Today
• Finish Cosmic rays
• Bowshock
• Upstream region (how to make plasma
waves)
• Begin Magnetosphere Convection
neutron monitors
Solar Flare can produce 1030 ergs
30
• But a single
Galactic
Cosmic Ray
can be over
1020 eV all
by itself
Cosmic Ray
energy flux
comparisons
Cosmic ray shower animation next
Cosmic Radiation
June 2006
Cosmic
Rays are the
prime
source for
ions in the
atmosphere
+,- ions generated
per second per
cubic centimeter
Last time we talked about the solar wind, now lets see
what happens when it hits the Earth’s environment
Now, start with
Bow Shock
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