Geomagnetic storms are responsible for the large increase of trapped electr
on fluxes in the magnetosphere resulting in the formation of radiation belt
s. Such belts can also be artificially produced by injection of electron be
ams. The dynamic evolution of the electron fluxes is very important for sat
ellite protection purpose. Up to now most of the existing studies have been
restricted to the stationary description of natural radiation belts. Recen
tly, great effort has been made for their dynamic description [Bourdarie et
al., 1996]. We have developed a numerical code, which is able to follow th
e time behavior of the electron population under influence of collisions wi
th tenuous atmosphere and resonant scattering by plasma waves. The code sol
ves the phase-averaged Fokker-Planck equation of the electron momentum dist
ribution function on magnetic shells within the Earth's inner magnetosphere
. The physical arguments incorporated in the code include phase-averaged, a
pproximate collision operators and quasi-linear diffusion due to resonant i
nteraction with whistler plasma waves. The magnetic field is supposed to be
tilted and decentered. Numerical experiments to simulate the decay and par
ticles' loss in an artificial Van Allen belt are presented, and comparisons
with available published data are discussed to validate the code [Abel and
Thorne, 1998].