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Seems like partially a Dennis Whyte puff piece. The problem all tokomaks have is that ELMs exist and will remove the inner lining of the containment unit over
by cjslep 8y ago
Seems like partially a Dennis Whyte puff piece.
The problem all tokomaks have is that ELMs exist and will remove the inner lining of the containment unit over time, and current cutting edge research is on how a plasma will react with specific impurities and their distribution within said plasma. A major problem is lack of true experimental evidence, as most fusion experiments are crude approximations of reality and then subsequent closed source, poorly documented, or guess-the-fellow-researchers code is at play.
Source: talked a lot this past holiday from a friend at ITER.
- xorfish 8y agohttps://en.wikipedia.org/wiki/Edge-localized_mode https://en.wikipedia.org/wiki/Edge-localized_mode For anyone wondering what ELMs are.
- lambdadmitry 8y agoAnother problem, apparently, is plasma disruptions [1]. They are more dramatic, can irreparably damage the vessel, and hard to solve or mitigate. ITER has a taskforce dedicated to them [2], but it remains to be seen if that approach will work (and the energy will still be dumped into the first wall and support structure, albeit less local than with relativistic electrons). [1]: https://en.wikipedia.org/wiki/Tokamak#Plasma_disruptions https://en.wikipedia.org/wiki/Tokamak#Plasma_disruptions [2]: https://www.iter.org/newsline/-/3183 https://www.iter.org/newsline/-/3183
- sandworm101 8y agoAnother approach to this is to not use solid walls. General Fusion (BC, Canada) is playing with the idea of a spherical plasma within a void of spinning liquid lead. The lack of solid walls makes for some very interesting options in terms of damage mitigation.
- lambdadmitry 8y agoThey already abandoned that idea AFAIK. Liquid lead wall introduced too much contamination into the plasma, making fusion impossible.
- pfdietz 8y agoMore specifically, they went to a scheme where liquid metal compressed the plasma more slowly against a solid inner column. The slowness was needed to keep the magnetic field below 100T, beyond which currents in the surface of the metal begin to vaporize it. But there are a host of other extremely challenging problems that pushes this idea to the "be very skeptical" column.
- DennisP 8y agoAs long as "over time" isn't too short of a time, the MIT has it covered. Their design makes it easy to crack open the reactor and replace the inner wall, which will be 3D-printed. They plan to do it annually.
- cjslep 8y agoI read the article. I wasn't clear in my original post. The issue isn't the ablation of the containment wall and replacing the wall, the issue is how to properly manage the plasma as the containment impurities disperse throughout the plasma and how it impacts the fusion, magnetic, pressure, and temperature characteristics on both a local and macro level. Which is a common problem between the MIT and other tokomak reactors.
- gitpusher 8y agoThis was my impression as well. Seems like the only significant development here is that superconducting tape might work better than regular magnets. Or it might not.
- ChuckMcM 8y agoI don't disagree with this: ELMs exist and will remove the inner lining of the containment unit over time, and current cutting edge research is on how a plasma will react with specific impurities and their distribution within said plasma. It is one of the things that I look forward to from the stellarator folks[1] is their ability to continuously run plasma up against a variety of materials. [1] https://www.ipp.mpg.de/w7x https://www.ipp.mpg.de/w7x