[[TOC(TBR/UserApp/Space/EMFISIS_on_RBSP, depth=2)]]

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

The RBSP-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.

PROBA 2 Block Diagram

The physics of the creation and loss of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A large range of field dynamics and time scales are involved in this physics from ring current magnetic fields to microscopic kinetic interactions such as whistler-mode chorus waves with energetic electrons. To measure these key field interactions, NASA has selected the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on the Radiation Belt Storm Probes (RBSP). EMFISIS is an integrated set of instruments consisting of a tri-axial fluxgate magnetometer (MAG) and a Waves instrument which includes a tri-axial search coil magnetometer and measures AC electric and magnetic fields from 10 Hz to MHz frequencies. The broad frequency range of the Waves instrument enables the identification of resonances and cutoffs from Waves to achieve high cadence, accurate plasma density measurements that are essential to RBSP theory and modeling efforts. The instruments are integrated through a Central Data Processor Unit (CDPU) which provides for flexible instrument operations in both burst and survey telemetry modes that can be optimized to address the specific physics of the many radiation belt processes. The EMFISIS multi-institution team comprises a group of knowledgeable space physics investigators, both experimental and theoretical, with the requisite capability, desire, and experience to accomplish the goals of the RBSP mission to further our nation’s space weather capability. In combination with the selected double probe electric field and particle investigations on RBSP, EMFISIS will provide the essential measurements necessary to open the frontier of predictive capability for the Earth’s highly variable radiation belts.

CDPU Board

Central Data Processing Unit

The CDPU Board is running an RTEMS-based application. The program binaries are located in the C-RAM on the CDPU. The CDPU uses a Fault Tolerant LEON3 implementation in an ACTEL RTAX2000. The Code is stored in and executed from the BAE C-RAMs (top row). The CDPU Board contains 2 Mbytes of C-RAM, 2-Mbytes of SRAM and 512 Mbytes of SDRAM for data buffering. The CDPU Flight Software uses RTEMS 4.9.2 to operate EMFISIS. The flight software provides the Command and Telemetry interfaces and coordinates the operation of the EMFISIS Suite of instruments described in Dr. Kletzings paper.

RBSP-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

RBSP-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

The EMFISIS shares booms with the Electric Fields and Waves (EFW) Instrument.

Instruments

Abstract

Radiation belt particle acceleration and loss is intimately connected to wave-particle interactions. To measurethese interactions, NASA will launch the two-satellite Radiation Belt Storm Probes (RBSP) mission in 2012. TheElectric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation on RBSP is anintegrated set of instruments consisting of DC magnetic field measurements from DC to 30 Hz and AC electric andmagnetic fields from 10Hz to 400 kHz. Examples of key wave science such as VLF hiss, magnetosonic equatorialnoise, electromagnetic ion cyclotron waves, and chorus are presented along with the mission and instrumentcomplement.

Introduction

The physics of the creation, loss, and transport of radiation belt particles is intimately connected to theelectric and magnetic fields which mediate these processes. A large range of field and particle interactions areinvolved in this physics from ions and ring current magnetic fields to microscopic kinetic interactions such aswhistler-mode chorus waves with energetic electrons. To measure these kinds of radiation belt interactions, NASAwill launch the two-satellite Radiation Belt Storm Probes (RBSP) mission in 2012. As part of the mission, theElectric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation is an integrated set ofinstruments consisting of a tri-axial fluxgate magnetometer (MAG) and a Waves instrument which includes a tri-axial search coil magnetometer.

The RBSP Mission

The NASA RBSP mission consists of two identical satellites in a common, elliptical, near-equatorial orbitwith perigee at 700 km and apogee and 5.7 RE. The orbital configuration is set up such that one satellite graduallyseparates from the other along orbital path, running ahead until it eventually overtakes the first satellite after a periodof about 9 months. The mission is well instrumented to measure the radiation belt environment includingmeasurements of electrons and ions from a few eV to several MeV and higher. These particle measurements coverthe key particle energies in the Earth’s radiation belts, the ring current, and the plasmasphere. The fieldmeasurements consist of DC and AC electric and magnetic field measurements covering the important frequenciesof interest for the geoelectric and geomagnetic fields, as well as the electromagnetic waves that fill the Earth’s innermagnetosphere.

This mission will be the first to provide dual point measurements throughout the inner magnetosphere. Withthis capability, we will, for the first time, be able to understand how different parts of the equatorial innermagnetosphere are (or are not) correlated and how they evolve as a function of magnetospheric drivers. With thefull complement of measurements, RBSP will be able to distinguish between the various particle energization,transport and loss processes that have been proposed to explain the dynamic character of the radiation belts. Whencoupled with theoretical development, this mission will enable more powerful, physics-based models to let us movecloser to the frontier of predictive capability for the radiation belt environment.

The EMFISIS Investigation

The EMFISIS investigation is a multi-instrument team composed of experimentalists and modellers at severalinstitutions. The lead institution is the University of Iowa which coordinates the entire investigation and alsoprovides the hardware for the Waves portion of the investigation including the tri-axial magnetic search coil sensors.The tri-axial fluxgate magnetometer and associated electronics are provided by the Goddard Space Flight Center.

The suite’s central data processor is provided by the University of New Hampshire. Modelling and data analysisefforts are being provided by the University of California, Los Angeles, the Los Alamos National Laboratory,Charles University of Prague, and in Institute for Space Research in Graz, Austria.

The DC magnetic field measurements are made using a three-axis fluxgate magnetometer and provide a fullvector magnetic field vector at a rate of 64 vectors/s, corresponding to a frequency range of 0-30 Hz. Themagnetometer has two primary ranges covering magnitudes of 0-65536 nT with 2 nT resolution and 0-4096 nT with0.13 nT resolution

The Waves portion of EMFISIS provides two types of wave measurements. The first type is a three axiselectric and magnetic field measurement covering the frequency range of 10-12000 Hz. The EMFISIS investigationhas developed the magnetic search coil sensor and associated electronics and the electric field signals are sent to theEMFISIS electronics from the Electric Field and Waves (EFW) investigation. By combining both electric andmagnetic measurements, digitized simultaneously by common electronics, RBSP will have a full vector electric andmagnetic field measurement to enable calculation of key quantities such as Poynting flux, polarization, planarity,and ellipticity for key wave moves such as VLF hiss, magnetosonic equatorial noise, and chorus. The second typeof wave measurement is a single axis electric field measurement over the frequency range 10-400 kHz. Thismeasurement is targeted at identifying emission at the upper-hybrid frequency which will be used to determinebackground plasma density.

The fluxgate magnetometer measurements, when combined with the electric field measurements of the EFWinvestigation, will provide the full vector measurements needed for studying lower frequency waves such aselectromagnetic ion cyclotron (EMIC) waves and ring current as well providing the background field direction foranalysing particle measurements. A summary of the field measurement ranges is shown in the following figure which includesthe FEW measurements as well as those of the EMFISIS investigation

RBSP Electric and Magnetic Field Measurement Ranges

Summary

The EMFISIS investigation for NASA’s RBSP mission provides the essential measurements of vectormagnetic and electric fields to unravel the physics of wave-particle interactions that are responsible for acceleration,transport and loss of radiation belt particles. Additionally, the EMFISIS measurements of DC magnetic fields willprovide information on much lower frequency phenomena such as EMIC waves and ring current variation. Withthese field measurements combined with excellent coverage of particle measurements, the RBSP mission promisesto reveal the clearest picture ever obtained of radiation belt physics= EMFISIS accommodation diagram =

RBSP-EMFISIS Data Products

MAG

• 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

WAVES

• 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

External links

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

• EMFISIS Investigation onthe RBSP Spacecraft