Braking of high-speed flows in the near-Earth tail
Braking of high-speed flows in the near-Earth tail
复制标题
DOI：
10.1029/97gl01062
复制
发表时间：
1997-05-15
影响因子：
5.2
通讯作者：
Haerendel, G
中科院分区：
文献类型：
--
作者：
Shiokawa, K;Baumjohann, W;Haerendel, G
本文根据AMPTE/AMTE 10卫星的观测结果，研究了径向距离为9 ~ 19地球半径（R-E）的近地中心等离子体片中高速离子流的可能制动机制。在这个范围内，速度超过400 km/s的气流几乎总是朝向地球的，这表明气流的来源超过了19 R-E。虽然当卫星接近地球时，高速流的发生率大大降低，但仍观察到速度高于600 km/s的高速流。我们认为，高速流动停止在等离子体片中偶极场和尾状场区域之间的清晰边界处。边界对应于中性片的内边缘。边界处磁场的平均跃变是6.7 nT，这是通过假设压力平衡从观测中估计的。定量地估计和讨论了由流动制动引起的惯性电流和由磁通量在停止点处堆积引起的电流与亚暴电流楔形成的关系。
We have studied possible braking mechanisms of high-speed ion flows in the near-Earth central plasma sheet for radial distances between 9 and 19 Earth Radii (R-E) on the basis of observations made by the AMPTE/IRM satellite. Flows with velocities in excess of 400 km/s are almost always Earthward for this range, indicating that the source of the flows is beyond 19 R-E. Though the occurrence rate of the highspeed flows substantially decreases when the satellite comes closer to the Earth, high-speed flows with velocities higher than 600 km/s are still observed. We suggest that the high-speed flows are stopped at a clear boundary between the regions of dipolar field and tail-like field in the plasma sheet. The boundary corresponds to the inner edge of the neutral sheet. The average jump of the magnetic field at the boundary, which is estimated from the observations by assuming a pressure balance, is 6.7 nT. The inertia current caused by the braking of the flow and the current caused by pileup of the magnetic flux at the stopping point are quantitatively estimated and discussed in relation to the formation of the substorm current wedge.