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Nope, this is good news. JET is a 1980s research project into how to contain a plasma and squish it enough to achieve fusion at all, not a practical generator.
by cstross 5y ago
Nope, this is good news.
JET is a 1980s research project into how to contain a plasma and squish it enough to achieve fusion at all, not a practical generator. It doesn't have superconducting magnets, it runs on big lumps of copper, with limited cooling and no way of recovering output power.
In the latest run, they achieved fusion and kept it running until JET ran out of power for its magnets. The plasma didn't touch the reactor walls, didn't destabilize, didn't crap out in any of the numerous other ways. They had to shut it down before it overheated and burned out.
(I've been reading reports for a while about the use of massive amounts of computer power -- and deep learning -- being necessarily to stabilize plasma in a reactor. That seems to be what this demonstrates.)
This is probably JET's swan song. They've pushed it as far as it can go; also, the D-T reaction produces surplus neutrons so tends to generate radioactive waste via secondary irradiation of the reactor core -- which makes it hard to get inside and fiddle with it.
- pclmulqdq 5y agoThis is a really great achievement for a fusion reactor, and actually is a breakthrough that makes me think that it might be on its way to serious commercialization. Unfortunately, a lot of other fusion news is not similarly fundamental, though, so it can get tiring to see "we made a few extra watts but the reactor still went unstable."
- ambrozk 5y agoA lot of research into plasma confinement is completely empirical. No theory at all. The scientists try new settings, see how they work, and draw a line on a graph extrapolating from them to higher power settings. That's why you need all these small experiments, which have no hope of generating net energy: because you're trying to solve plasma confinement by tinkering, without much of a map to guide you.
- gmueckl 5y agoConfined plasmas have complex behaviors that are really, really hard to model computationally. Experimentation definitely beats computation in this field.
- willis936 5y agoI would be surprised if they do not keep pushing for the Q=1 record. This last campaign was in support of ITER. Now that DT operations have resumed they wouldn't go out without a moonshot.
- somat 5y agoFor what its worth, the strongest magnets in the world are not superconducting but copper. My understanding is that the high magnetic field interferes with the superconducting mode. https://nationalmaglab.org/user-facilities/dc-field/instruments-dcfield https://nationalmaglab.org/user-facilities/dc-field/instrume... Not that it has anything to do with plasma research, I just thought it an interesting fact.
- sbierwagen 5y agoHere's a fun table at which field strengths various superconductors fall out of the superconducting mode https://www.researchgate.net/figure/Upper-critical-fields-and-coherence-lengths-for-sev-eral-type-II-superconductors-The_tbl1_273297345 https://www.researchgate.net/figure/Upper-critical-fields-an... ITER uses NbTi, SPARC uses YBCO.
- jrbdisoshs 5y ago
- regularfry 5y agoInterestingly one of the things they proved out in this experiment was a new core lining that doesn't get anywhere near as radioactive as the carbon walls they were using before. That was a bit of a big deal in itself: if it hadn't tracked theory as well as it did, it would have invalidated one of the material choices for ITER and knocked it back a fair bit.
- hinkley 5y agoCorrect me if I’m wrong but the neutrons eventually cause the reactor to eat itself as well, don’t they? Unless you can build a sacrificial layer inside to absorb all the damage you have to keep building new ones, even if it weren’t radioactive.