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A lack of understanding of plasma dynamics isn't preventing construction of a useful fusion reactor. Other energy sources being cheap and construction costs be

by Retric 3y ago

A lack of understanding of plasma dynamics isn't preventing construction of a useful fusion reactor. Other energy sources being cheap and construction costs being high are much larger limitations. We could have built a scaled up steady state tokamak using pure D-D fusion all the way back in the 1990's. We didn't because coal, fission, etc where plentiful/cheap and nobody was going to waste a trillion dollars on such technological dead end. The current technical challenges are all about bring the costs down. Designing and using a breeding blanket is far more complected than a steel wall, but D-T allows for a vastly smaller and therefore hopefully much cheaper device.

kragen 3y ago
tokamak researchers generally do not agree with you the humans only achieved breakeven in 02022, and not in a tokamak, but in an inertial confinement experiment, which is to say, a tiny bomb. thinking you need a trillion dollars is a symptom of not knowing how to do it; the trillion dollars are to spend on experiments
- Retric 3y ago
  Actually that trillion dollar number was from a Tokamak researcher. Though I am not sure how serious they where being when using it. With Tokamak's Q isn't a constant for a general design it's a result of scaling laws and a specific size thus ITER was chosen at Q >= 10 but they could have picked bigger or smaller target. EX: https://nucleus.iaea.org/sites/fusionportal/Shared%20Documents/FEC%202016/fec2016-preprints/preprint0759.pdf https://nucleus.iaea.org/sites/fusionportal/Shared%20Documen... In 1997 JET hit an equivalent Q of 0.67 using a 3m by 1.25m device and D-T. You can look at costs and scaling factors along with the output of DD vs DT fusion. I took a trillion dollar budget just mean ~10,000x the cost of JET which seems to line up reasonably well. Though making such a large jump in scale would have it's own challenges.
  - pfdietz 3y ago
    It's also always been possible to reach breakeven (and above) in magnetic mirrors. These are linear devices that leak out the ends, so just make them long enough and they will reach breakeven. The problem has been "long enough" has been "kilometers".

by Retric 3y ago

kragen 3y ago

tokamak researchers generally do not agree with you the humans only achieved breakeven in 02022, and not in a tokamak, but in an inertial confinement experiment, which is to say, a tiny bomb. thinking you need a trillion dollars is a symptom of not knowing how to do it; the trillion dollars are to spend on experiments

Retric 3y ago
Actually that trillion dollar number was from a Tokamak researcher. Though I am not sure how serious they where being when using it. With Tokamak's Q isn't a constant for a general design it's a result of scaling laws and a specific size thus ITER was chosen at Q >= 10 but they could have picked bigger or smaller target. EX: https://nucleus.iaea.org/sites/fusionportal/Shared%20Documents/FEC%202016/fec2016-preprints/preprint0759.pdf https://nucleus.iaea.org/sites/fusionportal/Shared%20Documen... In 1997 JET hit an equivalent Q of 0.67 using a 3m by 1.25m device and D-T. You can look at costs and scaling factors along with the output of DD vs DT fusion. I took a trillion dollar budget just mean ~10,000x the cost of JET which seems to line up reasonably well. Though making such a large jump in scale would have it's own challenges.
- pfdietz 3y ago
  It's also always been possible to reach breakeven (and above) in magnetic mirrors. These are linear devices that leak out the ends, so just make them long enough and they will reach breakeven. The problem has been "long enough" has been "kilometers".