Modeling of Cluster's electric antennas in space: Application to plasma diagnostics
Modeling of Cluster's electric antennas in space: Application to plasma diagnostics
复制标题
空间 Cluster 电天线建模：在等离子体诊断中的应用
DOI：
10.1029/2005rs003264
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发表时间：
2005
期刊：
影响因子：
1.6
通讯作者：
Bertrand Lefebvre
中科院分区：
文献类型：
--
作者：
C. Béghin;P. Décréau;J. Pickett;David Sundkvist;Bertrand Lefebvre
安装在集群卫星上的长臂电天线的主要特性是通过动力学和各向同性空间等离子体的有限元建模得出的，频率范围约为 1-100 kHz。该模型基于准静态条件下的表面电荷分布方法。两种类型天线（即双线和双探头）的阻抗是根据相对于局部等离子体频率和几个不同德拜长度归一化的频率来计算的。大多数代码输出都是使用分析估计来检查的，以便更好地理解所涉及的物理机制。作为副产品，双探头天线的有效长度和两个天线之间的互阻抗由代码计算。结果表明，如果能够在船上实施此类测量，人们不仅能够准确地确定天线的电特性，而且还能够估计局部等离子体参数。尽管如此，最近通过运行一种特殊的操作模式来测试互阻抗测量，在轨道上检查了该模型预测的一个有趣的特征。初步结果与预测总体一致，只是它们表明我们的电子分布麦克斯韦模型应该进行修改，以解释意外的低频响应。对同时获得的电子通量测量结果进行分析后，似乎可以通过对双分量分布的电子分布进行粗略调整来解释观测结果。
The main characteristics of the long‐boom electric antennas installed on board the Cluster satellites are derived from finite element modeling in a kinetic and isotropic space plasma, in the frequency range of about 1–100 kHz. The model is based on the surface charge distribution method in quasi‐static conditions. The impedances of both types of antenna, i.e., the double‐wire and the double‐probe, are computed versus the frequency normalized with respect to the local plasma frequency and for several different Debye lengths. Most of the code outputs are checked using analytic estimations for better understanding of the involved physical mechanisms. As a by‐product, the effective length of the double‐probe antenna and the mutual impedance between the two antennas are computed by the code. It is shown that if it had been possible to implement such measurements on board, one would have been able not only to determine accurately the electric characteristics of the antennas but also to estimate the local plasma parameters. Nevertheless, an interesting feature predicted by the model has been checked recently in orbit by running a special mode of operation for testing the mutual impedance measurement. The preliminary results are globally consistent with the predictions, except that they suggest that our Maxwellian model for the electron distribution should be revised in order to explain the unexpected low‐frequency response. After analysis of the electron flux measurements obtained simultaneously, it appears that a rough adjustment of the electron distribution with a two‐component distribution allows us to account for the observations.