bowshock • upstream region • begin magnetosphere...
TRANSCRIPT
Today
• Bowshock• Upstream region• Begin Magnetosphere Convection
Use Lorentz Force to explain single particle motions
Note on Biot-Savart Law, see: • http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/biosav.html
What to do first?Treat Earth’s B-field as Barrier in Solar Wind• 1st we have a Bow Shock because Solar
Wind is Supersonic (Super Alfvenic)• New Physics: Upstream Region• Magnetospheath – flow around
magnetopause• Reconnection of BIMF with Earth’s B field
So. Lets talk about the Bow Shock, and work our way into the magnetosphere
Today
From the ACE Spacecraft
http://pixie.spasci.com/DynMod/
How do Shock Waves Work?
• Shock propagation speed: not limited by plasma properties
• Example of sound speed and shock• Example of cars (p. 133 K&R)• Shock Wave causes an irreversible change
of state of the plasma
Upstream
Region Bow Shock
Magnetopause
Whenever you are in the electron foreshock, you see this plasma frequency wave
How to make waves in a plasma?
• EM Mode coupling• Mechanical stimulation• Non-thermal particle distributions =
instability to wave growth• …
Lets talk about Landau Damping and Wave Growth
This is a model of what you see in the foreshock: a background thermal distribution, and a fast ‘beam’ moving up the field line
After the plasma passes through the shock, the state of the plasma has irreversibly changed:
P, T and n (and B) are all changed irreversibly.
We have a new equation of state.
Upstream region
Bow Shock
Now lets examine plasma processes at the magnetopause