SM44B-07
Inner zone electron radial diffusion coefficients - An update with Van Allen Probes MagEIS data
Thursday, 17 December 2015: 17:21
2009 (Moscone West)
Thomas Paul O'Brien III1, S. G. Claudepierre2, J. F. Fennell3, Drew L Turner4, Timothy B Guild5, J Bernard Blake6, Joseph E Mazur7, James H. Clemmons7 and J. L. Roeder2, (1)Aerospace Corporation, Los Angeles, CA, United States, (2)The Aerospace Corp, Los Angeles, CA, United States, (3)Aerospace Corporation Los Angeles, Los Angeles, CA, United States, (4)Aerospace Corporation El Segundo, El Segundo, CA, United States, (5)The Aerospace Corporation, Chantilly, VA, United States, (6)Aerospace Corporation Santa Monica, Santa Monica, CA, United States, (7)Aerospace Corporation Chantilly, Chantilly, VA, United States
Abstract:
Using MagEIS data from NASA’s recent Van Allen Probes mission, we estimate the quiet-time radial diffusion coefficients for electrons in the inner radiation belt and slot, for energies up to ~700 keV. We provide observational evidence that energy diffusion is negligible. The main dynamic processes, then, are radial diffusion and elastic pitch angle scattering. We use a coordinate system in which these two modes of diffusion are separable. Then we integrate over pitch angle to obtain a field line content whose dynamics consist of radial diffusion and loss to the atmosphere. We estimate the loss timescale from periods of exponential decay in the time series. We then estimate the radial diffusion coefficient from the temporal and radial variation of the field line content. We show that our diffusion coefficients agree well with previously determined values. Our coefficients are consistent with diffusion by electrostatic impulses, whereas outer zone radial diffusion is thought to be dominated by electromagnetic fluctuations.
