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Hi, author here. We validated the neural network controller on the real plant in a couple of experiments. All experiments in the paper are based on data from ru
by 317070 5y ago
Hi, author here. We validated the neural network controller on the real plant in a couple of experiments. All experiments in the paper are based on data from running the controller on an actual tokamak.
There is a video of one of these experiments in the linked blogpost (figure 2), where we show imagery taken from a camera looking into the vessel. Next to it is a reconstruction of the shot, visualised on a cross-section of the torus.
The simulation not perfectly matching reality is indeed a major challenge, and the nature paper is mainly about showing how you can overcome that challenge. As others have said, plasma is a pain to model, and you cannot collect a ton of data on these machines. But it seems technology is coming at a point where we know how to work within these limits and still get it to work.
- klabb3 5y agoVery cool, and thanks for replying to laymen comments such as mine. Do you think this line of research will eventually feed back into improved designs of electromagnets, chambers and so on? My limited understanding of the field is that the optimal reactor design is a moving target that's changed a lot over the years due to engineering improvements in manufacturing, material sciences and so on.
- 317070 5y agoYeah, I think the main contribution of this paper in the long run, might be that the time is right for optimizing the controller together with the hardware? I'm imagining optimizing the plasma configuration, reactor shape, coil/sensor placement and controller all in one giant computational optimization. All the algorithmic components and models humanity needs to attempt this seem to be there.
- willis936 5y agoWell as long as there have been electronic computers they have been applied they have been applied to the problems of magnetic confinement. For tokamaks static configurations and dynamic controls have been simulated. For stellarators geometry optimizations have been done. The time has always been right for this application. Stellarators are particularly fun. First you optimize a last closed magnetic flux surface (a 3D sheet) with relatively simple plasma models, then you optimize coils (you need to weight things like magnetic field error, gaps big enough for heating and diagnostics, and coil complexity a la minimum radius), then you perform more accurate simulations to start the overall optimization loop again.
- ragebol 5y agoThere's a great episode of the Omega Tau podcast on this topic, not sure which one I mean from these though: http://omegataupodcast.net/tag/fusion/ http://omegataupodcast.net/tag/fusion/
- willis936 5y agoThere are 4 episodes on fusion. You're probably referencing 312 which talks about simulating stellarator plasmas a bit. Episode 22 is an intro to fusion power research and tokamaks, but could be skipped if you are aware of the big concepts. Episode 157 is an interview of a director at ITER: the largest fusion power project in terms of scale, ambition, and funding. ITER is expected to demonstrate net energy gain fusion within the next ten years. Episode 157 gives a good sense of where the cutting edge of fusion power research exists currently and its potential place in society. Episode 304 interviews the authors of a recent popular science book on tokamaks. This episode covers the history of fusion power research, and the economics involved in future power plants. Episode 312 is a set of interviews at W7-X: the current largest stellarator. This episode take a deeper dive into what fusion research is like and how threads are being tugged on. This same podcast also has interesting episodes on plasma physics and superconductors. The superconductor episode is especially worth listening to more than once.
- exo-cortex 5y agoHi! this is fantastic article! Years ago I was able to visit the "Wendelstein 7X" stelarator-type fusion reactor in greifswald (Germany) when it was still assembled. It was so cool. Do you think this approach of controlling plasmas also translates to these types of reactors? Reading your article I didn't understand a lot of things and wondered if there was some kind of fusion-reactor-physics word-list where the most important keywords are explained a little. (without reading a whole book on plasma physics :-)) Also the timescales are fascinating. How long is 200ms in a tokamak? How long does this reactor need to ignite or shut down the plasma?
- ali_m 5y agoI think one of the challenges with stellarators is that they are harder to simulate due to the twisted geometry of the chamber (with a tokamak you can often simulate a single 2D slice of the torus).
- willis936 5y agoAll optimized stellarator designs are periodic, so only one period (with correct boundary mapping) needs to be simulated. But yeah, it's a much larger search space.
- exo-cortex 5y agothat makes a lot of sense.