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Detailed Reference Information |
Horne, R.B., Thorne, R.M., Glauert, S.A., Albert, J.M., Meredith, N.P. and Anderson, R.R. (2005). Timescale for radiation belt electron acceleration by whistler mode chorus waves. Journal of Geophysical Research 110. doi: 10.1029/2004JA010811. issn: 0148-0227. |
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Electron acceleration inside the Earth's magnetosphere is required to explain increases in the ~MeV radiation belt electron flux during magnetically disturbed periods. Recent studies show that electron acceleration by whistler mode chorus waves becomes most efficient just outside the plasmapause, near L = 4.5, where peaks in the electron phase space density are observed. We present CRRES data on the spatial distribution of chorus emissions during active conditions. The wave data are used to calculate the pitch angle and energy diffusion rates in three magnetic local time (MLT) sectors and to obtain a timescale for acceleration. We show that chorus emissions in the prenoon sector accelerate electrons most efficiently at latitudes above 15¿ for equatorial pitch angles between 20¿ and 60¿. As electrons drift around the Earth, they are scattered to large pitch angles and further accelerated by chorus on the nightside in the equatorial region. The timescale to accelerate electrons by whistler mode chorus and increase the flux at 1 MeV by an order of magnitude is approximately 1 day, in agreement with satellite observations during the recovery phase of storms. During wave acceleration the electrons undergo many drift orbits and the resulting pitch angle distributions are energy-dependent. Chorus scattering should produce pitch angle distributions that are either flat-topped or butterfly-shaped. The results provide strong support for the wave acceleration theory. |
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Abstract |
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Keywords
Magnetospheric Physics, Radiation belts, Magnetospheric Physics, Magnetic storms and substorms, Magnetospheric Physics, Energetic particles, precipitating, Magnetospheric Physics, Energetic particles, trapped, Magnetospheric Physics, Plasma waves and instabilities, radiation belts, electron acceleration, wave acceleration, chorus waves, pitch angle diffusion |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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