7 3-4 Sept. 2008 EFW INST+SOC PDR EFW Science Overview Professor John R. Wygant (PI) University of Minnesota

13-4 Sept. 2008 EFW INST+SOC PDR

EFW Science Overview

Professor John R. Wygant (PI)University of Minnesota


EFW Instrument OverviewRBSP 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 SCSensors 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.

+Z4 3

5

6

2

1Not to Scale


Investigation TeamRBSP

Project OfficeAPL

EFW PIJohn Wygant

UMNRBSP SWG

EFW Co-I teamEFW PM

Keith GoetzUMN

EFW CAMKim Cooper

APL

LASP leadBob Ergun

LASP

MechanicalPaul Turin

UCB

SEDave Curtis

UCB

UCB PMJohn Bonnell

UCB

ElectricalMichael Ludlam

UCB

Flight SoftwarePeter Harvey

UCB

SMARon Jackson

UCB

DFBSusan Batiste

LASP

LASP PMMary Bolton

LASP

FinanceKate Harps

UCB

Ground SWWill Rachelson

UCB

UCB leadJohn Bonnell

UCB


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)


Mechanisms associated with energetic particle acceleration and transport (B. Mauk/APL)


The shock induced magnetosonic wave created a 5 order of magnitude increase in 13 MeV electronfluxes 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-4and 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


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.


Observations of large amplitude turbulent electric fields

E~500 mV/m Duration of spike 20-200 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.


EFW Amplitude vs Frequency


EFW/EMFISIS Amplitude vs Frequency


Time Duration of Intervals of Low Frequency Bursting Necessary for Understanding Wave Fields Responsible for Scattering/Acceleration of Energetic Particles

Structures Generating Small Scale Waves

Duration Events / day Total Burst Duration

Substorm injection front

600s 5 2000 s

Boundary between ring current and plasmasphere

600s 2 1200s

ULF/MHD wave fields Selected intervals

400s

2 800s

Shock induced magnetosonic waves

~ 1 minutes 0.005 Negligible

Bursts at Radial Distances of 2.0-5.8 Re (0.5 Re intervals)

60s 16 960

Total Seconds of Burst 1 Data

6040 s


EFW Targeted Energization/Transport Mechanisms and Structures

Mechanism/ Structures

Duration E-Field* (Spin plane)

E-field* (Spin axis)

Cold density (SC pot)

Interfer-ometric timing

1) Interplanetary shock impact

1-300 s 1 -300 mV/m

2 -300 mV/m

1-50 cm-3 ( n/n<50%)

NA

2) Injection events 5-600 s 1- 500 mV/m

2- 500 mV/m 1-50cm3 ( n/n<50%)

NA

3) Convection electric field

300 -36,000 s

0.3-15 mV/m

2-15 mV/m NA NA

4) MHD wave driven radial diffusion

10-600s 1- 40 mV/m

2- 40 mV/m

1- 50 cm-3 ( n/n<50%)

NA

5) Small scale/ large amplitude wave/ random structures

5 ms- 5 s

0.1-500 mV/m

2-500 mV/m 1- 50 cm-3

( n/n<50%)

Timing: 0.066 ms Velocity: 0-500 km/s

6) Plasmapause NA NA NA 1- 50 cm-3 ( n/n<50%)

NA

* Sensitivity for spin plane electric field larger of 0.3 mV/m or 10% of magnitude; for spin axis larger of 4 mV/m or 20% of magnitude; For small scale structures sensitivity is larger of 0.1 mV/m or 10%of magnitude.


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 <0.2 mV/m. RBSP ~twice as accurate.

Requirement is larger of either <0.3 mV/m or 10% of magnitude of E for Radial distance > 3.5 Re.

Accuracy of Large Scale Electric Field Measurement


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 0-500 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.: 0-500 mV/m Capability: 0-4V/m) E-fields ; B-fields and cold electron density variations 0-100 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 0-500 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 10-14 V2/m2Hz (TBR) at 1 kHz and3 x 10-17 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


Measurement Dynamic Range

Sensitivity (driving)

Frequency Range/Timing

Req; EFW MRD ELE

Req: EFW Inst.

Difficulty

Spin Plane Electric Field

0.3-500 mV/m

> 0.3 mV/m or 10% of signal for R>3.5 Re

15 Hz 38 46 Medium

Spin Axis Electric Field

2-500 mV/m > 2 mV/m or 10% of signal for R>3.5 Re

15 Hz 42 51 Medium

Cold Plasma Density (<30eV)

0.1 -50 cm-3

n/n ~50% 0.5 Hz 55 47 Easy

Spin E-field

0.3-500 mV/m

1.0 mV/m @ 50 Hz

3-D B 90 dB 0.3 pT @ 100 Hz

Small Scale Large Amplitude Wave/ Structures

n 1-50 cm-3 n/n ~10%

250 Hz* * in change matrix

42 spin 47 axial 71, 59

49 spin 52 axial 44 50

Easy

Interferometric Timing

0-500 km/s (0.1-30km)

NA 0.06 ms

61 45 Easy

EMFISIS Interface 3 D Wave E-field

90 dB (TBR)

Spin plane: 3x10-14 V2/m2Hz @ 1 kHz 3 x 10-17V2/m2Hz @ 100 kHz (Spin axis x 100 less sensitive)

10 Hz- 400 kHz

244,246 36, 208 Medium

Primary Measurement Requirements Flow to Instrument


LOGIC

AXB-01

LDO REG

+5V +15VF-15VF

DOOR2

BEB PWR -225V

BEB PWR +5VA

INSTRUMENT DATA PROCESSING UNIT (IDPU)

128K x 8

+5V +15VF-15VF

SYNC

FLT PWR1-6

Z80 CPU

SCM (X, Y, Z)

BACKUP56 D,S

FLT PWR1-6

S

FGM (X, Y, Z)

ANALOG FILTERING AND GAIN

MTR3

ACTEL

IMONs

DACs

+X

VSPHERE(V1-V6)

- +

IDPU PWR: +3.6VD

STATE1

DOOR5-6-Z

MTR5

+5V +15VF-15VF

POWER CTRL BOARD (PCB)

T

BEB ANALOG HK

+5V +15VF-15VF

RBSP EFW BLOCK DIAGRAM RBSP_EFW_SYS_100E CURTIS 2008-AUG-14

1.5V

USHER1-6

x6

-X

BEB PWR +225V

+5V +15VF-15VF

FLT POWER

V6

FILTER, I/F

TEMP6

INST & SC I/F

VMONs

FLT GND1-6

+Y

STATE4

MTR1

AXB-02

BEB ANALOG HK

ACTEST1-6

E x B, DFT, Waveforms

HTR 5

SERIAL TELEM-Y

IDPU PWR: -10V

STACER 5-6

FLT PWR, FLT GND 1-6

STATE5

- +

DIGITAL FIELDS BOARD (DFB)

MUX

DFB TLM (2)

AXB BOOM PWR

32K x 8PCB CMD, CLK, STB

FLOATING GND

MTR2

IDPU PWR

+28V+3.6VD+1.8VD

+5VD

S

BEB PWR +5VD

VMONs

ACTEL

DOOR1

DATA CTRL BOARD (DCB)

SPB BOOM PWR

DCB/DFB POWER

x3

STATE3

BEB CTRL(11)

3.3V

LVPS_SYNC

TEMP 5-6

ADC

HTR 6

V5

x3

Preamp

IDPU PWR: +1.8VD

MTR 5-6

PCB CMD, CLK, STB

+28V +225V-225V

SC IDPU PWR

256MB

DFB CMD, CLK, TLM(2), SYNC

SCM (X, Y, Z)

DOOR 1-4

LDO REG

STACER6, BACKUP56S

SPB-01

V4

x3

FLASH

TEMP5

- +

IDPU PWR I/F TOSPACECRAFT

SPB-04

PCB ANALOG HK

MUX,ADC (2)

+5V +15VF-15VF

PCB_ANALOG_HSK

BEB_CTRL(11)

DOOR6, BACKUP56D

BEB PWR -10VA

IDPU PWR

x6STATE2

GUARD1-6

DFB CMD, CLK (8MHz)

LVPS_SYNC

- +

- +

SPB-03

BEB PWRBOOM ELECTRONICS BOARD (BEB)

SERIAL CMDS

IDPU PWR: +5VD

PROM

FLUXGATEMAGNETOMETER

32GB

LOW VOLTAGE POWER SUPPLY (LVPS)

IDPU PWR: +5V

SPB-02

1.5V

EFW (X, Y, Z)

- +

T

EFW (X, Y, Z)

STACER5, BACKUP56S

t

t

V3

DIFFERENTIAL DRIVERS

MTR6

EMFISIS MEB

3.3V

BEB/PCB POWER

+28V +5VD

STATE6

DOOR5, BACKUP56D

BEB PWR +10VA

V2

MTR4

STATE1-6

MUX

BACK PLANE

SRAM

MTR 1-4

S

DATA I/F WITH SPACECRAFTDOOR4

IDPU PWR: -5V

HTR 5-6

INST CTRL, I/F

SDRAM

+Z

+28V +5V-5V

+10V-10V

IDPU PWR: +10V

BIAS1-6

DOOR3

V1

DFB SYNC (1Hz)

FGM (X, Y, Z)

1PPS / SPIN PULSE

+28V +10V-10V+5V


BACK-UP SLIDES


Effect of Attitude Uncertainty in E-VxB subtraction accuracy


RBSP Level 1 Baseline Measurement Goals Related to EFW

3-D Electric Field from DC to 10 Hz on two platforms (4.1.2.10)

3-D Wave Electric Field 10 Hz -10 kHz (Spectral: 20 bins) (4.1.2.9)

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. (4.1.2.14)

3-D Wave Magnetic Field 10 Hz-10 kHz (Spectral: 20 bins) (4.1.2.8)

Plasma Density 1 second resolution on two platforms (4.1.2.11)


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


Large Amplitude AlfvenWave at PSBL with imbedded largeamplitude LH “type” waves

R=5.2 Re, 0.82 MLT, MLAT~25 deg

Ez ~300 mV/m By~100 nT

Propagate parallel to B tpwards Earth

Vphase~ 3000-10000 km/s

E-Field (mV/m)(~800 Hz)

Z GSM

B-Field (nT)Y GSM

(8 Hz) Notice:Imbedded bursts of highfrequency waves ~1 V/mptp (greater in other components)

25 duration burst

Low freq

1000

-1000

0

100

0

50


QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.


Each EFW instrument shall consider a spin axis DC electric field (survey) measurement to be unobtainable when: 1) the spacecraft is in Earth shadow; 2) the spin axis boom pointing requirements are not met; 3) magnetic field data is not within required accuracy; 4) spacecraft attitude information is not within required specifications; 5) spacecraft velocity measurements are not within specification; 6) the electrostatic cleanliness specification is not capable of controlling differential charging of spacecraft surface (i.e., differential charging across spacecraft surface > 1 volt);

Validity Conditions for Spin Plane Electric Field Measurement

MRD ELE 494


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7 3-4 Sept. 2008 EFW INST+SOC PDR EFW Science Overview Professor John R. Wygant (PI) University of Minnesota