Particles and Fields PackagePre-Environmental Review

May 22 -23, 2012SEP (Solar Energetic Particles)

Davin Larson, Rob Lillis, Miles Robinson, Ken Hatch, David Glaser

Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission

1-2MAVEN IPER May 22-23, 2012

SEP instrument overview

• The Solar Energetic Particle (SEP) instrument measures the energy spectrum and angular distribution of solar energetic electrons (30keV–1 MeV) and ions (30 keV-12 MeV).

FoilCollimator

Thick Detector

Sm-Co Magnet (sweeps away electrons <350 keV)

Attenuator

Al/Polyimide/Al Foil(stops ions <250 keV)

Open Detector

Attenuator

Open Collimator

Foil Detector

IonsElectrons

SEP EM #1 in clean room

Reminder of SEP Instrument

• SEP (Solar Energetic Particle) Instrument consists of– 2 identical* Data Acquisition and Processing (DAP) boards (DAP1

and DAP2) housed in the PFDPU– 2 identical harness cables– 4 identical Detector Front End (DFE) boards each with a detector

stack– 2 identical Sensor housings - each one holds 2 DFE boards

DAP (x2)DFE (x4)

Detector Stack (x4)

Harness (x2)

PictureNotAvailable

Flight SensorPicture

Sensor Housing(x2)

EM

Additional SEP Flight Model Pictures

SEP Build Status (as of 2012-5-14)

• No significant changes since CDR• All Flight parts built and in-house

– (exception: White collimators still at Goddard)• Board Status

– All boards (4 DFE and 2 DAP) have been • Tested• Tuned• “Fixed”• Partially integrated with EM PFDPU• Cleaned• Stake and coat process scheduled for 2012-5-21

• Sensor housings (#3 & #4 -with white paint):– Assembled– Tested– Awaiting incorporation of DFE boards following stake/coat

• Spare Status:– 2 spare sensor housings (#1 & #2 - painted black) are built and tested

• 2 more sensor housings sent to Goddard for white paint• 2 sets of collimators (painted black) are assembled

– 2 spare DFE boards are built, tested (but not fixed)– 2 spare detector stacks– 0 spare DAP boards– 0 spare Harness

SEP Issues

• Painting of Sensor housings was problematic:– Initial (white) painting at SSL had non-uniform coverage and cracking

and/or poor adhesion.– Not clear that white paint would successfully pass environmental tests

(T/V specifically)– Sensors had to be stripped and cleaned. Not clear if paint would

adhere to stripped– Decided on 2 parallel paths:

• Prime flight: Painted 2 sensors white (performed at Goddard)• Backup flight: Painted 2 sensors black (performed at SSL)

– As additional backup: 2 more sensor housings manufactured and are being painted at Goddard with low priority

• Attenuator paddle misalignment during assembly/test• Paddles removed, retooled for higher torque and replaced. Design

changed before final assembly was complete.

• DAP Tuning – Took extra long time due to lack of 1% flight resistor values

SEP Flight Testing Status (as of 2012-5-14)

• Electrical– 50+ hours of testing split roughly equally between both

DAP/DFE units– Thermal cycle (on EM DAP unit only) to understand regulator

stability– DAP/DFE/Detector full end-to-end calibration performed with

sources on both units– DAP/DFE test pulse calibration completed on both units

• Mechanical– Mini-life tests on flight units completed– Voltage / actuation time test completed on flight units.– Magnetic tests (on magnet cage only) completed. Must be

repeated on final assembled sensor (prior to environments)

SEP PFR status

PFR Description Resolution Status

010 NCR White Paint Will be closed when Goddard delivers final white painted collimators.

Open

021 NCR DFE Protection Diodes

Diodes unnecessary on non-spinning spacecraft. Changed design to not include them.

Resolved

025 SEP DAP D722 Installed

Installed Reference with stubby leg. (MRB on 3/19) Closed

033 DAP regulator Ringing Installed feedback capacitor in parallel with feedback resistor. (MRB on 4/20)

Resolved

045 FPGA HFCLK Pulldown resistor

Design flaw. Removed 100 Ohm resistor (saved 50 mW!) Resolved

047 SEP DAP Regulator Ref Voltage

Change of resistor value to increase operational current delivered to 1.2V reference IC

Resolved

054 SEP Cross Talk Added negative feedback resistor to DFE (MRB on 5/11) and “1pF Tuning Cap” to DAP

Resolved

Resolved = Paper work not completed

SEP Documentation Status

• Comprehensive Performance Test (CPT)– Python Script written and executed successfully– Minor script modifications required in order to be run within

PFDPU environment (specifically attenuator actuation commands are different)

– Draft Document in progress• Vibe Test procedure

– Draft procedure document in progress• Thermal Vacuum Test Procedure

– Draft procedure submitted• Calibration Procedure

– Plan is defined– Draft document in progress

SEP Test Process

Assemble DFE in Sensor housing CPT Integration of DAP

with DPU

Sensor Calibration

Scattered light test

(with CPT)

Sensor Magnetics characterizationVibrationSensor Magnetics

characterizationCPT

Thermal Balance and Thermal

Cycling (with CPTs)

Sensor Magnetic characterization

Final Functional Test

Magnetics Testing

• Complete magnetic characterization is performed on each sensor unit Dipole and Quadrupole moments are computed at 30 cm distance.

• Testing is done before and after each Environmental test• Purpose:

– Meet magnetic cleanliness requirements.• Magnetic field at 4.5 m distance is determined from extrapolation of

near field measurements.– Insure that magnets have not broken or shifted as result of

testing.• Pass/Fail:

– Field at 4.5 meter <1nT– No significant change in dipole or quadrupole moments.

Magnet combinations in flight cages

• Red columns are as measured in the magnetic characterization coordinate system, while blue columns are in the SEP-to-spacecraft MICD coordinate system.

• F1 means flight cage for SEP Sensor 1.• S1 means spare cage for SEP Sensor 1.

CageSenso

ri,j,k,l magnets orientation Px Py Pz Px Py Pz

F1 3B016, B069, B092, B101

1 -1 1 -1 -4.46 0.112 0.837 -4.46 -0.837 0.112

F2 4B051, B060, B083, B154

-1 -1 1 1 -4.65 0.810 0.195 -4.65 -0.195 0.810

S1 2B003, B046, B102, B103

1 -1 1 -1 -1.54 16.60 3.35 -1.54 -3.35 16.60

S2 1B010, B058, B152, B155

-1 1 1 -1 -8.49 5.94 -1.26 -8.49 1.26 5.94

SEP Magnet cage characterization at 4.5 m

Sensor 1

Sensor 4Sensor 3

Sensor 2

0.03 - 0.11 nT 0.04 - 0.11 nT

Flig

ht

un

its

0.20 - 0.35 nT0.12 - 0.24 nT

Attenuator Testing

• 2 Actuator tests performed:– 30-cycle ‘mini-life tests’

• 34 V input, all 4 sensors.• Stroke duration recorded to verify consistent transition times,• Oscilloscope traces recorded

– 13-cycle ‘voltage sweep’ tests• 24 V - 36 V:expected range of spacecraft bus voltage.• Sweep: 36 V, 34 V,…, 26 V, 24 V, 26 V,…, 34 V, 36 V• Stroke duration recorded

– During both tests• Scope traces taken to verify that Both Actuators Not Open

Simultaneously “Banos test”

• Pass / Fail criteria:– Actuator must show consistent actuation times for a given

temperature and voltage.

Bus Voltage test for sensors 3 & 4

• Test done in air at 24C.• Takes >1 second to open at 24V: (will close however)

– Sensor 3 close & sensor 4 open cycle.– Not unexpected, given 20-30% increase in duration for 1 bar

versus vacuum.

Sensor 3

Sensor 4

Solid: openDash: close

Both switches not open simultaneously for all voltages (Not part of CPT)

Sensor 3 OPEN, 34 V

Sensor 3 CLOSE, 34 V

Sensor 4 OPEN, 34 V

Sensor 4 CLOSE, 34 V

SEP/DAP Test Facility

• Fully tested functionality of all boards, separately and integrated together

SEP CPT Objectives

• Objectives– Verify nominal power draw– Verify Commanding:

• Command counter must match commands sent (*)– Verify Telemetry:

• Housekeeping messages • Noise messages• Science messages• Memory Dump messages – Verify check sum and match LUT

– Verify DAC adjustment:• 6 Threshold levels• Baseline level• 3 Test pulse amplitudes• Bias voltage level control

– Run Test Pulser to Verify channel functionality coincidence and gain– Run Threshold Sweep to optimize Noise Level – Sweep Test Pulser to verify gain and baseline– Test with X-ray source (Am241) (when possible)

• Verify proper harness connection.• Verify channel gain• Verify wire bonds intact on all 8 detectors ( O, T, T, F) x 2 are functioning on each sensor.

– Actuate attenuator (open & close )– Test S/C controlled Heater/Temp Sensor (not yet complete).

• Pass / Fail Criteria:– All measured values above must be observed at nominal values and without variation beyond statistical

expectations

P1

P2

HeaterTest

Data Analysis Software Development

• All Data is stored in a single extensible (Common Block) file format. Includes:– Instrument raw telemetry from MISG with status– Raw commands sent to instrument– PFDPU telemetry– Log/Error messages– User Comments– GPIB data:

• Power Supply Voltage and Current• Multi-meter measurements• Signal Generator data

– Manipulator Data– Each common block header contains a time code to determine UTC and

resynchronize clocks• GSEOS Used for minimal real time displays and streaming of data

stream• Data streamed through socket connection to secondary computer

– IDL used for both real time and post analysis of data stream.

Example output from CPT

• Operator runs script: “sep_cpt.py”

• Script automatically:– Turns on data collection– Turns instrument on– Executes each subtest

automatically– Prompts operator to

introduce radiation source (when applicable)

• Collected data viewed with GSEOS and IDL in real time.

• Required Personnel:– Radiation certified

personnel to handle source and execute script.

– Davin Larson* – (followup data examination)

Example output from Functional Test

• Functional test provides a more complete “calibration”.

• Takes longer.• Must include a

radiation source

DAP008 Source Calibration Spectrum

• NAME A X0 S • O_0 267.3 17.30 2.059 • O_0 95.10 20.90 2.059 • O_0 93.63 26.30 2.059 • O_0 274.4 59.54 2.059 • T_0 1048. 17.30 2.662 • T_0 469.0 20.90 2.662 • T_0 240.0 26.30 2.662 • T_0 604.1 59.54 2.662 • F_0 1188. 17.30 2.116 • F_0 366.8 20.90 2.116 • F_0 168.3 26.30 2.116 • F_0 320.2 59.54 2.116

• 1.4431705 1.4470061 1.4881333

59.5 KeV - 2 keV rms

Open

Thick

Foil

Unresolved x-raypeaks

Threshold at~10 keV

ComptonX-ray at 48 keV

Fitting to 4 x-ray peaks from Am241.The 59.5 keV peak is primarily used for electronic calibration.

Example Test Pulse calibration

SEP Calibration Facilities

• SEP Sensor is mounted on manipulator with flight harness and operated inside chamber. Extender harness connects through bulkhead and connects to DAP board and GSE outside chamber.

SEP Resource Update

Power / DAP• 5.5 VA x 74 mA* =.41 W• -5.5VA x 51 mA* =.28 W• 5VD x 8mA =.04 W• 3.3VD x 8 mA =.03 W• 2.5VD x 84 mA =.21 W• Total= .97 W*Count rate dependent

Mass / Sensor• TBD (final assembly not

weighed)• No significant change from EM

– 621 g w/o thermal shield– 651 g with thermal shield

Test PulserSource

PS Current

SEP Trending Values

• Housekeeping Values– +/- 5 Volt regulated analog– +5 V digital– Bias Voltage– Bias Current Monitor– 3 Temperature monitors (DAP / TID-0 and TID-1) (not trended)

• Noise measurements:– Baseline level– Sigma

• Science Data– Am241 59.5 keV energy bin

• Attenuator actuation times• Current Draw (@ Instrument level only)• All Data saved at full time resolution providing the option of

retroactively trending other quantities.

SEP Flight Vibration Test levels

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0-80

-60

-40

-20

0

20

40

60

Hours

Tem

pera

ture

(C

)

SEP Thermal Vacuum Cycle

Survival Heater Functional

Operational Heater Functional

Turn on, TB

Turn on, TB

Turn off

Cycle Number: 1

LPTLPT LPT LPT LPT CPT

Bake-Out

LPTLPT LPT LPT CPT CPT

32 4 6 7 8

Hot Survival

5

LPT

Cold Survival

TVAC Functional PlanCycle Plan

1 (Survival)

Perform initial CPT at ambient, prior to pump down.Transition to Hot unpowered. Dwell at Hot for 12 hours (initial bakeout).Perform Hot Start CPT.Transition to Cold unpowered. Dwell at Cold for 12 hours.Verify Survival Heater operation. Perform Cold Start CPT.

2-7 Transition to Hot/Cold Operating, in operational mode continuously.run CPT at hot, cold and in transition.

8 Bakeout

PostDwell at hot survival temperature for remainder of 48 hour bakeout time, or until TQCM indicates acceptable level. Repeat CPT prior to removal.

SEP Schedule

1-31MAVEN IPER May 22-23, 2012

REQUIREMENT SEP DESIGN

PF78: SEP shall measure energy fluxes from 10 to 1e6 eV/cm2-sec-ster-eV

Compliance. SEP designed to measure energy fluxes from 10 to 1E7 eV/cm2-sec-ster-eV(Consistent with count rate of 20000 cnts/sec)(Shown measured count rates >30000 Cnts/sec)

PF79: SEP shall measure ions from 50 keV to 5 MeV

Compliance. SEP designed to measure energies from ~25 keV to 13 MeV(Test results show threshold at <10 keV.)

PF80: SEP shall have energy resolution dE/E of at least 50%

Compliance. SEP designed to have intrinsic energy resolution of <10 keV with programmable energy widths in increments of 1.5 keV providing better than 50% resolution(Measured intrinsic resolution is ~2 keV)

PF81: SEP shall have time resolution of at least 1 hour or better

Compliance. SEP has time resolution of 1 second (basic instrument measurement cadence).

SEP Level 3 Requirements

1-32MAVEN IPER May 22-23, 2012

MAVEN SEP Summary

• SEP FMs meet or exceed requirements.• Sensors and Boards are (almost) ready for final

(re)assembly• Flight Equipment kept in clean environment for PP• No (unresolved) anomalies• Risks:

– Receipt of white collimators from Goddard - Resolution:• Fallback: Will proceed with black collimators with slightly higher

expected operating temperature while in sunlight

– Survival of white paint in TV• Very low risk considering they have already survived thermal vac cycling• Fallback: Will proceed with secondary (black) flight sensor housings

• No residual risk (other than time constraints)

SEP Flux Intensity Accuracy Requirement

• Level 1 Science requirement: Determine flux to within 30% for Ions (> 50 keV)– Count Rate = Flux x efficiency x Geometric Factor x dE– J(E) = R(E) / ( eff(E) x G x dE(E) )

• dE(E) is determined by the Look UP Table (LUT) that bins the data. 1 bin = 1.46 keV. Variations (between channels) is ~2% but the value for each channel is known to much better than 1%.

• G [0.26 cm^2-ster] is a function of geometric optics only – (active detective area, Collimator solid angle. This is calculated using GEANT4. Eventual estimated uncertainty <5%

• R(E) [Cnts/sec]: Uncertainty determined by Poisson statistics: sqrt(N)/N. Need > 100 Cnts to attain 30% accuracy.

• Efficiency: This is the quantum efficiency of detection which is 1 for Energies well above threshold but approaches 0 within a few sigma of threshold. MeasuredElectronic threshold is ~10 keV. Energy lost in (1000 A) dead layer is ~16 keV. RMS Noise level is 2 keV.

Transmitted Energy of 40 keV proton through 1000A Al is 23keV. Since this is 6 sigma above the threshold level. The quantum efficiency is effectively 1 with negligible uncertainty. (1 sigma noise = 2 keV)

For 40Measured Electronic Threshold

Conservative

1000 A

SEP Flux Intensity Accuracy Requirement

• Level 1 Science requirement: Determine flux to within 30% for Ions (> 50 keV)– Count Rate = Flux x efficiency x Geometric Factor x dE– J(E) = R(E) / ( eff(E) x G x dE(E) )

• dE(E) is determined by the Look UP Table (LUT) that bins the data. 1 bin = 1.46 keV. Variations (between channels) is ~2% but the value for each channel is known to much better than 1%.

• G [0.26 cm^2-ster] is a function of geometric optics only – (active detective area, Collimator solid angle. This is calculated using GEANT4. Eventual estimated uncertainty <5%

• R(E) [Cnts/sec]: Uncertainty determined by Poisson statistics: sqrt(N)/N. Need > 100 Cnts to attain 30% accuracy.

• Efficiency: This is the efficiency of detection which is 1 for Energies well above threshold but approaches 0 within a few sigma of threshold. MeasuredElectronic threshold is ~10 keV. Energy lost in (1000 A) dead layer is ~17 keV. RMS Noise level is 2 keV.

Flux uncertainty is typically dominated by efficiency uncertainty for particles near threshold. SEP threshold/noise performance is so far below requirements that this uncertainty is no longer significant. The next dominant unknown is from calculation (~5%)

Transmitted Energy of 40 keV proton through 1000A Al is 23keV. Since this is 6 sigma above the threshold level. The quantum efficiency is effectively 1 with negligible uncertainty. (1 sigma noise = 2 keV)

Measured Electronic Threshold

Conservative

1000 A

•End of presentation

Thermal Image of EM#1 DAP board

This Board does NOT have voltage regulators

Dead Layer Effects

Dead Layer Effects

Measured Electronic Threshold

Conservative

PER Requirements

• Changes since the Critical Design Review • Program status and general test readiness • Test Plans and Specifications addressing:

– Test objectives/conditions/levels/configuration – Test facilities and certification – Test fixtures and support equipment – Instrumentation – Success/abort criteria – Personnel for each test: Test Director and Test conductors techs, QA, Safety, etc.

• Progress/status of safety data submissions, procedures and verification • Test flow including: calibration, when CPTs will be performed and number of thermal

vacuum cycles • Schedule • Documentation Status • Functional and environmental test history of the hardware • Product Assurance and Safety, including contamination • Previous anomalies, deviations, waivers and their resolution (including any excerptions

to applicable GOLD RULES and GEVS) • Identification of residual risk items • Open items and plans for close-out

Calibration Plan

• Functional calibrations are performed using Am241 radiation source:– 59.5 keV x-rays (closed – strong source)– 5.5 MeV Alpha particles (open – weak source)

• Low energy Particle Calibrations – Electrons done in B20 Calibration chamber with <50KeV electron gun.– Ions done in B20 Calibration chamber with <50 KeV ion gun.

• Final End-to-End calibration performed with sensors in B20 cal chamber following integration with PFDPU