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I've known about this chart for a long while, but recently I've become skeptical of it. What says that fusion would be a success even if that level of funding w

I've known about this chart for a long while, but recently I've become skeptical of it. What says that fusion would be a success even if that level of funding was reached? The most mature fusion reactor being built, ITER, is gigantic and it's not clear how it could be made cheaper or miniturized.

danaris 4y ago
That's part of the problem with fairly basic research like what we're putting into fusion. Without making the investment, doing the science and engineering to actually study these things and learn how they work and how we can do them better, we won't know how or whether they can be made cheaper, miniaturized, etc. This isn't the same kind of problem that most of us are used to dealing with in our daily lives—where the fundamental components, and the fundamental science, that make it all up are well-understood and fairly mature, and what we have to do is come up with creative ways to apply it. This is the kind of "we don't know if any specific avenue of research will ever pay back a positive monetary ROI, but pursuing them is important anyway" science that we need to be doing with or without fusion as a specific goal, because over time, it will produce years or decades of silence, punctuated by small, incremental improvements in our understanding of the universe...and then an amazing breakthrough like practical, commercially-viable fusion power. But only if we are willing to patiently fund it through those years or decades of boring stuff.
DennisP 4y ago
Actually it's quite clear: use REBCO superconductors. Tokamak output scales with the square of reactor volume and the fourth power of magnetic field strength. Double the field, 16X the output. Modern REBCO superconductors can support much stronger magnetic fields than ITER will manage. That's why CFS is building a reactor using REBCO which is much smaller than ITER, but should have the same performance. It'll be half the size of JET, which was built in a year. They're planning a net power attempt in 2025 and a lot of independent fusion researchers think they'll succeed. CFS is a spinoff from MIT, whose Alcator C-Mod had more powerful magnets than any other tokamak in the world.
- Stevvo 4y ago
  SPARC's 2025 timeline is a joke. They haven't even started hiring engineers yet, let alone building the thing because they still have no idea how to make a big enough REBCO magnet.
  - DennisP 4y ago
    They've already built a SPARC-size REBCO magnet, and demonstrated it at 20 Tesla for five hours. https://www.ans.org/news/article-3240/mit-ramps-10ton-magnet-up-to-20-tesla-in-proof-of-concept-for-commercial-fusion/ https://www.ans.org/news/article-3240/mit-ramps-10ton-magnet... https://news.mit.edu/2021/MIT-CFS-major-advance-toward-fusion-energy-0908 https://news.mit.edu/2021/MIT-CFS-major-advance-toward-fusio... It's pretty amazing that they did that without any engineers.
pfdietz 4y ago
That chart was about a proposed crash program for tokamaks. It was put together based on an optimistic (and disproved) idea about how tokamak physics would scale. Had that program actually been funded, it would have been a guaranteed failure.

danaris 4y ago

That's part of the problem with fairly basic research like what we're putting into fusion. Without making the investment, doing the science and engineering to actually study these things and learn how they work and how we can do them better, we won't know how or whether they can be made cheaper, miniaturized, etc. This isn't the same kind of problem that most of us are used to dealing with in our daily lives—where the fundamental components, and the fundamental science, that make it all up are well-understood and fairly mature, and what we have to do is come up with creative ways to apply it. This is the kind of "we don't know if any specific avenue of research will ever pay back a positive monetary ROI, but pursuing them is important anyway" science that we need to be doing with or without fusion as a specific goal, because over time, it will produce years or decades of silence, punctuated by small, incremental improvements in our understanding of the universe...and then an amazing breakthrough like practical, commercially-viable fusion power. But only if we are willing to patiently fund it through those years or decades of boring stuff.

DennisP 4y ago

Actually it's quite clear: use REBCO superconductors. Tokamak output scales with the square of reactor volume and the fourth power of magnetic field strength. Double the field, 16X the output. Modern REBCO superconductors can support much stronger magnetic fields than ITER will manage. That's why CFS is building a reactor using REBCO which is much smaller than ITER, but should have the same performance. It'll be half the size of JET, which was built in a year. They're planning a net power attempt in 2025 and a lot of independent fusion researchers think they'll succeed. CFS is a spinoff from MIT, whose Alcator C-Mod had more powerful magnets than any other tokamak in the world.

Stevvo 4y ago
SPARC's 2025 timeline is a joke. They haven't even started hiring engineers yet, let alone building the thing because they still have no idea how to make a big enough REBCO magnet.
- DennisP 4y ago
  They've already built a SPARC-size REBCO magnet, and demonstrated it at 20 Tesla for five hours. https://www.ans.org/news/article-3240/mit-ramps-10ton-magnet-up-to-20-tesla-in-proof-of-concept-for-commercial-fusion/ https://www.ans.org/news/article-3240/mit-ramps-10ton-magnet... https://news.mit.edu/2021/MIT-CFS-major-advance-toward-fusion-energy-0908 https://news.mit.edu/2021/MIT-CFS-major-advance-toward-fusio... It's pretty amazing that they did that without any engineers.

pfdietz 4y ago

That chart was about a proposed crash program for tokamaks. It was put together based on an optimistic (and disproved) idea about how tokamak physics would scale. Had that program actually been funded, it would have been a guaranteed failure.