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. } Design Overview THEMIS Uses FAST ESA Design Specifications:
(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.
Pulse Amplifiers
Digital Interface
& HV Sweep
HV Supplies }
MCP

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
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. ESA Solar Wind Attenuator
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
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 Survival (°C) Predictions (°C) Margin
Eclipse-Op
Science-Op
Cold
Hot
-50
-30 40
+65 -7 31 43 9
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. Temperature Monitoring and Control
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 /15/03
Complete Order of ETU Parts 12/11/03
ETU Ready 01/09/04
ETU Vibration Test TBD
CDR /15/04
Complete Any Redesign 04/14/04
Complete Order Parts 04/15/04
Complete Receiving Parts 05/26/04
Mechanical Delivery Unit /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
Issues to be Resolved
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.

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 & Test Requirements
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
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. Mechanical interface to signals
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

51. Errors and Responses
GSE software monitors serial instrument data stream for missing or corrupted data. All detected anomalies are logged, counted, and displayed in user interface.

52. Compatibility with next level integration
Mission Requirements
Compatibility with next level integration
Uses ITOS, LabWindows, C
PC standards (same platform through all mission phases)

53. Multiport Ethernet Hub/Firewall
Vacuum chamber
CMD Gate
Optional uplink to lab network
GSE
Interface
Board
Electron
gun
CMD Clock
Multiport Ethernet Hub/Firewall
CMD Data
ESA
TM Clock
Manipulator
TM Data
Analog HSK
LVPS
equivalent
GPIB via USB
Ethernet
PWR
GSE software: based
on Mike Hashii’s
STEREO GSE tools,
FAST calibration software
3-axis servo
amplifier
ACS-Tech80
Servo control card
Manipulator/HVPS
control workstation
RS232
GSE workstation
HVPS
GPIB
New components
Existing components

54. Test and Calibration 3 Axis Manipulator
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