Evidence for very weak pitch angle diffusion of outer zone electrons


  • Harold Leinbach,

  • Donald J. Williams


Integral fluxes of locally trapped and loss cone electrons >30 keV were measured with the low-altitude polar-orbiting satellite Ogo 6. In the outer zone, weak pitch angle diffusion region, the observed ratios of precipitated to locally trapped electron intensities were generally a few percent. However, the ratios of backscattered to precipitated electrons were often greater than one in situations where they should not exceed unity. We show that both loss cone detectors were usually counting a significant flux of locally trapped electrons scattered off the walls of their respective collimators. Under conditions leading to a minimum of wall-scattered electrons in the precipitation loss cone detector, the upper limit of the ratio of precipitated to locally trapped electrons can be set at 5 × 10−4 to 10−3. These values are consistent with theoretical calculations for weak (<30 mγ) whistler mode magnetic field amplitudes of the scattering waves. We suggest that previously reported loss cone/trapped flux ratios of a few percent (and the diffusion coefficients derived therefrom) are either incorrect or do not represent minimum diffusion conditions.