MPE

1
Overview and Mechanical/Thermal IFs to FPU
PACS IHDR

• MPE
• J. Schubert

2
Content

• Overview QM FPU, Status and Problem Areas
• Status PACS Mechanical I/F to S/C
• Status PACS Thermal I/F to S/C
• Allowed Mechanical Loads to GeGa Detector I/Fs
• Design and Changes on Cooler L0 I/Fs
• Allowed Mechanical Loads to Level 0 Cooler I/Fs
• Temperatures of LO I/F to HERSCHEL S/C
• In Orbit
• On Ground (IMT, and EQM)

3
Overview PACS FPU

• FPU QM structural parts manufacturing and
  assembly completed
• Housing compartments blackened with KT 70
• Top Optic mirrors integration and alignment
  started
• Thermal and Load/Structural Analysis finalized
• Mechanical, Thermal and Electrical I/Fs to the
  S/C and to Subunits frozen
• Warm and Cryo Vibration performed on STM
  structure with success
• Subunits delivered (Chopper) or within the end of
  the AIV phase
• Extremely tight schedule increases risk for all
  parties and possibly shifts problem to the FM

4
Overview (cont.)

• Open issues to be worked on
• Distribution board ? qualification/testing of
  PCB board not finalised, delaminating
  problem observed, investigation ongoing
• Mirrors ? Gold layer on 3 of 13 mirror batches
  did not pass the tape test, investigation
  ongoing
• Detector Array ? Delta cold vibration tests to
  be performed on Detector Array Components
  
• PhFPU ? Bolometer Kevlar suspension failed
  during cold vibration in STM FPU, cold delta
  vibration test in
  preparation
• PhFPU I/F to S/C ? a) mechanical load from S/C
  cooling is critical, b) not enough
  clearance between back shells of
  S/C harness and PhFPU connector panel
  (TBC)

5
PACS Mechanical I/F to S/C

• PACS FPU ICD Drawing Issue 27 DRAFT distributed
  to ESA Industry for comment, 04-July-03
• Major design changes compared to issue 25
  reworkedimplemented
• Level 0 S/C IF to GeGa detectors, pin to flat
  I/F (compliant to IID-A)
• Mechanical I/F to OB, pin diameter position
  (compliant to IID-A)
• Further detailed information added
• Cold/Warm configuration, Mounting Handling
  Equipment and Non Flight Items etc., drawing
  split into ten separate drawings
• Final release after working in ASTRIUM comments
  (received 9-Oct-03)
• PACS QM manufacturing finished, no further
  updates beyond Issue 27 foreseen
• Further requests/changes beyond Issue 27 are only
  possible via formal CR to PACS
• Level 0 Sorption Cooler I/F not reflected in
  Issue 27 anymore (separate drawing needed by CEA)
• Removing I/F-adapter (ECP6) accepted by ESA and
  Industry

6
PACS Thermal I/Fs to SC
GeGa Level 0
Level 1
PhFPU Level 0
GeGa Level 0 I/F (2x) Pin I/F changed to
rectangular I/F soldered to pin Conduct
resistance at I/F can be tuned to minimize
heating of blue detector
PhFPU/Cooler Level 0 I/F (2x)
Level 1
Level 1
GeGa Level 0
Level 1 I/F (3x) Thread distance changed from 33
mm to 37 mm
7
Mechanical Loads to Level 0 GeGa Detectors I/F

• Amendment to CR, H-P-PACS-ME- 008 issued
  29.Oct03, includes also updated mechanical load
  values for the GeGa Detectors L0 I/F to be in
  line with the changed mechanical I/F (pin to flat
  mounting I/F)
• Torque, longitudinal bending moment to central
  copper cold pin. lt 1.8 Nm
• Torque, rotation moment to the central copper
  cold pin lt 0.2 Nm
• Axial force to the central copper cold pin lt
  500 N
• Lateral force to the central copper cold pin lt
  100 N
• This IF loads regarded as uncritical
• For the fixation of the straps a mounting tool is
  foreseen

8
Engineering Change at PACS Thermal Cooler L0 I/F

• ECP PACS-ME-ECP 06, issued 27-July-03 agreed
  16-Oct-03
• Reason for ECP I/F temperature requirements of
  1.85K at the end of the cooler recycling phase,
  acc. H-P-PACS-CR-0009, cannot be met -gt 46h
  cooler hold time in question
• Proposal (agreed) Remove I/F adapter remaining
  contribution from PACS side to the overall
  thermal conductance (He-tank to Evaporator I/F)
  is now the contact resistance at the I/F to the
  cooler -gt 30 gained in thermal conductivity
  to the cooler I/F

New Design
Old Design
9
Mechanical Design at L0 Cooler I/F after ECP

• Changed Mechanical I/F Design at PACS Cooler
• S/C strap routing/ integration ?
• location of S/C temperature sensors
  ?
• Necessary design change on PhFPU side
• rerouting PhFPU 2K strap ?
• shifting 2K feed through ?
• I/F baffle to reduce radiation environment
  ?
• performed already
• CQM Parts manufactured ! ?
• BUT Mechanical loads from S/C ?

PhFPU Feed Through
PhFPU Baffles
PhFPU Cooling Strap to Bolometer
S/C Cooling Strap to Pump (cut in drawing, shown
partly only)
S/C Cooling Strap Evaporator
S/C Temp. Sensors
10
Mechanical Loads to Level 0 Cooler I/F

• Change Request to PACS IID-B H-P-PACS-ME- 008,
  Issued 26-Nov-2001, I/F Loads identified as
  Single point failure
• The mechanical loads arising from the level 0
  cooling straps to the fixation points of the
  cooling straps at the PACS FPU must be limited.
  Impact of no-change Damage of the mechanically
  sensitive thermal I/Fs during mounting and/or
  during launch can happen.
• Static load 50 N
• Dynamic load 50 grams (20.8G rms
  assumed)
• CR was not processed further. Reason missing
  final design of S/C level 0 cooling strap (under
  Industry responsibility)
• Current Design for the S/C cooling strap
• ½ mass of cooling strap, pulling at the Level 0
  I/F was 312 grams
• New ½ mass acc. AIR LIQUIDE study could be
  100-125 grams

11
Mechanical Loads to Level 0 Cooler I/F (cont.)

• First results from FEE on cooler switch I/F done
  by CEA-SBT (01-Oct-03)
• dynamical response of the switch,  (e.g. first
  eigenfrequency) depends on the additional mass
  fixed at the interface level -50
  grams, the first eigenfrequency is 194 Hz
  -100grams ..............................
  .......... 180 Hz -300
  grams.........................................
  140 Hz
• maximum admissible mass at I/F could be
  potentially increased to 100 grams. TN on FEE
  calculation in preparation.
• S/C cooling strap design needs to be balanced
  between conductance requirements (reduce cross
  section, change material TBC) and mechanical load
  requirements
• MPE proposes to perform a coupled FEE analysis,
  to take into account the dynamic behaviour of the
  S/C cooling strap and to perform a cold vibration
  test in "full" configuration (PhFPU/cooler/cooler
  switch strap) representative to the flight
  configuration
• Amendment to CR, H-P-PACS-ME- 008 issued
  29.Oct03, but 100 grams can not be guaranteed as
  long as no detailed FEE analysis is performed.

12
HERSCHEL L0 I/F Temperature to the Cooler
Evaporator

• Agreement reached on HERSCHEL Open Tank Solution,
  HERSCHEL L0 I/F meeting 30-Oct-03 _at_ESTEC

13
Estimation of PACS Level 0 I/F Temperatures in
Orbit

• HERSCHEL Tank Temperature 1.7K
• Material Pods Al 1050
• Open Pods Open Tank Solution for the
  Evaporator I/F
• Conductance data taken from AIR LIQUIDE analysis
  HP-2-AIRL-AN-0004

I/F Total Conductance W/K Max Heat Flux mW Calculated Temperature at IF K Max. Temperature allowed K OK
Blue Detector 0.039 ) 0.8 -1.63 1.72-1.74 2 Yes
Red Detector 0.082 0.8 1.71 1.75 Yes
Cooler Pump Condensation End of Cond. Low Temp. 0.061 ?10 500 ? 2 1.86 9.9 1.73 N/A 10 5 - Yes Yes
Cooler Evaporator Condensation End of Cond. Low Temp. 0.101 50 ? 15 ? 1 2.19 1.85 1.71 2.8 1.85 1.85 Yes Yes Yes
) Can be tuned at the I/F
14
Difference between Ground and Orbit

• Tilt of Cryostat
• The temperature of the cooler evaporator I/F at
  the end of the recycling phase defines the
  condensation efficiency of the 3He (hold time of
  the cooler)
• The difference between on ground and in orbit is
  the convective effect. This only affects the
  recycling phase. Once the cooler is cold,
  orientation does not matter.
• In orbit
  
  We can assume the in-orbit case
  corresponds to a 60-90 tilting for the cryostat
  on ground. At the end of the recycling phase, the
  power flowing through the evaporator strap is 18
  mW (measured 14 mW in the latest test).
• On ground
  
  If the cryostat can only be tilted 20,
  the power flowing through the evaporator strap at
  the end of the recycling phase can extrapolate to
  be about 30-35 mW !!!

15
Difference between Ground and Orbit (cont.)

• Herschel Tank Temperature
• Orbit 1.7K Ground (IMT) 1.7K to 1.8K
• Temperature shift at cooler I/F up to 100mK due
  to warm up after days
• L1 Temperature (PACS FPU temperature)
• Orbit 3K to 3.5K Ground(IMT) 6.3K
  to 7.3K
• Thermal load from L1 to L0 through switch base
  increased (0.45mW -gt 2mW)
• Impact to hold time (needs further assessment
  using measured values)
• Impact on the Net heat lift at 300mK (needs
  further assessment using measured values)
• Thermal Radiation Environment
• Orbit 9K 10K Ground
  (IMT) 8K 10K
• 5- 6 K, no impact expected, for 10 K we don't
  know (hard to calculate)
• cooler is pretty much covered by protective
  baffles and caps (best we could do)

It is assumed the heat sink to the cryostat drops
back down to 1.8 K once the condensation phase is
completed
16
Estimation of PACS Level 0 I/F Temperatures IMT

• Tank Temperature 1.75K
• Thermal radiation environment 8K-10K, not taken
  into account
• Level 1 temperature unknown 6.3K to 7.3K, not
  taken into account
• Conductance data taken from AIR LIQUITE analysis
  HP-2-AIRL-AN-0004, Al 1050

I/F Total Conductance W/K Max Heat Flux mW Calculated Temperature at IF K Max. Temperature allowed K OK
Blue Detector 0.27 ) 0.8 -1.63 1.78-1.81 2 Yes
Red Detector 0.043 0.8 1.77 1.75 (No)
Cooler Pump Condensation End of Cond. Low Temp. 0.036 ?10 ? 500 ? 2 2.02 15.5 1.81 N/A 10 5 - No Yes
Cooler Evaporator Condensation End of Cond. Low Temp. 0.035 20 deg tilt 80 (TBC) ? 35 (TBC) ? 1 4.04 2.75 1.78 2.8 1.85 1.85 No No Yes
) Can be tuned at the I/F
17
Estimation of PACS Level 0 I/F Temperatures EQM

• Tank Temperature unknown, used also 1.65K
• Thermal radiation environment unknown, should be
  ?5K
• Level 1 temperature unknown unknown, should be
  around 4K to 5K
• Conductance data taken from AIR LIQUITE analysis
  HP-2-AIRL-AN-0004

I/F Total Conductance W/K Max Heat Flux mW Calculated Temperature at IF K Max. Temperature allowed K OK
Blue Detector 0.062 ) 0.8 -1.63 1.66-1.68 2 Yes
Red Detector 0.212 0.8 1.65 1.75 Yes
Cooler Pump Condensation End of Cond. Low Temp. 0.106 ?10 ? 1000 ? 2 1.74 11.1 1.67 N/A 10 5 - No Yes
Cooler Evaporator Condensation End of Cond. Low Temp. 0.093 20 deg tilt 80 (TBC) ? 35 (TBC) ? 1 2.51 2.03 1.66 2.8 1.85 1.85 Yes No Yes
) Can be tuned at the I/F
18
Summery on PACS Level 0 I/F Temperatures

• In Orbit
• With the Open Tank Solution and with Al 1050
  for the HERSCHEL tank pods, PACS Temperature
  requirements on the L0 I/Fs can by fulfilled.
• On Ground
• It is not clear whether the PACS cooler can be
  recycled and/or run at 0.3mK with sufficient
  cooling power during IMT test.
• With a cryostat tilt of more than 20 degree, the
  situation can be improved by a factor 2.3 (for
  recycling only)
• IMT/EQM testing and testing conditions needs
  further assessments to be performed by all
  parties.
• Lionel Duband (CEA) needs to perform further
  calculations (tests?) using new validated
  boundary temperatures for the Ground test.