  Pulsar magnetospheres are thought to be filled with electron-positron plasma
generated in pair cascades. The driving mechanism of these cascades is the
emission of gamma-ray photons and their conversion into pairs via Quantum
Electrodynamics (QED) processes. In this work, we present 2D particle-in-cell
simulations of pair cascades in pulsar polar caps with realistic magnetic field
geometry that include the relevant QED processes from first principles. Our
results show that, due to variation of magnetic field curvature across the
polar cap, pair production bursts self-consistently develop an inclination with
respect to the local magnetic field that favors the generation of coherent
electromagnetic modes with properties consistent with pulsar radio emission. We
show that this emission is peaked along the magnetic axis and close to the
polar cap edge and may thus offer an explanation for the core and conal
components of pulsar radio emission.
