Cylindrical Electrostatic Probes

The purpose of this experiment was to study the global variations of electron temperature and electron concentration at S/C altitudes during solar maximum, and to study characteristics of the S/C ion sheath. The measurements were made with two cylindrical probes, operating as Langmuir probes. There were a boom probe and an axial probe. The axial probe extended 48.3 cm from the S/C, along the spin axis, and was centered among the four telemetry antennas on the underside of the S/C. This probe was capable of measurements undisturbed by the satellite motion only when the probe preceded the S/C in its motion through the plasma. The boom probe extended horizontally and outward (in S/C frame of reference) from a boom 1 m long, which in turn extended from an upper surface of the S/C at an angle of about 45 deg to the spin axis. This probe provided some observations during each S/C spin cycle that were free of S/C wake effects. The probes consisted of three concentric, electrically isolated, stainless steel tubes. The outer (0.24-cm diam and 23-cm long) tube floated at its own equilibrium potential and served to place the collector well away from the S/C plasma sheath. The middle tube (0.165-cm diam) extending 23 cm outward from the outer tube acted as an electrical guard for the collector. Its electrical potential was controlled. The collector (0.058-cm diam) extended 23 cm outward from the driven guard. During each 2-min sequence, a volt-ampere curve was obtained from the sawtooth voltage (-2 to +10 V) applied to the collector. This was interpreted in electron densities over a range from 1.E2 to 1.5E6 electrons per cc, and temperatures from about 400 to 5.E4 deg K. NSSDC has all the useful data that exist from this investigation.

本实验旨在探究太阳活动极大期时，在卫星轨道高度上电子温度与电子浓度的全球性变化，并研究卫星离子鞘的特征。测量工作采用两只圆柱形探头进行，它们作为朗缪尔探头运行。其中一只是悬臂探头，另一只是轴向探头。轴向探头沿卫星自旋轴方向从卫星本体延伸出48.3厘米，并位于卫星底部四个遥测天线中心。该探头仅在探头运动先于卫星穿过等离子体时，才能进行不受卫星运动影响的测量。悬臂探头则从长度为1米的悬臂上水平向外（以卫星本体为参考系）延伸，该悬臂又从卫星上表面以约45度角延伸至自旋轴。该探头在每个卫星自旋周期内提供了一些不受卫星尾流效应影响的观测数据。探头由三根同轴、电气隔离的不锈钢管组成。外管（直径0.24厘米，长度23厘米）在其自身平衡电位处漂浮，用于将收集器放置在远离卫星等离子体鞘的位置。中间管（直径0.165厘米）从外管向外延伸23厘米，作为收集器的电气保护管。其电位受到控制。收集器（直径0.058厘米）从驱动保护管向外延伸23厘米。在每个2分钟的序列中，通过对收集器施加锯齿形电压（-2至+10伏）获得伏安曲线。该曲线被解释为在每立方厘米1.E2至1.5E6个电子的范围内的电子密度，以及约400至5.E4开尔文的温度。NASA空间科学数据中心拥有此次调查中所有有用的数据。