A Brief Introduction to Space Plasma Physics.pdf - Institute of ...

• The exponent gives the phase of the wave.
The phase velocity specifies how fast a feature
of a monotonic wave is moving
v ph
=
ω r
k
2
k
•Information propagates at the group velocity. A
wave can carry information provided it is formed
from a finite range of frequencies or wave
numbers. The group velocity is given by
∂
v g
= r
ω
∂k
•The phase and group velocities are calculated
and waves are analyzed by determining the
dispersion relation
ω = ω(k)