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almost all of fusion development is basically plasma physics research. nuclear fusion itself is known science, its the plasma containment & stabilizing that har

almost all of fusion development is basically plasma physics research. nuclear fusion itself is known science, its the plasma containment & stabilizing that hard. so you can sustain the fusion & get positive yield. that said I'd much prefer all the money being burnt on ITER/tokamak would be better spent by spreading the bets into exploring concepts like W7 or inertial confinement or even MIT ARC kind of efforts. Grand efforts like ITER are just ensuring fusion is always 30 years out. My personal prediction is that we'll have fusion positive yield within a decade of when alternative energy becomes a significant portion (say 25% .. & growing) of total energy mix.

zlynx 10y ago
There really are physics that only work at very large scale, such as stars and black holes. It may be that we can only get fusion power generation working in huge reactors like ITER. It's also a good attempt at getting many countries working together. Ideally, more big brains working together will have better ideas and results. There's downsides to ITER too of course. But I think it's worth working on.
- Yizahi 10y ago
  ITER is actually a small scale model. Full scale would be DEMO, a few decades in the future :) .
- candiodari 10y ago
  There are fusion reactors that are 5 cm diameter. Total size less than a microwave. They're very useful but not energy-positive, though there are reports of one that was Q=0.2, which given that that one was fridge sized was pretty good. They're the only practical way we have of producing fast neutrons. They are critical in physics research, some medical treatments, fusion research, ... their is absolutely no even remotely practical alternative to them (they're microwave sized devices, using 4-10kw of power that replace synchotrons. Small synchotrons are basketball-field sized and need their own power station) (replace should be taken with a grain of salt since most places that have IEC fusors had no way in hell to afford a synchotron, so they are democratizing fast neutrons. Okay, that's perhaps a strong word but if you have a use for them, there's no reason why you couldn't operate one of these devices in any regular office) (ps: given how easy, hard to detect, and deadly mistakes with fast neutrons are, please do do it in an office building at least 100m away from me. As it stands though, they're completely unregulated) The reason we scale up is roughly: 1) Scaling laws work in favor of Q. Q should scale with something like the 3rd power of the size of the reactor. So it's much easier to build a huge Q>1 reactor. 2) Where to stick parts ? Fusion reactors require strong magnetic fields and the only real way we knew of doing that 20 years ago when these were designed was cyronically frozen. That means we need sections inside the reactor for superconductors, for crygenic cooling equipment (mostly piping). Even disregarding that, fast neutrons will destroy any material they touch, making it brittle and crumble. Aside from bigger reactors making sure more material can get destroyed without failure, one thing that they interact with well is large volumes of water. So if at all possible, we'd like large volumes of water inside the reactor too (for other reasons too, like one strategy for extracting power). That needs space, obviously. 3) It is much easier to keep things stable if their scale is larger. There is more reaction time for the control equipment, the fields involved are larger and move slower, ...
Yizahi 10y ago
Except when stellarator starts doing longer runs and requires more hardened materials (like ITER) and when we need more instrumentation in the containment walls (like ITER) and when we need to actually plan to harvest energy from it (like ITER) and somewhere at that point someone proposes yet another concept for fusion reactor, modern and not dragged down by all that "practical" stuff. Also fusion is not 30 years away, it is likely more, after ITER we'll have DEMO, that would take many years again and only after that we may have first practical reactors running.
boznz 10y ago
Got a friend at ITAR, when I asked him how many people work there, he said about 10%
- zachrose 10y ago
  Ha, I have the vague sense that that's a joke but I'm not exactly sure what it means?
  - beamatronic 10y ago
    The joke is that 90% of the people aren't "working".

zlynx 10y ago

There really are physics that only work at very large scale, such as stars and black holes. It may be that we can only get fusion power generation working in huge reactors like ITER. It's also a good attempt at getting many countries working together. Ideally, more big brains working together will have better ideas and results. There's downsides to ITER too of course. But I think it's worth working on.

Yizahi 10y ago
ITER is actually a small scale model. Full scale would be DEMO, a few decades in the future :) .
candiodari 10y ago
There are fusion reactors that are 5 cm diameter. Total size less than a microwave. They're very useful but not energy-positive, though there are reports of one that was Q=0.2, which given that that one was fridge sized was pretty good. They're the only practical way we have of producing fast neutrons. They are critical in physics research, some medical treatments, fusion research, ... their is absolutely no even remotely practical alternative to them (they're microwave sized devices, using 4-10kw of power that replace synchotrons. Small synchotrons are basketball-field sized and need their own power station) (replace should be taken with a grain of salt since most places that have IEC fusors had no way in hell to afford a synchotron, so they are democratizing fast neutrons. Okay, that's perhaps a strong word but if you have a use for them, there's no reason why you couldn't operate one of these devices in any regular office) (ps: given how easy, hard to detect, and deadly mistakes with fast neutrons are, please do do it in an office building at least 100m away from me. As it stands though, they're completely unregulated) The reason we scale up is roughly: 1) Scaling laws work in favor of Q. Q should scale with something like the 3rd power of the size of the reactor. So it's much easier to build a huge Q>1 reactor. 2) Where to stick parts ? Fusion reactors require strong magnetic fields and the only real way we knew of doing that 20 years ago when these were designed was cyronically frozen. That means we need sections inside the reactor for superconductors, for crygenic cooling equipment (mostly piping). Even disregarding that, fast neutrons will destroy any material they touch, making it brittle and crumble. Aside from bigger reactors making sure more material can get destroyed without failure, one thing that they interact with well is large volumes of water. So if at all possible, we'd like large volumes of water inside the reactor too (for other reasons too, like one strategy for extracting power). That needs space, obviously. 3) It is much easier to keep things stable if their scale is larger. There is more reaction time for the control equipment, the fields involved are larger and move slower, ...

Yizahi 10y ago

Except when stellarator starts doing longer runs and requires more hardened materials (like ITER) and when we need more instrumentation in the containment walls (like ITER) and when we need to actually plan to harvest energy from it (like ITER) and somewhere at that point someone proposes yet another concept for fusion reactor, modern and not dragged down by all that "practical" stuff. Also fusion is not 30 years away, it is likely more, after ITER we'll have DEMO, that would take many years again and only after that we may have first practical reactors running.

boznz 10y ago

Got a friend at ITAR, when I asked him how many people work there, he said about 10%

zachrose 10y ago
Ha, I have the vague sense that that's a joke but I'm not exactly sure what it means?
- beamatronic 10y ago
  The joke is that 90% of the people aren't "working".