Experimental study of the plasma acceleration/heating by large-amplitude Alfven waves in the space

阿尔芬波被发现在夜间磁层中向地球传播。它们被认为与电离层高度的极光活动有关。我们研究了在10-30Re的中尾区用GeoTail测量的电场和磁场的变化。我们发现了大幅度的电场涨落和相应的磁场涨落，它们的分量在垂直于环境磁场的方向上。根据电场和磁场的幅度之比，确定这些波动为阿尔芬波。这些大幅度的Alfven波往往沿着与等离子体流相重合的方向传播，并同时向地球传播。我们将进一步选择波动被明确识别为波的事件。我们将报告与等离子体性质对应的统计结果和阿尔芬波携带的能量通量的估计。

Alfven waves were found to propagate toward the earth in the nightside magnetosphere. They are considered to be associated with the auroral activity at the ionospheric altitudes. We have investigated the electric and magnetic field variations measured by Geotail in the mid-tail region, 10-30 Re. We found large-amplitude electric field fluctuations and the corresponding magnetic field fluctuations having the components in the direction perpendicular to the ambient magnetic field. These fluctuations were identified as Alfven waves from the ratio between the amplitudes of electric and magnetic field. These large-amplitude Alfven waves often propagate in the direction coincides with the plasma flow, and earthward at the same time. We will further select events in which the fluctuations are identified as waves definitely. We will report the statistical result about the correspondence with the plasma properties and estimation of the energy flux carried by the Alfven waves.