THEMIS Mission CDREFI- 1 UCB, June 14-18, 2004 THEMIS Electric Field Instrument (EFI) Mission CDR The THEMIS EFI Team

THEMIS Mission CDR EFI-1 UCB, June 14-18, 2004

THEMIS Electric Field Instrument (EFI)

Mission CDRThe THEMIS EFI Team


Outline

•Personnel and Organization•Summary of EFI Status at MCDR•Requirements, Specifications, and Design Compliance

•Requirements•Top-Level Design•Error Budgets

•Status of Subsystem Design, Fabrication, and Testing•Fabrication, Integration, and Test•Schedule: Henry Ford Help Us…•Operations Planning

•Deploy and Commisioning•Etc.


Personnel and OrganizationOrganizational Chart (all UCB unless noted):

• Prof. F. Mozer (EFI Co-I).• Drs. J. Bonnell, G. Delory, A. Hull (Project Scientists)• P. Turin (Lead ME), Dr. D. Pankow (Advising ME)• B. Donakowski (EFI Lead ME, SPB, Facilities)• G. Dalton (SPB, EFI GSE ME), K. McKee (ME), S. Martin (MT)• R. Duck (AXB ME)• D. Schickele (Preamp, Sensor Cables, Facilities ME)• S. Grimmer, R. Gupta (ME GSRs)• S. Jelinsky, S. Marker (Facilities and TVAC Staff)• S. Harris (BEB Lead EE), H. Richard (BEB EE)• J. Lewis, F. Harvey (GSE)• Technical Staff (H. Bersch, Y. Irwin, H. Yuan, B. Dalen, N.

Castillo) Wm. Greer (UCLA), et al.)• R. Ergun (DFB Co-I; CU-Boulder)• J. Westfall, A. Nammari, K. Stevens (DFB SysE, EEs; CU-

Boulder)• C. Cully (DFB GSR; CU-Boulder)


EFI Status at I-CDR• Requirements and Design:

– The current EFI design meets Mission and Instrument requirements.– The design is complete.– One new requirement (CG positioning) has been imposed post-PDR.

• Procurement:– All long-lead items have been procured in sufficient quantities to allow for

ETU and initial FLT production:– EEE parts ordered; rad testing of required parts complete.

– SPB and AXB mechanical items (custom wire cable, stacers, actuators, motors) are in-house, or on order with expected delivery on schedule for FLT build up.

– FLT machining on order, with expected 25% fulfilment (1-1/2 SC of parts) by early July, and remainder by end of July.

• Personnel:– Team is complete:

– All design engineering positions filled.

– One FT MT position filled Mar ’04; 0ne PT MT positions filled internally by personnel transitioning over from STEREO; two ME GSRs hired for summer and fall to support FLT production startup.

• Assembly and Test:– ETUs of all major elements have been assembled and partially or largely

tested.– Testing will be completed by July 2004.


RFA and Design Trade Closure• RFAs from I-PDR, M-PDR, and I-CDR all responded to a/o closed out:

– ESC Spec is on Rev. D1; includes detailed specs on the requirement and methods to achieve it; ESC roster developed in Feb ’04, allowing close collaboration between Swales and UCB on problem areas and mitigation techniques.

– EMI Spec completed Mar ’04.– Detailed Instrument I&T plan under development as part of ETU Testing;

synthesized from Polar, Cluster, etc.– Mechanical (INST-RFA 13, 14, 15, 19, 20, R03), and Electrical (INST-RFA

16AB, 17) arising from ICDR, as well as Internal Mechanical Review.

• Open Design Trades from PDR closed out:– Boom lengths set at 50/40/7.67 meters tip-to-tip based on CBE of Probe

mass properties and std. GSFC and UCB dynamic stability requirements and boom mode resonance keep-outs.

– Ti-N chosen over DAG-213 for SPB sensor coating.– Heritage brushed motor chosen for SPB deploy.– Braid biasing selected, and Distal Braid length set at 3 m.– DAC implementation on BEB chosen (ADC5544), and bias offset range of +/-

40 V maintained.– EFI filters on DFB chosen to be Bessel-type.


REQUIREMENT EFI DESIGN

IN-1. The Instrument Payload shall be designed for at least a two-year lifetime.

Compliance. Lifetime has been considered in all aspects of EFI and DFB design (parts, performance degradation, etc.).

IN-2. The Instrument Payload shall be designed for a total dose environment of 33 krad/year

(66 krad for 2 year mission, 5mm of Al, RDM 2)

Compliance. Common Parts Buy for Instrument Payload. All parts screened for total dose. Radiation testing planned if TID is unknown.

IN-3. The Instrument Payload shall be Single Event Effect (SEE) tolerant and immune to destructive latch-up.

Compliance. Common Parts Buy for Instrument Payload. All parts screened for total dose. Radiation testing planned if LET is unknown.

Mission Requirements



IN-7. No component of the Instrument Payload shall exceed the allocated mass budget in THM-SYS-008 THEMIS System Mass Budget.xls

Compliance.

SPB: 1.88 kg Allocated; 1.61 kg CBE (CAD model).

AXB: 2.30 kg Allocated; 1.97 kg CBE (CAD model).

BEB: 0.396 kg Allocated; 0.426 kg CBE (ETU)

DFB: 0.396 kg Allocated; 0.360 kg CBE (BB)

Harness: 0.58 kg (modeling)

(Harness, BEB and DFB tracked with IDPU)

IN-9. No component of the Instrument Payload shall exceed the power allocated in THM-SYS-009 THEMIS System Power Budget.xls

Compliance.

Preamps: 0.09 W Allocated; 0.08 W CBE (ETU).

note: Preamp power included in BEB allocation.

BEB: 1.76 W Allocated; 1.1 W CBE (ETU).

DFB: 1.00 W Allocated; 1.1 W CBE (BB+modeling).

IN-13. The Instrument Payload shall survive the temperature ranges provided in the ICDs

Compliance. SPB/AXB ICDs signed off. Verification by Environmental Test planned.

IN-14. The Instrument Payload shall perform as designed within the temperature ranges provided in the ICDs

Compliance. SPB/AXB ICDs signed off. Verification by Environmental Test planned. Special thermal shock testing of preamp ETU underway.




IN-16 The Instrument Payload shall comply with the Magnetics Cleanliness standard described in the THEMIS Magnetics Control Plan

Compliance. THM-SYS-002 Magnetics Control Plan. Budget for EFI Magnets (Boom Motors) is <0.75nT @ 2 meters; CBE by measurement is 0.25 nT @ 2 meters.

IN-17 The Instrument Payload shall comply with the THEMIS Electrostatic Cleanliness Plan

Compliance. Design, fabrication, and testing in accordance with THM-SYS-003 Electrostatic Cleanliness Plan.

IN-18 The Instrument Payload shall comply with the THEMIS Contamination Control Plan

Compliance. Design and fabrication in accordance with THM-SYS-004 Contamination Control Plan.

IN-19. All Instruments shall comply with all electrical specifications

Compliance. Design in accordance with THM-IDPU-001 Backplane Specification (BEB, DFB).

IN-20. The Instrument Payload shall be compatible per IDPU-Instrument ICDs

Compliance. THM-SYS-103 DFB-to-IDPU ICD signed off. THM-SYS-104 BEB-to-IDPU ICD signed off. Verification Matrices to be completed.

IN-21. The Instrument Payload shall be compatible per the IDPU-Probe Bus ICD.

Compliance. Both THM-SYS-108 Probe-to-EFI Radial Booms ICD. THM-SYS-109 Probe-to-EFI Axial Booms ICD are signed off. Verification Matrices to be completed.

IN-23 The Instrument Payload shall verify performance requirements are met per the THEMIS Verification Plan and Environmental Test Spec.

Compliance. THM-SYS-005 Verification Plan and Environmental Test Specification preliminary draft. Verification matrix to be completed.

IN-24 The Instrument Payload shall survive and function prior, during and after exposure to the environments described in the THEMIS Verification Plan and Environmental Test Specification

Compliance. THM-SYS-005 Verification Plan and Environmental Test Specification preliminary draft. Verification matrix to be completed.




IN.EFI-1. The EFI shall determine the 2D spin plane electric field at the times of onset at 8-10 Re.

Compliance. Via compliance with IN.EFI-5 and -13.

IN.EFI-2. The EFI shall determine the dawn/dusk electric field at 18-30 Re.

Compliance. Via compliance with IN.EFI-5 and -13.

IN.EFI-3. The EFI shall measure the 3D wave electric field in the frequency range 1-600Hz at the times of onset at 8-10 Re.

Compliance. Via compliance with IN.EFI-6, -8, -9, -10, and –11.

IN.EFI-4. The EFI shall measure the waves at frequencies up to the electron cyclotron frequency that may be responsible for electron acceleration in the radiation belt.

Compliance. Via compliance with IN.EFI-6, -8, -9, -10, and –11.

Science Requirements



IN.EFI-5. The EFI shall measure the 2D spin plane DC E-field with a time resolution of 10 seconds.

Compliance. On-board spin-fit of spin plane E-field at 3-s (one-spin) resolution.

IN.EFI-6. The EFI shall measure the 3D AC E-field from 1 Hz to 4kHz.

Compliance. 3-axis E-field measurement sampled at 8 ksamp/s. See AC Error Budget. Verified through Calibration.

IN.EFI-7. The EFI shall measure the Spacecraft Potential with a time resolution better than the spin rate (3 seconds; from ESA to compute moments).

Compliance. On-board spin-avg’d sphere potentials at 3-s (spin-rate) resolution; EFI data rate allocation includes single spheres at ¼-rate of E-field data.

IN.EFI-8. The EFI DFT Spectra Range shall be 16Hz to 4kHz, with df/f~25%.

Compliance. Spectral products from DFB cover 8 Hz to 8 kHz at 5%, 10%, or 20% BW (16, 32, or 64 bins)

IN.EFI-9. The EFI shall measure DC-coupled signals of amplitude up to 300 mV/m with 16-bit resolution.

Compliance. Analog gain and ADC resolution of DFB set accordingly. Verified through Calibration.

IN.EFI-10. The EFI shall measure AC-coupled signals of amplitude up to 50 mV/m with 16-bit resolution.

Compliance. Analog gain and ADC resolution of DFB set accordingly. Verified through Calibration.

Performance Requirements



IN.EFI-11. The EFI noise level shall be below 10-4 (mV/m)/Hz1/2.

Compliance. Low-noise preamp chosen (OP-15); good analog design practices throughout preamp, BEB and DFB; CBE is 3x10-5 on AXB, 3x10-6 on SPB. Verified through ETU testing.

IN.EFI-12. The EFI HF RMS (Log power) measurement shall cover 100-500 kHz with a minimum time resolution of the spin rate (on-board triggers).

Compliance. CBE of EFI response has gain of 0.8 out to 1 MHz; DFB provides HF-RMS at 1/16 to 8 samp/s.

IN.EFI-13. The EFI shall achieve an accuracy better than 10% or 1 mV/m in the SC XY E-field components during times of onset.

Compliance. See DC Error Budget Discussion.

Performance Requirements



DFB FUNCTIONAL REQUIREMENTS

IN.DPU-36. The IDPU DFB shall provide an FFT solution for determining the parallel and perpendicular components of E and B in both fast survey and burst modes and produce spectra for each quantity separately.

Compliance. DFB design includes FPGA-based projection (E dot B, E cross B) and FFT solutions. Verified through Test and Calibration of ETU.

IN.DPU-37. The IDPU DFB shall integrate FGM digital data and EFI data to produce E·B

Compliance. DFB design includes FPGA-based projection ( E dot B, E cross B) solutions. Verified through Test and Calibration of ETU.

EFI Board Requirements



BEB FUNCTIONAL REQUIREMENTS

IN.DPU-38. The IDPU BEB shall provide sensor biasing circuitry, stub and guard voltage control for the EFI.

Compliance. The BEB design provides 3 independent bias channels per sensor (BIAS,GUARD,USHER) and one shared bias channel for the SPB sensors (BRAID). Boom deployment is provided through the IDPU/PCB and DCB.

IN.DPU-39. The IDPU BEB shall distribute a floating ground power supply to the EFI sensors.

Compliance. The BEB design provides 6 independent floating grounds to the LVPS, and distributes the derived +/-10-V analog supplies to the six EFI sensors.

IN.DPU-40. The IDPU BEB shall generate six independent BIAS, GUARD and USHER voltages with an accuracy of 0.1% for distribution to the EFI sensors.

Compliance. The BEB design includes matched gain-setting components, along with >12-bit DAC, allowing accuracy of better than 0.1%; Verified through Test and Calibration of ETU, and loading of FLT boards.

EFI Board Requirements



IN.BOOM-5a. Deployed EFI Axials shall be repeatable and stable to = 1 degree and L/L = 1%.

Compliance. Adequate stiffness and angular alignment of AXB stacers and deploy system included in design; verified by testing of ETU.

IN.BOOM-5b. Deployed EFI Radials shall be repeatable and stable to = 1 degree and L/L = 1%.

Compliance. Proper SPB cable design (limpness, CTE) along with std. Cable winding procedures included in design; verified by testing of ETU.

IN.BOOM-6. EFI Axial Booms shall be designed to be deployed between 2 and 25 RPM about the Probe's positive Z axis.

Compliance. Adequate stiffness and angular alignment of AXB stacers included in design; verified by testing of ETU.

IN.BOOM-7. EFI Radial Booms shall be designed to be deployed between 2 and 25 RPM.

Compliance. Adequate strength margins on cable included in design; verified by proof-loading of cable and testing of ETU.

IN.BOOM-8. EFI Axial Booms deployed stiffness shall be greater than 0.75 Hz (1st mode).

Compliance. Part of AXB stacer spec; verified by Testing of ETU.

IN.BOOM-12. All deployed booms shall include TBD inhibits to prevent inadvertent release.

Compliance. Test/Enable plugs included in design. Red tag door (SPB) and tube (AXB) covers.

EFI Boom Requirements


EFI Block Diagram

A High-Input Impedance Low-Noise Voltmeter in Space

sensor

preamp

sheath

Floating groundgeneration

Bias channels

BIAS

USHERGUARD

BRAID VBraid

Vref

VBraidCtrl


Top-Level Design (1)

Diagram of THEMIS EFI Elements

AXIALBOOMS

RADIALBOOMS

EF1

EF2

EF3

EF4

EF5

EF6

SEARCHCOIL

SCM1

SCM2

SCM3

V6

V5

V4

V3

V2

V1

E12

E34

E56

E12AC

E34AC

E56AC

SC1

SC2

SC3

MUX16:1

ADC

ADC

FPGADSP Logic

DATA

COMMAND

1 PPS

±10V

±5V

+5V

+2.5V

Backplane I/F

SCM ±10V

8MHzClk

SCM Control

Digital Fields PWBStandard 6U Card

Micro-D

6 X SMA

E12logRMS

SCM ±10V

SCM Control

FGM4KHz

10Hz - 4KHz

100KHz - 500KHz

PreampEnclosure

Preamp PWB

GSE

SPB

AXB

BEB

DFB



Description of THEMIS EFI Elements• Three-axis E-field measurement, drawing on 30 years of

mechanical and electrical design heritage at UCBSSL.• Closest living relatives are Cluster, Polar and FAST, with parts

heritage from CRRES (mechanical systems, BEB designs, preamp designs).



Description of THEMIS EFI Elements• Radial booms:

– 22-m cable length (up to 50 m tip-to-tip deployed; SPB-X to be deployed to 50 m, SPB-Y to be deployed to 40 m).

– 8-cm dia., Ti-N-coated spherical sensor.

– 3-m, 0.009-inch dia. fine wire to preamp enclosure.

– SMA-actuated door release mechanism.

– Brushed motor design.

– Significant volume and mass relief relative to closest living relatives.

– USHER and GUARD bias surfaces integral to preamp enclosure.

– BRAID bias surface of 3-m length inboard of preamp (common between all 4 radial booms).

– Sensor is grounded through 10 Mohm resistance when stowed, providing ESD protection and allowing for internal DC and AC functional tests.

– External test/safe plug (motor,door actuator,turns click, ACTEST) to allow for deploy testing/safeing and external signal injection.



Description of THEMIS EFI Elements• Axial booms:

– 2.8-m stacer with ~1-m DAG-213-coated whip stacer sensor.

– New, fully-qualified Double DAD design based on FAST axial booms.

– New, fully-qualified FrangiBolt deployment actuation.

– Preamp mounted in-line, between stacer and sensor.

– USHER and GUARD bias surfaces integral to preamp enclosure.

– No BRAID bias surface.

– Sensor is grounded through 7 Mohm resistance when stowed, providing ESD protection and allowing for internal DC and AC functional tests.

– External test/safe plug (deploy actuator, ACTEST) to allow for deploy testing/safeing and external signal injection.



Bias Driver

Vin

+100VA

+10VA

-10VA

-100VA

AGND

Vsphere_Ref

Vout

+100VA

Vrefence ±40VDC

0 - 5V

Floating GND Driver

PreAmpIn

+100VA

+10VFloating

-10VFloating

-100VA

FloatingGND

AGND

VSphere

Vrefence ±40VDC

-10VBus

Power Filter

+10Floating

Floa

tingG

ND

-10Vin

-10Floating

+100Vin

-100V

+100V

-100Vin

+10Vin

AGND

+10FltVin

-10FltVin

+10V

-10V

-100VBus

±60VDC

Vrefence ±40VDCfreq

+100VBus

0 - 5V

0 - 5V

+10FltVout

Guard

+10FltVin

BiasControl

-10VFltVout

Bias

freq

freq

+10VA+10VBus

freq

-10FltVin

freq

-100VA

Guard Driver

Vin

+100VA

+10VA

-10VA

-100VAAG

ND

Vsphere_Ref

Vout

Usher Driver

Vin

+100VA

+10VA

-10VA

-100VA

AGND

Vsphere_Ref

VoutUsherControl

FloatGNDfreqPreAmp In

freq

Usher

freq-10VA

±60VDC12Vpp AC (to 500kHz)

GuardControl

AGND

Description of THEMIS EFI Elements•BEB block diagram:



Preamp Signal CharacteristicsDC voltage level: ± 60Vdc w.r.t. AGNDAC voltage level: 12 VppAC frequency band: DC – 500kHz

Floating Ground Driver SpecificationsInput: Preamp signal (VSPHERE)Input filter: 300 Hz (3dB)Output voltage level: ± 60Vdc w.r.t. AGNDOutput: References floating ground supply (± 10Vdc)

Bias, Usher, Guard SpecificationReference Input: Preamp signal (VSPHERE)Reference Input filter: 300 Hz (3dB)

Vref ± 40Vdc w.r.t. AGND, where FS DAC == Vref + 40Vdc

DAC resolution: 1 nA (12-bit DAC == 0.65 nA resolution on Bias)DAC accuracy: Opposing booms matched to 0.1%DAC step response: < 10 ms (For information only)

EE PartsSelection / Derating / Radiation / Gen'l. Specs

IAW Themis Product Assurance Implementation Plan (PAIP)

Output voltage level:

Description of THEMIS EFI Elements

•BEB Signal Processing and Control Specifications:



AXIALBOOMS

RADIALBOOMS

EF1

EF2

EF3

EF4

EF5

EF6

SEARCHCOIL

SCM1

SCM2

SCM3

V6

V5

V4

V3

V2

V1

E12

E34

E56

E12AC

E34AC

E56AC

SC1

SC2

SC3

MUX16:1

ADC

ADC

FPGADSP Logic

DATA

COMMAND

1 PPS

±10V

±5V

+5V

+2.5V

Backplane I/F

SCM ±10V

8MHzClk

SCM Control

Digital Fields PWBStandard 6U Card

Micro-D

6 X SMA

E12logRMS

SCM ±10V

SCM Control

FGM4KHz

10Hz - 4KHz

100KHz - 500KHz

Description of THEMIS EFI Elements•DFB functional block diagram:



Spin-fit Filters- E12, E34, E56,V1, V2, V3, V4- 50 Hz Filter- 128 S/s output

Efit (ID80)

FB #1 (6 bands)

Vfit (ID80)

VAFS (ID65)VBFS (ID66)

EFS (ID67)SCMFS (ID68)

VAPB (ID69)VBPB (ID70)

EPB (ID71)SCMPB (ID72)

VAWB (ID73)VBWB (ID74)EWB (ID75)

SCMWB (ID76)

Analog Selection

Normal mode- 8kS/s to ADC #1- 16kS/s to ADC #2

ADC #1 only mode- All to ADC #1

ADC #2 only mode- All to ADC #2

8kS/s AnalogQuantitiesV1, V2, V3,V4, V5, V6,E12DC, E34DC,E56DC, SCM1,SCM2, SCM3,E12HF

ADC #1128kS/s

ADC #2128kS/s

SignalRouting256kS/s

Filter Banks- Any two DCcoupled inputs- 11 frequencies- output from 1/16to 16 S/s

E12HF Processing- Peak Detect- Average

DerivedQuantities- ExB- EdotB- SCMxB- SCMdotB

Fast Survey Filters- All V, E, SCM- 0.8 - 100 Hz Filter- 2 -256 S/s

Particle Burst Filters- All V, E, SCM- 0.8 - 100 Hz Filter- 2 -256 S/s

Wave Burst Filters- All V, E, SCM- 200 - 4/6 kHz Filter- 512 S/s - 8/16 kS/s

FFT Unit- All V, E, SCM,Derived Quantities- Hanning Window- 1k/2k point FFT- Calculate power- Create 16, 32, or64 pseudo-logspaced bins

Spec2 (ID78)Spec1 (ID78)




HFAve (ID81)

HFPeak (ID81)

Fbank1 (ID64)

Fbank2 (ID64)

FbankT2 (ID81)

FbankT1 (ID81)

FB #2 (6 bands)

FB #1 (All 11 bands)

FB #2 (All 11 bands)

On During FastSurvey Only.

Always On.

EWB (ID75)

SCMWB (ID76)

8-bit Psuedo-logCompressor19 8 bit:includes the # ofleading zeros (upto 15) and the 4MSBs.

8-bit Psuedo-logCompressor19 8 bit:includes the # ofleading zeros (upto 15) and the 4MSBs.

Acquisition Processing Telemetry

16kS/s AnalogQuantitiesE12AC, E34AC,E56AC

Description of THEMIS EFI Elements•DFB signal flow block diagram:



Description of THEMIS EFI Elements• DFB Signal Processing and Control Requirements:

– +/- 100 V analog input relative to AGND.

– CMRR >= 80 dB on differential E-Field channels.

– DC-coupled E-fields and sensor potential waveforms from 0-4 kHz.

– AC-coupled E-fields from 0-6 kHz.

– AC-coupled SCM (AC B-field) from 0-4 kHz.

– Log(AKR POWER) from 100-500 kHz.

– E-field and sensor potentials for on-board Spin Fit data processing.

– Filter bank with df/f better than 25% from 8 Hz to 4 kHz.

– On-board projection of E and dB into ExB/E.B coordinates for FFT processing (“Derived Quantities”).

– On-board computation of FFT spectra (Standard and Derived Quantities).



Performance Specification• Spacecraft potential: +/- 60 V, 1.8 mV resolution, better than

46 uV/m resolution (allows ground reconstruction of E from spacecraft potential to better than 0.1 mV/m resolution).

• DC-coupled E-field: +/- 300 mV/m, 9 uV/m resolution, 0-4 kHz.

• AC-coupled E-field: +/- 50 mV/m, 3.0 uV/m resolution, 0-6 kHz.

• AKR log(Power) channel: 1 uV/m to 4.5 mV/m RMS amplitude, 400-kHz bandwidth, 100-500 kHz.

• 16-bit resolution.



Thermal Predicts:

SubsystemSurvival Operation Deploy

Cold Hot Cold Hot Cold Hot

SPB -20 C 65 C N/A N/A -12 C +35 C

AXB -60 C 80 C N/A N/A -20 C +50 C

Preamp -121 C 60 C -65 C 60 C N/A N/A

BEB,DFB

(IDPU)

-50 C 65 C -30 C 45 C N/A N/A

180-min-long eclipse 60-min-long eclipse


Error Budgets

DC (ie. spin frequency or less):• Mechanical and Electrical design chosen to keep individual sources of

systematic error on SPBs less than 1.0 mV/m:– CMRR of differential E-field channels >= 80 dB.– DC Gain within a few parts in 1000 of 1.0; better than 1% component

matching then ensures CMRR >= 80 dB.– ESC requirements on potential uniformity and area of freely-charging

exposed surfaces (eg. Insulators).– Different boom lengths (40 and 50 m) chosen to allow detection of systematic

errors due to wake and boom shorting effects.– Fine wire length reduces shorting effect to 5% or less.– Improved Preamp Mechanical design reduces differential photocurrent

collection by factor of 3-10 relative to Cluster-II (3 sufficient).– Increased requirement on CG placement accuracy to ensure alignment of

boom pairs to better than 0.5 degrees (see detail, next slide).

• AXB error budget more liberal, due to shorter length (errors scale as 1/L to 1/L3), and lack of Mission Requirement; few mV/m:– 4-cm control of +Z/-Z boom lengths to counteract shift of electrical center

along spin axis (antenna mast vs. separation ring).– ESC requirements (AXB measurements will provide for a sensitive test of

ESC compliance on-orbit).


CG Placement Requirement

CG Offset Effect on Systematic Error in Sunward E-Field:

•Center-of-Gravity (CG) offset from center of SPB boom system drives angular offset between opposing fine wires.•Opposing fine wires go through sun-alignment at different spin phases, leading to systematic bipolar error signal.•Primary effect is on instantaneous sunward E-field component.•CG positioning Requirement of 1 part in 100 of SPB Cable pivot radius (approx. 4 mm, or 0.166 inch) drives magnitude of error below 0.8 mV/m, worst-case.

(CG offset)/(pivot radius)

0.001

0.01


Error Budgets

EFI Spectral Coverage and System Noise Estimates

AKR band

CDI

BBF

Preamp and Rbias

Current Noise

Preamp VoltageNoise

axial

radial

Maximum Spectra(DC-Coupled)

1-LSB Spectra(DC-Coupled)

flat

1/f

1/f3

Spinfrequency

4-kHzAnti-aliasing roll-off

10-HzAc-coupled roll-in


Error Budgets

•RE02 BB Limits set to give S/N of > 3 for expected AKR amplitudes.•RE02 NB limits set to drop equivalent BB spectral density below expected amplitudes below 4 kHz on SPB.


Error Budgets

•7.5 pF input capacitance of preamp has significant effect on gain above 100 Hz:

•SPB AC gain is 0.65.•AXB AC gain is 0.45.

•Rolloff frequency from DC to AC gain (resistive to capacitive coupling) is predominantly controlled by sheath resistance, which is under direct control via sensor bias current.•AC gain in both cases is still sufficient to achieve required measurements over desired frequency interval.


EFI Subsystem Design, Fabrication, and Test Status


Assembly and Test To-Date

ETUs • AXB (1 unit): assembled March ’04; RT and TVAC deploy

tested, March ’04; redesigned, rebuilt, redeployed April ’04; Sensor redesign, May ’04; Straightness, May ’04; Horiz. Deploy (length cal), June ’04.

• SPB (1 unit): assembled April ’04; Housing, Door, and Door Actuator redesigned and rebuilt May ’04; vibe’d June ’04; TVAC and RT Deploy, June ’04.

• Preamp Enclosure: Four ETUs built, April, ’04 and integrated into ETU Cables, SPB, and AXB; Cable termination redesigned, May ’04 (post-I-CDR); revised ETUs to be built June ’04.

• Cables: One Prototype, two ETU Sensor Cables, and one special Thermal Cable fabricated March 29 – April 9, ’04; integrated with ETU Preamp PWBs and ETU SPB and AXB for vibe testing, and Preamp Thermal Model Simulator.



ETUs (con’t)• Preamp PWB: Two ETU Preamp PWB assembled April 9 ’04; integrated

with ETU Preamp PWBs and ETU SPB and AXB for vibe testing. One Flight-like PWB assembled for Preamp Thermal Modeling (nominal operation at –130 C!).

• BEB: One ETU built, Mar ’04; functional testing, Mar-Apr ’04, design qualified, meets required specifications; Integrated BEB-Preamp-Cable testing ongoing, June ’04.

• DFB: One BB ETU with core FPGA functionality (CDI interpreter, waveform filters and filter banks) completed mid-May ’04; successfully integrated with BEB, DCB, and EFI/BEB EGSE, mid-May ’04; true ETU fab and assy late June-early July ’04.



GSE and Harnessing• EGSE: BEB/EFI Electrical GSE complete and characterized, April ’04;

spare unit with reduced fuctionality to support BEB Flight Board Testing, on-order, June ’04.

• Faraday Boxes: two Faraday boxes with internal fixtures and wiring (signal paths and Plasma Simulators), complete, June ’04.

• MGSE: AXB TVAC fixtures done; AXB FrangiBolt simulator done; AXB HDeploy Track, TBC, June ’04; SPB TVAC Takeup Reels, TBC, June ’04 for SPB TVAC; SPB TVAC Fine Wire Deploy Reels, TBC, June ’04.

• TVAC Harnessing: design complete, April-May ’04; SPB ETU built, May ’04; AXB to be built, July ’04.

• ETU Harnessing: design complete, May ’04; under fabrication to support II&T, June ’04.

• Misc. Test Harnessing: dual boom unit Y-Test Harness, built May ’04. Breakout boxes, etc., designed and built as needed.


Near-Term Testing

Mechanical• AXB and SPB Vibe (June 9 and 10) – units passed.• SPB TVAC (Deploy Testing) (June 18-25; pending completion of

B20 “Bayside” refurbishment), AXB TVAC complete and successful.

• AXB and SPB Deploy Calibrations (late June).• Testing required to support FLT machining orders complete.

Thermal• Long-Eclipse Thermal Simulation and Thermal Shock (aka. L-N2

Dunk) for Preamp, -130 C to 60 C (May 2004; July 2004)

Electrical• Integrated electrical testing of EFI and BEB (all of June 2004;

EFI/BEB EGSE complete; Faraday Boxes complete in late April).• Formal Preamp Thermal Qualification (TVAC cycles and DPA)

(Jul-Aug 2004, parallel with F1 FLT build).

Suite-Level Testing (II&T)• EFI ETU delivered to II&T July 2004.


Parts Procurement, Qual, and Contamination

Long-Lead Items• All long-lead items in-house or on schedule for delivery to support

July ’04 start of Flight production.– Custom Cable– SPB Flight motors, bearings, slip rings, machine parts.– AXB Flight stacers, bearings.– Preamp Enclosure machine parts and Cable Fab fixtures.– BEB parts kits.– DFB parts kits.– Preamp parts kits.

Qualification Testing• All parts passed radiation (AD5544 DAC and LTC1604 ADC, in

particular).• Formal qualification of Preamp OP-15 and design via TVAC and

DPA in parallel to ETU and Initial Flight Build (July ’04).

Contamination• All suspect parts sent to UCLA for magnetic characterization (eg.

SPB motors and geartrain).


EFI Integration and Test Plans


Facilities

ETU Testing• Refurbished UCBSSL Silver B20 “Bayside” TVAC Chamber

– Accommodates up to 4 SPB.

• UCBSSL Addition High Bay “Geoffrey” TVAC Chamber– Accommodates fully-deployed AXB vertically.

• Vibe Testing done off-site.

• AXB Horizontal Deploy Track.

• SPB Vertical Deploy Fixtures in High Bay– Alternately, Std. Horizontal Deploy in SSL “Dungeon”.

FLT Testing• Same facilities as ETU, plus:

• New UCBSSL Silver B20 “EFI Snout” TVAC Chamber– Accommodates fully-deployed AXB horizontally.

• Vibe testing done off-site.


Calibration and TestMechanical and Electro-Mechanical

• SPB Deploy Length– Turns Count– Deploy Rate

• SPB Door Actuation and Function• AXB Deploy Length

– Repeatability– Stiffness and Straightness

• SPB Door SMA and AXB Deploy FrangiBolt Currents• SPB and AXB Cable Continuity and Isolation during Deploy

Electrical• EFI/BEB Calibration

– Quiescent and Operational Currents– DC Functional Tests (Gain, Offset, CMRR, Linearity, 0.1% Matching)– AC Functional Tests (Transfer Function, CMRR, Slew Rate,

Linearity)

• EFI/SCM/FGM via DFB Phase Intercalibration– See Suite-Level I&T.


Assembly and Test Flow

SPB Assembly and Test Flow, based on ETU Experience:


SPB Assembly and Test Plan


SPB Assembly and Test Plan


Instrument (Suite) I&T PlanIntegration and Test

• Instrument I&T takes place at UCBSSL.• Environmental (TVAC, Vibe, Suite EMC as per THM-SYS-005

Environmental Verification Spec).• Limited and Comprehensive Performance Testing:

– SPB Motor Simulators (aka. Motor-in-a-Box) and AXB Test FrangiBolts (aka. FrangiBolt-in-a-Box) used for pre- and post-environmental functional tests of deploy mechanisms, as well as dummy electrical loads during “fake” TVAC deploy testing.

– Internal DC and AC functional test capability used for pre- and post-environmental functional tests of sensors; sensors may be directly stimulated via ACTEST line on Test/Enable plug.

• End-to-End SPB and AXB TVAC Deploy Testing (IDPU-controlled; Motor-in-a-Box and FrangiBolt-in-a-Box).

• Integrated Fields System (DCB, DFB, EFI, SCM, FGM) modes testing: Nominal, Slow, Fast, Torturous Data Exchange, and “Mode X”.

• Phase intercalibration between EFI, SCM, and FGM performed using EFI Test/Enable Plugs, SCM Mu-Metal Box, FGM TCU and 12-channel, 16-bit, +/- 10-V National Instruments DAC system.


S/C (Probe) I&T Plan

Integration and Test• Probe I&T takes place at Swales Aerospace.• Environmental (TVAC, Vibe, Shock, EMI; as per THM-SYS-005

Environmental Verification Spec).• Limited and Comprehensive Performance Testing:

– Sensors via internal DC and AC Functional Test capability, monitored through ITOS.

– Actuators via external Boom Loads Simulator (BLS) and Test/Enable plugs, monitored through ITOS.

– Sensors may be stimulated externally via breakout on BLS, if required (non-standard test).

– Initial ITOS requirements outlined, Apr 2004.

• Red/Green tag items:– One red tag Snout Cover per SPB (4 total).

– One red/green Test/Enable plug per SPB (4 total).

– One red tag Tube Cover per AXB (2 total).

– One red/green Test/Enable plug supporting both AXBs (1 total)


EFI Production Schedule


F1-F2 Production Schedule

SPB

AXB

CalsBEB

Preamp

Cables

5 Jul ‘04

13 Sep ‘04

4 Oct ‘04

26 Jul ‘04

Vibe

TVAC, RT


FLT Production Schedule

•Grassroots estimate, based on ETU experience (1 person-day/subassy, TVAC and RT testing experience, electrical checkout, etc.).•Subassembly Assy tasks (eg. SPB Motor, Spool, etc.) carry 100% margin.•Rate setting steps are Mechanical Test and BEB Board Test (3-week durations).•3-week delivery cadence, with 2-week overlap between Fn Boom Assy and Fn+1 Subassembly Assy work.•5-week delivery cadence removes all overlap between successive Boom and Subassembly Assy work.•Downstream schedule risk will be reduced by using Subassembly schedule margin and larger summer labor pool (F1) (GSRs) to lay in overstock for F2 through F6.•Dedicated TVAC personnel (Jelinsky, McKee, Marker) used to reduce schedule risk from spreading Engineering staff thinly between Assembly, Test, and I&T.

Predicted Delivery Date to II&T and Probe I&T vs. Required

(01 JUL 2004 start)

Cadence F1 F2 F3 F4 F5 F6

3-Week 13 SEP 04 OCT 25 OCT 15 NOV 06 DEC 17 JAN

5-Week 13 SEP 18 OCT 23 NOV 09 JAN 13 FEB 20 MAR

II&T 28 SEP 23 NOV 23 NOV 18 JAN 18 JAN 15 MAR

Probe I&T 10 FEB 06 APR 04 MAY 06 JUN 01 JUL N/A


EFI Mission Operations


Deploy and Commissioning

• Draft Deploy and Commissioning plan developed Nov 2003.

• Draft plan refined Mar 2004 in response to revised launch date (21 Aug -> 21 Oct 2006).

• EFI SOH to be determined on all probes using stowed DC and AC functional test capability during initial on-orbit check-out.

• Instrument SOH used to determine probe assignment.

• EFI deployed on all probes after placement in initial science orbits.

• EFI deployed in 6 to 7 steps:– 5 to 6 intermediate deploy lengths with spin up for SPB.– 1 step to deploy both AXB.

• Primary constraints on deploy and commissioning:– 1 30-minute TM contact per 3-1/2 hours (thermal).– Desire to gather science data at intermediate deploy lengths

and in different plasma regimes.



• Deploy cycle on single probe (each step >= 3-1/2 hours):– Deploy SPB-X, wait for transmitter to cool down, run Slow

Sweep if desired, take Diagnostic Mode data if desired.– Deploy SPB-Y, wait for transmitter to cool down, run Slow

Sweep if desired, take Diagnostic Mode data if desired.– Spin Up to desired spin rate for beginning of next deploy

cycle.

• Slow Sweep: 4 BRAID, 3 USHER, 3 GUARD and 32 BIAS settings; 1152 steps, 1 step/spin, approx. 1 hour duration, data rate TBD (baseline is Diagnostic Mode, which may be overkill).

• Diagnostic Mode data:– 2 or 3 DCE channels at 32 samp/s (3.75 deg/samp).– 4 to 6 V channels at 8 samp/s (few mm spatial resolution).– 1536 to 2304 bps; supported out to P1 Apogee for Real-Time

contacts.



• P3 and P4 deploy first:– 2-day, 2-orbit cycle: P3 deploying one orbit, P4 quiescent,

then swap.– Full deploy and commissioning takes 14 days.

• P1 and P2 deploy next:– P2 on 2-day, 1-orbit cycle: deploy on outbound, quiescent on

inbound; 14 days total.– P1 on 4-day, 1-orbit cycle: deploy on outbound, quiescent on

inbound; 28 days total.– P1 deploy cycle maybe accelerated depending upon

experience gained and data gathered during P3 and P4 deploy and commissioning.

• P5 deploys last:– 1 or 2-day cycle, with full deploy and commissioning taking 7-

14 days.



Nominal Deploy and Commissioning Schedule


Operations and Data Validation

Operations• Slow Sweeps and diagnostic data taken several times per

year, upon first entry into a new plasma regime, and after long-duration eclipses to maintain optimal bias settings and monitor EFI state-of-health.

• EFI instrument mode set by ~30 registers on BEB; a typical mode will be specified with ~200 commands, valid over a typical one month period, once deploy and commissioning are completed.

Data Validation• Both sphere potentials and differential E-field data gathered

in all waveform modes, allowing for initial verification of E-field data.

• Intercomparison of Eperp and –VxB from ESA and FGM to establish offsets and boom shorting effects.


Operation and Data Validation

Data Rates (can change on-orbit; DFB mode commands)• Slow Survey

– Spin-fit radial and spin-avg’d axial E-fields; spin-avg’d SC potential (via ptcls).

– Filter Bank of one axis.

• Fast Survey– 3 E-field at 32 S/spin; 2-3 sphere potentials at 8 S/spin.

– Filter Banks of Standard or Derived quantities.

• Particle Burst– 3 E-field at 128 S/s; 2-3 sphere potentials at 32 S/s.

– Filter Banks as in Fast Survey.

• Wave Burst– 3 E-field at 1024 or 4096 S/s; 2-3 sphere potentials at 256 or 1024

S/s.

– Filter Banks as in Fast Survey.

• Diagnostic Mode – 3 E-field at 32 S/s; 6 sensor potentials at 8 S/s.


Operations and Data Validation

Nominal Sensor Biasing (CPS and PSBL; Prediction):

CPS PSBL

SC Potential <20 V and stable for CPS-PSBL plasma regimesWhen sensors run at 20 nA/sensor;Rsheath approx. 50 Mohm.

Documents

THEMIS Mission CDREFI- 1 UCB, June 14-18, 2004 THEMIS Electric Field Instrument (EFI) Mission CDR The THEMIS EFI Team