Ion Composition Instrument (ESIC)

ESIC measures the 3D distribution functions of the major ion species, H, He+, He++, and O+. It consists of a
retarding-potential analyzer (RPA), followed by a toroidal energy-per-charge (E/q) analyzer with disk-shaped field of view,
followed by a 20 kV post-acceleration into a time-of-flight (ToF) analysis section. Without RPA operation, the E/q range is
15 eV to 40 keV, otherwise it starts at essentially zero volts. To accommodate the large dynamic range in ion fluxes, the
instrument has split the 360 degrees FoV into two 180 degree sections whose sensitivities differ by a factor 100. Moments
of the distributions of all 4 ion species are computed on board and are available every 4 spins, i.e., every 6 seconds.
The instrument is identical to the CODIF portion of the CIS instrument on CLUSTER.

ESIC测量主要离子种类H、He+、He++和O+的3D分布函数。该系统由一个延迟电位分析器（RPA）组成，其后连接一个具有圆形视场的环状能量/电荷（E/q）分析器，再接以20 kV的后加速进入飞行时间（ToF）分析区域。在未开启RPA操作的情况下，E/q的范围为15 eV至40 keV，否则起始电压几乎为零。为适应离子通量的大动态范围，该仪器将360度的视场分割为两个180度的部分，其灵敏度相差百倍。所有四种离子种类的分布矩在仪器上板计算，并每旋转四次（即每6秒）提供一次。该仪器与CLUSTER上CIS仪器的CODIF部分完全一致。