burning...
  - maccam94 6y ago
    You don't need AI, just use stronger magnets[1]. ITER was conceived before high temperature superconducting magnets were discovered, so it has more trouble maintaining plasma stability. 1: https://www.youtube.com/watch?v=KkpqA8yG9T4&t=39m0s https://www.youtube.com/watch?v=KkpqA8yG9T4&t=39m0s MIT-affiliated company building a reactor using these magnets: https://cfs.energy/technology https://cfs.energy/technology
    - pfdietz 6y ago
      These reactor concepts are still very large for their power output, compared to fission reactors.
- landryraccoon 6y ago
  Without giving a strong opinion either way on whether this particular project is a good investment or not : Science, as an institution imo undervalues good marketing and good PR. For profit enterprises are under no illusion that they can succeed without good marketing and public perception. If large expensive projects like this are needed to increase public awareness and support for basic scientific research then I am all for them. Society is willing to spend billions on projects that give no tangible return and are all perceptions (for example, sports stadiums) so if some of that instead is spent promoting Science that’s a good thing. Any actual discoveries in fundamental science that come out would be a bonus too, but getting people excited about research is an end unto itself.
  - Aerroon 6y ago
    I think a problem with ITER for PR isn't the cost. It's time. I learned about it and got excited more than a decade ago. It'll still take years of time for it to be finished. I'm not really sure how to express this, but the huge amount of time just diminishes the impact of it for me.
    - godelski 6y ago
      One could also argue that it would be developed faster if they had more money. It wouldn't be a linear relationship, but there is a definite relationship between the two. But fundamentally I agree. It is hard to stay excited about something to come for decades.
    - layoutIfNeeded 6y ago
      I have similar feelings about the James Webb Space Telescope too.
    - nitrogen 6y ago
      Think of it like the construction of a legendary cathedral. The prolonged commitment required is part of its impressiveness.
      - 6y ago
- ummonk 6y ago
  I’d compare it to the human genome project. Look where we are now with full genome sequencing for the cost of a laptop.
- peterlk 6y ago
  I had a conversation with nomeone who worked on ITER who was of the name opinion, and my follow-up question to him was: "how much money would I need to raise to get us over the line". His answer was calm and sincere: "I think, something like 3 trillion US dollars". That's prohibitively expensive for private markets. No one will take that bet. It needs to be proven to be possible first.
- jandrese 6y ago
  > investing would skyrocket (a government would have to be dumb not to substantially invest in PROVEN fusion devices). Even if it is proven to work that's no proof that it's economically sustainable. The enormous complexity and required scale are huge barriers to adoption. Most of the advantages of fusion reactors are already enjoyed by fission reactors, and it's not like the fusion reactors are going to have that much of an easier time managing public perception. "They're building a H-Bomb in your back yard!" Worse, since fusion reactors aren't useful for making bombs government investment is basically guaranteed to be tepid. It's only advantage is saving the environment, which doesn't get votes, and environmental groups will likely be lukewarm on the plants just like they are with fission. Sure it doesn't release CO2, but /nuclear waste/ is a huge boogeyman, even when you're talking about low level incidentals like irradiated gloves and bits of piping.
  - Jedd 6y ago
    > Even if it is proven to work that's no proof that it's economically sustainable. If it is proven to work, then it removes one of the key unknowns: Does it work? If it can produce more power than it consumes, then it's ahead of the smaller demonstration reactors that have already been built and demonstrated. > The enormous complexity and required scale are huge barriers to adoption. Hence they're building this one. > Most of the advantages of fusion reactors are already enjoyed by fission reactors, Say what? What do you think the advantages of fusion reactors are, and same question for fission reactors? > and it's not like the fusion reactors are going to have that much of an easier time managing public perception. "They're building a H-Bomb in your back yard!" 'This reactor can be built far enough away that even if it explodes - and it can't - you won't notice. You won't notice it going off, and you won't notice cancer and birth defects, vast tracts of land cordoned off, water sources rendered toxic, etc for the next few hundred years. And we don't have to bury the waste product somewhere for a millennia or more.' Sounds like a much easier sell. > Worse, since fusion reactors aren't useful for making bombs government investment is basically guaranteed to be tepid. How many power stations are owned by governments around the western world today? It feels like most of the interesting things happening in high tech now are all privately funded. If / when this works, and there's money in it, government lack of interest due to inability to make bombs from it (and that all sounds dubious to me) is irrelevant.
perl4ever 6y ago
Indeed, we know that a fusion reactor will work if scaled up to about 1.4 x 10^27 cubic meters...
cartoonfoxes 6y ago
> Gkeyll contains ab-initio and novel implementations of a number of algorithms, and perhaps is unique in using a JIT compiled typeless dynamic language for its implementation. LuaJIT. Neat. I assumed this stuff was still all in FORTRAN.

ArtWomb 6y ago

Good answer. It's referred to as the Lawson criterion for those wishing a deeper dive: https://en.wikipedia.org/wiki/Lawson_criterion https://en.wikipedia.org/wiki/Lawson_criterion Regarding simulations, plasma physics can in a very real sense be viewed as the predominant driver for supercomputing research and funding. Ratio of fusion budget allocations to total global energy demand remains woefully pitiful. On order of something like 30B / 100T or 0.03%.

godelski 6y ago

This is the main issue and I don't want to make it any more complicated. But I do want to explain something because people hear arguments between fusion scientists. Within the field no one really doubts that ITER is going to work (there's a few, of course, but the majority don't doubt). The thing they are arguing over is if it is needed. The big reason for ITER is not to generate power but to demonstrate that sustainable fusion is achievable. The idea is that if there is a demonstration people will stop shying away from it and investing would skyrocket (a government would have to be dumb not to substantially invest in PROVEN fusion devices). The counter argument is that there is enough funding and that they will beat ITER to the punch with small scale reactors (much closer to the path for devices that would provide actual energy to our grid). My take is "don't put all your eggs in one basket."

ArtWomb 6y ago
>>> small scale reactors I believe this is the DoE position. Leverage AI/ML to design smaller magnetic confinement. With the goal toward commercialized products and partnerships. JET was on track to breakeven. And I think most of the researchers involved believe they would have gotten there if the funding hadn't been cut. I think what they want is simply long term commitments. The sort of thing that is risky in fiscal budgets that can change year to year ;) Final Report of the Committee on a Strategic Plan for U.S.Burning Plasma Research (2018) http://brookhaventech.com/wp-content/uploads/2018/12/Burning-Plasma-Fusion-Plan.pdf http://brookhaventech.com/wp-content/uploads/2018/12/Burning...
- maccam94 6y ago
  You don't need AI, just use stronger magnets[1]. ITER was conceived before high temperature superconducting magnets were discovered, so it has more trouble maintaining plasma stability. 1: https://www.youtube.com/watch?v=KkpqA8yG9T4&t=39m0s https://www.youtube.com/watch?v=KkpqA8yG9T4&t=39m0s MIT-affiliated company building a reactor using these magnets: https://cfs.energy/technology https://cfs.energy/technology
  - pfdietz 6y ago
    These reactor concepts are still very large for their power output, compared to fission reactors.
landryraccoon 6y ago
Without giving a strong opinion either way on whether this particular project is a good investment or not : Science, as an institution imo undervalues good marketing and good PR. For profit enterprises are under no illusion that they can succeed without good marketing and public perception. If large expensive projects like this are needed to increase public awareness and support for basic scientific research then I am all for them. Society is willing to spend billions on projects that give no tangible return and are all perceptions (for example, sports stadiums) so if some of that instead is spent promoting Science that’s a good thing. Any actual discoveries in fundamental science that come out would be a bonus too, but getting people excited about research is an end unto itself.
- Aerroon 6y ago
  I think a problem with ITER for PR isn't the cost. It's time. I learned about it and got excited more than a decade ago. It'll still take years of time for it to be finished. I'm not really sure how to express this, but the huge amount of time just diminishes the impact of it for me.
  - godelski 6y ago
    One could also argue that it would be developed faster if they had more money. It wouldn't be a linear relationship, but there is a definite relationship between the two. But fundamentally I agree. It is hard to stay excited about something to come for decades.
  - layoutIfNeeded 6y ago
    I have similar feelings about the James Webb Space Telescope too.
  - nitrogen 6y ago
    Think of it like the construction of a legendary cathedral. The prolonged commitment required is part of its impressiveness.
    - 6y ago
ummonk 6y ago
I’d compare it to the human genome project. Look where we are now with full genome sequencing for the cost of a laptop.
peterlk 6y ago
I had a conversation with nomeone who worked on ITER who was of the name opinion, and my follow-up question to him was: "how much money would I need to raise to get us over the line". His answer was calm and sincere: "I think, something like 3 trillion US dollars". That's prohibitively expensive for private markets. No one will take that bet. It needs to be proven to be possible first.
jandrese 6y ago
> investing would skyrocket (a government would have to be dumb not to substantially invest in PROVEN fusion devices). Even if it is proven to work that's no proof that it's economically sustainable. The enormous complexity and required scale are huge barriers to adoption. Most of the advantages of fusion reactors are already enjoyed by fission reactors, and it's not like the fusion reactors are going to have that much of an easier time managing public perception. "They're building a H-Bomb in your back yard!" Worse, since fusion reactors aren't useful for making bombs government investment is basically guaranteed to be tepid. It's only advantage is saving the environment, which doesn't get votes, and environmental groups will likely be lukewarm on the plants just like they are with fission. Sure it doesn't release CO2, but /nuclear waste/ is a huge boogeyman, even when you're talking about low level incidentals like irradiated gloves and bits of piping.
- Jedd 6y ago
  > Even if it is proven to work that's no proof that it's economically sustainable. If it is proven to work, then it removes one of the key unknowns: Does it work? If it can produce more power than it consumes, then it's ahead of the smaller demonstration reactors that have already been built and demonstrated. > The enormous complexity and required scale are huge barriers to adoption. Hence they're building this one. > Most of the advantages of fusion reactors are already enjoyed by fission reactors, Say what? What do you think the advantages of fusion reactors are, and same question for fission reactors? > and it's not like the fusion reactors are going to have that much of an easier time managing public perception. "They're building a H-Bomb in your back yard!" 'This reactor can be built far enough away that even if it explodes - and it can't - you won't notice. You won't notice it going off, and you won't notice cancer and birth defects, vast tracts of land cordoned off, water sources rendered toxic, etc for the next few hundred years. And we don't have to bury the waste product somewhere for a millennia or more.' Sounds like a much easier sell. > Worse, since fusion reactors aren't useful for making bombs government investment is basically guaranteed to be tepid. How many power stations are owned by governments around the western world today? It feels like most of the interesting things happening in high tech now are all privately funded. If / when this works, and there's money in it, government lack of interest due to inability to make bombs from it (and that all sounds dubious to me) is irrelevant.

perl4ever 6y ago

Indeed, we know that a fusion reactor will work if scaled up to about 1.4 x 10^27 cubic meters...

cartoonfoxes 6y ago

> Gkeyll contains ab-initio and novel implementations of a number of algorithms, and perhaps is unique in using a JIT compiled typeless dynamic language for its implementation. LuaJIT. Neat. I assumed this stuff was still all in FORTRAN.