  We present numerical simulations of electron-positron pair cascades in the
magnetospheres of magnetic neutron stars for a wide range of surface fields
(B_p = 10^{12}--10^{15} G), rotation periods (0.1--10 s), and field geometries.
This has been motivated by the discovery in recent years of a number of radio
pulsars with inferred magnetic fields comparable to those of magnetars.
Evolving the cascade generated by a primary electron or positron after it has
been accelerated in the inner gap of the magnetosphere, we follow the spatial
development of the cascade until the secondary photons and pairs leave the
magnetosphere, and we obtain the pair multiplicity and the energy spectra of
the cascade pairs and photons under various conditions. Going beyond previous
works, which were restricted to weaker fields (B < a few x 10^{12} G), we have
incorporated in our simulations detailed treatments of physical processes that
are potentially important (especially in the high field regime) but were either
neglected or crudely treated before, including photon splitting with the
correct selection rules for photon polarization modes, one-photon pair
production into low Landau levels for the e^+e^-, and resonant inverse Compton
scattering from polar cap hot spots. We discuss the implications of our results
for the radio pulsar death line and for the hard X-ray emission from magnetized
neutron stars.
