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

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

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.

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)

Selected SST Calibration results Pre Environment Review

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

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

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

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

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

SST Vibration Testing (Pictures of Probe 2 units)

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

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 2005 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

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

SST TVAC Testing

Thermal Profile

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

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.

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

SST Sensors testing in Thermal Vac CP Tests SST Sensors testing in Thermal Vac Electrical – DFE assembly Detector functionality Detector gain (location of Am241 60 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

SST TV Tests SST Serial Number Test Date Following Initial Build 001, 002 13 Jan 05 003, 004 22 Apr 05 006, 008 scheduled: 9-1-2005 007, 009 May 25, 2005 010, 011 Mechanical assembly complete, awaiting electronics mods 005, 012

SST Current problems and issues

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.

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