摘要
Energetic outer radiation belt electron phase space density （PSD） evolution due to interaction with whistler-mode chorus at different L-shells is investigated by solving the diffusion equation including cross diffusion terms. It is found that the difference of diffusion rates for different L-shells occurs primarily at pitch angles 0°-50° and around 90°. In particular, diffusion rates for L = 6.5 are found to be 5-10 times larger than that for L = 3.5 at these pitch angles. In the presence of cross terms, PSD for - MeV electrons after 24h decreases by about 25, 12, 10 and 8 times at L = 3.5, 4.5, 5.5 and 6.5 near the loss cone, and increases by about 55, 45, 30 and 20 times at larger pitch angles, respectively. After 24 h, the ratios between - MeV electron PSDs from simulations without and with cross diffusion at L = 3.5, 4.5, 5.5 and 6.5 are about 350, 600, 800 and 800 near the loss cone, and become 5, 5.5, 6.5 and 8 at pitch angle 90°, respectively. These results demonstrate that neglect of cross diffusion generally results in the overestimate of PSD, and the cross diffusion plays a more significant role in the resonant interaction between chorus waves and outer radiation belt electrons at larger L.
Energetic outer radiation belt electron phase space density （PSD） evolution due to interaction with whistler-mode chorus at different L-shells is investigated by solving the diffusion equation including cross diffusion terms. It is found that the difference of diffusion rates for different L-shells occurs primarily at pitch angles 0°-50° and around 90°. In particular, diffusion rates for L = 6.5 are found to be 5-10 times larger than that for L = 3.5 at these pitch angles. In the presence of cross terms, PSD for - MeV electrons after 24h decreases by about 25, 12, 10 and 8 times at L = 3.5, 4.5, 5.5 and 6.5 near the loss cone, and increases by about 55, 45, 30 and 20 times at larger pitch angles, respectively. After 24 h, the ratios between - MeV electron PSDs from simulations without and with cross diffusion at L = 3.5, 4.5, 5.5 and 6.5 are about 350, 600, 800 and 800 near the loss cone, and become 5, 5.5, 6.5 and 8 at pitch angle 90°, respectively. These results demonstrate that neglect of cross diffusion generally results in the overestimate of PSD, and the cross diffusion plays a more significant role in the resonant interaction between chorus waves and outer radiation belt electrons at larger L.
基金
Supported by the National Natural Science Foundation of China under Grant Nos 40925014, 40774078 and 40874076.
