title: Development and performance of a suprathermal electron spectrometer to study auroral precipitations.
abstract: The design, development, and performance of Medium-energy Electron SPectrometer (MESP), dedicated to the in situ observation of suprathermal electrons in the auroral ionosphere, are summarized in this paper. MESP employs a permanent magnet filter with a light tight structure to select electrons with proper energies guided to the detectors. A combination of two avalanche photodiodes and a large area solid-state detector (SSD) provided 46 total energy bins (1 keV resolution for 3-20 keV range for APDs, and 7 keV resolution for >20 keV range for SSDs). Multi-channel ultra-low power application-specific integrated circuits are also verified for the flight operation to read-out and analyze the detector signals. MESP was launched from Poker Flat Research Range on 3 March 2014 as a part of ground-to-rocket electrodynamics-electrons correlative experiment (GREECE) mission. MESP successfully measured the precipitating electrons from 3 to 120 keV in 120-ms time resolution and characterized the features of suprathermal distributions associated with auroral arcs throughout the flight. The measured electrons were showing the inverted-V type spectra, consistent with the past measurements. In addition, investigations of the suprathermal electron population indicated the existence of the energetic non-thermal distribution corresponding to the brightest aurora.
authors.affiliation: Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238, USA.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ogasawara
authors.affiliation: University of Texas at San Antonio, One UTSA circle, San Antonio, Texas 78249, USA.
authors.forename: Guy
authors.initials: G
authors.lastname: Grubbs
authors.affiliation: Goddard Space Flight Center, National Aeronautics and Space Administration, 8800 Greenbelt Rd, Greenbelt, Maryland 20771, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Michell
authors.affiliation: Goddard Space Flight Center, National Aeronautics and Space Administration, 8800 Greenbelt Rd, Greenbelt, Maryland 20771, USA.
authors.forename: Marilia
authors.initials: M
authors.lastname: Samara
authors.affiliation: Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238, USA.
authors.forename: Jason L
authors.initials: JL
authors.lastname: Stange
authors.affiliation: Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Trevino
authors.affiliation: Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238, USA.
authors.forename: James
authors.initials: J
authors.lastname: Webster
authors.affiliation: Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238, USA.
authors.forename: Jörg-Micha
authors.initials: JM
authors.lastname: Jahn