For a good laugh from the University of Washington

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Chris Bradley
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Re: For a good laugh from the University of Washington

Post by Chris Bradley » Tue Oct 14, 2014 4:59 pm

I disagree with the condescension towards this paper. It is highly relevant and probes whether the experimental end-point for tokamak and its ilk is a scientific or a practical one.

I am all aboard with tokamak as an ongoing science project, but shudder when people suggest it is now 'an engineering project'.

I have questioned, and continue to do so, what the actual experimental objective of ITER is. It seems to serve no particular purpose and is a political hodgepodge without a true goal, which, consequently, will fail because of that alone.

As alluded to in other threads, and recent posts, there are known, viable routes forward for long term fission power (beyond slow reactors) that mankind should be pursuing. We should be fully powered by renewable and nuclear by now. I view it as a form of self-destruction of the human race that we are not there yet, and politics is to blame. (On a side note, I am sure this is why we have not observed other intelligent species in the Universe - because organised technological societies only last for a few hundred years before they naturally implode, politically. The control of unlimited and free power is both a magnificent danger but is simultaneously essential. It is a naturally unstable conundrum.)

Dan Tibbets
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Re: For a good laugh from the University of Washington

Post by Dan Tibbets » Sun Nov 02, 2014 1:47 am

1 / 10th scale does not necessarily grow linearly in terms of output. If the 1/10th scale refers to linear dimensions, then increasing 10 fold would result in 1000 fold increase in volume, thus only 1 MW would translate into 1000 MW. Even this may be misleading though. Factors like magnetic field strength scaling may contribute as much or more as would temperature achieved.

Having said that, the projections from all fusions efforts are at least somewhat speculative at best. Perhaps the least speculative is tokamak approaches as they have approached Q=1 closely. Still the engineering to reach continuous rated power output is formidable. Two or three plants may be necessary in order to have one operational at any given time. And this is at a cost that is probably well above 10 billion dollars per plant. With tokamaks there has been nay sayers that base their arguments on these issues. Curiously, the tokamak community seems to ignore these economic realities. They are not pushing scale models as a predictor of final performance implement and cost . It is all about the physics.* This is perhaps less useful than actual efforts to present scaling predictions to a final product. At least such predictions are predictive of what is reasonable. Of course all of this remains speculative, but at least it is speculation on a small scale compared to tokamaks.
This doesn't meany any snake oil sales pitch should be funded. But if the physics at the current stage of development and the engineering predictions are reasonable, then ignoring such approaches when they are truely trivial in cost, is a dis service. The field reverse configurations seem to be gaining popularity and credibility at this time. Conversely, I do not think they have yet achieved anything close to the temperature or containment requirements. Electrical fusion (name Dr Parks is now using for the IEC aspects of the Polywell has at least achieved reasonable temperatures and densities. Confinement may also be even better than predictions. Of course other concerns are now becoming apparent which challenge prevous scaling predictions . How to get the darn electrons into the machine seems to be the dominate question now.

* Actually I am probably being unfair to the tokamak community. But the economic realities do seem to be minimized. The research is expensive and slow. But, if successful, the deployment will be even more expensive yet. This at least, is different for more energy dense proposals. The research is cheaper and the speculative deployment is much cheaper. Yes, even cheaper (or at least comparable) to a coal fired steam plant, especially when fuel costs are factored in. After all if thermal conversion is used the fusion reactor is equivalent to the incinerator in a coal plant. Most of the building and maintenance cost is in the steam plant. A tokamak is an exception to this. More dense alternate fusion reactors can reasonably be projected to cost much less than the tokamak behemoth - provided they work at all.

In short ;) there are three questions:
1) Can fusion give positive energy balances? I think yes, tokamaks at least are very close now.
2) If the physics work, can the engineering solutions be developed? This is a tremendous challenge for tokamaks, even if ITER is successful as predicted. Other approaches have their own challenges, but I believe none are as formidable as for tokamaks.
3) Can fusion power be economical? Probably not for tokamaks, unless someone can develop a high Beta tokamak. For other approaches, the question is more uncertain. Known cost scaling analysis techniques though do suggest that it is possible, if physics predictions are anywhere close to reality.

PS: One fusion reactor system that has been proven to work is the Sun. The ancillary physics and engineering issues are progressing towards increasingly attractive solutions. Solar cell (with cost and efficiency improvements), wind turbines, etc. are the "steam plants" for this fusion reactor.

Dan Tibbets

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