David Kirtley: recommendation

Transcript context

…Are you simulating at the level of a particle? Is there some quantum mechanical aspects to this also? How low does it go? We have multiple codes at different levels, because one of the main computational challenges is… amazingly, even given all that we have been building for fusion systems, computers are still not fast enough to simulate everything. And so, we have a number of codes that we use. One we call fluid codes, where you treat the ions, the electrons, all these fusion particles. You treat them as fluids, as gases, ideal gas law, with electromagnetic forces. In those, we can simulate not just the fusion fuel, which is important, but all of the electrical circuitry. We talked about capacitors, and magnetic coils and the electrical current and the switches. Well, we actually simulate the full thing, starting literally with a SPICE model. More of that electrical engineering. We start with the SPICE model and use that to drive the plasma physics model, and that’s one level of simulation. We use that to do design work, and then also to try to understand how we think the machine will run. But then we go one level deeper and we start thinking about particles, and we think about the ions, and we treat the ions as particles, and we look at the ion behavior. For that one, the computational resources are several orders of magnitude larger. Luckily, a lot of the work in GPUs, the AI data center work is directly applicable to those simulations. It’s been able to speed up our work, which is pretty fascinating. That’s a whole another tangent we can go down. Those hybrid codes we call them, particle and cell codes now treat the ions as particles, and that lets us measure and simulate the behavior. I mentioned the stability criteria, S star over E, the top behavior. That behavior, we now need these more advanced codes to be able to simulate, and those are more modern. We’ve only been able to apply those in practice for the last few years, actually, which is pretty fascinating that the old stability rules were built off of testing, empirical tests, where now we can simulate that, and we know why they work and how they work and we can do some predictions on them. And so that’s really fascinating that we’ve been able to push those boundaries. And what are the different variables you’re playing with? Are you still playing with topology? What are the different variables in play here?…

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