THEMIS MISSION PDR/CAREFI- 1 UCB, November 12-14, 2003 THEMIS ELECTRIC FIELD INSTRUMENT (EFI) Dr....

THEMIS MISSION PDR/CAR EFI-1 UCB, November 12-14, 2003

THEMIS ELECTRIC FIELD INSTRUMENT (EFI)Dr. John Bonnell and the THEMIS EFI Team

University of California-BerkeleyUniversity of Colorado-Boulder


Outline

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

•Top-Level Design•Designs of Individual Elements

•Design Drivers and Compliance•DC Error Budget•AC Error Budget

•Schedule•Design•Long-Lead Procurement•ETU

•EPR Results


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)• R. Duck (AXB ME)• D. Schickele (Preamp, SPB ME)• C. Smith (THEMIS Thermal Eng)• S. Harris (BEB Lead EE)• H. Richard (BEB EE)• R. Abiad (BEB FPGA Eng)• G. Dalton (EFI GSE Mechanical and General Mechanical)• J. Lewis, F. Harvey (GSE)• Technical Staff (H. Bersch, Y. Irwin, H. Yuan, et al.)• R. Ergun (DFB Co-I; CU-Boulder)• J. Westfall, A. Nammari, K. Stevens (DFB Eng; CU-Boulder)• C. Cully (DFB GSR; CU-Boulder)


EFI Status at MPDR• Design:

• The current EFI design meets Mission and Instrument requirements (exception: SPB mass estimate).

• The design will be ready for ETU fabrication on schedule.• The critical paths on the design (SPB boom length, AXB deploy and

stability,Preamp electro-mechanical and thermal, DFB FPGA definition and requirements) have been identified, and design elements are mature (exception: radial boom length (see EPR-Radial Booms)).

• Procurement:• All long-lead items have been identified:

– EEE parts ordered; rad testing of required parts arranged.– SPB and AXB mechanical items (custom wire cable, stacers, actuators,

motors) have been ordered, with exception of SPB motors (see Schedule and Procurement)).

• Vendors for mechanical and electrical machining and fabrication identified at mission-wide level.

• Personnel:• Team is essentially complete:

– All design engineering positions filled.– Two remaining MT positions to be hired Nov-Dec ’03; on-board by ETU

in Jan-Feb ’04.


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. DFB design includes latchup mitigation circuits on ADCs, inclusion contingent upon results of LTC1604 radiation testing.

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; 1.92 kg CBE (CAD model).

AXB: 2.30 kg Allocated; 2.00 kg CBE (CAD model).

(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; 0.07 W CBE (BB).

BEB: 1.76 W Allocated; 1.67 W CBE (BB).

DFB: 1.00 W Allocated; 0.86 W CBE (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 planned.




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.

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 and 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 (TBR) 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, and boom deployment 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.

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 (stiffness, tempco) 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


Top-Level Design (2)

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).


Radial Booms

Description of THEMIS EFI Elements• Radial booms:

• 20.8 to 27.8 m long.

• 8-cm dia., DAG-213 or Ti-N-coated spherical sensor.

• 3-m fine wire to preamp enclosure.

• USHER and GUARD bias surfaces integral to preamp enclosure.

• BRAID bias surface of 3 to 6-m length prior to preamp (common between all 4 radial booms).

• Sensor is grounded through 10 Mohm (TBR) 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/enabling and external signal injection.


Axial Booms

Description of THEMIS EFI Elements• Axial booms:

• 4-m stacer with ~1-m DAG-213-coated whip stacer sensor.

• 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 TBD 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/safing and external signal injection.


Performance Specification

Performance Specification• EFI radial sensor baseline will be 41.6 m, tip-to-tip.

• EFI axial sensor baseline will be ~10 m, tip-to-tip.

• 16-bit resolution.

• 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.

• AC-coupled E-field: +/- 50 mV/m, 1.5 uV/m resolution.

• AKR log(Power) channel: <= 70 uV/m amplitude, 100-500 kHz bandwidth.


DFB Functional Block Diagram

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

Ba

ck

pla

ne

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


DFB Data Flow Block Diagram

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

Efit (ID64)

FB #1 (6 bands)

Vfit (ID64)

VAFS (ID67)VBFS (ID68)

EFS (ID69)SCMFS (ID70)

VAPB (ID71)VBPB (ID72)

EPB (ID73)SCMPB (ID74)

VAWB (ID75)VBWB (ID76)EWB (ID77)

SCMWB (ID78)

SelectionLogic

16 analog dataquantities:V1, V2, V3,V4, V5, V6,E12, E34, E56,E12AC, E34AC,E56AC,E12logRMS,SC1, SC2, SC3

A/D #1128kS/s

A/D #2128kS/s

A/D routing256kS/s

Filter banks:- Any two inputs- 11 frequencies- output from 1/16to 16 S/s

AKR (LogRMS)signal

8-bit psuedo-logcompressor

ExB unit

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

FFT Unit

8-bit psuedo-logcompressor

Spec2 (ID81)Spec1 (ID81)


Spec2 (ID80)

Spec1 (ID80)


HFAve (ID65)

HFPeak (ID65)

Fbank1 (ID66)

Fbank2 (ID66)

FbankT2 (ID65)

FbankT1 (ID65)

FB #2 (6 bands)

FB #1 (All 11 bands)

FB #2 (All 11 bands)

Below Line is OnDuring FastSurvey Only

Above Line isAlways On


EFI Data Rates

Data Rates• Slow Survey

• Spin-fit radial and axial E-fields; SC potential (via ptcls).

• Filter Banks.

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

• Filter Banks and FFT spectra.

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


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

1024 samp/s.


• Diagnostic Mode (TBR)• E-field and sphere potentials at >= 32 samp/s.

• Bias control levels at >= 1 samp/s.


Individual Design Elements

• Radial Boom Unit (Spin-Plane Boom, or SPB)

• Boom Motor Driver Board (BMD)

• Axial Boom Unit (AXB)

• AXB and SPB Thermal Modeling

• Preamp (Mechanical and Electrical)

• Boom Electronics Board (BEB)

• Digital Fields Board (DFB; see Top-Level Design)

• GSE (Mechanical and Electrical)


SPB Design Overview

4 x Attach Legs with G10 Spacers for Thermal Isolation

Brushless Gearmotor

With Bevel Gears

Meter Wheel

Base

(Magnesium)

Sphere and Preamp

Release Doors

(Spring Preloaded)

Main Wire Spool

Exit Tube


Customization of Design for THEMIS Use

Wire Length• Increased to 18 m; capability of 25 m.

Packaging for mounting to THEMIS Probe

Structure Attachment• Magnesium replaced 6061 Al for weight savings

Sphere Coating• Titanium Nitride may replace DAG 213

DC Gearmotor• Same Motor Manufacturer (Globe Motors)• Similar Performance (300 ounce-inches Torque)• Brushless Unit Selected over Brushed

• Brushless better design in vacuum

• Better Thermal Characteristics

• Less Stray Magnetic Field

• Higher Performance in smaller package

• New Electronics Drive Package Required (BMD)• Designed in-house

• Prototype up-and-running 5 weeks without problems


Theory of OperationIntegration and Launch

• Stowed and Unpowered• Wire Wound about Spool, constrained by pinch wheels• Release Doors Closed• Sphere/Pre-Amp Constrained by Release Doors

Deployment• Release Doors Opened via SMA Pin-Puller• Spin of S/C puts outward force on Sphere and Preamp• Motor Acts as brake to prevent motion; coaxial wire in tension• Motor powers rotation of Meter Wheel • Sphere and Preamp is payed out • Release Doors Close Back Around Wire• As Centrifugal Force exceeds 2G at Sphere, Sphere Key Reel Spring

force is overcome and Sphere moves away from Preamp• Monitoring

• Limit Switch on Shaft counting Rotations• Tension Sensor to sense High Tensile Force

Science Ops• Deployed Booms Configuration Unchanged


Theory of Operation

Meter Wheel

Preamp

Motor

Main Wire Spool

Pinch Rollers

Release Doors

Sphere

Motor Drive Electronics


Materials and Construction

Standard UCB Construction• Most Components Machined Aluminum

• 6061 T6 and 7075 T73

• Alodined and Anodized

• Machined Plastics• PEEK

• Machined Magnesium Alloy AZ31B• Chosen for Weight Relief in Structure

• Not MSFC-SPEC-522 High Resistance to SCC– Table II ‘Moderate Resistance’– Requires MUA for use

Thermal Treatments• Surfaces covered with VDA tape or blankets• No Heaters Required

Common manufacturing techniques used • No Unusually Tight Tolerances • No Difficult Fabrications


BMD Requirements:• Brushless DC Motor driver

• Sense rotor position with Hall Effect devices

• Drive stator coils based on commutation logic

• Supply voltage: 28 ± 6 Volts

• Load current: ~300 mA

• Higher radiation environment than IDPU (100-kRad)

• Short term exposure (6 months)

SPB Boom Motor Driver (BMD)


Motor Driver Board

Brushless Gearmotor

BMD Block Diagram


Axial Boom (AXB) Overview

AXB are integral part of THEMIS probe• Primary probe structure provided by Swales Aerospace• AXB located along center axis of probe• AXB deployment through top and bottom decks of

probe.

Test & Safe Plug

Lower Deck Mount

Composite Tube

Antennae Mount (TBD by Swales)

AXB relative to THEMIS Probe Internal View

AXB Assembly

THEMIS Probe

Upper Deck Mount

Upper AXB

Lower AXB

AXB Housing


Axial Boom General Assembly

Whip Canister (Whip Sensor Inside)

Double Deploy Assist Device

(“DDAD”)

Tube Mounting Brackets

Preamp

Cable Bobbin

Stacer Canister (Stacer inside)

INDIVIDUAL BOOM IN STOWED CONFIGURATION

Frangibolt Actuator (inside)

Whip Doors

DDAD Doors

STACER

Design Modifications• Stacer Length• Double Deploy Assist Device• SMA Frangibolt Actuation• Whip Sensor

Roller Nozzles

Whip Posts


AXB Theory of OperationIntegration & Loading

• Whip Sensor is loaded into whip canister• Whip canister is locked to the preamp by the whip clamp• Stacer is loaded into stacer canister, DDAD doors hold the DDAD, and

whip doors hold the whip canister• Removable stacer pin is inserted through stacer tip piece, which locks the

stacer, DDAD, and Whip canister to the boom assembly• Cable is spooled around the cable bobbin• Stacer actuation bolt is threaded into Stacer tip piece and Frangibolt

actuator is slid over bolt and screwed tight with nut.• Stacer pin and whip clamp are removed• Boom is loaded into housing

Deployment• SMA Frangibolt is actuated and actuation bolt is broken.• Stacer tip piece is released• DDAD extends and initiates stacer deployment• DDAD separation opens whip doors, initiating whip sensor deployment

Science Ops• Deployed boom configuration unchanged


Whip Sensor

Deployed Properties• Whip sensor deployed length: 40 inches • Stacer deployed length: 150 inches

Stacer

Frangibolt ActuatorCable Bobbin with Cable

DDAD

DDAD Doors

Stowed Boom Deployed DDAD

4”

4”

Stacer Canister

Stacer Tip Piece

Whip Canister

Whip Doors

Roller Nozzle

Deployed Boom

Deployed Whip Sensor

150”

40”

Theory of Operation


AXB Assembly & Materials

Standard Flight Materials• AL 6061 T6, SST 440, Eligiloy, PEEK, M55J Graphite

Composite.

Standard Flight Coatings• DAG-213, DAG-154, Type 3 Hard Anodize.

Long Lead Items (see Schedule and Procurement)• Stacers, Multi-conductor wire, FrangiBolts.


SPB and AXB Thermal (1)Heat Transfer

• 80 mW dissipated at preamp irrelevant to bus temperatures.

• Essentially inert hunks of metal after deployment

• Long eclipse temperatures:

• Top deck, -93 C.

• Bottom deck, -36 C.

• Preamp, -170 C.

• AXB and SPB are heat leaks for bottom deck, and are isolated with 1/8-th inch G10 spacers.

• All surfaces covered with low e VDA tape or blankets.

• External snout of SPB dominates its heat leak; black-body open end of AXB tube dominates its heat leak.

Monitoring and Control• Probe bus monitors near one SPB; no monitoring on AXB.

• No thermistors in preamp.

• No operational heaters required.

• No survival heaters needed after deploy.

• Unlikely to need deploy heaters.


SPB and AXB Thermal (2)

AXB/SPB Limits (°C)

Predictions

(°C)

Margin

(°C)

Cold Hot Cold Hot

Deployment 0 30 8/-17 35/36 8/-17 -5/-6

Pre-Amp 52 -130

•Steady state prediction based on deck temperature from Swales•Cold prediction from cold orbit, not long eclipse.•Hot prediction from hottest orbit and attitude.

•Will not deploy in extreme hot or cold cases.•Better predictions await more complete instrument thermal models.


• Evolution of CLUSTER-II sphere/”puck” design

• Simple design, flight-proven components

3m thin wire, d ~10 mil

sphere, d ~8 cm

Preamp Housing, d ~2.3 cm

3m

Preamp Housing, d ~2.3 cm

1 m

Preamp and Sensor Geometry


Preamp Requirements

DC - 500 kHz

DC: Coupling impedances up to 10,000 M.

AC: Minimize capacitive voltage division (low input capacitance)• Radial Ccoupling ~13 pF, Axial Ccoupling ~6.5 pF

Wide temperature range (+100-370º K)

Survive high radiation exposure (~750 kRad/year behind 1 mm of Al)


Preamplifier Mechanical Design

Goal: Minimize preamp-sphere interference

(shadowing, photoelectrons, potential geometry…)

Cable Holder

Peek Stub

Socket HolderCan Shield Can Isolator

(optional) PC BoardWave Spring

0-80 Flat HeadScrew

Ferrule

Fuzz Button

Top

Pin (Keystone)BottomSocket (Hypertronic)

Guard

Front Shield

TO-99Screw Fitting


Sphere Preamplifier SensorElectronics Design

±40 V


Preamplifier IC

Op-Amp: OP-15AJ

MIL-STD 883, CRRES Heritage

Rin ~1012 ohms, Cin ~3 pF

Low Power Dissipation (<80 mW)

Internally compensated, unity-gain stable

Capability to drive capacitive loads (>4000 pF)

40 kRADs with little performance degradation (satisfied behind ~7 mm Al over two years)


Functional Requirements• Spin Plane Booms, for each provide:

• Floating Ground Driver• “Bias”, “Stub”, “Usher” programmable potentials• “Braid” programmable, switchable potential• AC test signal source

• Axial Booms, for each provide:• Floating Ground Driver• “Bias”, “Stub”, “Usher” programmable potentials• AC test signal source

BEB Requirements


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:

BEB Requirements (con’t)


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

-100VA

AGND

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

BEB Analog Electronics


EFI_

P10V

A

EFI_P100VA

BR AID 1

FV1_P10VA

J 501

D D 26F

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EFI_C LK

SH IELD 3

BEB_H SKP

10M

FV6_GN DFV6_M10VA

J 512

AGN D

U SH ER 5

Analog Mux

+10V

IN

AGN D

-10V

IN

D GN D

+5VD

BIAS

1CU

SHER

1CG

UAR

D1C

BIAS

2CU

SHER

2CG

UAR

D2C

BIAS

3CU

SHER

3CG

UAR

D3C

BIAS

4CU

SHER

4CG

UAR

D4C

VOU

T

Se lec t3Selec t2Selec t1Selec t0

USH

ER6C

USH

ER5C

BIAS

6C

GU

ARD

5C

GU

ARD

6C

BIAS

5C

Se lec t4

Tem

pA

Tem

pB

AC TEST6

P500

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U SH ER 2 FV4_GN D

SH IELD 2

GU AR D 5

EFI_P10VA

BackPlane

BIAS1U SH ER 1

FVF3_P10VA

EFI_P10VA

BR AID 4

U SH ER 4BR AID 2

t

TH ER MISTOR

GU AR D 3

Front Panel

EFI_M10VA

EFI_M10VA

GU AR D 2

BR AID 1

EFI_P100VA

FV1_M10VA

FV4_P10VA

AC TEST3

BIAS5

J 515

U SH ER 6

BR AID 5

FVF1_M10VA

BIAS2

AC TEST2

GU AR D 1

EFI_P10VA

EFI_

M10

VA

FV5_M10VA

FVF5_M10VA

FVF1_P10VA

VSPH ER E3

J 516

VSPH ER E4

10M

VSPH ER E6

BR AID 3

FV6_P10VA

SH IELD 4

VSPH ER E5

FV2_GN DFV2_M10VA

FV1_GN D

EFI_M100VA

EFI_M100VA

BR AID 6

FV5_P10VA

AC TEST1

FV1_M10VA

FVF6_M10VA

J 513

EFI_P100VA

FV2_P10VA

Same TreatmentChannels 3/4Channels 5/6

Braid Driver

BREF

1_R

ESET

BREF

1_SE

TBR

EF0_

RES

ETBR

EF0_

SET

V3_IN

V1_IN

BSEL

_RES

ETBS

EL_S

ET

BR AID 1

BR AID 2

BR IAD 3

BR AID 4

+100VBus

+10VBus

-10VBus

-100VBus

AGN

D

Brai

dCon

trolU SH ER 3

VSPH ER E1

GU AR D 4

FVF2_M10VA

EFI_C MD

FV5_GN D

J 514

FV3_GN D

SH IELD 6

EFI_D GN D

FV3_P10VA

FV4_M10VA

BIAS4

FVF5_P10VA

EFI_

VP5D

VSPH ER E3

Control Block

C LK

C MD

BIAS1C

U SH ER 1C

GU AR D 1C

BIAS2C

U SH ER 2C

GU AR D 2C

BIAS3CU SH ER 3CGU AR D 3C




+5V

D GN D

AC TEST1AC TEST2AC TEST3AC TEST4AC TEST5AC TEST6

MSE

L0M

SEL1

MSE

L2M

SEL3

BR AID C

+2.5V

MSE

L4

BR EF0_SET

BR EF1_SET

BSEL_SET

BR EF0_R ESET

BR EF1_R ESET

BSEL_R ESET

FVF4_M10VA

BR AID 4

FV1_P10VA

AC TEST5

Channel 1

PreAmp In

+100

VBus

+10FltVin

-10FltVin

-100

VBus

+10V

Bus

-10V

Bus

AGN

D

GuardC ontro l

Bias C ontro l

U s herC ontro l

FloatGN D

Bias

U s her

Guard

+10FltVout

-10VFltVout

FV3_M10VA

AC TEST4

J 502

D D 26F

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FVF2_P10VA

EFI_M100VA

EFI_VP2.5D

AGN D

FV2_P10VA

FVF4_P10VA

BIAS3

GU AR D 6

BR AID 2

FVF6_P10VA

VSPH ER E1

SH IELD 1

VSPH ER E2

J 503

D D 26F

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FVF3_M10VA

SH IELD 5

BR AID 3

EFI_D GN D

EFI_M10VA

FV1_GN D

BIAS6

J 511

Channel 2

PreAmp In

+100

VBus

+10FltVin

-10FltVin

-100

VBus

+10V

Bus

-10V

Bus

AGN

D

GuardC ontro l

Bias C ontro l

U s herC ontro l

FloatGN D

Bias

U s her

Guard

+10FltVout

-10VFltVout

EFI_P100VA

EFI_P10VA

FV2_GN D

EFI_VP5D

FV2_M10VA

BEB Block Diagram


+10VA

+10VA

10K

BSEL_RESET

+100VA

+100VBus

10K

10K

10K

10M

V3_IN

-10VA

+10VA

AGND

+10VA

BREF0_SET

+100VA

421D

-100VA

Q1

2N2222A

Q1

2N2222A

+10VBus

-100VBus

+10VA10M

BRAID1

421D

BSEL_SET

BRAID4

BREF0_RESET

BRIAD3

BREF1_SET

10K

10M

V1_IN

10M

BREF1_RESET

Q2

2N2222A

421D

Braid Driver

Vin

+100VA

+10VA

-10VA

-100VA AGND

Vsphere_Ref

Vout

10K

Power Filter

-10Vin

+100Vin

-100V

+100V

-100Vin

+10Vin

AGND

+10V

-10V-10VBus

BraidControl

-10VA

Q2

2N2222A

Q1

2N2222A

10M

-100VA

Q2

2N2222A

BRAID2

1M

BEB Braid Bias


Mechanical GSE Requirements

Functional Requirements• Provide for simulation of actuators and motors during

functional tests, FSW testing, etc.

• Connect through test/enable plugs on SPBs and AXB pair.


Electrical GSE

Block Diagram of EFI/BEB GSE


Electrical GSE Requirements (1)

Power/Thermal/Mechanical• Provide regulated voltages.

• Facilitate current measurements.

• 6U VME support (w/out Wedgelocks) for BEB.

• Portable and rugged for transport.

• Open rack for access while under test.

• Connectors acceptable for Flight interconnection

Electrical Interface• Backplane interface per IDPU backplane specification.

• 1 MUX’d analog housekeeping output (ANA HSK).

• GSE interface circuitry must be flight-grade.



Command and Telemetry Handling• GSE sends 24-bit CDI commands per ICD specification.

• Command format is compatible with IDPU and MOC GSE (TBD).

• Before DFB and DCB, data is from GSE’s IEEE-1394 ADC.

• Afterwards data is extracted from telemetry.

Test Support Equipment• GSE controls GPIB function generator and +/- 100-V

supplies.

• “Faraday cage”-type test fixture (pairs for SPB and AXB).

Compatibility with Next Level of Integration• Uses ITOS, Matlab (or equiv), C.

• PC standards.

• Easy accessibility to data for offline processing (FTP, HTTP, etc.).



Data Manipulation and Display• Plot any of 16 channels over user-specified timespan.

• Calculate 2N-point FFT on user-specified channels.

• Compute and display power spectra and transfer functions of user-specified channels.

• Display control values for GPIB and GSE interface equipment.

• Support hardcopy output.

• Raw and derived data, as well as configuration information stored in tabular ASCII format file.

• Data manipulation and display scriptable to allow for automation of test and cal procedures.


DC Error Budget (1)

The estimated electric field along the direction between the two probes is E=(v1-v2)/2L.

Errors arise from and are mitigated by:• Errors in baseline (L).• Errors in v1 and v2; eg. (v1-v2) or each individually.


DC Error Budget (2)

Errors in baseline (L).• Fly as long of booms as possible, given resources (41.6-m

baseline, ~55-m possible w/in mass resources).• Control boom length to 1%.• Trim deploy length to 4-cm accuracy to allow for electrical center

offsets (AXB in particular).• Increase fine wire length to reduce boom shorting effect

(observed up to 20% on Cluster; predicted 5% on THEMIS (better Lf/L)).

• Fly dual-length system to allow for differentiation between geophysical and SC fields.


DC Error Budget (3)Errors in v1 and v2; eg. (v1-v2) or each individually.

• Use TI-N or DAG-213 coating on sensors for uniform photoemission. Keep all sensors clean pre-launch.

• Use high-impedance preamp (1012 ohm) to reduce DC attenuation.

• Current-bias sensor to reduce sheath impedance and susceptibility to photoemission asymmetries (20-100 Mohm typ.; 0.2-0.5 mV/m SPB systematic).

• Mount sensor on fine wire and reduce emission area of preamp to reduce magnitude and effect of asymmetric photoemission (3-10 times smaller than Cluster; < 0.5 mV/m SPB systematic).

• Use USHER and GUARD surfaces to control photocurrents to sensor (>= 20-V bias range, well above bulk of photoelectron energies).

• Use fine wire and BRAID bias surface to reduce ES wake effects (scale with D/L or 1/L; roughly equivalent to Cluster). Fly dual-length SPB system to detect ES wake effects.

• Enforce 1.0-V electrostatic cleanliness specification on THEMIS to reduce SC potential asymmetry effects to < 0.1 mV/m on SPB; 0.1-V goal reduces AXB effects to this level as well.


AC Error Budget

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


Schedule (1)

Design (Definition and BB)• Preamp Mechanical (Aug-Oct ’03; complete).

• Preamp Electrical (Aug-Oct ’03; complete).

• BEB (Jul-Oct ’03; complete).

• BMD (Sep ’03; complete).

• SPB (Aug ’03 – Nov ‘03; freezing design Nov 21).

• AXB (Jun ’03 – Dec ’03; freezing design Nov 14).

• DFB (Aug ’03- Dec ’03; 50%).


Schedule (2)

Long-Lead Parts• AXB stacers (ordered Sep ’03; delivery by 26 Dec ’03 (12-wk lead

time))• SPB wire cable (final RFQ issued 7 Nov; final order expected by

17 Nov; delivery by 15 Jan ’04)• FrangiBolt actuators (final RFQ issued 7 Nov; final order expected

by 17 Nov; early delivery of 3 units late Dec; remainder in late Jan ’04).

• SPB motors:• Original vendor on brushless motors (Avnet/Globe) returned with 21-

week, rather than 12-week lead time. This would push EFI F1 delivery back 3 months, leaving no schedule slack for delivery to II&T.

• Exploring two options:– New brushless vendor (MicroMo) with space-qualified pedigree. 12-wk

lead time (pushes F1 delivery back 1 month to 16 Jul ’04. Example ordered for validation Nov 17-21; order to follow if passes validation.

– Brush motors from Avnet/Globe. Original SPB design. 8-wk lead time (no schedule impact). Additional magnetic impact.


Schedule (3)

EM/ETU• SPB

• Mach, Dec ’03; Assy, Dec ’03 – Jan ’04; Test, Feb ’04.

• AXB• Mach, Dec ’03 – Jan ’04; Assy, Feb ’04; Test, Feb ’04.

• Preamp (Mechanical and Electrical)• Layout/Fab/Assy, Oct-Nov ’03; Test, Dec ’03.

• BEB• Layout/Fab, Nov-Dec ’03; Build, Dec ’03; Test, Dec ’03.

• BMD• Layout/Fab, Nov-Dec ’03; Build, Dec ’03; Test, Dec ’03.

• DFB• Layout/Fab, Jan-Mar ’04; Build, Mar ‘04; Test, Apr ‘04.


Summary of EPR Findings

•Radial Boom design (1,2,3,9; Draft findings, 3 Nov 2003):•Dynamic stability issues (spin/trans MOI ratio) (Bus EPR)•Dual-length/longer-length designs

•Axial Boom design (6,10):•Deploy force margin•Length vs. noise margin, whip vs. sphere sensors.

•Attitude information and jitter requirements (14).•Miscellaneous mechanical findings (15,18,5):

•Deploy sequence modeling.•Boom deployment temperature.•SPB miter gear life testing.

•Hot parts and thermal stresses•Gain and Filter Specifications of EFI and SCM on DFB (4,8,12).•BEB FPGA specification and programming (20).•Preamp electro-mechanical design (11).•Electrostatic Cleanliness Specification (RFA UCB-8)(7,17).•EMI/EMC Specification (RFA UCB-9)(13).•Detailed I&T plan development (RFA UCB-10)(19).


EPR Findings—Radial Booms

•Dynamic stability issues:•Bus and Instrument team analysis of dynamic stability not in accord; question is proper spin/transverse MOI ratio for non-rigid boom systems on THEMIS.•Swales analysis indicates shorter AXB (60%) or longer SPB required to achieve stable configuration (Bus EPR finding).

•Longer-length/Dual-length designs (science-driven):•56-m (2x(25+3)m system) tip-to-tip SPB possible with current mechanical design.•Direct improvement in DC error budget (30%).•Allows for dual-length (21/28 m) system that would allow the detection of ES wake effects (not mission critical, however).•Mass hit (56 g/SPB) for 7-m cable addition; fuel hit (~60%, 452 g increase) for final spin up.

•Resolution:•Must be resolved by Jan ’04 (EFI F1 Cable Assy); Cable Assy schedule margin allows push back to Apr ’04, if necessary.•Dynamic stability analysis is ongoing at Swales and UCB.


EPR Findings—Axial Booms

•Deploy force margin and AXB length repeatability:•AXB design may not have enough deploy force margin to ensure dL/L = 1% repeatability of deploy length.•Resolution: AXB ETU testing (Feb ’04).

•Length vs. Noise Margin; whip vs. sphere sensor response•Current AXB length (~9-m effective, 10-m tip-to-tip) allows only factor of 3 S/N margin at 4 kHz (CBE of system noise level).•SC perturbations will strongly affect DC E-field in AXB (several mV/m, dependent upon SC potential (plasma conditions).•AXB whip sensor may have different response para/perp to B than SPB sphere+wire sensor.•Resolution: AXB length can not be reduced significantly without compromising 3D AC measurement. AXB lengths will be trimmed based on simulation results to reduce DC offset due to SC potential (final length Feb ’04 (AXB F1 Mach)). Literature on antenna response to be investigated to determine significance of whip vs. sphere effect (no mitigation planned; different capacitance of SPB and AXB sensors already known, and part of electrical Calibration plan).


EPR Findings—Attitude

•Attitude knowledge and jitter requirements are modest, and achievable by Bus and Instrument designs.

•5.6 degree (10%) knowledge required; better than 1 degree (0.5%) achieved via post-processing of FGM and EFI data.•Better than 3-degree accuracy and jitter in spin phase required for accurate on-board spin fits of E-field data; current IDPU design provides much better than 0.1 degrees.

•Alignment requirements more stringent, driven by DC error budget of SPB.

•Opposing pairs of SPB booms must align within 1 degree to bring systematic error due to differential photoemission below 1 mV/m for nominal biasing scheme and sphere sheath impedances.


EPR Findings—Misc. Mech.

•UCB should initiate kinematic and dynamic modeling of the boom deploy sequences.

•Resolution: Kinematic model of boom deploy already exists (Th_booms3d.xls; D. Pankow) at UCB as tool for understanding timing, spin-up requirements, mechanical loads, boom/SC modes, coriolis displacements, etc.•Resolution: Algor product will be taken under advisement as part of on-going resolution of dynamic stability question (see Radial Booms; Jan ‘04).

•Boom deployment temperature range should be defined.•Resolution: Boom deployment temperature range will be defined as part of I&T test flow (Dec. ’03-Jan. ‘04).

•SPB miter gear life testing under worst-case load required.•Resolution: Such testing will be included in SPB I&T test plan (Dec ’03 – Jan ’04).


EPR Findings—Hot Parts

•High-dissipation (> 100 mW) parts should be identified, and junction temperature coefficients tabulated.

•Resolution: Data will be provided to thermal analysis as required.


EPR Findings—Gain/Filter

•DC/AC-coupled dynamic range and solitary waves•Large-amplitude (>=100 mV/m) solitary waves have been observed at frequencies from 1-1000 Hz on Polar and Cluster in the THEMIS observation region. Such waves will saturate the AC-coupled (10 Hz-6 kHz) E-field channels with a dynamic range of +/- 50 mV/m.•Resolution: Other channels can handle the large-amplitude events, although not simultaneously. DC-coupled (0-4 kHz) channels have a dynamic range of +/- 300 mV/m. Dc-coupled sphere/whip voltages have +/-60-V range (3 V/m on SPB, ~13 V/m on AXB). AC-coupled gain may be reduced to allow higher rate sampling of large-amplitude signals (TBR, Nov-Dec ’03, DFB ETU design).

•Filter specifications•SCM channels use Butterworth, EFI uses Bessel. Difference means non-trivial phase differences and time-domain responses over entire 0-4 kHz range, maximizing between 1-4 kHz, preventing direct comparison of time-domain signals.•Resolution: Trade between filter types underway; component value issue; active filter topology doesn’t change (TBR, Nov-Dec ’03, DFB ETU design).


EPR Findings—BEB FPGA

•BEB FPGA specification and programming•Resolution: BEB FPGA requirements are modest and now well-defined (CDI interface, DAC control, Analog housekeeping), and common to most IDPU boards, allowing FPGA programmer (R. Abiad, UCB) to work on design and programming within BEB ETU schedule (Build/Test, Dec ’03).


EPR Findings—Preamp

•Bootstrapping and guarding of preamp inputs•Bootstrapping and guarding of preamp electronics in the current electromechanical design should be reviewed. Potentials of all conductors need to be defined (can, shields, etc.).•Resolution: Current design does not include input guard, based on estimated input capacitance of preamp enclosure. Preamp ETU Assy and Test begins early Dec ’03 to characterize input capacity, and allow for changes and re-evaluation before FLT fabrication begins (Jan ’04).


EPR Findings—ESC

•Electrostatic Cleanliness Specification and Enforcement•Resolution: Rev. B of THM-SYS-003 Electrostatic Cleanliness Plan has been posted for review and will be signed off in Nov ’03. It includes a complete specification of electrostatic cleanliness requirements as well as verification procedures. The specification sets a 1-V potential uniformity requirement under an 8 nA/cm2 current density, with 0.1-V potential uniformity as a goal (see DC Error Budget for discussion).


EPR Findings—EMI/EMC

•Electromagnetic Interference/Cleanliness Specification•Resolution: A Draft of the THEMIS EMI/EMC Specification has been posted for review and will be signed off in TBD. This specification is modeled on that for the FAST mission, adapted to the instrument properties on THEMIS (SCM/EFI system noise levels and expected wave amplitudes). Testing and verification of compliance with EMI/EMC TBD, and requires some work, due to low frequencies of interest (0-4 kHz).


EPR Findings—I&T Plan

•I&T test flow needs to be defined to include development, ETU, qualification and acceptance testing.

•Resolution: An EFI I&T plan will be developed in Dec ’03 to support qualification and acceptance testing of the EFI ETU in Jan-Mar ’04.

THEMIS MISSION PDR/CAREFI- 1 UCB, November 12-14, 2003 THEMIS ELECTRIC FIELD INSTRUMENT (EFI) Dr....

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Transcript of THEMIS MISSION PDR/CAREFI- 1 UCB, November 12-14, 2003 THEMIS ELECTRIC FIELD INSTRUMENT (EFI) Dr....