  A new model for the high-energy emission from pulsars is developed by
considering charged particle motion in the fields of a spinning, highly
magnetised and conducting sphere in vacuum. A generally applicable
approximation to the particle motion in strong fields is developed and applied
to the numerical modelling, and the radiation emitted by curvature emission is
summed to generate light curves. The model predicts many of the observed
features of pulsar light curves. This paper outlines the basic properties of
the model; a subsequent paper will discuss the statistical properties of a
population of model pulsars and apply the model to the known gamma-ray pulsars.
