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Lets get to the point, really. The only way magnetic confinement will ever achieve confinement times conducive to technologically useful power output will come

by ohiovr 5y ago

Lets get to the point, really. The only way magnetic confinement will ever achieve confinement times conducive to technologically useful power output will come from electromagnetic field strengths beyond what we are capable of doing at the present time with bitter superconductor magnets. And should we discover the secret to making this superlative magnetic field, we will need structures capable holding it together without smashing itself to bits. Stronger magnets mean tighter and tighter gyroradii. Every atomic collision pushes the plasma to the edges and there is no magic to stopping it. There is really no such thing as magnetic confinement. The magnetic fields only slow the progression to the walls. It can work if the progression is slow enough. 17 telsa magnets is only a fraction of the strength needed for anything practical. Go for 100 teslas or come back and say it will be another 30 years. Whoever figures out the hypermagnet will be just one step away from producing net fusion that is useful. I'd say divert all attention to that instead of new tokamaks. We know tokamak will work (economically too), if it only had the secret ingredient of unbelievably powerful magnets.

DennisP 5y ago
So I assume you're familiar with the scaling laws of tokamak fusion and can show your work? Because here's a presentation by the head of MIT's fusion program, who introduces those scaling laws and concludes that the latest commercially-available superconductors are indeed sufficient for net power, from a reactor of reasonable size and structural strength: https://www.youtube.com/watch?v=KkpqA8yG9T4&t=1370s https://www.youtube.com/watch?v=KkpqA8yG9T4&t=1370s
- ohiovr 5y ago
  I never saw Lockheeds "show your work" on their proposal for a fictitious reactor that could supply 100 megawatts from a tractor trailer bed. Yet they got billions of dollars of funding for it. If I had a 100 tesla magnet wouldn't that be useful for tokamaks? Because iter's 17 tesla magnet isn't going to lead to a revolution. It is only another iteration over the JET tokamak which barely had success, but enough success to be a viable lead. If the government listened to crackpots like me they could have saved billions of dollars. Its pretty simple really. A charged particle when it slams into another will gyrate in a magnetic field. If that magnetic field is twice as strong, the gyro-radius is half as wide. And the containment vessel would require half the volume. It takes many many strikes to fuse two nuclei. That is why it is necessary to have ultra powerful magnets. Because it might take dozens or hundreds of strikes, each one potentially enlarging the radius of the circulating plasma. Maybe stellerators have an edge but I don't see it with my limited knowledge. But simple brute force ought to get 'the job done'.
  - DennisP 5y ago
    I'm talking about Commonwealth and Tokamak Energy, which use fields quite a bit stronger than ITER, taking advantage of newer superconductors than ITER. The relevant scaling law is that tokamak energy output goes up with the fourth power of magnetic field strength. According to the presentation I linked, that allows ITER-level output from a reactor a tenth the volume of ITER. Assuming that works out, a reactor somewhere between those two sizes should get us to commercial levels.
    - ohiovr 5y ago
      This kind of goes along with my theme. By the time the expensive experimental reactor is at the end of the planning stage an new magnetic force regime is introduced changing the whole perspective of the experiment. It would be best to scrap those experiments and focus attention on the new technologies because 17 tesla magnets are not the most powerful magnets in the universe and we have a long way to go to find what is possible on our home world. The magnetic field is the foundation of fusion energy at this time sans xray compression.
  - refulgentis 5y ago
    Take a breathe...hold....and exhale...now go take another pass at the article, you're far off from it, its basically an answer to the questions you're raising. Then riff on this: The reply, and article, reference CFS, a public/private initiative by MIT, where the gentlemen whose laws you are referencing had a major breakthrough via a materials science breakthrough that allows the ITER magent you're discussing to be produced a couple orders of magnitude smaller, changing all of the problems.
mabbo 5y ago
While I'm generally inclined towards pessimism when it comes to new technology, there is something to be said for when billions of dollars start being invested in a large number of companies chasing the same dream. One could argue that these funds are being poorly invested, but that begs the question: why now? Why didn't we see this money being 'thrown away' 10, 15, 20 years ago? What's changed that those with the means to make such investments believe that now is the right time to be putting money into long shots? And so I'm left to have one simple hope: maybe the very rich people have hired people smarter than me to assess if there's a chance in hell this will work. It sure seems like a lot of people suddenly think they can do it.
- ohiovr 5y ago
  Seems like a rich man's dream since the 90's with Paul Allen's funding of trialpha. Penicillin wasn't discovered from people throwing billions of dollars of research money around: a discovery that saved hundreds of millions of lives was simply a happy accident found by a pair of eyes that could put 2 and 2 together.

by ohiovr 5y ago

DennisP 5y ago

So I assume you're familiar with the scaling laws of tokamak fusion and can show your work? Because here's a presentation by the head of MIT's fusion program, who introduces those scaling laws and concludes that the latest commercially-available superconductors are indeed sufficient for net power, from a reactor of reasonable size and structural strength: https://www.youtube.com/watch?v=KkpqA8yG9T4&t=1370s https://www.youtube.com/watch?v=KkpqA8yG9T4&t=1370s

ohiovr 5y ago
I never saw Lockheeds "show your work" on their proposal for a fictitious reactor that could supply 100 megawatts from a tractor trailer bed. Yet they got billions of dollars of funding for it. If I had a 100 tesla magnet wouldn't that be useful for tokamaks? Because iter's 17 tesla magnet isn't going to lead to a revolution. It is only another iteration over the JET tokamak which barely had success, but enough success to be a viable lead. If the government listened to crackpots like me they could have saved billions of dollars. Its pretty simple really. A charged particle when it slams into another will gyrate in a magnetic field. If that magnetic field is twice as strong, the gyro-radius is half as wide. And the containment vessel would require half the volume. It takes many many strikes to fuse two nuclei. That is why it is necessary to have ultra powerful magnets. Because it might take dozens or hundreds of strikes, each one potentially enlarging the radius of the circulating plasma. Maybe stellerators have an edge but I don't see it with my limited knowledge. But simple brute force ought to get 'the job done'.
- DennisP 5y ago
  I'm talking about Commonwealth and Tokamak Energy, which use fields quite a bit stronger than ITER, taking advantage of newer superconductors than ITER. The relevant scaling law is that tokamak energy output goes up with the fourth power of magnetic field strength. According to the presentation I linked, that allows ITER-level output from a reactor a tenth the volume of ITER. Assuming that works out, a reactor somewhere between those two sizes should get us to commercial levels.
  - ohiovr 5y ago
    This kind of goes along with my theme. By the time the expensive experimental reactor is at the end of the planning stage an new magnetic force regime is introduced changing the whole perspective of the experiment. It would be best to scrap those experiments and focus attention on the new technologies because 17 tesla magnets are not the most powerful magnets in the universe and we have a long way to go to find what is possible on our home world. The magnetic field is the foundation of fusion energy at this time sans xray compression.
- refulgentis 5y ago
  Take a breathe...hold....and exhale...now go take another pass at the article, you're far off from it, its basically an answer to the questions you're raising. Then riff on this: The reply, and article, reference CFS, a public/private initiative by MIT, where the gentlemen whose laws you are referencing had a major breakthrough via a materials science breakthrough that allows the ITER magent you're discussing to be produced a couple orders of magnitude smaller, changing all of the problems.

mabbo 5y ago

While I'm generally inclined towards pessimism when it comes to new technology, there is something to be said for when billions of dollars start being invested in a large number of companies chasing the same dream. One could argue that these funds are being poorly invested, but that begs the question: why now? Why didn't we see this money being 'thrown away' 10, 15, 20 years ago? What's changed that those with the means to make such investments believe that now is the right time to be putting money into long shots? And so I'm left to have one simple hope: maybe the very rich people have hired people smarter than me to assess if there's a chance in hell this will work. It sure seems like a lot of people suddenly think they can do it.

ohiovr 5y ago
Seems like a rich man's dream since the 90's with Paul Allen's funding of trialpha. Penicillin wasn't discovered from people throwing billions of dollars of research money around: a discovery that saved hundreds of millions of lives was simply a happy accident found by a pair of eyes that could put 2 and 2 together.