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Do I understand correctly that no actual fusion took place? This just heated the plasma using an external power source as a test.
by WithinReason 4y ago
Do I understand correctly that no actual fusion took place? This just heated the plasma using an external power source as a test.
- mikeyouse 4y agoHere's a related article explaining the most recent test; https://phys.org/news/2023-02-power-plasma-gigajoule-energy-turnover.html https://phys.org/news/2023-02-power-plasma-gigajoule-energy-...
- cstross 4y agoFusion reactor R&D generally avoids actually starting a fusion reaction unless they're ready to trash the reactor: current reactor designs can only manage D+T fusion, which generates a shitload of neutrons and leaves the reactor interior structures highly radioactive, making modification for further experiments problematic. (No-one is anywhere near achieving the energies needed for aneutronic fusion.) For example, the JET (Joint European Torus) Tokamak at Culham began operation in 1983 but experiments with tritium only started in 1991; maintenance and upgrades after 1998 relied on a remote handling system as it was no longer safe for human technicians to work inside the reactor containment in shutdown. https://en.wikipedia.org/wiki/Joint_European_Torus https://en.wikipedia.org/wiki/Joint_European_Torus
- howenterprisey 4y agoD-T definitely trashes the reactor, but D-D generates fewer neutrons, so human maintenance is generally OK afterwards. C-Mod at MIT ran this way for a while. You just needed to wear a dose meter.
- mikeyouse 4y agoSmall nit if you've never seen it written down, they're 'dosimeters'.
- sp332 4y agoPolywell reactors have been doing D-D fusion since 2005, and measuring very few neutrons produced.
- DennisP 4y agoLots of R&D uses deuterium, the neutron output is lower-energy and a handy diagnostic. Even hobbyists with fusors run on deuterium. Getting net power with deuterium is harder than D-T, but just fusing some deuterium isn't hard. The same goes for aneutronic fuels, as long as you reach the necessary temperature. Helion for example claims to have achieved a significant amount of D-He3 reactions. LPPFusion has published research saying they've achieved boron fusion temperatures, though not with boron fuel, or the triple product needed for net power from boron. (They're using deuterium though, and getting neutrons.)
- AtlasBarfed 4y agoONe of the issues with Fusion: those neutrons mean it isn't the infinite clean energy source: using the reactor makes nuclear waste from the reactor vessel. Also, even if a viable fusion reaction is produced, it has the same problem as fission reactors: you have to be price competitive with grid storage and load levelling reactors. I can almost guarantee that fusion will never beat solar/wind. Maybe they'd get away with not being NIMBY'd like the fission reactors and overregulated, but if they don't, costs go up.
- CodeWriter23 4y agoI’m no physicist, but I’m pretty sure presence of plasma in these gizmos indicates fusion. I think though you’re asking if it was a self-sustaining reaction, and my impression (could be wrong) they did the ignition and they are stress testing the device and it’s heating and cooling systems.
- aqme28 4y agoThere are a lot of relatively cold plasmas that don’t indicate fusion. Well, sure, maybe a few particles defy the odds and fuse, but really you’re seeing basically none unless the heat and density get high enough.
- zardo 4y agoUnless they mention fusion, they are likely using test plasma that isn't going to fuse.
- pantalaimon 4y agoYou can create a plasma in your microwave, that doesn't mean there is fusion.
- lazide 4y agoYou can buy an inexpensive plasma cutter at harbor freight that is happy to generate as much plasma as you want (while cutting metal). It definitely isn’t doing any atomic fusion anywhere. It’s also what arc welders weld with. Plasma is ionized gas (hence conductive), the ‘fourth state of matter’ and while usually hot, it doesn’t necessary have to be. [https://en.m.wikipedia.org/wiki/Plasma_(physics) https://en.m.wikipedia.org/wiki/Plasma_(physics)]
- CodeWriter23 4y agoPresented in the context of “in these gizmos”. I did not say all plasma is fusion.
- lazide 4y agoMost of these will be using plasma which is not fusing most of the time for testing, validation, etc. Fusing plasma makes a lot of neutrons which cause problems, including irradiating things.
- aqme28 4y agoI believe this was an experiment to see that they can put a lot of energy into the reactor, and take a lot of energy out of it as well. Both of these are necessary criteria for a power plant.
- pantalaimon 4y agoYes Wendelstein 7-X is not intended to produce fusion, it's an experiment to evaluate the stellarator concept.
- DennisP 4y agoThey do plan to fuel it with deuterium and run it over 100 million degrees. They'll get fusion neutrons out of that. What they don't plan is deuterium-tritium fuel or a net power attempt. https://euro-fusion.org/devices/wendelstein-7-x/ https://euro-fusion.org/devices/wendelstein-7-x/