The role of hot plasma in magnetospheric convection
The role of hot plasma in magnetospheric convection
复制标题
热等离子体在磁层对流中的作用
DOI：
--
复制
发表时间：
1977
期刊：
影响因子：
--
通讯作者：
D. Southwood
中科院分区：
文献类型：
--
作者：
D. Southwood
一些作者已经表明，磁层中热等离子体的存在可以严重改变强加的对流模式，甚至阻止其渗透到低纬度地区。在这里，借助简单的理论模型，我们认为，重要的参数管理这样的效果是热等离子体的压力，它的数密度，和电离层的电导率。这样做的结果是可以给出对该现象的流体描述。对流的变化自然会在环流内缘附近产生东西向的压力梯度，这些压力梯度会产生东西向的气流，从而产生屏蔽效应。我们表明，等离子体压缩能量损失焦耳耗散在电离层中的这些流量迅速成立的夜侧。在向阳面的过程是缓慢的，但我们得出结论，向阳面的电导率是控制最终环电流渗透的参数。在长的时间限制的流体近似打破，我们定性地讨论了发展的稳态流型和碰撞等离子体行为的影响，在此限制。
Several authors have shown that the presence of hot plasma in the magnetosphere can severely modify an imposed convection pattern and even prevent its penetration to low latitudes. Here with the aid of simple theoretical models we argue that the important parameters governing such effects are the hot plasma pressure, its number density, and the ionospheric conductivity. A result of this is that a fluid description of the phenomenon can be given. Changes in convection naturally give rise to east-west pressure gradients near the ring current inner edge, and these give rise to east-west flows, which cause the shielding effect. We show that plasma compressional energy is lost in Joule dissipation in the ionosphere in these flows which are rapidly set up on the nightside. On the dayside the process is slower, but we conclude that the dayside conductivity is the parameter controlling final ring current penetration. In the long time limit the fluid approximation breaks down, and we qualitatively discuss the development of steady state flow patterns and the effects of collisionless plasma behavior in this limit.