Where reconnection shows up: the Sun and tokamaks

14:27magnetic fields like near the sun or inside of a taco mac >> and then you're like it doesn't quite work >> it doesn't quite work >> I I will what's funny I the two videos two movies I watched on my flight back from North Carolina. >> Yeah. >> Two days ago was the F1 movie which you had recommended. >> Quite good. We could have done without the love story, but that's another thing. >> Yeah. >> And then Tenant, which talked about uh Tokamax and nuclear cuz they're basically long story shorten there was there was a a nuclear nexus. So it's funny that both things >> are are now being applied here to this one. [laughter] Yeah. >> So real plasmas, right? We've got finite

15:07resistivity because obviously like zero resistivity is not a thing. It's not a thing, >> right? Unless you're a superconductor, but at this heat you're not going to be a superconductor, right? [laughter] >> So, so the resistivity means that this magnetic field that second term you're going to have this diffusion of the magnetic field, right? And that violation of the ideal magneto hydrodnamics is no longer something that we're going to do. And what you end up getting is something called current sheets. Because wherever you have these magnetic fields and they crisscross and you go from let's say magnetic field going one way to magnetic field going the other way, you're going to get these current sheets. Over here, what you're seeing is the magnetic the current

15:47sheets around the sun. So in the center there, that's the sun. And then you can see the orbits of the inner planets and the orbit of Jupiter on the outside there. >> That sheet, it looks kind of like a flamingo dancer when when >> when they twirl, right? And the skirt like moves around in a certain way. That sheet is the border between where the magnetic field points towards the sun and where the magnetic field points away from the sun. >> Interesting. Okay. >> Okay. Because imagine if you have a magnetic field going this way and a magnetic field going this way, you got to pass through zero. Yes. >> Right. Cuz you got to you got to do this. >> Yeah. Yeah. >> And if it's in a small enough space, you have a very high gradient. You have a very high change in the magnetic field.

16:27And so the current is going to sort of >> collapse in that in that plane, right? And so you get these current sheets. This is just a direct consequence of Maxwell's equations. Got it. Okay. So this is again just fundamental electronamics. So so that's the heliocentric current sheet. And >> you know at at where the earth is that current sheet is like very small, >> right? Very small in magnitude. Unless you get like these mag massive coronal mass ejections and then and then it destroys our electricity. >> Every time I log on onto Twitter aka X Yeah. Someone is, oh, the the the this is the one. >> It's happening. >> This is the one that's going to wipe everything out. >> Yeah. Yeah. Exactly. Well, it never has.

17:09I mean, no, we've had some pretty bad ones actually. >> Yeah. And look, let's knock on wood cuz it's a thing. >> It is a thing. >> So, with this current sheet, right? >> Yep. >> That what's happening is that diffusive term is competing with that heat convective term, right? And what ends up happening is in the mathematics, what you really care about is the ratio between these two competing forces, >> which is the the first part of that equation with the the double cross and then the thing that looked like the equating equation.