Friday, March 30, 2012


After seeing more stories on the subject ofsolar tornadoes (which I noted a little while back) I was going to try a post on magnetic reconnection: what you can get when you twist plasma around like that. Turns out that Wikipedia does a good enough job already, so I'll point you there and save the electrons. There are still mysteries: "A current problem in plasma physics is that observed reconnection happens much faster than predicted by MHD in high Lundquist number plasmas: solar flares, for example, proceed 13-14 orders of magnitude faster than a naive calculation would suggest, and several orders of magnitude faster than current theoretical models that include turbulence and kinetic effects."

Reconnections can produce intense electric fields thanks to the rapidly varying magnetic fields, and these electric fields accelerate electrons and protons to relatively high energies--much higher you'd estimate from their kinetic energy in the hot plasma. The magnetic fields of collapsed stars, and of supernovae, may do the same thing, but with much higher intensity; and that's been proposed as the source of some of the cosmic rays that bombard us. We can't track the cosmic rays back to their progenitor stars (if that is really the source) because the galactic magnetic fields, weak though they are, act over large enough distances to bend charged particles this way and that.

When I saw that solar tornado I thought "particle accelerator."


Assistant Village Idiot said...

I read a phrase like 13-14 orders of magnitude and despair. Beyond my ken, and I'm a math guy. Mere symbols to be moved.

james said...

Think of it as the difference between your monthly car payment and the federal debt. (Actually, that's just the naive calculation--they say that the more complex one is only a factor of a thousand too low.)

james said...

Oops. Make that a candy bar and the federal debt.