1. THEMIS Solid State Telescope Instrument (SST)
FM 2&3 Instrument Suite PER
The THEMIS SST Team

2. Outline Summary of SST Status at FM2/3 I-PER
Test Results To-Date (Instrument- and Suite-Level)
Summary
Calibration results
Vibration
TVAC
PFR Status
Fulfillment of Mission Requirements
Tests To Be Completed at Suite Level

3. SST Status at FM2/3 I-PER Requirements and Design: Procurement:
No major changes to Requirements or Design since M-CDR
All RFAs from previous reviews closed out
Procurement:
All Mechanical sensors are complete.
F4 & F5 Sensor electronics are undergoing modifications.
Personnel, Assembly and Test:
8 detectors had been fully assembled
6 had undergone full environmental testing
Mods implemented to eliminate sunpulse current surge have delayed final production.
Reduction in Force completed, July ‘05.
Final SST team includes one Scientist (Instrument Lead), One postdoc.

4. Sun Pulse disturbance Summary
Discovered that A225 preamp draws relatively large current when coming out of saturation following a sun pulse. (~100 mA for ~50 ms) (~Jan-Feb 05)
Does not affect the operation of the SST.
Current pulse perceived as a problem to other instruments.
Solution: MOD#1 add FET to turn off detector during sunpulse.
Risks: Detectors could not be biased beyond FET rating (30V*70%) AND eliminate sunpulse simultaneously.
Determined that Depletion voltage of some (~25%) detectors is beyond FET rating. (~April-May) Thus MOD#1 is not functionally usable (did not cause any harm however).
Established that SCM is highly susceptible to voltage fluctuations on the positive power line. (July).
Begin MOD#2 on flight sensors: Placing FETs directly on the summing node. (August) Drawbacks:
FET capacitance increases intrinsic noise, and therefore higher threshold can be expected.
Preamps more susceptible to conducted noise. (Sensors #3 & #4)
Sensors for Probes 1,2 & 3 have MOD#2 implemented. (note that Flight 3 and 4 sensors have been swapped)

5. Selected SST Calibration results
Pre Environment Review

6. Noise level (which characterizes the threshold energy) :
Tests – Calibration
Noise level (which characterizes the threshold energy) :
Determined by ramping down the threshold level and
recording the response of the sensor
Electron calibration :
Low-energy measurements done with our photo-electron gun facility (<50keV) at cold temperature
Radioactive sources used for higher energies
Ion measurements :
done with the 170keV gun at APL (Maryland)
Am241 ~5.5MeV Alpha peak
DAP boards and flight sensors – tested with IDPU

7. Sensors are noisier after this rework
Threshold level tests
S06 & S08
S06 & S08
Before the shunt switch implementation
measured at cold temperature
Post-rework
measured at cold temperature
Sensors are noisier after this rework

8. Response to electron gun
FLIGHT#2 – S3A Foil
22keV
26keV
30keV
34keV
38keV
42keV
46keV
Energy threshold measured < 30keV at cold temperature

9. Response to low-energy proton
FLIGHT#2 – S3B Open
30keV
35keV
75keV
100keV
150keV
Protons measured above 30keV (at room temperature)
Energy threshold expected < 30keV at cold temperature

10. Response to low-energy oxygen
FLIGHT#2 – S3B Open
60keV
75keV
100keV
150keV
Oxygen measured above 60keV (at room temperature)
Energy threshold expected < 60keV at cold temperature

11. SST Vibration Testing
(Pictures of Probe 2 units)

12. SST Acceptance Level Dynamic Test
Per UCB THEMIS Document THM-SST-PRC-002
All 3 Axes
Sine Survey, 0.5 G, 5 – 2000 Hz
Sine Strength per Swales TM2430-RevD, 29 November 2004
Random
Per Swales Document TM2430-RevD
12.51 G RMS
1 min duration per axis
All Vibration Testing Performed at Quanta Laboratories
Retesting (if required)
‘Workmanship Shake’
Validate any design changes following original Flight build shake
Validate rework of any failures on previous vibration test
Entire vibration protocol, single axis only
Acceptance Sine Strength Specification
SST Flight Unit
Acceptance Level Random Specification

13. SST Acceptance Level Dynamic Test SST Serial Number
Test Date Following Initial Build
Retest Date (Rework/Redesign)
001, 002
13 Jan 05
To be performed upon completion of suite level testing
003, 004
22 Apr 05
Workmanship vibe required
006, 008
May
007, 009
~June, 2005
Exact date available upon request
Workmanship vibe required after
mod#2 is completed
010, 011
Mechanical assembly complete, awaiting electronics mods
Full Vibration not completed
005, 012

14. SST Acceptance Level Dynamic Test
Deviations from Test Specification (Notching/Force Limiting/Aborts)
None
SST First Natural Frequency: 213 Hz (Requirement: >75 Hz)
Good Sine Survey Consistency from Unit to Unit (within 10 Hz)
Retesting due to Hardware Redesign
Reinforcement plate bond failure led to stress fracture formation on SST 001 support structure
Resolution: Support structure redesigned and strengthened in high stress areas
Flight-like ETU passed qualification level dynamic test performed on 2 Feb 2005
Flight Unit Status
Flight Units for Probe 1 scheduled for 2nd vibration test upon completion of suite level testing
Flight Units for Probe 2 completed vibration testing on 22 April 2005
Flight Units for Probe 3 scheduled for vibration testing on 6 May 2005
X-Axis Testing
Y-Axis Testing
Z-Axis Testing

15. SST TVAC Testing

16. Thermal Profile

17. SST Sensor Thermal Testing Status
Sensors 1 +2 (F1)
P2: (S03 and S04).
No major problems
P3: (S06 and S08)
Not yet tested.

18. SST Thermal Vac test diagram
SST GSE
DAP
Router
DaqPad
HP triple supply
+5V, -5V, +2.5
Triple supply
SMA: +3.9V, Heater:+25V
Dual 26 pin
feed through
Thermal
Isolators
Door-
Heater
Test box
PCB-
Not used
Am241
All Sensor testing is done with a DAP board and GSE equipment.

19. SST Sensor Thermal Testing measurements
SST Sensors
Two sensors tested simultaneously in “Themis snout” using thermal isolators
2 (4 if time permits) full cycles – Hot: +50 C Cold: –50 C 4 hours at each soak
First cycle has additional non op soak at +55C and –65C
Thermal Vac tests are aided with DAP/GSE external to chamber
All counts, noise, HKP values are recorded with GSE
The following variables are monitored and recorded continuously for each sensor (using DAQPAD at 1 sec resolution)
(2x2) Preg current (voltage across 0.3 Ohm)
(2x2) Nreg current (Voltage across 0.6 Ohm)
(2x1) Internal thermistor temperature (Vtherm - Powered by DAP)
(2x1) Heater current (voltage across 2 Ohm resistor)
(2x1) External thermistor temperature (Vth– Biased by GSE DaqPad
Also recorded:
(1) Analog housekeeping channel
(1) Reference voltage
Attenuator
Actuated manually (automatically on Probe 2 and later).
Close time / open time measured with a scope
Thermocouple temperatures recorded by TV facility
DAP Board – Tested with IDPU

20. SST Sensors testing in Thermal Vac
CP Tests
SST Sensors testing in Thermal Vac
Electrical – DFE assembly
Detector functionality
Detector gain (location of Am keV peak)
Baseline determination
Test Pulser response (calibration of test caps)
Noise characterization vs. Temperature
Bias current vs. Temperature
Thermistor checkout & calibration
Cross Talk
SPB FET functionality over temperature range (not yet done on P1 sensors)
Mechanical
Attenuator Mechanism and feedback test.
Heater strip de-lamination testing
Thermostat cycle test (would like ~2 dozen cycles)
Kinematic Flexure testing
Pre/Post testing
Magnetic characterization
Magnetic dipole and quadrapole moments

21. SST TV Tests SST Serial Number Test Date Following Initial Build
001, 002
13 Jan 05
003, 004
22 Apr 05
006, 008
scheduled:
007, 009
May 25, 2005
010, 011
Mechanical assembly complete, awaiting electronics mods
005, 012

22. SST Current problems and issues

23. Misc mods to DAP to improve performance
Problems and issues
SST Sensor 03- A Foil detector extremely noisy following large burst of electrons during calibration. Micro bursting of detector suspected. – Detector stack replaced.
ETU Dap channel 12 – Surface mount transistor missing 1 of 3 solder points. – Fixed
Misc mods to DAP to improve performance
SST Sensor 03- channel 3 – excessive noise observed during preliminary testing. - shunt switch FET replaced.
SST Sensor 04- channel 3 – excessive oscillations observed. Again FET suspected and will be replaced.

24. SST Mission Requirements Fulfillment:
FM2 and FM3 MR fulfillment noted in THEMIS Verification Matrix (see MSE Presentation).
Integrated SST and component parts compliant with mission requirements with following exceptions:
Addition of sunpulse suppression FETs will add noise and increase threshold at least 20%. Might make low energy ion threshold (30 keV) difficult to attain.
Sensors 06 and 08 still require instrument Thermal Vac test