Magnetic Mirroring and the Loss Cone
A particle's pitch angle increases as it moves into a region of stronger magnetic field and decreases as it moves into a region of weaker field.
In a simple magnetic mirror geometry the magnetic field reaches a minimum value at the center of the geometry and a maximum value at the end. Particles within such a geometry can follow a range of trajectories, as described below.
stuck in the center
A particle with pitch angle cannot
move into a region of stronger magnetic field, so a particle with
the center of the magnetic mirror, where B = Bmin) cannot move away
from the center of the mirror.
straight and narrow
On the other hand, a particle with pitch angle is
free to move anywhere and readily travels out of the magnetic mirror.
trapped in the mirror
In a magnetic mirror geometry, particles with pitch angles in the following range are trapped within the magnetic mirror:
into the loss cone
However, particles with are
said to be in the loss cone and can escape the magnetic mirror.