Bibliographic Details
| Title: |
Competitive Influences of Different Plasma Waves on the Pitch Angle Distribution of Energetic Electrons Inside and Outside Plasmasphere. |
| Authors: |
Li, L. Y., Yu, J., Cao, J. B., Chen, L. J., Reeves, G. D., Blake, J. B. |
| Source: |
Geophysical Research Letters; 1/16/2022, Vol. 49 Issue 1, p1-10, 10p |
| Subject Terms: |
ELECTRON distribution, PLASMA waves, SPECIFIC gravity, RADIATION belts |
| Abstract: |
By analyzing the Van Allen Probe B observations and 2‐D simulations, we found that the competitive influences of different plasma waves on the pitch angle distribution of energetic electrons (hundreds of keV) depend on density of ambient plasmas and relative intensity of waves. In the high‐density plasmasphere (>70 cm−3), plasmaspheric hiss is able to effectively remove small pitch angle electrons (<60°), while the participation of intense magnetosonic (MS) waves merely increases part of large pitch angle electrons (>60°). The combined diffusions by the two waves create pancake‐like electron pitch angle distributions in the high‐density region. Outside the plasmapause, the same‐intensity MS waves and weak exohiss waves mainly reduce large pitch angle electrons and thus create butterfly‐like pitch angle distributions in the low‐density trough (<70 cm−3). These results indicate that energetic electrons could have different pitch angle distributions under similar wave environments but different plasma densities. Plain Language Summary: Plasmaspheric hiss and exohiss waves can remove radiation belt electrons, whereas magnetosonic (MS) waves mainly accelerate radiation belt electrons and create butterfly‐like pitch angle distributions. When these waves appear simultaneously in the same region, their competitive influences on high‐energy electrons are not understood clearly. Here, the in‐situ observations by Van Allen Probe B show the different responses of the pitch angle distribution of energetic electrons to the coexisting of MS waves and hiss or exohiss waves under different plasma densities. By simulating the electron energy and pitch angle diffusions caused combinedly by the two waves, we found that the competitive influences of different plasma waves on energetic electrons depend not only on the relative intensity of waves but also on the density of ambient plasmas. These results improve our understanding of the formation mechanisms of different electron pitch angle distributions under similar wave environments but different plasma densities. Key Points: Energetic electrons have pancake‐like pitch angle distributions in the high‐density plasmasphere of coexisting hiss and MS wavesPitch angle distributions of energetic electrons become butterfly‐like in the low‐density trough of coexisting exohiss and MS wavesCompetitive influences of different plasma waves on energetic electrons depend on ambient plasma density and relative intensity of waves [ABSTRACT FROM AUTHOR] |
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| Database: |
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