The nearby radio pulsar B0950+08 with full duty cycle is targeted by the
Five-hundred-meter Aperture Spherical radio Telescope (FAST, 110 minutes
allocated), via adopting polarization calibration on two ways of baseline
determination, in order to understand its magnetospheric radiation geometry as
well as the polar cap sparking. % The radiation of the main pulse could not be
informative of magnetic field line planes due to its low linear polarization
(<10%) and the position angle jumps, and the polarization position angle in
the pulse longitudes whose linear fractions are larger than ∼30% is
thus fitted in the classical rotating vector model (RVM). % The best RVM fit
indicates that the inclination angle, α, and the impact angle, β,
of this pulsar are 100.5∘ and −33.2∘, respectively,
suggesting that the radio emission comes from two poles. % Polar cap sparking
in the vacuum gap model, either the annular gap or the core gap, is therefore
investigated in this RVM geometry, resulting in a high-altitude magnetospheric
emission at heights from ∼0.25RLC​ to ∼0.56RLC​, with
RLC​ the light cylinder radius. % It is evident that both sparking
points of the main and inter pulses are located mainly away from the magnetic
pole, that is meaningful in the physics of pulsar surface and is even relevant
to pulsar's inner structure.Comment: 13 pages, 9 figures, submitte