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New records on Wendelstein 7-X

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243 points greesil | 7 comments | 21 Jul 25 15:18 UTC | HN request time: 0s | source | bottom
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tgtweak ◴[21 Jul 25 16:28 UTC] No.44637097[source]▶
This article has zero quantifiable information in it aside from the duration... which has no context. Who's recordkeeping this stuff? What are the other results so far? What is the tipping point where it is net positive? how long does it need to sustain a net positive fusion reaction to produce sufficient power for grid consumption? Are there other losses (thermal generation inefficiencies) that make the target even farther than energy-in<energy-out?
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1. tgtweak ◴[21 Jul 25 17:00 UTC] No.44637515[source]▶
Here is an actual article with some context - and a reality check that other experimental reactors in the past have sustained similar triple product for longer durations... https://www.ipp.mpg.de/5532945/w7x
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2. i_am_proteus ◴[21 Jul 25 17:35 UTC] No.44637993[source]▶
>The fact that W7-X results are on a par with JET is remarkable because JET had three times the plasma volume of Wendelstein 7-X.

What's important here is that W 7-X is a stellarator, a different type of fusion reactor from almost all prior reactors (they are tokamaks), with a smaller volume than the co-record holder.

That a stellarator gets these results with a much smaller fusion volume is promising for the performance of future larger stellarators, since fusion reactors typically become more efficient as they get larger.

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3. tgtweak ◴[21 Jul 25 17:53 UTC] No.44638226[source]▶
All good information, entirely missing from the original article -
4. johannes1234321 ◴[21 Jul 25 21:29 UTC] No.44640624[source]▶
> from almost all prior reactors (they are tokamaks)

Tokamak and Stllerator are about equally old, 1953 vs 1954, while both types where for a period developed in secrecy behind either side of the iron curtain till end of the 1960ies where collaboration started.

IPP was founded in 1960 (by, among others, my dad) and focussed on Stllerator since then (while collaborating in JET and ITER around their tokamak projects)

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5. cenamus ◴[22 Jul 25 07:11 UTC] No.44644042{3}[source]▶
Apparently stellarators only became feasible recently, mostly due to vastly improved computing power, which they need to optimize the crazy shapes (https://www.ipp.mpg.de/w7x gives an idea)

(Heard that on a podcast with two of the lead physicists/engineers working there)

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6. johannes1234321 ◴[22 Jul 25 09:00 UTC] No.44644717{4}[source]▶
Yes, they are complex and require both, complex calculation and precise manufacturing and 7x is the first one being energy-positive, but tokamaks aren't really ahead either.
7. noobermin ◴[22 Jul 25 09:01 UTC] No.44644727[source]▶
NIF did it with an EVEN smaller plasma volume.

Sorry this is nice for the Wendelstein itself but they are overselling it, albeit in a way that isn't too out of the norm with academic press releases.