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ESA Plasma Analyzer Instrument Preliminary Design Review

ESA Plasma Analyzer Instrument Preliminary Design Review Charles Carlson, Bill Elliot, Paul Turin, Jim Lewis University of California - Berkeley. Overview. Generic Subsystem Requirements & Specifications Heritage Design Overview Block Diagram Component Descriptions

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ESA Plasma Analyzer Instrument Preliminary Design Review

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  1. ESA Plasma Analyzer Instrument • Preliminary Design Review • Charles Carlson, Bill Elliot, Paul Turin, Jim Lewis • University of California - Berkeley

  2. Overview • Generic Subsystem • Requirements & Specifications • Heritage • Design Overview • Block Diagram • Component Descriptions • Mechanical and Thermal • Mass and Power • Schedule • Issues

  3. Requirements and Specifications • Measurement • The ESA instrument measures 3-D electron and ion energy distribution functions over the Energy range 10 eV to 30 keV. Typical energy sweep has 16 or 32 energy samples • A full 4-pi distribution measurement is produced during each spin • Sweep rate of 32/spin gives dense sample of 3-D particle distributions • Raw measurements are compressed to selectable “reduced distributions” and moments • Implementation • Ion and electron “top-hat” electrostatic analyzers have 180 degree field of view • Field of view is divided into 8 electron and 16 ion elevation bins • Plasma analyzers have hardware programmed functions: sweep rate, sweep waveform, energy range, data collection rates. These functions are set by command. • Higher level data formatting and computed products are carried out in the ETC board. • Energy sweep is exponential with programmable starting energy and step ratio

  4. Heritage • ESA Instrument Design is based on FAST plasma instrument • Nearly identical measurement requirements • Well proven design – all 16 FAST ESA detectors remain fully functional after 7 years in orbit (Design requirement was 3 years in high radiation environment) • Flight hardware designs and calibration facilities can be used with minor changes • Flight spare components are available for critical functions. Design will use existing ACTEL 1020 gate array components. • THEMIS instrument uses FAST strategy of “dumb” sensor having hardware defined measurement modes, combined with a “smart” processor-based interface board that performs data formatting and higher level computations. The ETC board provides this intermediate processing for both the ESA and SST.

  5. MCP Pulse Amplifiers DigitalInterface & HV Sweep HV Supplies } Design Overview • THEMIS Uses FAST ESA Design • (1/2 of a FAST module) • Modular for efficient testing, assembly and repair • Entrance sealed and nitrogen purged • Changes from FAST: • Solar Wind Ion Attenuator • Ion Detector Anode Location • Cover Release Mechanism • (TiNi Nanomuscle-125) • Specifications: • 180 degree elevation field of view with a minimum angular resolution of 22.5 degrees. • To resolve the solar wind the IESA will have a field of view with enhanced resolution of approximately 5.62 degrees.

  6. Block Diagram • Electronics design is nearly direct copy from FAST • Three circuit modules plug together for efficient assembly and test • MCP pulse amplifiers are Amptek A121 with programmable gain • All discrete logic, counters, and HV DAC drivers are Actel FPGAs • HV supplies are a mature design built at UCBSSL

  7. Analyzer/Anode/Preamp • Themis will use FAST module design • IESA/EESA Analyzers • Analyzer deflection plates • Aperture closer mechanism • UV rejection Cu-Black coating • Nitrogen purge system • Anode Boards • Mounts MCPs • HV Interface connectors • HV coupling capacitors • Preamp Board • Amptek A121 preamps • Actel logic arrays • Anode and Logic board interfaces FAST ESA module

  8. MCP/Anode Board Assembly • Anode boards includes: • MCP Mounting Hardware • “Spring finger” clamp rings • HV electrode connections • Nitrogen purge plumbing • HV Interface • HV Plugs and wiring • HV filter capacitors • Bias resistor Top Bottom • Materials • Polyimide/glass PCB • PEEK mounting rings • KAPTON spacers • Gold plated BeCu springs • Preamp Interface • Limit resistors & clamp diodes • Preamp interface connector

  9. MCP Preamp/Accumulator • Preamp board includes: • 24 AMPTEK A121 hybrid preamps • 3 ACTEL logic arrays contain: • 24 x 14 bit accumulators • Command/Data Interface • Command interpreter • Test pulse generator • Commandable selective anode blocking • MCP Anode board interface • Radiation “spot shielding” for preamps

  10. HV Sweep & Digital Interface FAST Sweep/Interface Board Themis board is about 30 % shorter length • HV Sweep/ Interface board includes: • Main data interface to ETC board and IDPU power board • HV fixed and sweep supply control • HV Sweep waveform generator (Amptek HV-601 high voltage optocouplers) • Housekeeping multiplexer • Plug-in interface to anodes and HV supplies

  11. FAST HV Supply Assembly FAST HV Interface Board (mounts on back side of Sweep/Interface board) Themis board is about 30 % shorter length • HV Assembly board includes: • Four HV supplies with interface mother board (FAST example has 6 supplies) • HV supply assembly and Digital interface boards share structural mount plate • HV supplies have HV sockets that mate directly with HV plugs on HV sweep board and on anodes. • Themis option may share a single positive/negative raw supply, reducing total requirement to 3 supplies. Decision pending prototype test and risk evaluation

  12. HV Supply and VMI Multiplier A single FAST HV Supply shown with a sample FAST HV multiplier module and a candidate commercial replacement module from VMI (HM402N10). A total of 25 HV supplies on FAST have operated without incident for seven years. • The VMI multiplier is an attractive replacement for the SSL fabricated component: • Huge saving of in-house technician work • VMI part has been tested for use on STEREO • The multiplier is physically and electrically compatible with existing FAST design • VMI part is smaller – will allow single plus/minus supply for raw sweep source

  13. Electrical Interface & Power • ESA Power Interface is from the IDPU power control board • Switched Services with regulation and current limiting: • - 5V, + 5V, +5V (digital), +11V • +28 V separately switched for HV supplies • Data Interfaces (Digital and Analog) are with the ETC Board • Serial Data • Data Clock • Command Data • Command Gate • Command Clock • Analog Housekeeping (mux addressed via command interface)

  14. Mechanical Overview • Electrostatic Analyzer (ESA) Instrument • THEMIS ESA • ESA Exploded View • Typical ESA ANODE Assembly • Typical ESA Hemisphere Assembly • Hemisphere Assembly X-Section • Covers Closed X-Section • Covers Open X-Section • Cover Release in Cocked (Closed) Position • Cover Release in Shot (Open) Position • NanoMuscle 125 • Solar Wind Attenuator • Nitrogen Purge Connection • Electrical Connections • Thermal • Mass • Mechanical Schedule • THEMIS Probe • Issues to be Resolved • Reference, Cover Mech. Open • Reference, Cover Mech. Closed

  15. THEMIS ESA

  16. ESA Exploded View

  17. Typical ESA ANODE Assembly

  18. Typical ESA HEMISPHERE Assembly

  19. Typical Hemisphere X-Section • Design Features: • Interior Surfaces of Outer Hemisphere is Serrated & Interior Surfaces of Both Hemispheres are Copper Black Coated for UV Rejection • Exit Grid Isolates the Analyzer Optics from MCP Bias Voltages • Both Hemispheres Mounted to Single Structural Plate to Ensure Good Alignment

  20. Covers Closed X-Section

  21. Covers Open X-Section

  22. Cover Release in Cocked (Closed) Position

  23. Cover Release in Shot (Open) Position FORCE IS 3X REQUIRED

  24. NanoMuscle-125

  25. Overview • ESA Solar Wind Attenuator • Purpose is to reduce ESA geometric factor, reduce solar wind flux by factor of X for central 90 deg of 180 deg FOV • Design utilizes SMA actuation scheme flown on HESSI and used on STEREO STE instrument • Expected max usage is 10,000 cycles over 2 years Designed for 80,000 cycle life test • Mass = 35g per ESA stack • Power = 800mA for <1 sec • Requires only open loop timed pulse (control loop closed mechanically) • Duty cycle = 1 cycle/min max • Utilizes Honeywell hermetic switches – long flight heritage • Prototype vibration test within one month

  26. Mechanism Nanomuscle End-of-Travel Switches Bellcrank Attenuator Bridle Cams Bellcrank Attenuator Screen Nanomuscle

  27. Mechanism Continued Nanomuscle pulls on Bellcrank Switch roller falls into cam dimple, holds attenuator in deployed position at end of stroke Opposite cam holds attenuator in stowed position

  28. Mechanism Continued Attenuator stowed Attenuator deployed

  29. External View Attenuator Stowed Attenuator Deployed

  30. Margin Analysis • Nanomuscle rated at 125g pull force • Switch lever spring force set to provide <40g force at actuator • Provides force ratio >3 • Actuator only need to overcome switch spring force for ½ of stroke – opposite switch serves to pull cove in over last half of stroke

  31. Nitrogen Purge Connection • Purge Connection • A Nitrogen Line is connected to the ESA Purge Fitting preflight to purge the Interior of the Analyzer. • The Nitrogen is supplied at 5 psig and is regulated and filtered in-line at each Anode to supply 1 liter/hour.

  32. Electrical Connections • Mechanical Systems Requiring Electrical Connections • SMA Device • GND • VDC • Hemisphere Covers Open Switch • NO • NC • C • Enable / Disable Function • Survival Heater and Thermostat

  33. Mass • Mass • On Target at 1.96 kg estimated (budget is 2.02 kg)

  34. Thermal - ESA • Heat Transfer • Power Dissipation • 1.88 W predominantly on rear boards • Conduction • Corner panel reaches –60 °C in long eclipse • Therefore the ESA is not attached to the corner panel • Mounted to the back of the IDPU and a brace to the bottom deck if needed. May be isolated to run cooler • Radiation • All surfaces covered with low ε VDA tape or blankets • Apertures dominate the heat leak

  35. Thermal - ESA • Temperature Limits • Predictions from Swales • Cold prediction from 3 hour eclipse orbit • Hot prediction from hottest orbit and attitude • Average operating temperature around 30 °C • Better predictions await more complete instrument thermal models

  36. Thermal - ESA • Temperature Monitoring and Control • Modified Interface Monitoring • Probe Bus will monitor the ESA temperature on the ESA itself • Instrument Monitoring • IDPU will process additional thermistors if needed • Heaters • No operational heaters are required • Survival heaters will keep ESA above Eclipse-Op limits • Two heater services provided by the probe bus • Primary service thermostat closes at –43 • Secondary service thermostat closes at –48 • May use one heater for both IDPU and ESA, depends on coupling

  37. ESA Mechanical Schedule • Mechanical Schedule Summary • Start Mechanical Design 07/30/03 • PDR 10/15/03 • Complete Order of ETU Parts 12/11/03 • ETU Ready 01/09/04 • ETU Vibration Test TBD • CDR 03/15/04 • Complete Any Redesign 04/14/04 • Complete Order Parts 04/15/04 • Complete Receiving Parts 05/26/04 • Mechanical Delivery Unit 1 06/25/04 • Mechanical Delivery Units 2 & 3 07/02/04 • Mechanical Delivery Units 4 & 5 07/09/04

  38. THEMIS Probe

  39. Cover Release Mechanism Preliminary Prototype to be built 11/15/03 Vibration Testing will be done 11/30/03 (GEVS –SE REV A) Modified NANOMUSCLE-125 Heritage (Other SMA devices have been used by SSL on HESSI and other projects. Materials (PEEK, Teflon, SS, TiNi Wire) Electronics By SSL Redundant Actuator Studying the Possibility of Doubling the Nanomuscle-125 “Back-To-Back” for Redundancy. Issues to be Resolved

  40. Reference, Cover Mech. Closed

  41. Reference, Cover Mech. Open

  42. ESA S/C Interface Requirements • Interface to Spacecraft • ESA Mounts to IDPU (0.12 Watts/deg C Coupling) • Thermal Joint TBD • “Foot” Mounts to Bus • ESA Extends Through Corner Panel With Clearance and Some Sort of Radiation Closeout • Constrained By 3.25” Furthermost Stand-Off of the ESA from the Corner Panel • ESA Should Be Very Close to the Middle (Top to Bottom) of the Corner Panel (Science Requirement)

  43. S/C Interface Continued • Thermal Finish to be VDA Tape or Blanket, Gold Alodine. • Avoid Blankets (Blankets Could Cause Problems With Field of View). • Maintain Fields of View (180 deg up/down from edge of Aperture, Approximately +/-10 side/side). • Purge Gas Fitting. • Enable/Disable Tagged Plug Located (TBD).

  44. ESA S/C Integration & TestRequirements • ESA + IDPU Will Be Assembled and Installed as a Single Unit • This Requires Removal of One Wire Boom and the Battery (Swales is on Board) • We will conduct a vibration test of the Combined ESA + IDPU. • We Need to Ensure that Cover Open Mechanism is Cocked (Cocking Pin Visible)

  45. Mass & Power • The estimated ESA Instrument design is within the allocated weight and power allocations of: • 2.0 Kg • 2.0 Watts

  46. ESA GSE

  47. Power / Thermal / Mechanical • Power • Provide regulated voltages • Facilitate current measurements • Mechanical • 6U VME support (without Wedge-locks) • Portable and Rugged for transport • Open rack for access while under test • Connectors are acceptable for flight interconnection

  48. Electrical Interface • Mechanical interface to signals • Before DCB & ETC, GSE connector as defined for ESA-to-IDPU • Afterwards data is taken through DCB connector. • Analog Housekeeping • One MUXed analog housekeeping value • Electrical Quality • GSE Interface circuitry must be flight grade

  49. Command and Telemetry Handling • Commands (when DCB & ETC present) • Sends CDI 24-bit commands per ICD specification • User command interface in STOL • Reads STOL command files • Compatible format with IDPU GSE and MOC GSE • Commands (before DCB) are CDI • Telemetry • Before DCB & ETC, data is taken directly by GSE h/w • Afterwards data is extracted from packet telemetry.

  50. Data Manipulation and Display • Calibration software (per FAST). • Input data or outputs from calculations can be displayed, saved to disk, and/or plotted with library routines. • Convenient access to data for offline processing (FTP, HTTP, etc.) • Supports “screen print” capability

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