MICROTEXTURE IN THE PULSAR RADIO-EMISSION ZONE

This paper completes an analysis of a non-linear mechanism for pulsar radio radiation. This non-linear process results from the evolution of relativistic two-stream instability in the pulsar magnetosphere, which gives rise to strong Langmuir turbulence. There are stable Langmuir soliton-like solutions, called 'Langmuir microstructures', which may form a lattice in the magnetosphere. These Langmuir microstructures naturally produce three different types of radiation. The first is direct radiation of the microstructures themselves when perturbed in a direction perpendicular to the magnetic field lines. This is sufficient to account for the observed radio luminosities and temporal microstructures as long as the perpendicular gradient of the amplitude of the Langmuir soliton is important. The second is curvature radiation of the microstructures when they move along the dipolar magnetic field lines. This has to be considered as a marginal phenomenon because it would require extreme conditions to be efficient enough. The third radiation mechanism is due to the acceleration of beam particles interacting with the lattice of Langmuir microstructures. When some coherence is maintained between the phases of the beam particles, for instance by modulation of the beam, the radiated power produced through this interaction can reach a high level. It is efficient enough to account for observed radio luminosities, even if the gradient of the amplitude of the microstructures is small.