TallDave wrote:If ignition can be reached, even inside a machine that can't hold together for long enough for remotely economic energy-production, then a major psychological barrier towards investment in and development of, nuclear fusion will have been overcome.
1)I think the larger psychological barrier to investment involves whether tokamaks can ever be economically competitive.
I strongly believe that the success of ITER will have a positive impact in all areas of fusion research.
2)Or it will simultaneously discredit the idea of economic fusion power and suck up money that could have gone to alternate approaches.
Because the other approaches are so far away from burning plasmas developing them is like drawing lots. We could spend the rest of eternity fiddling around with an endless number of low-energy non-ignitable plasmas and not funding any of them on to the next level.
3)I have to point out again the flaw in this logic: tokamaks are further along because vastly more money has been pumped into them.
This might be like two men trying to develop a trade route to China in pre-industrial times, one of whom wants to get there by digging a hole, while the other wants to build a ship. The first man receives 90% of the funding, the other begins building a ship and trying to map how long the voyage will be. After a year, the hole gets deeper and deeper, and the first man says "Look at all the progress we've made! We're hundreds of feet closer; the other guy hasn't gotten an inch closer yet!"
Given that the ITER path has very little chance of being useful even if it does work, the fact it's more likely to work isn't a big incentive to build it. And we could do materials testing for a lot less than $20B.
4)I'm not against ITER per se, and I hope it does get built. But we can fund 10 other approaches at WB-100 levels for the same money, and if we have to choose between one or the other I don't think that's a hard choice.
1) That is the second psychological barrier, but I think the second psychological barrier is one private enterprise might take on once the first way successfully passed. If you ask for money to develop an economic fusion device from an investor, the first question he might ask you is "is controlled fusion even possible, I thought they were at it for 50 years and never even achieved any success", if you can point to a device that has already achieved burning plasmas, point out what aspects of its design make it uneconomic and then explain how your rival idea addresses these economic issues. I think you'll get a longer audience then if the possibility of controlled nuclear fusion itself is still up in the air.
Remember a lot of people aren't even sure whether fusion is possible at all. I remember when this forum was first established, many people who posted here weren't aware that JET almost achieved DT breakeven. If we cancel ITER it may be interpreted by the wider non-scientific community as a concession of defeat, as proof that a burning plasma cannot be achieved and as a result could hurt fusion across the board.
2) That's a fair point, in our student meeting I remember the then head of Culham said "If ITER isn't successful, fusion is finished." This comment disturbed me and I pointed out that there are other potentially succesful approaches even if the tokamak doesn't work. I'm glad that the USA is saving is fusion funding for investment in other approaches, but I think its good that ITER is being built by someone, otherwise there'd be a good chance that fusion could lose momentum, like the breeder reactor program.
3) That's true, and if thirty years ago someone asked me "should we cut our funding in all these other programmes for tokamaks?" I don't think I would have, but what's done is done. Tokamak's have recieved more funding that the other approaches and there is far more experimental data supporting the feasibility of ITER as a burning plasma device than any other concept (again due to lack of funding for the others). Plasmas are inherently unpredictable and incalculable, as a result they have the capacity to suprise and the suprises are generally nasty. A proposed burning plasma device with less experimental data backing it has a much larger capacity to deliver unpleasant surprises with worse than predicted performance. I won't believe that a rival concept on paper has a high chance of delivering a burning plasma until I see it, once I see those neutrons I'm all for scrapping ITER, but we shouldn't scrap ITER for a fantasy, we should pursue it and other smaller scale approaches in tandem.
4) ITER or 10 other small scale approaches which together cost a similar budget but whose physical behaviour is far far less well understood and are much more likely to dissappoint?
I think I'd rather fund ITER along with 3 to 5 of those small scale operations it would only add 30% to the fusion budget. Don't forget if all of those 10 lower budget approaches hit dead ends that would strike a tremendously damaging blow to the fusion programme.
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