ESA Plasma Instrument Mission PDR

1. ESA Plasma Instrument Mission PDR Dr. C. W. Carlson and Themis ESA Team UC Berkeley SSL

2. Overview • ESA Plasma Instrument • Requirements & Specifications • Heritage • Design Overview • Block Diagram • Component Descriptions • Mechanical and Thermal • Mass and Power • Test and Calibration

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. Mission Requirements

6. Mission Requirements

7. Science Requirements

8. Performance Requirements

9. ESA Development Team • ESA Systems • Definition and Specifications: Charles Carlson, UCB • Analog and Digital Systems: Charles Carlson, UCB • Mechanical and Thermal: Bill Elliot, Paul Turin • Ground Support Equipment: Jim Lewis, UCB • Power Systems (LVPS, HVPS): Peter Berg, UCB • Thermal: Chris Smith, UCB • Calibration and Test Facilities: Mario Marckwordt, UCB • IDPU Instrument Interface: Robert Abiad • Flight Software: Frank Harvey, UCB • ESA Support Functions • Probe Interfaces: Ellen Taylor, UCB • Reliability and Quality Assurance (R&QA): Ron Jackson, UCB • Parts Engineering: Jorg Fischer, UCB

10. 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: • Ion Detector Anode pattern • 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.

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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)

19. 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

20. Test and Calibration • UCBSSL has automated calibration facilities (FAST, WIND heritage) that will be used for THEMIS ESA calibrations • Facility uses cryogenic pumped vacuum chambers with computer controlled ion and • electron guns and 3-axis manipulators • All six ESA units (5 flight/ 1 spare) use identical calibration procedures adapted from FAST • Full environmental testing (Thermal / Vacuum, EMC, Vibration) 3 Axis Manipulator Calibration Chamber