The generation of non aspect sensitive plasma density irregularities by field aligned drifts in the lower ionosphere
The generation of non aspect sensitive plasma density irregularities by field aligned drifts in the lower ionosphere
复制标题
通过低电离层中的场对准漂移产生非方面敏感的等离子体密度不规则性
DOI：
10.1007/s00585-000-0799-y
复制
发表时间：
2000
影响因子：
1.9
通讯作者：
K. Schlegel
中科院分区：
文献类型：
--
作者：
T. Robinson;K. Schlegel
提出了一种通过与地磁场对齐的电子漂移在高纬度较低电离层中产生几乎没有方位敏感性的等离子体密度不规则性的理论。该理论是通过流体方程发展起来的，其中不稳定机制涉及电子碰撞加热的正反馈。当场对准的电子漂移速度超过几公里 s−1 时，这种效应会使下 E 区中波长超过几十米的波变得不稳定，而该区域的碰撞效应足够大。此外，阈值条件几乎与波传播方向无关，并且不稳定波以远低于离子声速的速度传播。还考虑了这种新的不稳定性可能在最近的雷达反向散射观测中发挥的作用，这些观测是在下E区沿接近地磁场的方向传播的短尺度不规则性。
A theory of the generation of plasma density irregularities with virtually no aspect sensitivity, in the lower ionosphere at high latitudes, by electron drifts aligned with the geomagnetic field, is presented. The theory is developed through fluid equations in which the destabilising mechanism involves positive feedback from electron collisional heating. When field aligned electron drift speeds exceed a few km s−1, this effect destabilises waves with wavelengths in excess of a few tens of metres in the lower E-region, where collisional effects are sufficiently large. Furthermore, the threshold conditions are almost independent of the wave propagation direction and the unstable waves propagate at speeds well below the ion acoustic speed. The role that this new instability may play in recent radar backscatter observations of short scale irregularities propagating in directions close to that of the geomagnetic field, in the lower E-region is also considered.