Q: Magnetization?

[Erhannis]

I'm interested in doing some electromagnetic simulations, but less simulations of propagating waves and more simulations of the interactions between currents and charged particles and ferromagnetic materials - for instance, currents inducing magnetization of an iron core, which in turn affects the motion of nearby charged particles. It's not clear to me if Meep supports that. It seems like it supports scenarios that are (imo) significantly more complex than that, so I'd hope it also supports the simpler case, but neither the docs nor the issues contain the word "magnetized", according to search, so I'm unsure. How much code is there between where the system is and where it would need to be to simulate such a system? Which parts are missing?

[stevengj]

Meep supports magnetic materials, but it sounds like what you are interested in is magnetostatics. A time-domain code is not a good tool for statics.

Also, if you want to simulate the motion of free electrons (e.g. electron beams) being affected by electromagnetic fields, that is a very different problem and is also not supported by Meep. (You can put electron beams as sources in Meep, but you cannot easily simulate the back-action of the resulting fields on the free charge motion. The latter requires a simulation of the Newton–Lorentz equations of motion for each particle, which you would have to do separately from Meep.)

[Erhannis]

Oh - I was under the impression that magnetostatics required things be held static; apparently this is only sorta the case? I'm not sure precisely what wikipedia means by "rapidly" in "Magnetostatics is even a good approximation when the currents are not static – as long as the currents do not alternate rapidly." So depending on how rapid is rapid, it's possible magnetostatics would work. In cases where currents ARE rapidly changing, what would one use rather than magnetostatics? (I'd have imagined "magnetodynamics", but googling that just turns up magnetohydrodynamics, haha.) Just electromagnetics, or some other system?