[abefetterman]

The other efforts you mention are much further from having Q>1 (energy producing) fusion. FRCs and focus have not even reached Q=0.000001 and have little theoretical basis for being power producing. Stellerators have their own problems as well. Tokamaks have achieved Q=0.69, and so ITER has very little risk of missing its goal of Q>1 if it does get constructed and run DT.

I agree that fusion is severely underfunded, and that it is dangerous for us to put all our eggs in the Tokamak basket. And this article is pretty strange for its fixation on DEMO which at this point might as well be made of unicorn horns. But ITER was proposed and is supported by a huge number of scientists for a good reason: it's the best way for us to hit a goal that fusion science has been dreaming of for 50 years, that is key to understanding and designing real fusion reactors.

[IanCal]

The ARC reactor is a tokamak design though, just (I appreciate the work this word is doing in this sentence) smaller and with much more powerful magnets. They quite explicitly want to not have a different type of reactor.

[shaqbert]

Problem w/ the ARC reactor is that it is just a design. The real life engineering challenges are still daunting. E.g. for the supra conductors at the Wendelstein 7-X, which provide a much less powerful magnetic field, just assembling and connecting the supra conductor cables for each module was a mind blowingly complex and fickle process that was described at length in this (unfortunately German) super awesome podcast [0].

[0]: http://alternativlos.org/36/

[DennisP]

Yes but stellarators are much more complicated to build than tokamaks. They accept the construction difficulty in exchange for simpler plasma physics.

[abefetterman]

ARC is not designed to be cheaper or faster to build than ITER. Its purpose is closer to that of DEMO (engineering breakeven). ITER data will be critical for verifying the ARC design.

[IanCal]

I thought that one of the very fundamental ideas behind ARC was about trying to get the scale down so that it can be built more cheaply and quickly (not requiring global collaboration).

In the talk here: https://www.youtube.com/watch?v=KkpqA8yG9T4 he talks about ITER being too slow. Certainly the smaller SPARC reactor looks like they want to get things up and running far before ITER is performing fusion experiments, and the possible timescale for ARC is before

While their timescale might be optimistic or wrong, it doesn't sound like they're planning to wait for ITER.

I'm not in the field though so things might not match up with this output or I'm missing something obvious.