Scattering and Diffraction in Magnetospheres of Fast Pulsars

We apply a theory of wave propagation through a turbulent medium to thescattering of radio waves in pulsar magnetospheres. We find that underconditions of strong density modulation the effects of magnetosphericscintillations in diffractive and refractive regimes may be observable. Themost distinctive feature of the magnetospheric scintillations is theirindependence on frequency. Results based on diffractive scattering due to small scale inhomogeneitiesgive a scattering angle that may be as large as 0.1 radians, and a typicaldecorrelation time of $10^{-8}$ seconds. Refractive scattering due to large scale inhomogeneities is also possible,with a typical angle of $10^{-3}$ radians and a correlation time of the orderof $10^{-4}$ seconds. Temporal variation in the plasma density may also resultin a delay time of the order of $10^{-4}$ seconds. The different scaling of theabove quantities with frequency may allow one to distinguish the effects ofpropagation through a pulsar magnetosphere from the interstellar medium. Inparticular, we expect that the magnetospheric scintillations are relativelymore important for nearby pulsars when observed at high frequencies.Comment: 19 pages, 1 Figur