Thermal Vacuum Test 1 GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 GLAST Large Area GLAST Large Area Telescope Telescope LAT Pre-Shipment Review Thermal Vacuum Test Jesse Armiger Thermal Vacuum Test Director Stanford Linear Accelerator Center Gamma-ray Large Gamma-ray Large Area Space Area Space Telescope Telescope
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GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 1 GLAST Large Area Telescope LAT Pre-Shipment Review.
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Thermal Vacuum Test 1
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 8 of 12
GLAST Large Area TelescopeGLAST Large Area Telescope
LAT Pre-Shipment Review
Thermal Vacuum Test
Jesse ArmigerThermal Vacuum Test Director
Stanford Linear Accelerator Center
Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope
Thermal Vacuum Test 2
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AgendaAgenda
• Test Overview and Major Test Event Log
• Compliance To Requirements
• Correlation Results
• Thermal Test Observations
• Summary
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Test PictureTest Picture
Thermal Vacuum Test 4
GLAST LAT Project September 15, 2006: Pre-Shipment Review
• Thermal analysis correlation– No abnormal observations– Complete by October 30
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Heater System VerificationHeater System Verification
• Survival heater system maintained all temperatures within limits during Survival Thermal Balance – Unregulated and regulated feeds at minimum voltage
• Unregulated feed at 25v and regulated feed at 27v – Grid heaters cycled at primary set points – Radiator Antifreeze heater duty cycle under review
• Demonstrated primary VCHP heaters could close Radiators at 70% power
• Functionally demonstrated all primary and redundant Radiator antifreeze and Grid heaters
• Demonstrated TCS could maintain RIT at all operational levels
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Heat Pipes and Thermal InterfacesHeat Pipes and Thermal Interfaces
• Heat Pipes– All Heat Pipes functioned normally
• DSHP and XLATs operated as expected• VCHPs opened/closed Radiators as designed
• Interfaces– No baseplate outliers
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Unit Temperature DistributionUnit Temperature Distribution
GLAST LAT Project September 15, 2006: Pre-Shipment Review
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• Hot Case - Temperatures generally lower than predicted
• Cold Case –– Temperatures generally higher than predicted– Radiator Anti-freeze and grid survival heaters off– VCHP heaters
• 9.7 watts to maintain RIT between -6oC and -5oC (23% duty cycle)• Locked on to maintain RIT between -1oC and 0oC
• Survival Mode– Temperatures generally higher than predicted– Radiator Anti-freeze and grid survival heater use about 7 amps– Heater Power use higher than predicted
GLAST LAT Project September 15, 2006: Pre-Shipment Review
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Test Predictions vs. ActualsTest Predictions vs. Actuals
Component
Cold Survival Limits
Cold Operating
Limits
Hot Operating
LimitsHot T.B. Predict
Hot T.B. Actual
Hot T.B.Delta
Surv. T.B.
PredictSurv T.B.
ActualSurv T.B.
DeltaCold T.B. Predict
Cold T.B. Actual
Cold T.B.Delta
Cold T.B. Predict
Cold T.B. Actual
Cold T.B.Delta
TKR(SSD) -15 -15 30 25 23.9 1 -10.3 -4.4 -6 -1 6 -7 4 2.7 1CAL BP -30 -15 25 17.8 15.7 2 -4.4 -3.3 -1 0.2 1.6 -1 5.5 4.9 1EPU* -40 -30 45 15 17 -2 -5 -0.9 -0.6 0 3.4 3.4 0GASU* -40 -30 45 12.7 18.3 -6 -5 -3.6 -1 0.2 5.1 -5 4.8 7.8 -3PDU* -40 -30 45 9.8 18.4 -9 -5 -3.6 -1 0.7 6.2 -6 5.1 10.1 -5SIU* -40 -30 45 15 17.7 -3 -5 -3.3 -2 -0.8 0 -1 3.5 4.4 -1TPS* -40 -30 45 15.7 19.1 -3 -5 3.2 4.5 -1 8.1 8.3 0TEM* -40 -30 45 22.2 18.4 4 -5 -3.8 -1 3 1.6 1 7.9 4.9 3ACD BEA -30 -15 30 15 11.7 3 -4.8 1.3 -0.6 2 6.5 2.9 4ACD TDA -40 -30 35 21.5 19.7 2 -12.2 -3.4 -9 -1.9 10.3 -12 1.7 11.3 -10RIT -6 0 15 9.1 6.9 2 -5.7 -6.7 1 -5.6 -6.8 1 0.4 -3 3All temperatures are in degrees CTemperatures shown are for the hottest/coldest extremity of the subsytem, except as indicatedTemperature predicts are from model without any marginBased upon the latest Power Summary of 536 Watts LAT disipation, not including the thermal subsystem(*) Temperatures shown are for the box interface to its heat sinkTemperatures measured for all electronics except TEM are internal, not at box interface
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• ACD temperature sensor exceeded its red alarm limit of 40C (unit proto-qual = 40C) – This sensor reached a maximum of 42C; the temperature
excursion may have been caused by sensor malfunction– This was not unexpected because the ACD is bounded by a
thermal blanket on one side and Tracker Towers with goal temperatures of 40-45C
– The ACD project manager has indicated that this temperature poses no risk to the ACD
– Recommend an ACD red limit of 45C for the observatory test
Thermal Test ObservationsThermal Test Observations
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• LAT start up sequence from cold survival NCR #?– The normal start up sequence involves incrementally
powering up the LAT in a manner which does not exceed the power budget
– The planned sequence involved powering up the TCS last but it turned out that this step had to be performed earlier in order to stay within the budget
– This minor change will be documented and implemented in the normal turn on sequence to be performed during observatory level testing
Thermal Test ObservationsThermal Test Observations
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• The LAT thermal vacuum test was accomplished ahead of schedule and without any major incident. Three thermal balances (hot, cold and survival) and four thermal cycles were performed.
• Thermal data readout by VSC was very noisy and inaccurate; this caused hardship during the test.
• Minor incidents were corrected efficiently.
• Complete LAT Thermal Vacuum test report by October 31.– Include thermal model correlation
SummarySummary
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Major Thermal Vacuum Test Events Major Thermal Vacuum Test Events 1/21/2