Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss: 2. Time evolution of the distribution function
Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss: 2. Time evolution of the distribution function
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DOI：
10.1029/95ja01556
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发表时间：
1995-11
影响因子：
--
通讯作者：
J. Kozyra;C. E. Rasmussen;Ronald H. Miller;E. Villalón
中科院分区：
文献类型：
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作者：
J. Kozyra;C. E. Rasmussen;Ronald H. Miller;E. Villalón
模拟了与导管等离子体嘶嘶共振相互作用时，弹跳平均环电流/辐射带质子分布的演变。等离子体的嘶嘶声被认为是由环电流电子产生的，并被高能质子所抑制。因此，能量在高能电子和质子之间传递，利用等离子体的嘶嘶声作为媒介。这个问题并不是自行解决的。在模拟期间，假设与环电流电子（未在模型中表示）的相互作用在高能质子阻尼存在的情况下保持波幅，从而使波谱保持固定。Kozyra et al.（1994）已经计算了俯仰角、横俯仰角/能量和能量的扩散系数，本研究采用了这些系数。模拟处理能量范围E≥80kev，在此范围内，波扩散比其他质子损失过程（即库仑阻力和电荷交换）在更短的时间尺度上运行。这些其他损失过程不包括在模拟中。模拟的一个有趣结果是，能量扩散在接近大气损失锥边缘的中等俯仰角处达到最大。在模拟期间，在中等俯仰角下，能量的扩散在弹跳平均质子分布函数中产生了一个数量级的增强。由于粒子在小俯仰角的散射较弱，损耗锥几乎是空的。反射平均通量分布，映射到电离层高度，导致局部镜像质子通量升高。OGO 5观测到，在350至1300公里高度和50°至60°不变纬度上，局部镜像高能质子的数量级增强（Lundblad和Soraas， 1978）。质子分布在俯仰角上具有高度的各向异性，损失锥几乎为空。观测到的分布与模拟结果之间的相似性提出了一种可能性，即等离子体的相互作用在形成和维持亚极光电离层各向异性质子沉淀的特征区中发挥了作用。进一步评估这一过程的重要性取决于对内磁层中传导等离子体的嘶嘶声在空间和时间上的分布的了解。
The evolution of the bounce-averaged ring current/radiation belt proton distribution is simulated during resonant interactions with ducted plasmaspheric hiss. The plasmaspheric hiss is assumed to be generated by ring current electrons and to be damped by the energetic protons. Thus energy is transferred between energetic electrons and protons using the plasmaspheric hiss as a mediary. The problem is not solved self-consistently. During the simulation period, interactions with ring current electrons (not represented in the model) are assumed to maintain the wave amplitudes in the presence of damping by the energetic protons, allowing the wave spectrum to be held fixed. Diffusion coefficients in pitch angle, cross pitch angle/energy, and energy were previously calculated by Kozyra et al. (1994) and are adopted for the present study. The simulation treats the energy range, E ≥ 80 keV, within which the wave diffusion operates on a shorter timescale than other proton loss processes (i.e., Coulomb drag and charge exchange). These other loss processes are not included in the simulation. An interesting result of the simulation is that energy diffusion maximizes at moderate pitch angles near the edge of the atmospheric loss cone. Over the simulation period, diffusion in energy creates an order of magnitude enhancement in the bounce-averaged proton distribution function at moderate pitch angles. The loss cone is nearly empty because scattering of particles at small pitch angles is weak. The bounce-averaged flux distribution, mapped to ionospheric heights, results in elevated locally mirroring proton fluxes. OGO 5 observed order of magnitude enhancements in locally mirroring energetic protons at altitudes between 350 and 1300 km and invariant latitudes between 50° and 60° (Lundblad and Soraas, 1978). The proton distributions were highly anisotropic in pitch angle with nearly empty loss cones. The similarity between the observed distributions and those resulting from this simulation raises the possibility that interactions with plasmaspheric hiss play a role in forming and maintaining the characteristic zones of anisotropic proton precipitation in the subauroral ionosphere. Further assessment of the importance of this process depends on knowledge of the distribution in space and time of ducted plasmaspheric hiss in the inner magnetosphere.