TY - JOUR AU - Kazama, Yoichi AU - Wang, Bo-Jhou AU - Wang, Shiang-Yu AU - Ho, Paul T. P. AU - Tam, Sunny W. Y. AU - Chang, Tzu-Fang AU - Chiang, Chih-Yu AU - Asamura, Kazushi PY - 2017 DA - 2017/12/11 TI - Low-energy particle experiments–electron analyzer (LEPe) onboard the Arase spacecraft JO - Earth, Planets and Space SP - 165 VL - 69 IS - 1 AB - In this report, we describe the low-energy electron instrument LEPe (low-energy particle experiments–electron analyzer) onboard the Arase (ERG) spacecraft. The instrument measures a three-dimensional distribution function of electrons with energies of $$\sim 19$$ eV–19 keV. Electrons in this energy range dominate in the inner magnetosphere, and measurement of such electrons is important in terms of understanding the magnetospheric dynamics and wave–particle interaction. The instrument employs a toroidal tophat electrostatic energy analyzer with a passive 6-mm aluminum shield. To minimize background radiation effects, the analyzer has a background channel, which monitors counts produced by background radiation. Background counts are then subtracted from measured counts. Electronic components are radiation tolerant, and 5-mm-thick shielding of the electronics housing ensures that the total dose is less than 100 kRad for the one-year nominal mission lifetime. The first in-space measurement test was done on February 12, 2017, showing that the instrument functions well. On February 27, the first all-instrument run test was done, and the LEPe instrument measured an energy dispersion event probably related to a substorm injection occurring immediately before the instrument turn-on. These initial results indicate that the instrument works fine in space, and the measurement performance is good for science purposes. SN - 1880-5981 UR - https://doi.org/10.1186/s40623-017-0748-6 DO - 10.1186/s40623-017-0748-6 ID - Kazama2017 ER -