Global Monitoring of the Terrestrial Ring Current - ESA Space ...

Bounce
motion
Alpbach Summer School, 2002
Second adiabatic invariant
J = ∫ p//
ds
The particle moves up and down the field line, bouncing
between mirror points in the northern and southern
hemispheres. The adiabatic invariant J associated with
the bounce motion is conserved if the magnetic field
changes only on a time scale that is long compared to the
bounce period.
Proton drift
motion
Electron drift
motion
that is much longer than Alpbach the Summer drift School, period.
2002
Third adiabatic invariant
B × ∇H
( µ , J , x,
t)
v D =
=
2
qB
r 2
E×
B µ B × ∇B
p!
! B × k
= + +
2
2
2
B γqB 2mγqB
The slowest of the three quasi-periodic quasi periodic motions is drift
around the Earth. In a guiding-center guiding center bounce-averaged
bounce averaged
condition, the charged particle drifts across the magnetic
field with a velocity vD. . The adiabatic invariant associated
with the drift motion, the magnetic flux inside the drift
orbit, is conserved if E and B change only on a time scale
that is much longer than the drift period.