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Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS)

The EMFISIS investigation will focus on the important role played by magnetic fields and plasma waves in the processes of radiation belt particle acceleration and loss. EMFISIS offers the opportunity to understand the origin of important magnetospheric plasma waves as well as the evolution of the magnetic field that defines the basic coordinate system controlling the structure of the radiation belts and the storm-time ring current.

EMFISIS Science Investigation Objectives:

  • Differentiate among competing processes affecting the acceleration and transport of radiation particles
  • Differentiate among competing processes affecting the precipitation and loss of radiation belt particles
  • Quantify the relative contribution of adiabatic and non-adiabatic processes on energetic particles
  • Understand the effects of the ring current and other storm phenomena on radiation electrons and ions
  • Understand how and why the ring current and associated phenomena vary during storms

EMFISIS Instrument Suite:

Central Data Processing Unit (CDPU): Instrument control, spacecraft interface, on-board analysis, 50 Mbyte mass memory.

Tri-axial Magnetometer (MAG)
MAG is a tri-axial fluxgate magnetometer: Vector B, DC-15 Hz, 0.1 nT accuracy, three sensors on rigid boom.

WAVES, a tri-axial search coil magnetometer and sweep frequency receiver.

Waves Components:

  • Magnetic field - vector B
    10 Hz - 12 kHz
    sensitivity: 3x10-11 nT2Hz-1 @ 1 kHz
    3 sensors on rigid boom

  • Electric field - spin-plane E
    10 Hz- 12 kHz (vector)
    10 kHz-400 kHz (single channel)
    sensitivity: 3x10-17 V2m-2Hz-1 @ 1 kHz
    shares booms with Electric Fields and Waves (EFW) Instrument
EMFISIS accommodation diagram

Van Allen Probes-EMFISIS Data Products:


  • Rapid delivery of four vectors/second in a variety of coordinate systems (GSE, GSM, S/C, etc.)
  • Later delivery of 20 vectors/second (32 vectors/second burst) at full Level 1 quality


  • Spectral matrices for 10 Hz –12 kHz with a 6-second cadence (more often is desired and necessary for some objectives)
  • Spectrum, wave normal, and polarization summaries, based on both on-board and ground processing at 6-second cadence (or more often)
  • Electric field spectrum to 7 MHz with 6-second cadence; electron density from fUHR and continuum radiation cutoff
  • Simultaneous 6-channel waveforms
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