7 3-4 Sept EFW INST+SOC PDR EFW Science Overview Professor John R. Wygant (PI) University of Minnesota

8 3-4 Sept EFW INST+SOC PDR EFW Instrument Overview RBSP EFW Features Four spin plane booms (2 x 40 m and 2x 50 m) Two spin axis stacer booms (2x6 m) Spherical sensors and preamplifiers near outboard tip of boom (400 kHz response) Flexible boom cable to power sensor electronics & return signals back to SC Sensors are current biased by instrument command to be within ~ 1 volt of ambient plasma potential. Main electronic box (sensor bias control filtering, A-D conversion, burst memory, diagnostics, mode commanding, TM formatting ) EFW Science quantities include: E-fields:(V1-V2, V3-V4, V5-V6) Interferometric timing: SC-sensor potential (V1s, V2s, V3s, V4s, V5s, V6s) SC Potential : (V1+V2)/2, (V3+V4)/2 Interface to EMFISIS instrument Electrostatic cleanliness spec: variations of potential across spacecraft surfaces smaller than 1 Volt. +Z Not to Scale

9 3-4 Sept EFW INST+SOC PDR Investigation Team RBSP Project Office APL EFW PI John Wygant UMN RBSP SWG EFW Co-I team EFW PM Keith Goetz UMN EFW CAM Kim Cooper APL LASP lead Bob Ergun LASP Mechanical Paul Turin UCB SE Dave Curtis UCB UCB PM John Bonnell UCB Electrical Michael Ludlam UCB Flight Software Peter Harvey UCB SMA Ron Jackson UCB DFB Susan Batiste LASP LASP PM Mary Bolton LASP Finance Kate Harps UCB Ground SW Will Rachelson UCB UCB lead John Bonnell UCB

Sept EFW INST+SOC PDR Science Objective : Measure electric fields associated with a variety of mechanisms “causing particle energization and scattering” in the inner magnetosphere. These mechanisms include:  Energization by the large-scale “steady state and storm time convection E-field”.  Energization by substorm “transient fronts”propagating in from the tail.  “Radial diffusion of energetic particles” mediated by “ULF waves”.  Transport and energization by interplanetary “shock generated transient fronts.”  Adiabatic and non-adiabatic energization by “electromagnetic and electrostatic” waves and (“random”) structures. Level-1 Science and Measurement Objectives (1)

Sept EFW INST+SOC PDR Mechanisms associated with energetic particle acceleration and transport (B. Mauk/APL)

Sept EFW INST+SOC PDR The shock induced magnetosonic wave created a 5 order of magnitude increase in 13 MeV electron fluxes in <100 seconds resulting in a new radiation belt that lasted two years The large scale electric field produced a ~70 kV potential drop between L=2 & L-4 and injected ring current plasma. dDst/dt= - 40 nT/hr MHD waves: an important mechanism for radially diffusing and energizing particles. CRRES measurements of the E-field during a pass through the inner magnetosphere: interplanetary shock induced electric field, large scale MHD waves, and enhancement in convection electric field. E-Fields in the Active Radiation Belt

Sept EFW INST+SOC PDR Level -1 Science Objectives for EFW High Time Resolution Burst Measurements: ....derive and determine electrostatic and electromagnetic field amplitudes, frequency, intensity, propagation direction, spatial distribution and temporal evolution with sufficient fidelity to calculate wave energy, polarization, saturation levels, coherence, wave normal angle, phase velocity, and wave number for a) VLF and ELF waves, and b) random, ULF, and quasi-periodic electromagnetic fluctuations. .....determine the types and characteristics of plasma waves causing particle energization and loss including wave growth rates; quantifying adiabatic and non- adiabatic mechanisms of energization and loss ; determining conditions that control the production and propagation of waves.  EFW focuses on large amplitude low frequency electric fields, density perturbations, and inter-sensor timing. EMFISIS measures higher frequency and lower amplitude waves (Chorus) and the upper hybrid line frequency(plasma density) are measured by EMFISIS.

Sept EFW INST+SOC PDR  Observations of large amplitude turbulent electric fields   E~500 mV/m  Duration of spike Hz  Polarized perpendicular to B   B~0.5 nT (not shown)  Hodograms for E and B Complicated quasi 3D structure full 3D and 3DB  Waves electrostatic with phase fronts ~perp to B  Large amplitude thermal plasma variations measured from SC potential variations:Result in order of magnitude changes in index of refraction wave time scales: trapping motivates SC potential measurements  Position R=5.2, Mlat 25 deg, MLT=0.5  Observed during nearly conjugate ~400 keV electron microburst interval by low altitude SAMPEX.

Sept EFW INST+SOC PDR EFW Amplitude vs Frequency

Sept EFW INST+SOC PDR EFW/EMFISIS Amplitude vs Frequency

Sept EFW INST+SOC PDR Time Duration of Intervals of Low Frequency Bursting Necessary for Understanding Wave Fields Responsible for Scattering/Acceleration of Energetic Particles

Sept EFW INST+SOC PDR EFW Targeted Energization/Transport Mechanisms and Structures

Sept EFW INST+SOC PDR Measured and model average large scale convection electric field in inner magnetosphere. Traces are for different values of geomagnetic activity. Kp varies: 1-8. Quiet time field accurate to 3.5 Re. Accuracy of Large Scale Electric Field Measurement

Sept EFW INST+SOC PDR  Spin plane component of E-field at DC-15 Hz (>0.3 mV/m or 10% accuracy) over a range from 0 to 500 mV/m at R>3.5 Re  Spin axis component of E at DC-15 Hz (>4 mV/m or 20% accuracy) over a range from mV/m at R>3.5Re.  Spacecraft potential measurements providing estimates of cold plasma densities of 0.1 to ~50 cm-3 at 1-s cadence (dn/n<50%).  Burst recordings of large amplitude (Req.: mV/m Capability: 0-4V/m) E- fields ; B-fields and cold electron density variations cm-3 with accuracy of 10% (derived from SC potential) over frequency range from dc to 250 Hz.  Interferometric timing of intense (>300mV/m) small scale electric field structures and non-linear waves: timing accuracy of.06 ms for velocities of structures over km/s.  Low noise 3-D E-field waveforms to EMFISIS 10 Hz to 400 kHz with maximum signal 50 mV/m. For spin plane sensors: a dynamic range of 100 dB & sensitivities of 3 x V2/m2Hz (TBR) at 1 kHz and3 x V2/m2Hz (TBR) at 100 kHz. For spin axis sensor pairs the dynamic range and sensitivity is an order of magnitude less. Driving MRD/ELE Measurement Requirements

Sept EFW INST+SOC PDR Primary Measurement Requirements Flow to Instrument

Sept EFW INST+SOC PDR

Sept EFW INST+SOC PDR BACK-UP SLIDES

Sept EFW INST+SOC PDR Effect of Attitude Uncertainty in E-VxB subtraction accuracy

Sept EFW INST+SOC PDR RBSP Level 1 Baseline Measurement Goals Related to EFW 3-D Electric Field from DC to 10 Hz on two platforms ( ) 3-D Wave Electric Field 10 Hz -10 kHz (Spectral: 20 bins) ( ) The mission shall be capable of taking concurrent full 3D magnetic and 3D electric waveforms with at least 20 k samples/s, which is sufficient to support an unaliased bandwidth of 10 kHz, to determine the propagation characteristics of waves up to 10 kHz. ( ) 3-D Wave Magnetic Field 10 Hz-10 kHz (Spectral: 20 bins) ( ) Plasma Density 1 second resolution on two platforms ( )

Sept EFW INST+SOC PDR SAMPEX in low altitude orbit encounters outer radiation belts ~10 minutes after Polar about 1 hour in MLT distant SAMPEX observes rapid time variations (0.1-1 seconds) in 500 keV electron fluxes Fluxes vary by almost order of magnitude Consistent with strong scattering of electrons due to waves (similar to Cattell et al. this meeting) Coincides with Polar L-value

Sept EFW INST+SOC PDR Large Amplitude Alfven Wave at PSBL with imbedded large amplitude LH “type” waves R=5.2 Re, 0.82 MLT, MLAT~25 deg  E z ~300 mV/m  B y ~100 nT Propagate parallel to B tpwards Earth Vphase~ km/s E-Field (mV/m) (~800 Hz) Z GSM B-Field (nT) Y GSM (8 Hz) Notice:Imbedded bursts of high frequency waves ~1 V/m ptp (greater in other components) 25 duration burst Low freq

Sept EFW INST+SOC PDR

Sept EFW INST+SOC PDR Validity Conditions for Spin Plane Electric Field Measurement MRD ELE 494

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