Source for that?
Looking at the German Wikipedia entry, the HELIAS method was invented in the late 80s. I don't see anything about the 7-X design actually having been computed back then. In fact, even the 2002 experiment Wendelstein 7-AS wasn't fully optimised.
Also, Tokamaks were invented in the 1950s. JET started operating in 1983. ITER was proposed in 1987. Given even just a little bit of path-dependency, there really wasn't any realistic overlap.
This paper published in 92 mentions that the 7-X was being designex at that time. I remember having seen images of the proposed field coil configuration in 91 or 92. So I might have bern off by a few years. But the plans must have bern complete for the project start in 1994.
I do research at W7-X, so I can confirm that to the best of my knowledge, the design was computed a long time ago. Building the actual device took a while.
Would you happen to know what kind of compute power was required? Was it run on a colleague's PC or workstation or did it require supercomputer time?
By the way, the unusual shapes of the coils can be understood intuitively from this picture: https://imgur.com/a/Bq3ABfQ. A plasma needs to be confined with a magnetic field in order to be heated to extreme temperatures, and a toroidal field (produced by the currents in the red coils) is unstable due to particle orbit drifts. You need to add a twist to the field for it to be stable (using the green coils). But if you unroll the surface of the torus, you can approximate the currents in both green and red coils using the discrete blue coils, and they're easier to build.
[1] https://aip.scitation.org/doi/abs/10.1063/1.860481 [2] http://iopscience.iop.org/article/10.1088/0029-5515/27/5/018...
http://epsppd.epfl.ch/Sofia/pdf/P4_192.pdf
Alas, it "just" seems to talk about extending the coil design for a reactor, not the rest. I am guessing most of that would be similar as for other fusion reactors, see for example MIT's Pathway to Fusion Energy:
Though I don't really understand the significance of the "pebbles" in this system.
> the stellerator design, in a deep and fundamental way, simply isn't possible without massive computational power, whereas we've been building tokamaks since before massive cheap computational power.
does not square with Wikipedia:
> Stellarator ... The first Model A started operation in 1953 ...
It was just an enormous challenge to build this thing. Things like building and validating the field coils required a lot of effort and some novel approaches that they had to come up with along the way.