In this paper, random variations in the pitch-angle of charged
particles that move in a turbulent magnetic field have been investigated.
In the astrophysical theater, this situation is realized
by cosmic rays and solar particle events, both of which experience
continuous deflections either in the interstellar turbulence
or in the solar-wind induced turbulence. In both cases, the random
component superposes a mean magnetic field – e.g., the
galactic magnetic field or the Parker-spiral solar magnetic field
– which gives rise to a preferred direction when investigating the
scattering processes. This motivates the transformation to a coordinate
system in which the pitch angle is taken to be a basic
variable of the particle motion.