THEMIS Mission CDR 1 UCB, June 16, 2004 THEMIS T IME H ISTORY OF E VENTS AND M ACROSCALE I NTERACTIONS DURING S UBSTORMS RESOLVING THE MYSTERY OF WHERE,

THEMIS Mission CDR 1 UCB, June 16, 2004

THEMISTIME HISTORY OF EVENTS AND MACROSCALE INTERACTIONS DURING SUBSTORMS

RESOLVING THE MYSTERY OF WHERE, WHEN AND HOW AURORAL ERUPTIONS START

THEMIS Mission Critical Design Review – SST Instrument MaterialTHEMIS Mission Critical Design Review – SST Instrument MaterialJune 16, 2004June 16, 2004University of California, BerkeleyUniversity of California, Berkeley


SST SubsystemMission Critical Design Review

Davin Larson - Lead

Thomas Moreau – Design/Modeling

Ron Canario - Electrical

Robert Lee – Mechanical

Jianxin Chen (Baja) - Actel

Jim Lewis – GSE

Robert Abiad – ETC design


Overview

Solid State Telescopes:• Measure Energetic Electrons and Ions• Energy Range:

– H+: 25 keV to 6 MeV (possible ~3 MeV)

– Electrons 25 keV to ~800 keV

• Angular Coverage:– Theta

– 4 look directions (+55, +25, -25, -55)– Resolution: ~ 30 deg FWHM

– Phi– 32 sectors– Resolution: ~20 deg FWHM

• Geometric Factor: ~0.1 cm2-ster (~1/3 of WIND)• Pinhole Attenuator: Cuts geometric factor by 64


Sensor Unit Schematic

FoilCollimator

Thick Detector

Sm-Co Magnet

Attenuator

Al/Polyamide/Al FoilOpen Detector

Foil Detector

Attenuator

Open Collimator


REQUIREMENT SST 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 SST design (parts, performance degradation, etc). Primary Impact: Attenuator added to protect detectors from “radiation”.

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. All parts screened for total dose. Radiation testing planned if TID is unknown.

(All major parts tested to 50 krad.)

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

Compliance. Most parts screened for SEE. Radiation testing planned if LET is unknown.

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

Compliance.

Sensor: 554 gm x2 (Measured)

Harness: 141 gm x2 (1.73 meter)

(DAP Board 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.

DFE + DAP: 1200 mW (Estimate @ 10 kHz count rate)

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

Compliance.

DAP: –40 to 65

DFE: -65 to 100 (Heater required to survive eclipse)

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

Compliance.

DAP: –30 to 40

DFE: -55 to 70

Mission Requirements



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

Compliance?. THM-SYS-002 Magnetics Contamination Control Plan. Budget for SST Magnets is <2 nT @ 2 meters. (Compliance if SST budget is increased, still meets overall system budget)

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

Compliance. THM-SYS-003 Electrostatic Cleanliness Plan. Box electrically isolated.

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

Compliance. THM-SYS-004 Contamination Control Plan (Partially driven by SST)

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

Compliance. THM-IDPU-001 Backplane Specification.

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

Compliance. THM-SYS-105 ESA and SST Electronics Card (ETC) Specification. Verification Matrices to be completed.

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

Compliance. THM-SYS-111 SST-to-Probe ICD. 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.

Mission Requirements



IN.SST-1. The SST shall perform measurements of the tailward-moving current disruption boundary speed using the finite gyroradius technique

Compliance. Provided by Full Distribution Functions (FDFs).

IN.SST-2. The SST shall measure the time-of-arrival of superthermal ions and electrons of different energies emanating from the reconnection region to determine RX onset time.

Compliance. 3 second time resolution of FDFs

IN.SST-3. The SST shall obtain partial moments of the plasma electron and ion distributions in the magnetotail plasma sheet

Compliance. Partial moments produced by ETC board.

IN.SST-4. The SST shall obtain measurements of ion and electron distribution functions with one spin resolution (<10sec required)

Compliance. Full distribution functions at 1 spin resolution obtained in burst mode.

IN.SST-5. The SST shall measure energetic electron fluxes as close to Earth as 6RE geocentric, at all local times.

Compliance. Attenuator lowers flux sufficiently to avoid saturation at this distance

IN.SST-6. The SST shall measure energetic ions in the solar wind, at the magnetopause and in the magnetosheath.

Compliance.

Science Requirements



IN.SST-7. The SST shall measure energetic particles over an energy range of 30-300keV for ions and 30-100keV for electrons found in the magnetotail plasma sheet .

Compliance.

Electrons: ~25 keV to ~800 keV

Ions: ~25 keV to ~2 MeV (possibly 6 MeV)

IN.SST-8. The SST energy sampling resolution, dE/E, shall be better than 30% for ions and electrons.

Compliance.

Intrinsic energy resolution is ~6 keV with 1.5 keV binning. Measured full system resolution is 8 keV @ 30 keV

IN.SST-9. The SST shall be capable of measuring differential energy flux in the range from: 10^2 to 5x10^6 for ions; 10^3-10^7 for electrons (keV/cm2-s -st- keV) whilst providing adequate counts within a 10 second interval.

Compliance. Max counting rate estimated at 50,000 cps (per detector). Two geometric factors:

G1 ~ 0.1 cm2-ster

G2 = G1/64.

IN.SST-10. The SST shall measure over 90 deg. in elevation with a minimum resolution of 45 deg.

Compliance.

Elevation: +/- 60 deg, Resolution:~37 deg.

IN.SST-11. The SST shall have an azimuthal resolution of 45 deg.

Compliance.

Azimuthal resolution = 22.5 deg

IN.SST-12. The SST shall supply the high energy partial moments at one spin time resolution.

Compliance.

Performed by ETC board

IN.SST-13. SST calibration shall ensure <20% relative flux uncertainty over the ranges defined above.

Compliance. Measured pre-flight;

Verified by in-flight calibration.

Performance Requirements


ETC BoardDCB

Block Diagram

SensorUnit 1

(2 DFEs A&B)DAP Board

(Data Acquisition & Processing)

Bac

kpla

ne

SensorUnit 2

(2 DFEs A&B)

IDPU

SST Instrument:•2 Sensors with attenuators (4 DFEs)

•2 Cable bundles

•1 DAP Board (inside IDPU)

PCB(Power Control Board)

Other Boards

~1.7 m cable (x2)

DFE = Detector Front End Hea

ter

Pow

er

&

SM

A P

ower


Sensor Cross Section

Each sensor unit is a:• Dual-double ended solid state

telescope• Each double ended telescope

(1/2 sensor) has:– Open collimator– Pinhole attenuator paddle

– Reduces count rate during periods of high flux

– Reduces radiation damage from intense fluxes of low energy ions

– Magnet (Open side)– Filters out electrons <400 keV – Leaves ion flux nearly

unchanged

– Triplet stack of SSDs– DFE board

– Preamp / shaping electronics

– Thin Polyamide Foil– Filters out ions <~350 keV – Leaves electron flux nearly

unchanged

– Another attenuator paddle– Foil Collimator


Detector Pixelation

Detectors similar to STEREO/STE• Produced at LBNL/Craig Tindall PI

Active area

Guard ring

10 mm

5 mm

Additional Pixels not used for Themis

300 microns thick


Typical Electrical Connection Between Detector and Flex-Circuit

SST Mechanical Design

Kapton Flex-Circuit

Detector (pixelated side)

Wirebond Loop

(NOT to scale – actual loop height < 300 micron)



Detectors (4)

Spring Clamp

Spring Plate (2)

Detector Board Composition (exploded view)

PEEK Spacer (4)

BeCu Gasket (3)

Kapton Flex-Circuit (4) AMPTEK Shield

KaptonHeater

Thermostat

DFE Board Subassembly



DFE Board Subassembly Relative Positions (2 per sensor)

AMPTEK Shielding

Detector Stack Subassembly

Multi-Layer Circuit Board (62 mil thickness)

Foil Frame

Thermostat



Magnet-Yoke AssemblyCo-Fe Yoke (2)

Sm-Co Magnet (4) (currently not visible)

Aluminum Magnet Cage



Attenuator Assembly

Attenuator (4)

Cam (2)

SMA Lever (2)



Actuators and Position Switches

Honeywell SPDT Hermetically Sealed Switch (2)

SMA Actuator (2)



Support Structure

(front section)

Kinematic Flexure (2)

Rigid Mounting Flange



Bi-Directional Fields-of-View



Sensor Orientation Relative to Spacecraft Bus




Sensor Unit Mounting Using Kinematic Flexures• Each sensor mounted to spacecraft panel at

three points– One rigid mounting flange– Two mounting flanges with kinematic flexures

• Allows relative motion due to CTE differences between sensor structure and spacecraft panel– Predicted expansion differential along instrument

axes with 120 ºC temperature gradient:– X-Axis: 0.006” (0.15 mm)

– Y-Axis: 0.013” (0.33 mm)

• Flexure dimensions sized to keep maximum bending stresses below 6061-T6 yield strength– Factor of Safety (F.S.) > 1.4 per NASA-STD-5001



Attenuator Actuation – CLOSED position

Honeywell Switch (extended-position)

SMA Actuator (extended)

Honeywell Switch (compressed-position)

SMA Actuator (retracted)



Attenuator Actuation – OPEN position

Honeywell Switch (compressed-position)

SMA Actuator (retracted)

Honeywell Switch (extended-position)

SMA Actuator (extended)



Attenuator Control – CLOSED to OPEN (INITIAL)

CLOSEAttenuator

OPEN Attenuator

PCB

+5V

SST Sensor

+5V

GNDGND

MonitorMonitor

PCB

SPDT Switch

FREE COMPRESSED

C C

NC NC

NONO

FRONT SMA(ACTIVE)

BACK SMA

HIGHLOW



Attenuator Control – OPEN to CLOSED (INITIAL)

PCB

+5V

SST Sensor

+5V

GNDGND

MonitorMonitor

PCB

SPDT Switch

CLOSEAttenuato

r

OPEN Attenuator

COMPRESSED FREE

C C

NC NC

NONO

FRONT SMABACK SMA(ACTIVE)

LOWHIGH



Attenuator Mechanism Cycling Test• Run over 40,000 cycles• Pivot shaft (303 Stainless) showed significant

abrasion damage on contact surfaces with sapphire bearings• Subsequent shafts to be treated as follows:

– Titanium Nitride (TiN) coating to increase hardness

– Tungsten Disulfide (WS2) coating for dry film lubrication

• Required SMA stroke reduced from 3.5 mm to 3 mm for additional operating margin (maximum stroke: 4 mm)

• Mechanism test will be performed again with modified components on ETU (late April 2004) with minimum target of 150,000 cycles• Target values based on 10 times expected

number of actuations on-orbit• Cycle counting will not be necessary for flight

components



Analysis Results - Modal Analysis• ALGOR FEMPRO Version 13.30

– First Mode @ 600 Hz

– Second Mode @ 1200 Hz

– Third Mode @ 1550 Hz

• Modal frequencies > Delta II minimum levels

Finite element model with mass simulators



Analysis Results – Quasi-Static Acceleration• ALGOR FEMPRO Version 13.30• 40g load along each instrument axis

– X-axis maximum stress: 3040 psi– Y-axis maximum stress: 1730 psi– Z-axis maximum stress: 1440 psi

• F.S. > 1.4 above yield strength for 6061-T6

X Axis Load Y-Axis Load Z-Axis Load



Electronics and Cabling• DAP Board

– Located within IDPU– Type 6U card– Radiation shielded with 5mm of aluminum– Will be discussed in further detail in IDPU section

• Harness (per sensor)– Approximate length of 1.73m x 64 gm/m – Composition:

– 13 x 36 AWG coaxial cables - 6 Signals, 6 Test, 1 Bias voltage– 3 x 28 AWG wire - 2 Door monitors, 1 Temperature– 3 x 24 AWG (TT) - Door Open/Close power & return– 2 x 26 AWG (TP) - Heater supply– 3 x 26 AWG (TT) - Preamp Power

– 26 pin HD Cannon at each end


SST Sensor

Mass Summary:

Sensor mass= 553.5 gm

Cable mass (173 cm) = 141 gm

Total x2= 1389 gm


SST Sensor Mass Estimate

SST Mass EstimatesItem Mass

[g]Items/unit Mass [g] Actual Mass % %

SensorsMagnets 9.6 4 38.4 6.7Yoke 33.2 2 66.4 11.6Magnet and Yoke Cage 16.7 1 16.7 2.9Retainer plates and fasteners 1.4 4 5.7 1.0Sub total Magnet Assembly 127.2 22.2Housing 20 mil (front and back) 107.1 1 107.1 18.7Bottom closeout 62.5 mil 14.3 1 14.3 2.5Collimators (with baffles) 14.4 4 57.7 10.1Attenuator cover 18.6 2 37.2 6.5Thermal Spacer 0.3 6 1.9 0.3Baseplate Washer 1.6 3 4.9 0.9Housing fasteners 0.8 16 12.2 2.1Sub total Housing 235.3 41.0Attenuator (axle/4 paddles/2 cams, 2 levers,2 bearings, 8 set screws)10.6 1 10.6 1.9HM Switch Assembly (mounting plate, spring, nut plate, plunger, set screw, screws)9.8 2 19.6 3.4HM Switch (w/ aux lever) 5.8 2 11.7 2.0SMA actuator (nanomuscle, T-bone, nut plate and screws) 4.6 2 9.2 1.61/2 Winchester w/o wire 1.7 2 3.3 0.6Sub total Attenuator 54.4 9.5Connector (26 pin DD w/ nut plate) 9.2 1 9.2 1.6Internal wires 10.0 1 10.0 1.7DFE board (unloaded) 10.3 2 20.6 3.6DFE EEE parts 5.7 2 11.4 2.0Amptek 225FB 2.3 6 14.0 2.4Amptek Shield Cover (2mm Brass) 18.0 2 36.0 6.3Detectors 0.0 8 0.0 0.0Detector Stack 10.0 2 20.0 3.5Polyamide Foil & Holder 1.9 2 3.7 0.7Thermostat 7.8 2 15.6 2.7Heater Patch 2.2 2 4.3 0.71/2 Winchester w/o wire 1.7 2 3.3 0.6screws and pem nuts 1.1 8 8.5 1.5Sub total DFE assembly 156.6 146.7 27.3

Sensor Total: 573.5 573.5 553.5 gm 100.0 100.0



Nitrogen Purge Connection• Nitrogen line is connected to SST purge fitting during pre-flight

operations to purge instrument interior

• Gas supplied at 5 psig– Regulated and filtered flow rate of 1 liter/hour

Supply fitting

Vent


Electronics Block Diagram

Signal chain: 1 of 12 channels shown

ADC

FPGACoincidence

Logic &Accumulators

Memory

DACThresh

Gain

PD

BLR

A225FBPreampShaper

DFEBoard x4 DAP Board

Test Pulser

Bias Voltage

x12

x 3


T Out

+4.5 V

-2.5 V

O Out

-35 V

F Out

F Test in

T Test in

O Test in

Current DFE Design

~200 A Polysilicon + ~200 A Al

pn

np

np

pn

~200 A Polysilicon

T

F

O

300 micron thick detectors

225FB

225FB

225FB

Outside Grounded

Pixelated side ~1200 A Dead layer


DFE Schematic


DFE Schematics

Detector Front End Schematic

–Single Channel


Preamps/Shaping

Using Amptek 225FB (6pin sip Hybrid - special request)Characteristics:

• ~6 keV electronic noise (with 1.5 cm2 detector)• ~2.5 uS shaping time (time to peak)• ~26 mW (Increases with negative supply voltage) • 100 Krad (still needs ~2mm Cu shield)• Operating range: -55 to +125 C• Dual supply allows negative output pulses

B


DFE Layout

ETU board layout (version 2). • A225FBs have 2 mm Cu radiation

shielding• Caps/Resistors have ~0.5mm Al

shielding• Detectors located near Preamps• Flexible, rugged design

3- A225FBs

Cu shield

Detector Stack

Version 3 (Flight) is nearly indistinguishable from Version 2


ETU DFE Assembly

A225FB

Detector Stack

26 Pin HD

A sideA sideB side

Winchester connector to Attenuator

Assembly/testBracket

Shield/Heater not shown


ETU DFE Assembly

DFE In Test Box


DFE/Mechanical Mating

DFE assembly and housing/attenuator assembly can be adjusted/tested separately and then mated.

ETU Issues: Intermittent shorting of one diode - resolved


Progress Summary

DAP (Data Acquisition & Processing) Board Summary• ETU #1

– 3 of 12 channels loaded

– Fully functional with some issues:– Oscillation of threshold DACs (fix: compensate)– Commercial MUX not functioning at +/- 5V (fix: use flight MUX)– Baseline restore locks up occasionally (fix - found)– Pulse generator not linear at low end– Various Minor problems (i.e. all diodes loaded backwards)

• ETU #2 (same PWB with some different components)– 12 of 12 channels loaded

– Board to be used for thermal vac and testing of ETC

• ETU #3 (could potentially be flight quality)– Layed out and in production

– Should fix all known problems except pulse generator linearity


Peak Digitizer Schematic


DAP Layout

Layout:•Started: ~2004-01-05•Finished: ~2004-03-24•Two Boards built up

•1 partially loaded•1 fully loaded

•Rev 2 in progress


Power EstimatesSST Power Estimates Current

2.5 5 5 5+2.5V D

(mA)+5V D (mA)

-5V A (mA)

+5V A (mA)

Power mW

DFE electronicsA225FB (assumes 2.5 volt negative ref) 1.800 3.450 26.25

x 12 21.600 41.400 315.00

IDPU electronicsADC channelsOP462 2.200 2.200 22.00CA3080A 0.075 0.075 0.75MAX907 1.400 7.00LTC1604 0.955 0.650 0.955 12.80Gate transistors 0.016 0.08subtotal 0.955 2.925 4.646 42.63ADC subtotal x 12 11.460 35.100 55.752 511.56

Threshold (quad)AD5544 0.000 0.050 0.25OP462 2.200 2.200 22.00subtotal 2.200 2.250 22.25TH subtotal x 3 0.000 6.600 6.750 66.75

LT1217 1.000 1.000 10.00

Test Pulse & Bias controlAD5544 0.000 0.000 0.050 0.25OP462 0.000 2.200 2.200 22.00TP&BC subtotal 0.000 2.200 2.250 22.25

Bias Voltage circuitAD648 0.680 0.680 6.80

POR 0.200 1.00FPGA (actel) 0.000 48.000 240.00SRAM (128K) 0.000 0.00

1173.36

Total 0.000 59.660 67.180 107.832 1173.36 mW

Estimated Power Consumption: ~1200 mW


ACTEL Development

• Designed by Jianxin Chen – Baja Technologies• First installed 2004-04-12 (Now on Rev 4)• Functionality:

• Controls 12 ADCs– Monitor / Count threshold events - Working– Monitor peak detect signal - Working– Produce convert strobe - Working– Coincidence detection - Working (further testing still needed)– Readout ADC (energy) - Working

• Psuedo-logrithmic energy binning– ADC measurement used as address of LUT to increment

accumulators (LUTs and accumulators stored in SRAM) - Working

• Data Readout (controlled by ETC board) - Working• Command Data Interface (CDI) (loads tables) -Working• Test Pulser control – Working (not optimum design however)• Noise measurement – not yet implemented

– Periodic conversions to measure “noise”

• Analog Housekeeping control – Working


Progress Summary

GSE Equipment• GSE software

– Working great!

• Calibration Vacuum Chamber– Now Operational

– Minor problems (ports smaller than desired)

• Ion gun– Arrived early but damaged in shipment

– Beam misalignment makes it difficult to obtain low energy H

– Being fixed this week.

• Electron gun– Adapter ring to accommodate smaller ports is in shop.

• Misc. Cabling, fixtures, feedthroughs etc.– Done


Progress Summary

Differences between ETU Sensor #1 and Flight units:• Flight Thermostat will switch at –50C (instead of –25C)• Heater pads will be lower power (on order)• Heater wires to be electrically shielded (if needed)• Thin foil mounted on support structure instead of circuit

board (done for ease of assembly)• Minor mods to DFE board and flex circuits (out for fab now)• Collimator baffles affixed with screws instead of epoxy• Flight detectors to be used (instead of STEREO spares)

No major design changes!

Ready to begin production of flight units (pending outcome of thermal/vac tests


ETU Sensor Testing

ETU Sensor with Cd109 source

88 keV photons

Test Pulser22-25 keV photons

<7 keV FWHM Resolution


ETU Sensor Testing

ETU Sensor with Am241 source

59.5 keV photons

Test Pulser14 & 17.5 keV photons (not resolved)



ETU Sensor & DAP Testing

Am241 Source

59.5 keV photons

Test Pulser14 & 17.5 keV photons


GSE display of complete SST unit (DFE+DAP) data flow


SST System Performance

0

20

40

60

80

100

120

0 20 40 60 80 100 120 140 160

Pulse Size (~keV)

Mean Bin

FWHM (Bin x10)

FWHM (keV x10)

Response is (reasonably) linear

~5 keV Noise

<8 keV noise

ETU Sensor#1 with DAP ETU#2 Response

(Test performed with external pulser)


Progress Summary

ETU Update (since PCDR)• Attenuator cycle testing

– shaft hardening/lubing didn’t help much

– Sapphire bearings replaced with ball bearings

– Attenuator cycle test #2b started June 7, 2004

– >50,000 cycles as of June 11, 2004

• Functional and characterization tests completed.• Vibration (16g) Qualification Test on June 11, 2004

– Mechanical functional : Passed ! (No obvious failures)

– Electrical functional : TBD

– Electrical characterization: TBD

• Thermal Vacuum Tests– Scheduled for late June 2004 (after spin-plane booms)


PDR RFA Responses

RFA #: UCB-6 Instrument: SSTRFA Title: SST Operating Temperature Review: UCB Instrument EPR Date of Review: October 15-

16, 2003 Reviewer: Shelley Organization: SelfRecommended Action:Take all practical steps to reduce average operating temperature of

the SST instrument or at least its sensor elements.Rationale:The thermal analysis indicated an average operating temperature

of 25C with a wide variation around that average. For noise levels consistent with the desired performance of this instrument, operating temperatures should be closer to 0-10C.

Response:Nominal operating temperature is –20 C and can be adjusted

pending future testing.


PDR RFA Responses

RFA #: UCB-7 Instrument: SST

Review: UCB Instr EPR Date of Review: Oct 15-16, 2003

Reviewer: McCarthy Organization: U. Wash.

Recommended Action:Reconsider the following design decisions:a. Changing the sweep magnet to better exclude 250-400 keV electrons.

- Done – 50gm/sensor mass penalty

b. Operating the detectors at an average temperature 0 C instead of 25 C. - Done

c. Increasing the ion energy range to include the 6 MeV calibration point. – Final decision still pending test results

d. Use of high-Z materials (tungsten) near the detectors should be evaluated in terms of locally generating bremsstrahlung x-ray background. – Baffles are BeCu. SmCo magnets shielded by Al.

e. Sun glints not only temporarily blind the particle detectors, but preamp can saturate and require additional time to recover. This effect to be measured, especially with their thinner dead layers. No Change yet


PCDR RFA: INST-06

TITLE: Temperature Dependence of Net Residual Field from SST Yoke

REQUESTED BY: Ed Shelley, Michael McCarthySPECIFIC REQUEST: Stray field from SST magnetic system can

be expected to have a temperature dependence due to mechanical changes in gap. This can exceed effect due to magnetic coefficient of SmCo. As a minimum, measure field in gap as a function of temperature. Note: stray fields may not scale with total field. If it does, this is not likely to be a problem, since effect in gap is on order of or less than 1%

RESPONSE: We tried to measure the ETU gap field over a temperature range of –50 to +40 C. We found an apparent 14% increase in field strength over this range. We do not expect the stray field to vary in the same manner. A test of stray field temperature dependence is in progress.


Magnetics Testing

Magnet Cage assembly #1• Measured Py for 19 magnets (All values were very close)• Selected 4 magnets for assembly #1• Measured dipole and quadrapole moments of assembly• Found significant residual dipole moment along x-axis• Contribution of dipole and quadrapole nearly equal at 2 m• Conclusion: Px and Pz of individual magnets are important


Magnetics Testing

Magnet Cage assembly #2• Measured Px, Py & Pz for 15 magnets• Selected 4 magnets for assembly #2• Measured dipole and quadrapole

moments of assembly #2• Still Found significant residual dipole

moment:• P=[ -0.244, -0.343, -0.012] nT-(2m)^3

• Q= B (nT) at 2 m

Angle in x-y plane

-0.034 -0.389 -0.009

-0.389 0.018 ?

-0.009 ? 0.016

•B(dipole @ 2m) = .84 nT•B(quad @ 2m) = .60 nT


Magnetics Testing

Sent Magnet Cage assembly #2 to UCLA for testing• Results are virtually the same• Contribution of dipole and quadrapole fields are similar at 2 m:

• B(dipole @ 2m) = .88 nT• B(quad @ 2m) = .59 nT

• The sum of both contributions exceeds requirement (0.75 nT @ 2m)

-350

-300

-250

-200

-150

-100

-50

0

50

100

150

0 100 200 300 400 Series1

Series2

Series3



PCDR RFA: INST-07

TITLE: Wire Bond Testing RFA CODE: INST-07REQUESTED BY: Joe Osche, Michael McCarthy, Henry

HeetderksSPECIFIC REQUEST: Wire bonds may fail. Test and qualify wire

bonding on detector. Install redundant wire bonds to increase reliability.

RESPONSE: Redundant bonds will be made on all flight detectors. Qual test Procedure: Wire bonds are made on a test detector prior

to and following the wire bonding of all detectors in a stack. Destructive pull tests are performed on these test bonds to qualify the bonds in the associated detector stack.

This test procedure was followed during the assembly of ETU stack #4 (However, redundant bonds were not made despite our requests to do so.)

Wire bonds must also pass vibration tests along with the sensor unit. (Qualification vibe test on 6-11-2004 results: TBD).


PCDR RFA: INST-08

TITLE: Thermal Twisting of Flexure Mounts RFA CODE: INST-08

REQUESTED BY: Henry Heetderks, Michael McCarthy

SPECIFIC REQUEST: The slots on the "quasi-kinematic" feet should be orthogonal to a line drawn to a common point. (In the case with one fixed foot, the other two should point toward it.) Heetderks thinks P. Turin recognizes this and will get it fixed. Correct flexure mounts to eliminate thermal twisting.

RESPONSE: A FEA was performed on the current design to quantify the stresses developed in the feet flexures due to the non-perpendicularity of the bolt-to bolt lines and the flexures combined with the max temperature excursion expected. The results showed a maximum stress of 4600 lb/in2 which is a factor of seven below yield for aluminum. Thus, we see no reason to modify the design, given that the required changes would cause problems with part geometry and would necessitate relocating the SSTs on the spacecraft panel, potentially causing FOV clearance issues.


PCDR RFA: INST-09

TITLE: Testing of Detectors RFA CODE: INST-09REQUESTED BY: Joe OscheSPECIFIC REQUEST:

• Risk of detectors not working. Perform and document a test for the performance verification of the detectors prior to placing them in the instrument.

RESPONSE: (We will do this )• Wire bond tests (see RFA-08)• LBL responsibilities:

– Leakage current test– Breakdown voltage test– Depletion voltage test

• SSL responsibility: (after assembly in stack)– Short/Open circuit test – Diode test– Leakage current test (including light sensitivity)


PCDR RFA: INST-10

TITLE: Fairing Debris RFA CODE: INST-10

REQUESTED BY: Michael McCarthy

SPECIFIC REQUEST: • Include a fairing cleanliness requirement to mitigate debris

dropping into uncapped detectors apertures.

RESPONSE:• We will write a detector surface cleanliness requirement.

Swales will use this requirement to determine the fairing cleanliness requirements.

– <10 Angstrom condensate (NVR < 0.1 g/cm2)

– <1% obscuration (Level 500 cleanliness)

– No large debris


PCDR RFA: INST-11

TITLE: SST Sensitivity to Sun Glints RFA CODE:INST-11

REQUESTED BY: Michael McCarthy

SPECIFIC REQUEST: • As part of the cal/checking procedure, the instrument should be

checked for sensitivity to sun glints and degree of solar blindness.

RESPONSE: We will do this. (BTW: Detectors are known to be very sensitive to light and will not function properly in direct sunlight.)

• Prior to installation in sensor, detector stacks will be tested for leakage current as a function of incident light to verify correct application of Aluminum layer on open detectors.

• Sun pulse recovery times will be measured on the ETU.• A stray light leakage test is planned.


PCDR RFA: INST-12

TITLE: SST Analog-Actel Interface RFA CODE: INST-12

REQUESTED BY: Henry Heetderks

SPECIFIC REQUEST: The current interface between the analog electronics and the Actel in the SST will give multiple transitions at the Actel when the slow analog signals change. This is probably OK but should be recognized in the design. I.e. if you were using a counter in the Actel to keep track of the number of particles by counting transitions of the peak detector, you will get an answer which is way too high. Abiad is an expert on this. Verify that there is not a problem with this interface.

RESPONSE:• We have verified there is no problem with this aspect of the

interface. The possibility of multiple transitions in the comparator output was recognized prior to the Actel design specification and had been accounted for.


PCDR RFA: INST-R11

TITLE: SST Flexure Stresses RFA CODE: INST-R11

REQUESTED BY: Michael Sholl

SPECIFIC REQUEST: Show that thermal stresses in SST mounting base flexures are not too high under a 120 degrees C temperature delta.

RESPONSE:

Please see response to RFA-08


PCDR RFA: INST-R12

TITLE: SST Shutter Imbalances RFA CODE: INST-R12

REQUESTED BY: Michael Sholl

SPECIFIC REQUEST: Make a statement on allowable SST shutter imbalance to prevent rattling during launch.

RESPONSE: • The Attenuator Assembly axis of inertia shall be within

0.9 mm (0.035 inch) of the rotational axis.

P.S. The shutter was observed to remain closed throughout the ETU vibration test (6-11-2004).



SST MECHANICAL INTERFACES



Interface Between SST Sensors and Spacecraft Bus• THM-SYS-111: Probe to SST Interface Control Document

– Summarizes mechanical and thermal interfaces with spacecraft

• THM-SST-ICD-001-B: Interface Control Drawing– Page 1: Overall unit dimensions, mounting footprint, and field-of-view

requirements– Page 2: Purge access and non-flight hardware dimensions– Page 3: Sensor orientation relative to spacecraft bus– Page 4: Sensor external thermal finish



THM-SST-ICD-001-B: Interface Control Drawing – Page 1












SST TEST REQUIREMENTS



Unit Level Test Requirements

• Attenuator Mechanism Cycling– ETU target of 150,000 cycles (10x expected on-orbit maximum value)

• Vibration– Per THEMIS Instrument Payload Environmental Verification Plan and

Test Specification THM-SYS-005B – Sine burst, random, sine sweep – Updated test levels to be provided by Swales in place of GEVS

(Qualification @ 15.8g)

• Thermal-Vacuum– Per THEMIS Instrument Payload Environmental Verification Plan and

Test Specification THM-SYS-005B– Sensor alone

8 CyclesTemperature range: -60 C to +40 C

– Sensor w/ DAP in IDPU2 CyclesTemperature range: -30 C to +40 C



THEMIS Environmental Test Matrix

COMPONENT (ITEM)

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COMMENTSInstrument Payload 6 UCB T9 T10 T10 T10 T10 6 -30 to +45 -40 to +50 -40 to +55 M3 T14 1000 100 SST Sensor 2 UCB T1 A2 T4 T5 A7 M1 T7 T9 2 -65 to +40 -52 to +13 -75 to +50 -65 to +30 T11 M2 A 100 A

notes:T1 0.25g sweep from 5 Hz to 2000 HzA2 Analysis to show margin on Yield at 2.0 x limit load; and Ultimate at 2.6 x limit loadT3 Test conducted at 1.25 x limit load T4 ETU tested to Qual; F1 tested to Protoflight; F2-F6 tested to Acceptance. Levels from coupled loads analysisT5 ETU tested to Qual; F1 tested to Protoflight; F2-F6 tested to Acceptance (sine profile in thm-sys-005)T6 ETU tested with SC shock testA7 Analysis to show margin at 2 x maximum pressure differential (launch ascent profile in thm-sys-005)M1 Mass, CG and MOIs measuredT7 At least 10 x number of actuations during the mission life, unless mechanism is on Limited Life Items ListT8 SPB Motor to go through Life Test - operation after 6 months (TBR)T9 Safe-to-Mate and compliance to ICD prior to Integration

T10 Per MIL-STD-461C (levels in thm-sys-005) T11 Grounding checked for each component prior to integrationM2 DC Magnetics measured prior to Instrument Payload integrationM3 AC Magnetics measured in mag facility at Probe Level

T12 Total Dose and SEE Testing at part level if necessaryT13 60C for 48 hours prior to TV w/ integrated payloadT14 Contamination Verification w/ TQCM during Instrument Payload Thermal Vac

CONTAMINATION OTHERHARDWARE MECHANICAL ELECTRICAL THERMAL


Solid State Telescope

Thermal

Christopher Smith

Thermal Engineer

[email protected]

510-642-2461


SST

• Mounts directly to the corner panel on three 1/8 inch isolators

• Has four open apertures that are sometimes obscured by attenuators

• Must operate at 10 Deg C or less


SST Geometry Model

Alodined

Aluminum

AZ 2000 IECW

Ebanol

Black Body /

Alodined Aluminum


SST Model Inputs

• Optical materials– Ebanol– AZ 2000 IECW White Paint– Alodined Aluminum

• Thermophysical materials– Aluminum, 6061– ULTEM

• Heaters– Two 5 watt heaters per sensor head controlled by redundant

thermostats– Set points –50 and -42

• Conductors– 3 ULTEM isolators to corner panel, 0.0078 < G < .0133 W/C

each

• Power Dissipation– 0.135 W Watts Nominal per Sensor


SST Case Sets


SST – Nominal Plots

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

0 50K 100K 150K 200K 250K 300K

SST - Alodine and AZ 2000 IECW White Paint, 10 W Heater (04/12/04)SAA 103 Hot Aperture Closed - SAA 103 Hot - SAA 90 Cold - SAA 77 Cold - SAA 77 Cold Low Power

Tem

pe

ratu

re

Time

SST1 TOP SST1 COLLIMATOR SST 1 INTERNAL CORNER PANEL SST2 INTERNAL SST1 HEATER SST2 HEATER SST1 TOP

SST1 COLLIMATOR SST1 INTERNAL CORNER PANEL SST2 INTERNAL SST1 HEATER SST2 HEATER SST1 TOP SST1 COLLIMATOR

SST1 INTERNAL CORNER PANEL SST2 INTERNAL SST1 TOP SST1 COLLIMATOR SST1 INTERNAL CORNER PANEL SST2 INTERNAL

SST1 TOP SST1 COLLIMATOR SST1 INTERNAL CORNER PANEL SST2 INTERNAL


SST – Top and Bottom to Sun Plots

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20K 30K 40K 50K 60K 70K 80K 90K 100K 110K 120K 130K

SST - Alodine and AZ 2000 IECW White Paint, 10 W Heater (04/12/04)SAA 0 Cold - SAA 180 Cold

Tem

pera

ture

Time

SST1 TOP SST1 COLLIMATOR SST1 INTERNAL CORNER PANEL SST2 INTERNAL SST1 HEATER

SST2 HEATER SST1 TOP SST1 COLLIMATOR SST1 INTERNAL CORNER PANEL SST2 INTERNAL


SST Results Table


SST – Coldest Heat Map


SST Hottest Heat Map


Design Details

Thomas Moreau


Detector system• Measure electrons and protons > 20 keV

Geometrical analysis• Collimator aperture• Solid state detector size• Thin foil

– Stop protons < 350 keV

• Magnet system– Deflect electrons < 400 keV– Not to disturb particle trajectories out of the magnet gap– Low stray magnetic field at the position of the magnetometers

• Attenuator System– Reduce count rate during high flux– Reduce radiation damage (especially to open side)

Sensor Considerations


Detector System

Detectors stacked in “Triplet” sequence:• Foil (F) | Thick (T) | Open (O)

• Area used 1.32 0.7 cm2

• Front detectors F and O are 300 m thick while T is 600 m (with two detectors back to back)

• Detectors associated with a system of coincidence/anticoincidence logic

OTF OTF

OTF OTF

F T O


Collimator System

3D numerical model (GEANT3) of the collimator with detectors/foil

• Collimator baffle offers 42 23 rectangular full field-of-view

• Be-Co knife-edges intercept out-of-beam low-energy particles and reduce scattered light

• Aluminum housing shielding (0.5 mm) stops normally incident protons < 8 MeV and electrons < 400 keV

• Al/Polyimide/Al (LUXÉL) three layer foil (~1500Å/4m/1500Å) absorbs protons < 350 keV while permitting electrons ~20 keV to penetrate

• Geometric factor ~ 0.1 cm2sr


Telescope Response

Monte-Carlo simulation• 3D ray tracings are performed: a clean

electron-proton separation is obtained

• Particles’ angular distributions are determined ( 27 14 FWHM)

• Efficiency plots of the electron-proton detectors are determined for different energies


Magnet System

Magnetic circuit design• 4 permanent magnets (Dexter

Magnetic Technologies) + 2 yokes (Vacuumschmelze, Germany)

• Two oppositely oriented dipoles

• Stray fields < 1.5 nT at 2m distance

Magnet gap


Particle tracing simulations

Magnet System

400 keV (e)

30 keV (e)

30 keV (p)800 keV (e)


Tests and Calibration

Thomas Moreau


Tests Magnet System

• 2 magnet assemblies assembled for prototype• Spot-checks of measured magnetic field versus those

obtained from the analytical calculations are done: small discrepancy due to the misalignment of vector magnetization and the non-uniformity of magnetization

• The discrepancy of magnetic properties between 4 magnets of each assembly is minimized

• Magnetic induction in the center of the gap is measured ~2.23 kG (in agreement with 2.24 kG of the model)

• Mapping of the magnetic field strength at SSL and additional measurements at IGPP/UCLA are done: magnetic moments of each assembly are characterized (used to derive the stray fields)

• To save weight, yokes will be shaved until they went to the saturation (to be done)


Tests and Calibration

Need to characterize the sensor response in terms of: • Species (electron, proton, oxygen and helium ions)• Energy: - determine the detection threshold for a particular

channel- determine the energy thresholds for the coincidence

counting rate channels - to provide the look-up tables

• Angle: - determine the off-axis response (including information on the response to scattered particles)

• Dead time

Other goals:• Determine the electron and proton detection efficiency of individual

counting rate channels

• Sun pulse recovery

• Use the calibration data to verify and adjust the mathematical model


Calibration Set Up

• Initial calibrations at SSL, Ba-133, Bi-207, Cd-109 and Cs-137 conversion electron sources will be used to determine channel energies over the range 62 keV to 1060 keV

• Low-energy (up to 50 keV) and detection efficiency calibration for both electrons and protons will be done at the new SSL acceleration facility

• Additional energy and detection efficiency calibration with both electrons and protons with a high-energy accelerator (above 300 keV) if needed


SST GSEJim Lewis


SST/DAP GSE Block Diagram

SSTSensor

GSE workstationBenchLVPS GPIB via USB

Ethernet

GSE software: basedon Mike Hashii’sSTEREO GSE tools

6U GSEInterface

Board+

Niosembeddedprocessor

Ethernet router

Lab network

DAP_HSK

SST TLM

SST CMD

SST CLK

SST SectorClk

SST TLM ENA

3-axis servoamplifier

Manipulator

Electronor ion gun

HVPS

Vacuum chamber

PCI motioncontroller

DAPPower

Data

PWR

Digital MultimeterGPIB

Ethernet


SST/DAP GSE Software

Capabilities:• Scripted or interactive entry of CDI, GPIB, and manipulator

commands

• Simulates ETC board to command DAP and acquire telemetry

• Real-time display of counter histograms, raw hex telemetry dumps, analog housekeeping values, manipulator status

• Monitoring of CDI commands to mirror DAP memory operations and validate correct DAP FPGA operation

• Telemetry and log messages archived to disk for later examination and processing

• Device control– GPIB programmable LV and HV power supplies, digital multimeter– Internal PCI motion controller, external servo amp and motor drive– TCP/IP interface to 6U VME GSE Interface Board for sending CDI

commands, acquiring telemetry and analog housekeeping values


Contamination Control

• Standard cleanliness procedures will be followed• The sensor units will have a dry Nitrogen purge

system and red tagged covers (removed at last possible opportunity)

• Nitrogen purge can be removed for transport (<24? hours) with sensor in sealed containers.

• Red tape to cover apertures during spin balance• Sensor contamination from fairing during launch –

still open issue• Attenuators should be in the closed position during

satellite manuevers.


Vacuum Chamber Refurb

Not really a refurb!

ReGen valve

Roughing valve

Cryo pump

Compressor

Gate valve

Convectron -1

Ion chamber

Ion Chamber valve

IG-1

IG-2

VacuumChamber

New Purchase

Convectron -2

Turbopump

Backingpump

Turbo controller

Scroll Pump

Vent valve


Ion Gun Specifications

10/6/2003

List of Specs

1 energy range 1KeV to 50 KeV2 energy width 0.5% over full range or 50eV, whichever is greater3 energy stability 1% over full range for 20 minutes

4 particle flux 1000 to 100000 particles/s/cm2

5 beam cross section 4 cm diameter6 beam flux stability <2% for 20 minutes7 beam flux variation <20% over cross section

8 species H+, He+, Ne+, O+, N+, Ar+, (Kr+)9 mass resolution distinguish above species10 system footprint not to exceed 9' x 4' (preference, not required)11 power requirement 120VAC

12 cooling requirements preferably air, but H2O OK

13 lead time 4 to 5 month14 vacuum system req ability to interface to 250 l/s turbo pumping system


Ion Gun Schematic


Detector Schedule


Schedule


Schedule


Schedule


End of Presentation

Documents

THEMIS Mission CDR 1 UCB, June 16, 2004 THEMIS T IME H ISTORY OF E VENTS AND M ACROSCALE I NTERACTIONS DURING S UBSTORMS RESOLVING THE MYSTERY OF WHERE,