In the presence of a magnetic field a charged particle experiences a Lorentz force
Rearranging,
which has the solution
where,
for 
.
Letting 
The angle, 
is known as the Pitch Angle. The above descriptions of the particle
trajectory can be used to determine the radiation charactersitics of the
particle through equation 180. The latter can be cast into a more
convenient form,
Comparing 192 and 193
Susbstituing into equation 193
Why can we ignore protons?
where 
is the Thomson cross section and 
.
For an isotropic probability distribution
where 
.
For an ensemble of particles 
.
which describes both emitted and received power.
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