moon
The Mission

Instruments

Electrostatic Analyzer

Table of eESA and iESA Parameters

Table of eESA and iESA Parameters (from McFadden, et al., 2008a)

ParameterValueComments

  
Electron Electrostatic Analyzer Spherical top-hat
ΔR/R0.0637.5 mm inner hemisphere radius
Analyzer constant7.90 to 4 kV sweep supply
Energy Range2 eV to 32 keV 
Analyzer Energy Resolution17% (15%)ΔE/E measured (predicted)
Measurement Energy Resolution32%Typical 31-step log energy sweep
Energy Sweep Rate32 per spin~94 ms for nominal 3s spin
Instantaneous Field of View180° x 6° FWHM180° centered on spin plane
Anode Angle Resolution22.5°8 anodes
Field of View each spinsteradians
Analyzer Geometric Factor0.0075 cm²-sr-E
0.0047 cm²-sr-E
Predicted from simulations, analyzer only
One 90% exit grid and 70% MCP efficiency
Sensor Geometric Factor0.0066 cm²-sr-EFrom in-flight calibration, includes grid losses, MCP efficiency @ 10eV
Counter readout1024 per spin~3 ms
Full Distribution Array32E x 88Ω32 or 128 spin cadence, continuous
Burst Distribution Array32E x 88Ω1 spin cadence, 30-60 min/orbit
Reduced Distribution Array32E x 6Ω or
32E x 1Ω
1 spin cadence, continuous, 6Ω in FS mode
1Ω in SS mode
 
Ion Electrostatic Analyzer Spherical top-hat
ΔR/R0.07537.5 mm inner hemisphere radius
Analyzer constant6.20 to 4 kV sweep supply
Energy Range1.6 eV to 25 keV 
Analyzer Energy Resolution18% (19%)ΔE/E measured (predicted)
Measurement Energy Resolution32%Typical 31-step log energy sweep
Energy Sweep Rate32 or 64 per spin64/spin in solar-wind mode with 16 energies
Instantaneous Field of View180° x 6° FWHM180° centered on spin plane
Anode Angle Resolution5.6° to 22.5°16 anodes
Field of View each spinsteradians
Analyzer Geometric Factor0.0181 cm²-sr-E
0.0073 cm²-sr-E
Predicted from simulations, analyzer only
Two 90% grids and 50% MCP efficiency
Sensor Geometric Factor0.0061 cm²-sr-EFrom in-fligt calibration, includes grid losses and MCP efficiency @ 500eV
Counter readout1024 per spin~3 ms
Full Distribution Array32E x 88Ω32 or128 spin cadence, continuous
Burst Distribution Array32E x 88Ω1 spin cadence, 30-60 min/orbit
Reduced Distribution Array24 E x 50Ω or
32E x 1Ω
1 spin cadence, continuous, 50Ω in FS mode
1Ω in SS mode