We present numerical simulations of the electron-positron plasma creation process in a simple neutron star magnetosphere. We have developed a set of cascade `kernels, which represent the endpoint of the pair cascades resulting from monoenergetic photon seeds. We explore two popular models by convolving these kernels with the seed photon distributions produced by curvature radiation and by inverse Compton scattering. We find that the pair plasma in either case is well-described in its rest frame by a relativistic Maxwellian distribution with temperature near mc^2/k_B. We present cascade multiplicities and efficiencies for a range of seed particle energies and stellar magnetic fields. We find that the efficiencies and multiplicities of pair creation are often lower than has been assumed in previous work.
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