Ion Velocity Investigation

This investigation uses a planar retarding potential analyzer, designed to obtain measurements of relative thermal-ion velocity, plasma density, and ion temperature. The ion angle of arrival can be determined by use of a square aperture collimator and a split collector. Together with knowledge of spacecraft motion, this allows computation of the three-dimensional thermal-ion motion along the orbital path. Plasma density and temperature are calculated by interpretation of the volt-ampere profile produced by the instrument for a given impressed voltage pattern on the grids and collector. Ion velocity measurements are obtained once each spacecraft spin period (10 s).

本研究采用平面延迟电位分析仪，旨在获取相对热离子速度、等离子体密度和离子温度的测量值。通过使用正方形孔径准直器和分割收集器，可以确定离子到达角度。结合对航天器运动的了解，这允许计算沿轨道路径的三维热离子运动。通过解释仪器产生的伏安特性曲线，并根据给定的栅极和收集器上的施加电压模式进行计算，得出等离子体密度和温度。每次航天器自旋周期（10秒）都会进行一次离子速度的测量。