Development and performance of a suprathermal electron spectrometer to study auroral precipitations

Area of Science:

• Space Physics
• Atmospheric Science

Background:

• Auroral phenomena are driven by energetic particle precipitation into the Earth's ionosphere.
• Understanding suprathermal electron dynamics is crucial for auroral physics.
• In situ measurements are vital for validating theoretical models of auroral acceleration.

Purpose of the Study:

• To detail the design, development, and performance of the Medium-energy Electron SPectrometer (MESP).
• To conduct in situ observations of suprathermal electrons within the auroral ionosphere.
• To characterize electron energy spectra associated with auroral arcs.

Main Methods:

• Utilized a permanent magnet filter and light-tight structure for electron energy selection.
• Employed avalanche photodiodes (APDs) and a solid-state detector (SSD) for broad energy coverage (3-120 keV).
• Integrated multi-channel, ultra-low power application-specific integrated circuits for signal processing.

Main Results:

• Successfully measured precipitating electrons with 120-ms time resolution.
• Observed inverted-V type electron spectra, consistent with prior research.
• Identified energetic non-thermal electron distributions correlated with intense auroral displays.

Conclusions:

• MESP provides effective in situ measurements of suprathermal electrons in the auroral ionosphere.
• The instrument successfully characterized electron energy distributions during auroral events.
• Findings support the existence of energetic particle acceleration mechanisms responsible for bright auroras.