Low-Energy Particle Experiments - Electron Analyzer (LEP-e)



Principal Investigator

  • Paul Ho (Academia Sinica, Taiwan)

Project Manager

  • Shiang-Yu Wang (Academia Sinica, Taiwan)

Project Scientist

  • Sunny W. Y. Tam (National Cheng Kung University, Taiwan)

Project Engineer

  • Yoichi Kazama (Academia Sinica, Taiwan)


  • Bo-Jhou Wang (Academia Sinica, Taiwan)

Support Scientist

  • Tzu-Fang Chang (National Cheng Kung University, Taiwan)
  • Chih-Yu Chiang (National Cheng Kung University, Taiwan)


  • Kazama, Y., B.-J. Wang, S.-Y. Wang, P. T. P. Ho, S. W. Y. Tam, T.-F. Chang, C.-Y. Chiang, and K. Asamura, Low-energy particle experiments--electron analyzer (LEPe) onboard the Arase spacecraft, Earth, Planets and Space, 69(1), 165., doi:10.1186/s40623-017-0748-6, 2017.

Instrument Specifications

upper part180DIA x 200Hmm
lower part170D x 180W x 90Hmm
Power consumption8.8W44V*0.20A, incl. PSU’s efficiency
Raw data production24.6kbyte/spinScience data, w/o compression
G-factorw/o mesh
Coarse ch9.34e-4cm2 sr keV/keVAverage, measured
Fine ch2.15e-4cm2 sr keV/keVAverage, measured
Energy range~19 - 19,000eV@4kV HV
Energy resolution9.2%FWHM, measured
Field of views2.98 x ~270degScience data, w/o compression
Angular resolution
Coarse ch2.89 x 21.5degEL x AZ, FWHM, measured
Fine ch3.05 x 4.71degEL x AZ, FWHM, measured

Measurement Principle

Low-Energy Particle Experiments - Electron Analyzer (LEPe) onboard the ERG spacecraft measures three-dimensional distribution functions of low energy electrons. The LEPe instrument consists of a tophat-type electrostatic analyzer, multi-channel plates (MCP), high-voltage power supplies and power supply units. The analyzer selects energies of electrons from ~19 eV to 19 keV in 32 energy steps. LEPe has a fan-shaped field of views, which changes its direction by spin motion to measure in 16 spin-phase directions.

Other Information

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