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Particles and Fields Package (PFP) Instrument Preliminary Design Review

Particles and Fields Package (PFP) Instrument Preliminary Design Review Solar Wind Ion Analyzer (SWIA). Jasper Halekas Greg Dalton Ellen Taylor. I. Introduction. Introduction Jasper Halekas Science Requirements Jasper Halekas System Design Jasper Halekas

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Particles and Fields Package (PFP) Instrument Preliminary Design Review

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  1. Particles and Fields Package (PFP) Instrument Preliminary Design Review Solar Wind Ion Analyzer (SWIA) Jasper Halekas Greg Dalton Ellen Taylor

  2. I. Introduction • Introduction Jasper Halekas • Science Requirements Jasper Halekas • System Design Jasper Halekas • Optics Design Status Jasper Halekas • Mechanical Design Status Greg Dalton • Electrical Design Status Ellen Taylor • Schedule/Wrap Up Jasper Halekas

  3. SWIA Team • SWIA Instrument Lead: Jasper Halekas • Lead Mechanical Engineer: Greg Dalton • Lead Electrical Engineer: Ellen Taylor • Thermal: Chris Smith • FPGA: Dorothy Gordon • FSW [PFDPU]: Peter Harvey • Power Supplies: Peter Berg, Selda Heavner • GSE: Tim Quinn • Detectors: Mario Marckwordt • Facilities: Steve Marker • Purchasing/Contracts: Kate Harps, Jim Keenan, Misty Willer • PF Manager: Dave Curtis • PF Lead Mechanical Engineer: Paul Turin • STATIC Lead/SWIA Consultant: Jim McFadden

  4. SWIA Status/Documentation • Designing to PF FRD, instrument specs, MICD, and numerous systems documents • MAVEN-PFIS-RQMT-0016 • MAVEN-PF-SWIA-001h_Requirements • MAVA0240299_SWIA_MICD • MAVEN_PF_SYS_002 - MAVEN_PF_SYS_023 • Schematics and mechanical design done for all boards • Anode board already in layout • Digital and Preamp/MCP boards going to layout soon • Leveraging STATIC prototype effort for HVPS, digital • FPGA specification complete, design in progress • MAVEN_PF_SWIA_012B_FPGA_Specification • FSW specification complete • MAVEN_PF_FSW_002C_SRS • Active parts list complete, passive parts list in progress, MCPs ordered • Ready to build EMs

  5. Top Level Requirements/Documentation Performance Requirements Documents MAVEN-program-plan-appendix-v28_L1Req.doc (Level 1) MAVEN-PM-RQMT-0005, Mission Requirements (Level 2) MAVEN-PFIS-RQMT-0016, PFP Requirements (Level 3) Mission Assurance Requirements MAVEN-PM-RQMT-0006, Mission Assurance Requirements MAVEN_PF_QA_002, PFP Mission Assurance Implementation Plan Mission Operations MAVEN-MOPS-RQMT-0027, Mission Operations Requirements Environmental Requirements Document MAVEN-SYS-RQMT-0010 Spacecraft to PFP ICD MAVEN-SC-ICD-0007 PFDPU to SWIA ICD MAVEN_PF_SYS_004B_PFDPUtoInstrumentICD.doc

  6. Instrument Peer Reviews • Conducted PF subsystem-level peer reviews at UCB/SSL May 10-12 • Actions and responses discussed in this presentation: • Mechanical Review • Dalton, Turin • Analog/Front End Review • Halekas • Digital/FPGA Review • Taylor, Gordon • Actions and responses discussed in other presentations: • Power Converter Review • Berg • Flight Software Review • Harvey

  7. II. SWIA Science Requirements • Requirements • Compliance • Trade Studies • Data Products

  8. MAVEN Level 1 Requirements

  9. SWIA Science Goals • Primary Goal: Measure solar wind and magnetosheath proton flow around Mars • Additional Goals: • Constrain charge exchange rates • Measure basic space plasma processes throughout Martian system

  10. PF Level 3 Requirements

  11. Proton Flux Range at Mars V n ASPERA Data T • Lowest fluxes expected for low speed flows in sheath • Worst case: Low density • 50 km/s, 1 cm-3, 50 eV • Peak 1x106 eV/(cm2 sr s eV) • Wings1x105eV/(cm2 sr s eV) • Highest fluxes in solar wind • Worst case: Low temperature • 300 km/s, 20 cm-3, 1 eV • Peak 5x1011 eV/(cm2 sr s eV) • To measure full range of velocities, SWIA therefore must measure differential fluxes from 1x105 to5x1011 eV/(cm2 sr s eV) • Important to cover full range in order to parameterize atmospheric loss throughout Mars’ history

  12. SWIA Trade Studies • Original CSR design had A111F preamps, low-current microchannel plates, and no attenuator • This design would have provided dynamic range of only ~105 between background count rates and count rates where dead time issues become significant • Dead time corrections difficult with A111 (ill-defined dead time) • Low current MCPs would have saturated in high flux solar wind • New baseline has A121 preamps, high-current MCPs, and an attenuator • Attenuator allows variable geometric factor for different conditions • Can measure diff. energy fluxes of 1x104 to 7x1011 eV/(cm2 sr s eV) • A121 has well defined dead time • No preamp or MCP saturation issues even in high flux solar wind • All changes approved by CCB

  13. SWIA Count Rates (RFA: AFE I.A.2) • SWIA geometric Factor 0.0056 cm2 sr eV/eV • 360° full sensor sensitivity, including grid transmission and MCP efficiency • Divided among 10x4.5° anodes in sun direction (highest fluxes), 14x22.5° anodes away from sun • Small anode geometric factor 0.000070 cm2 sr • Large anode geometric factor 0.00035 cm2 sr • SWIA (per anode) count rate capability ~1 Hz to 2 MHz • A121 preamplifier count rate capability 2 MHz with no dead time corrections (up to 12 MHz periodic) • High current MCP count rate capability ~2 MHz per small anode • ~10 c/s sensor background spread over all anodes • Attenuator gives additional factor of ~25 dynamic range • SWIA differential energy flux range 1x104 to 7x1011 eV/(cm2 sr s eV) • Sufficient to make quality measurements in sheath and solar wind for all conditions and achieve MAVEN science goals

  14. SWIA Data Products • P0 = Full resolution data product • Huge data volume • Mainly for calibration purposes • P1 = Full coverage “coarse resolution” data product • 48 energies X 16 angles X 4 deflection angles • 20% energy resolution, 22.5° angular resolution • Mainly for magnetosheath/magnetosphere (also pickup ions) • P2 = Reduced coverage “fine resolution” data product • Pick region of phase space centered around solar wind beam • 48 energies X 10 angles X 12 deflection angles • 10% energy resolution, 4.5° angular resolution • For solar wind measurements

  15. SWIA Telemetry Notes/Assumptions: • Mode 1 = Magnetosphere, Mode 2 = Solar Wind. • We send some “Coarse Distribution” P1 products in Mode 2 to look for pickup ions. • We generally do not send any “Fine Distribution” P2 products while in Mode 1. • Italicized lines indicate alternate binning schemes that increase temporal resolution at the expense of angular/energy resolution/coverage. • E = Energy Step, A = Anode, D = Deflector Step. • Increased data rates during conjunction will allow higher cadence data.

  16. III. SWIA System Design • Overview • Block Diagram • Heritage/Lessons Learned • Accommodations • Resources

  17. SWIA Mounting & FOV 90O X 360O TOTAL FOV 40O X 40O SWEET SPOT Nadir Sun • Sweet spot optimized for SW • Rest of FOV optimized to • measure ion flow in sheath, • where flow deflection primarily • lies in Sun-Nadir plane Sun Nadir (except at periapsis)

  18. SWIA External Views View of Anti-Sunward/Nadir Side • Cover • External Grids • External Harnessing • Deflector voltages • Heaters/Temp Sensors • Cover Actuator • Attenuator Control • Purge Port • Connector to Spacecraft • Connectors to PFDPU • High Voltage Enable Plug on sunward side Mounting Feet

  19. SWIA Cutaway View from Sunward/Anti-Nadir • Attenuator Mechanism • Top Cap Cover • Deflectors • Hemispheres • Purged MCP Volume • Anode Board • Houses MCPs • Preamp/MCPHV Board • HVPS Board • Digital Board • LVPC Board • HV Enable Ions

  20. SWIA Block Diagram

  21. SWIA Heritage THEMIS ESA • SWIA very similar to THEMIS IESA, with the addition of deflectors (SWEA) and an attenuator (THEMIS SST) • Long history of successful electrostatic analyzers at SSL • Rockets: Many • Wind (w/ CESR): 4 • FAST: 16 • Mars Observer (w/ CESR): 1 • Mars Global Surveyor (w/ CESR): 1 • Lunar Prospector: 1 • STEREO (w/ CESR): 2 • THEMIS: 12 • SWIA, SWEA, and STATIC will be built by the same team (including the same key engineers) as their predecessors

  22. SWIA Board Heritage THEMIS Anode THEMIS Preamp THEMIS HVPS, MCP HV THEMIS LVPS STATIC Prototype HVPS STATIC Prototype Digital • SWIA Anode board much like THEMIS, already in layout • SWIA Preamp board nearly same components as THEMIS • Minus ACTEL, Plus MCP HV • SWIA HV supply nearly same as STATIC prototype • SWIA MCPHV & LVPS nearly same as THEMIS • SWIA Digital board nearly same as STATIC prototype

  23. Lessons Learned • NASA Lessons Learned • Numerous lessons, but some recurring highlights • Test in an “as flown” configuration • Watch out for ESD • Careful parts selection and proper installation is crucial • Another lesson: LLIS database is only accessible ~50% of the time, and not when you want to look at it! • SSL Lessons Learned • Build modularly • Make sure it’s easy to assemble/disassemble and test components separately • Test how you fly • Make sure GSE/ground software works the same as DPU/flight software • Heritage designs usually had a good reason for their choices • We have returned to FAST/THEMIS designs for many components

  24. SWIA Accommodations • SWIA sensor mounted on the sun-facing deck • Provides a clear FOV in the sunward direction • Mounted such that the 360x90° FOV is mostly clear, and oriented to provide good velocity measurements in the sheath • Nominally thermally isolated from the deck • Power, Commands, and Telemetry via PFDPU • Attenuator controlled by PFDPU • Voltage sweep controlled by PFDPU • Data processing via PFDPU • Two redundant spacecraft-monitored temp sensors and heater wires • Spacecraft-powered redundant 1-time non-explosive actuator for top cap cover (contamination control) • Purge Connection

  25. SWIA Safety/Contamination Issues • Near-continuous Purge Required • MCPs require contamination control • Up to 24 hours off purge OK (top cap seals analyzer volume) • T0 purge required due to long encapsulation • Red-tag Dust cover • Internal cover and dust cover must remain closed except for special tests (limited duration) • High voltage must remain off on the ground except for in calibration vacuum chamber • Green-tag high voltage enable plug • Software interlock prevents accidental activation • High voltage must be turned off on deep dips for pressures above 5x10-5 Torr

  26. SWIA Mass Budget • CBE mass based on a combination of: • Solid model with realistic mass properties • Measured STATIC prototype board mass • Measured mass of heritage parts and boards

  27. SWIA Power Budget • Power estimates were compared to and consistent with heritage designs and/or similar prototype STATIC system • FPGA Power was estimated using Actel Power Estimator Spreadsheet • HV power supply efficiency is conservative compared to heritage designs • Average power for sweep supply and MCP takes into account operational scenarios (realistic sweep profile and mid-range MCP voltage)

  28. IV. SWIA Optics Design Status • Overview • Attenuator • Deflectors • Calibration/Testing • RFA Closeout

  29. SWIA Optics Overview • Sweeping inner hemisphere voltage selects energy • Sweeping deflector voltages selects theta angle • Discrete anodes select phi angle • Optics same as Cluster CODIF • Plus deflectors • Exactly same as STATIC • All internal surfaces blackened and outer hemisphere, top cap, • and deflectors serrated to eliminate photon and ion scattering

  30. SWIA Concentricity (RFA: AFE I.A.3) • Precise alignment of hemispheres and top cap critical • Proven FAST/THEMIS design ensures hemisphere concentricity to better than a few thousandths of an inch • Top cap alignment to better than five thousandths of an inch assured by tapering the cover that it seats against • Mechanical design ensures <~2% error from misalignment Top Cap Offset Study (0.025 cm = 10 mill)

  31. SWIA Attenuator (Rec: AFE II.1) “Sweet Spot” • Moveable attenuator reduces extreme solar wind fluxes by a factor of 25 in ±22.5° “sweet spot” covered by narrow anodes • Also improves energy and angular resolution for highly collimated (low-temperature) solar wind fluxes • Geometric factor varies smoothly outside of sweet spot, allowing pickup ion measurements outside of ±45° phi angle

  32. SWIA Deflection Optics Attenuated Un-Attenuated • Deflection optics • Linear with deflection voltage • Geometric factor constant in sweet spot, slightly reduced outside • Angular width variable • Meets requirements over full ±45° theta deflection range

  33. SWIA Energy/Angle (RFA: AFE I.A.5) (phi resolution set by anode size: 4.5° around sun, 22.5° elsewhere) 15% 10% 7° 3° <1° <1° • Checked multiple simulation techniques (AFE I.A.5) E/V vs. θ Resp. Discrete sampling Monte Carlo sampling Energy and angle resolution meet or exceed all requirements

  34. Calibrations THEMIS φ Cal FAST E-θ Cal We perform systematic calibrations of angular and energy response Any deviation from simulation results indicates a fabrication/assembly issue

  35. Calibration Facility • Vacuum chamber with ion/electron sources and 3-axis manipulator • Manipulator, ion source, and instrument all controlled by same GSE, enabling automated calibration scans over wide range of energies & angles • Facility renovation currently in progress THEMIS ESA in calibration chamber

  36. SWIA Subsystem Testing • MCPs scrubbed and baked, then tested (usually in anode fixture) in vacuum chamber with charged particle source to screen for pulse height distribution and background • Four sets of MCP plates on order • Best set reserved for flight instrument, three more for EM and spare • Stored in N2 dry boxes to eliminate contamination • Preamps tested individually and screened for threshold, gain uniformity, noise susceptibility, dead time and pulse width • Three sets of preamps to be purchased • Best set for flight instrument, two for EM and spare • Each electronics chain tested end to end using an integrated test pulser capacitively coupled to preamp inputs • Test pulser frequency varies with time step (controlled by FPGA) • Divider on preamp board to stimulate adjacent anodes with different frequencies • Allows identification of any source of noise or crosstalk

  37. SWIA System-Level Instrument Testing • Comprehensive Performance Test & Calibration • End-to-end testing from particle optics through front end and digital electronics to data products • Use test pulser for CPT to achieve near end-to-end test • Calibration in vacuum provides full system test • Verify analyzer and deflector voltage sweeps (vacuum only) • Test attenuator • Test pulse height distributions to determine optimum MCP bias voltage and preamp threshold • Check that energy and angular response matches expectations from simulation and meets requirements (vacuum only) • Verify uniform energy/angle response • Check hemisphere concentricity • Determine relative anode/MCP sensitivity • Verify data binning and higher level products • EMC, Magnetics, Vibration, Thermal Vac during PF I&T

  38. Analyzer/Front End RFA Closeout RFAs: 4 Recommendations: 1

  39. IV. Mechanical Design Status • Overview • Materials/Construction • Mechanical Details • Analysis • RFA Closeout

  40. SWIA Assemblies and Features Attenuator/ Cover Release Analyzer Anode Electronics PFDPU-S/C Connectors Mounting Feet

  41. Materials and Construction • Standard UCB Construction: • Machined/Etched Parts • 6061-T6 Aluminum • 2024-T8 Aluminum • 544 Bronze • 303 Stainless Steel • Delrin AF, PEEK 450G, Vespel SP-1/3 • BeCu • Finshes • Alodine • Anodized • Gold Plating • Ebanol C, Black Chrome, Z307, DAG-213, Black Electroless Nickel (TBD) • Thermal Treatments • Blankets (LM supplied) • Thermal Taping (LM supplied) • Long lead Items • MCP • TiNi P5 Pin Pullers

  42. SWIA Analyzer Construction Outer Grids Cover Release/ Attenuator Top Deflector Mount Top Deflector Aperture Ring Bottom Deflector Bottom Deflector Mount Cover in Closed Position Outer Hemisphere Inner Hemisphere Hemisphere Mount Spider Plate

  43. SWIA Cover and Attenuator Construction Cover Spring P5 Extended Cover Down Aperture Down and Caged 0.2” Cover Open, Aperture Down Cover Open, Aperture Up

  44. SWIA MOBI Motor Assembly MOBI Motor Assembly (shown extended) Bellcrank Slide/ Detent Bellcrank up position Limit Switch 0.125” Bellcrank down position Switch Roller • MOBI Motor Force: 1.1N • Force required for actuation: 0.3N

  45. SWIA MCP Construction

  46. SWIA Purge Operation Purge Spring Purge Connection (1/8” NPT) N2 • 5 psi N2 purge pressure MCP’s

  47. SWIA Electronics Board Stackup Standoffs between boards and shields LVPS Digital Deflector/ Sweep HV Supply Preamplifier/MCP HV Supply Anode MCP Protective Cover

  48. SWIA Electronics Box Construction HV Enable on Pigtail LVPS to PFDPU Digital to PFDPU Inner Hemisphere HV HV to Deflectors Preamplifier Hypertonics KA-17 to Anode Digital pigtails to MDM on Preamplifier Boards rigidly mounted to this panel

  49. SWIA Mounting, Harness, and Purge N2 Purge Connection Harness Connectors

  50. SWIA Aperture Mechanical Analysis Attenuator Assembly Static Stress Analysis: 288g baseline mass 100G static load Results: Max Stress: 173MPa Margin to yield/ultimate: 1.5

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