Review: Frozen in Condition - University of...

Review: Frozen in Condition

Plasma and B-field move together

Another way to think of this is by transforming the E field into the moving frame so Ohms Law is

Which just becomes the frozen in condition for large σ

Dominated by vxB term

Evolution of solar magnetic fields over three solar cycles

• http://en.wikipedia.org/wiki/File:Evolution_of_Magnetism_on_the_Sun.ogv

http://www.hao.ucar.edu/research/siv/images/full_pred12.gif

Babcock Theory summary:

1. Differential solar rotation winds up the B-field

2. Flux ropes become buoyant, and pop up (stops B-field growth)

3. Sunspots migrate/diffuse annihilating more equatorward (preceding) spots, and changing polar polarity from with following spots

4. This changes poloidal field and winding adds opposite polarity B (unwinds)

Meridonal flow

Butterfly diagram (sunspots)

Photosphere, Chromosphere, Corona

What is a Plasma?• Nothing less than the 4th state of matter• When a Solid heats up, it melts to

become a liquid• When a Liquid heats up, it evaporates

to become a gas• When a Gas heats up, it ionizes to

become a plasmaNote: Chapter 2 of Kivelson&Russell is an intro to Plasma Physics

Kinetic to potential energy ratio is very large!

particles

Fn=Ae(-1/2mv2/kT)

+qΦ

Shielding of potentials inside a plasma

Debye, or shielding distance in a plasma

Plasma Frequency is given by the square root of the density n, times a constant!