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Title:Motion of charged particles in pulsar magnetospheres
Author(s):Zachariades, Haris Andrea
Doctoral Committee Chair(s):Jackson, E.A.
Department / Program:Physics
Subject(s):charged particles
pulsar magnetospheres
Lorentz-Dirac equation
Abstract:The motion of charges in the magnetosphere of pulsars is studied from two complementary points of view: (i) For the case of aligned magnetic and rotational axes we solve a fluid version of the Lorentz-Dirac equation, in the Landau approximation, for a two-component plasma. We start from an approximately force-free initial condition and numerically integrate the equations of motion for a time equal to 1.6% of one stellar rotation period. We find that the system tends to a charge-separated state in which a negative charge region above the poles is separated by a vacuum gap from a positive charge region near the equator. We see the formation of force-free regions and a tendency of the vacuum gap to spread as the integrations proceed. The energies attained by the charges are only mildly relativistic and radiation reaction does not play an important role during the integrations. The negative charge above the polar region is electrostatically bound and there is a force-free region towards which negative charge tends to flow. Some positive charge is magnetically confined near the stellar equator and other positive charge crosses magnetic field lines moving outward to the region beyond the light cylinder. The outward motion of positive charge is due to the relative magnitudes of the electric and magnetic fields. (ii) For the case of non-aligned axes we study the single particle dynamics for electrons movlll ing in the region beyond the light cylinder, again using the Landau approximation to the Lorentz-Dirac equation. The effect of the inner magnetosphere is taken into account by adding a central attractive charge. We find that there exists a class of solutions corresponding to bounded orbits beyond the light cylinder. In an independent particle picture, particles started with different initial conditions within the basin of attraction of this class of orbits eventually form corotating patterns beyond the light cylinder. For a frequently occuring particle configuration we find emission from radio to 1-ray frequencies with a spectrum different than that of synchrotron radiation. We also show the existence of phase locked dynamics for this system. These results suggest a possible structure of the outer magnetosphere of a non-aligned pulsar.
Issue Date:1992
Genre:Dissertation / Thesis
Rights Information:1992 Haris Andrea Zachariades
Date Available in IDEALS:2011-05-04
Identifier in Online Catalog:3473707

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