Last time we had an overview of some aspects of the bow shock, magnetosheath, and the magnetosphere.
Now, start with Bow Shock
Today
• Bowshock
• Upstream region (how to make plasma waves)
• 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
• WHAT is an equation of state?
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