The Analyzer for Cusp Ions (ACI) on the TRACERS Mission

Area of Science:

• Space Physics
• Magnetospheric Physics
• Plasma Physics

Background:

• The magnetospheric cusp is a critical region for energy and particle transfer between the solar wind and Earth's magnetosphere.
• Understanding ion dynamics in the cusp is essential for comprehending space weather phenomena and magnetospheric processes.

Purpose of the Study:

• To describe the capabilities of the Analyzers for Cusp Ions (ACIs) instrument onboard the TRACERS mission.
• To highlight how ACI measurements contribute to the TRACERS mission's science objectives concerning cusp ion dynamics.

Main Methods:

• Utilizing toroidal top-hat electrostatic analyzers on a spinning platform for full angular coverage.
• Employing two closely spaced spacecraft in low Earth orbit for comprehensive data acquisition.
• Measuring ion velocity distribution functions with high cadence (312 ms) and good energy/angular resolution.

Main Results:

• ACI instruments offer a broad ion energy range (∼8 eV/e to 20,000 eV/e) with 47 logarithmic energy steps.
• Achieving fractional energy resolution of ∼10% and instantaneous angular resolution of 22.5° × ∼6°.
• Demonstrating the capability to detect cusp boundaries and characterize ion steps with sensitivity and precision.

Conclusions:

• The ACIs are well-suited for detailed in-situ measurements of ion behavior in the magnetospheric cusp.
• These measurements are crucial for advancing our understanding of cusp processes and their impact on space weather.