A Simulation Study of Kilometric Radiation Generation Along an Auroral Field Line

P. L. Pritchett and R. J. Strangeway

Institute of Geophysics and Planetary Physics,
University of California at Los Angeles

Department of Physics,
University of California at Los Angeles


J. Geophys. Res., 90, 9650-9662, 1985
(Received January 14, 1985; revised June 11, 1985; accepted June 12, 1985)
Copyright 1985 by the American Geophysical Union
Paper number 5A8480
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Figure Captions

Fig. 1. Variation of the electron gyrofrequency , the plasma frequency/gyrofrequency ratio / , and the characteristic perpendicular momentum p as a function of geocentric distance along an auroral field line [from Strangeway, 1985].

Fig. 2. The electron distribution function at three altitudes along an auroral field line. Contours of constant phase density are shown for the magnetospheric electron population (solid circles) and for the ionospheric electron population (dotted circles).

Fig. 3. The electron density as a function of geocentric distance along an auroral field line. The curve labeled "data" gives the observed variation [Calvert, 1981]. The curve "fit," which is the sum of n and n given by equations (10) and (11), is best fit to this observed density.

Fig. 4. Coordinate system used in the two-dimensional particle simulations.

Fig. 5. Electron momentum-space distributions in a two-dimensional simulation with 1.5 R auroral parameters. (a) Initial distribution (t = 0). (b) Distribution at saturation (t = 850). (c) Contours of f(p, p) at saturation. The contour values range from 0.056fmax for outermost dotted contour to 0.944fmax for the innermost solid contour. The spacing between countours is linear.

Fig. 6. Same as Figure 5 except for a one-dimensional simulation with = 90° and 2.5 R auroral parameters. The saturation plots in Figures 6b and 6c are for t = 2400.

Fig. 7. Time history of (a) the total tranverse electric energy E and (b) the extraordinary mode energy | E | for mode 28 in a one-dimensional simulation with = 90° and 1.5 R auroral parameters. The electric energies are normalized to the initial electron kinetic energy (K. E.).

Fig. 8. Time history of the tranverse electric field amplitudes squared for mode 28 in a one-dimensional simulation with = 90° and 1.5 R auroral parameters. The solid curve shows the extraordinary mode | E | , while the dashed curve shows the ordinary mode | E | multiplied by a factor of 124. The field amplitudes have been averaged over half a gyroperiod.

Fig. 9. Time history of the tranverse electric field amplitude squared for mode 28 in a one-dimensional simulation with oblique propagation and 1.5 R auroral parameters. The different growth rates for propagation at 85° and 95° to the magnetic field are apparent.

Fig. 10. Time history of total tranverse electric energy E in one-dimensional simulations with 2.5 R auroral parameters for various values of .

Fig. 11. The tranverse electric energy density | E(k, k)| for a two-dimensional simulation with 1.5 R auroral parameters.

Fig. 12. Electron momentum-space distributions in a one-dimensional simulation with 1.75 R auroral parameters and 75% magnetospheric electrons, 25% ionospheric electrons. (a) Initial distribution (t = 0). (b) Magnetospheric component saturation (t = 1600). (c) Total distribution at saturation. (d) Contours of f (p, p) at saturation.


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