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2009年2月21日THEMIS-C卫星在磁尾X=-15.7RE(RE为地球半径,1RE=6371km)观测到典型的磁通量绳事件.采用Grad-Shafranov重构技术研究该磁通量绳的特性、内部磁场和电流结构.研究表明,磁通量绳不变轴位于GSM(geocentric solar magnetospheric coordinates)坐标为(-0.3975,0.8905,0.2213)的方向,基本位于晨昏方向;通量绳的横截面尺度约为2RE,内部轴向磁通量为1.3×106Wb.与经验模型相比,在对磁通量绳几何形状不做约束的情况下,重构出磁尾X=-15.7RE处磁通量绳横截面上的磁场、电流强度分布图像.通量绳核心部位具有无力场位形结构,而随着径向距离的增加,磁场在偏离轴对称分布的区域逐渐表现为非无力位形.
On February 21, 2009, a typical magnetic flux rope event was observed at the magnet tail X = -15.7 RE (RE is the Earth’s radius, 1 RE = 6371 km). The Grad-Shafranov reconstruction technique was used to study the characteristics of the flux rope, Internal magnetic field and current structure.The results show that the invariant axis of the magnetic flux rope is in the direction of (-0.3975,0.8905,0.2213) at GSM (geocentric solar magnetospheric coordinates), basically in the twilight direction, and the cross section of flux rope is about 2RE , The internal axial flux is 1.3 × 106Wb.Compared with the empirical model, the magnetic field on the cross section of the magnetic flux rope with magnetic tail X = -15.7RE is reconstructed without constraint to the magnetic flux rope geometry, and the current intensity Distribution image.The flux core has weak force site structure, and with the increase of radial distance, the magnetic field gradually appears as the non-powerless position in the area deviating from axisymmetric distribution.