Electric Field Measurements in a Tenuous Plasma with Spherical Double Probes
Electric Field Measurements in a Tenuous Plasma with Spherical Double Probes
复制标题
DOI：
10.1002/9781118664391.ch1
复制
发表时间：
2013-03
期刊：
影响因子：
--
通讯作者：
A. Pedersen;F. Mozer;G. Gustafsson
中科院分区：
文献类型：
--
作者：
A. Pedersen;F. Mozer;G. Gustafsson
通过对地球观测卫星、国际空间环境工程师协会-1号、维京海盗号、Geotail号和CRRES号飞行任务的实验，获得了用球形双探头测量地球磁层准静态电场和波动电场的经验。这些实验是通过从探针向航天器施加电流来主动控制球形探针，从而使探针达到接近等离子体电位的更小、更舒适的探针-等离子体阻抗。由于光电子的发射，航天器（和探测器）将在磁层等离子体中产生正电势：光电子实际上提供了航天器/等离子体和探测器/等离子体之间的必要接触。对这些过程的理解是理解电场测量的必要条件，在一个稀薄的等离子体，也是影响测量的寄生效应。根据过去的经验，将有可能测量准静态航天器自旋平面分量的电场垂直于航天器的太阳方向的精度为0.25 mVm-1的顺序和精度稍低的航天器太阳方向的双探头自旋平面接近黄道。当航天器自旋轴接近航天器-太阳方向时，精度可以得到很大的提高。这种测量的时间分辨率主要受遥测技术的限制;探头和相关的电子设备允许测量高达几MHz的电场。电场双探针测量的自然双产品是航天器/等离子体电势的确定，这反过来又提供了关于等离子体密度变化的高时间分辨率信息。
Experiences with spherical double probes for measurements of quasistatic and wave electric fields in the Earth's magnetosphere were gained by experiments which were part of the GEOS, ISEE-1, Viking, Geotail and CRRES missions. These experiments were built with active control of the spherical probes by forcing a current from the probes to the spacecraft and thereby bringing the probes to a smaller and more comfortable probe-plasma impedance close the plasma potential. A spacecraft (and probes) will come to a positive potential in a magnetospheric plasma due to emission of photoelectrons: photoelectrons are in fact providing the necessary contact between spacecraft/plasma and probe/plasma. The understanding of these processes is a necessary condition for understanding electric field measurements in a tenuous plasma and also the spurious effects which influence measurements. Based on past experience it will be possible to measure quasistatic spacecraft spin plane components of the electric field perpendicular to the spacecraft-Sun direction with an accuracy of the order of 0.25 mVm -1 and with somewhat less accuracy in the spacecraft-Sun direction for double probe spin planes close to the ecliptic. When the spacecraft spin axis is close to the spacecraft-Sun direction, the accuracy can be considerably improved. The time resolution of such measurements is mainly limited by telemetry; probes and associated electronics permit measurements of electric fields up to a few MHz. A natural bi-product of electric field double probe measurements is the determination of the spacecraft/plasma potential which in turn provides high time resolution information about plasma density variations.