Role of Ducting in Relativistic Electron Loss by Whistler‐Mode Wave Scattering
Role of Ducting in Relativistic Electron Loss by Whistler‐Mode Wave Scattering
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DOI：
10.1029/2021ja029851
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发表时间：
2021-10
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通讯作者：
A. Artemyev;A. Demekhov;X.‐J. Zhang;V. Angelopoulos;D. Mourenas;Y. Fedorenko;J. Maninnen;E. Tsai;C. Wilkins;S. Kasahara;Y. Miyoshi;A. Matsuoka;Y. Kasahara;T. Mitani;Y. Shoichiro;K. Keika;T. Hori;S. Matsuda;S. Nakamura;M. Kitahara;T. Takashima;I. Shinohara
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文献类型：
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作者：
A. Artemyev;A. Demekhov;X.‐J. Zhang;V. Angelopoulos;D. Mourenas;Y. Fedorenko;J. Maninnen;E. Tsai;C. Wilkins;S. Kasahara;Y. Miyoshi;A. Matsuoka;Y. Kasahara;T. Mitani;Y. Shoichiro;K. Keika;T. Hori;S. Matsuda;S. Nakamura;M. Kitahara;T. Takashima;I. Shinohara
高能电子与电磁哨声模式波（哨声）的共振相互作用对地球外辐射带中电子通量的动力学有重要贡献。在低地磁纬度，这些波是非常有效的俯仰角散射和降水到电离层的低赤道俯仰角，几十keV的电子和加速的高赤道俯仰角电子相对论能量。相对论性（数百keV），电子也可以通过与哨声的共振相互作用而沉淀，但这需要波准平行传播而不会显著降低强度到高纬度，在那里它们可以与比赤道更高能量的低赤道俯仰角电子共振。在非均匀磁场中，远离赤道源区域的波传播导致射线从最初的场对准方向发散，并通过与超热电子的朗道共振产生有效的波阻尼，从而降低了波在高纬度散射电子的能力。然而，波的传播可以沿着沿着场对齐的密度峰（管道）进行管道化，从而防止射线发散和波阻尼。因此，这种管道可能导致显着的相对论性电子沉淀。我们提出的证据表明，管道哨声有效地沉淀相对论电子。我们同时采用近赤道和地面测量的哨声和低海拔电子降水测量ELFIN立方体卫星。我们发现，管道波（出现在地面上）有效地散射相对论电子进入损失锥，相反，非管道波（地面上不存在）沉淀只有<150 keV的电子。我们的研究结果表明，管道哨声可能是相当重要的相对论电子损失，他们应该进一步研究统计，并可能纳入辐射带模型。
Resonant interactions of energetic electrons with electromagnetic whistler‐mode waves (whistlers) contribute significantly to the dynamics of electron fluxes in Earth's outer radiation belt. At low geomagnetic latitudes, these waves are very effective in pitch angle scattering and precipitation into the ionosphere of low equatorial pitch angle, tens of keV electrons and acceleration of high equatorial pitch angle electrons to relativistic energies. Relativistic (hundreds of keV), electrons may also be precipitated by resonant interaction with whistlers, but this requires waves propagating quasi‐parallel without significant intensity decrease to high latitudes where they can resonate with higher energy low equatorial pitch angle electrons than at the equator. Wave propagation away from the equatorial source region in a non‐uniform magnetic field leads to ray divergence from the originally field‐aligned direction and efficient wave damping by Landau resonance with suprathermal electrons, reducing the wave ability to scatter electrons at high latitudes. However, wave propagation can become ducted along field‐aligned density peaks (ducts), preventing ray divergence and wave damping. Such ducting may therefore result in significant relativistic electron precipitation. We present evidence that ducted whistlers efficiently precipitate relativistic electrons. We employ simultaneous near‐equatorial and ground‐based measurements of whistlers and low‐altitude electron precipitation measurements by ELFIN CubeSat. We show that ducted waves (appearing on the ground) efficiently scatter relativistic electrons into the loss cone, contrary to non‐ducted waves (absent on the ground) precipitating only <150 keV electrons. Our results indicate that ducted whistlers may be quite significant for relativistic electron losses; they should be further studied statistically and possibly incorporated in radiation belt models.