B6_Mecahnical_Thermal_IF_42106_44907

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					PACS IHDR                                          12/13 Nov 2003




                                  PACS IHDR



  Overview and Mechanical/Thermal IFs to FPU


                                         MPE
                                     J. Schubert




 Overview and Mechanical/Thermal IFs to FPU                    1
PACS IHDR                                             12/13 Nov 2003


                                     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 Ge:Ga 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)




 Overview and Mechanical/Thermal IFs to FPU                       2
PACS IHDR                                                   12/13 Nov 2003


                          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




 Overview and Mechanical/Thermal IFs to FPU                             3
PACS IHDR                                                         12/13 Nov 2003


                             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)


 Overview and Mechanical/Thermal IFs to FPU                                    4
 PACS IHDR                                                            12/13 Nov 2003

                        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 reworked+implemented
   – Level 0 S/C IF to Ge:Ga 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 (ECP#6) accepted by ESA and Industry



  Overview and Mechanical/Thermal IFs to FPU                                      5
    PACS IHDR                                                          12/13 Nov 2003

                              PACS Thermal I/Fs to SC

                                              Ge:Ga
                                              Level 0
                                                             Level 1


                                                                       PhFPU
GeGa Level 0 I/F (2x)                                                  Level 0
Pin I/F changed to
rectangular I/F soldered
to pin; Conduct                                                         PhFPU/Cooler
resistance at I/F can be                                                Level 0 I/F (2x)
tuned to minimize
                         Level 1
heating of blue detector
                                                   Level 1
                           GeGa
                           Level 0


                        Level 1 I/F (3x)
                        Thread distance changed
                        from 33 mm to 37 mm


      Overview and Mechanical/Thermal IFs to FPU                                     6
PACS IHDR                                                                   12/13 Nov 2003


          Mechanical Loads to Level 0 Ge:Ga Detectors I/F

•    Amendment to CR, H-P-PACS-ME- 008 issued 29.Oct03, includes also
     updated mechanical load values for the Ge:Ga 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.   < 1.8 Nm
      –   Torque, rotation moment to the central copper cold pin            < 0.2 Nm
      –   Axial force to the central copper cold pin                        < 500 N
      –   Lateral force to the central copper cold pin                      < 100 N


•    This IF loads regarded as uncritical
•    For the fixation of the straps a mounting tool is foreseen




    Overview and Mechanical/Thermal IFs to FPU                                          7
    PACS IHDR                                                                                                                                                                              12/13 Nov 2003


          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 -> 46h cooler hold time in
           question
      –     Conductance Estimation Remove I/F adapter; remaining contribution as calculated side to
           Proposal (agreed): HERSCHEL TANK to PACS Sorption Cooler I/F (Evaporator)from PACSby PACS the
           overall thermal conductance (He-tank to Evaporator I/F) is now the contact resistance at
             NEW DESIGN                                    BASELINE DESIGN
           the I/F to the cooler -> ~ 30% gained in thermal conductivity to the cooler I/F
             PROPOSAL                                                  1
                                                                      Q = 20 mW

                                                                                                                                          Cooling                PACS
                                                                                                                                          Strap                  Sorption
                                                 1
                                                Q = 20 mW                                                                                 from                   Cooler I/F
                                 Cooling
                                 Strap                                                                                                    Bolometer                               2.5 K/W
                                 from                          PACS                                                                       Buffer                                                    PACS
                                 Bolometer                     Sorption                                                                   Amplifier            PACS I/F           1.75 K/W *)
                                                               Cooler I/F                                                                                      Adapter
                                 Buffer
                                                                                2.5 K/W      PACS                                                                                 2.5 K/W
                                 Amplifier
            2 eg ib
           Q = n lig le                                                         0.88 K/W *)                                                                    Rigid Part         1.49 K/W *)
            u g y lin
           d rin rec c g                                                                                                                                       SC
                                                                                     ed
                                                                                assum very high                                                                                        ed
                                                                                                                                                                                  assum very high
                                                                                                  SPACECRAFT PART **)




                                                                                                                                                                                                     SPACECRAFT PART **)
                                                                     Flexible                                                                                          Flexible




                                                                                                                                                                                                                           TOTAL 16.25 K/W
                                         Rigid Part                  Part
                                                                                0.83 K/W *)                                                                            Part
                                                                                                                                                                                   0.83 K/W *)
                                                                                                                        TOTAL 11.39 K/W
                                         with larger
                                         cross
                                         section
                                                                                 1.67 K/W                                                                                          1.67 K/W
            *) PACS estimation

            **) 15 K/W Specification,
            15 K/W acc. ASTRIUM
            CR: HP-2-ASED-CR-0012 in                   Post                      2.44 K/W                                                             Post                         2.44 K/W
            response to “Instrument
            Thermal Link I/F Meeting“,
             4.4.2003                                  Flang                                                                                          Flang
                                                       Wall                     0.57 K/W                                                              Wall                         0.57 K/W

                                                               He                2.5 K/W          T0 = 1.65 K... 1.7 K                                           He                 2.5 K/W          T0 = 1.65 K... 1.7 K




                                             New Design                                                                                                       Old Design

     Overview and Mechanical/Thermal IFs to FPU                                                                                                                                                                                              8
PACS IHDR                                                                     12/13 Nov 2003

                    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
PhFPU Feed
                                                                   sensors                          
Through
                                                          •   Necessary design change on
                                               PhFPU          PhFPU side
PhFPU Cooling                                  Baffles
Strap to                                                       •   rerouting PhFPU 2K strap 
Bolometer
                                                               •   shifting 2K feed through       
                                                               •   I/F baffle to reduce radiation
                                                                   environment                    
                                                              performed already
                                                          •   CQM Parts manufactured ! 

S/C Cooling Strap     S/C Temp.   S/C Cooling Strap to
Evaporator            Sensors     Pump (cut in drawing,   •   BUT: Mechanical loads from
                                  shown partly only)          S/C ?


  Overview and Mechanical/Thermal IFs to FPU                                                   9
    PACS IHDR                                                          12/13 Nov 2003

                  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




     Overview and Mechanical/Thermal IFs to FPU                                        10
PACS IHDR                                                                       12/13 Nov 2003

           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.



    Overview and Mechanical/Thermal IFs to FPU                                                 11
PACS IHDR                                                                                                                                                                  12/13 Nov 2003

    HERSCHEL L0 I/F Temperature to the Cooler Evaporator
•     Agreement reached on HERSCHEL Open Tank Solution, HERSCHEL L0
      I/F meeting 30-Oct-03 @ESTEC

                                                                             Temperature along L0 Cooling Line to PACS
                                                                                        Evaporator Switch, Orbit Condition,
                                                                   2.00
                                                                          Heat Flow: 15 mW (end of condensation phase)                                                                                                                1.97K @ 15 mW
                                                                          Tank: 1.7K
                                                                   1.95   Pods: Al 1050
                                                                          Load on I/F ~100 gram
                                                                   1.90




                                                 Temperature [K]
                                                                          Upper Temperature Limit                                                                                                                                           1.85K @ 15 mW
                                                                   1.85
                                                                          for Evaporator Switch 1.85K


                                                                   1.80


                                                                   1.75                   Close Tank                                                                                                                                         Open Tank

                                                                   1.70
                                                                                                                                                                                Data from Lo Thermal Links, Thermal Analysis
                                                                                                                                                                                HP-2-AIRL-0005, Issue 3
                                                                   1.65




                                                                                                                                                                                                6) Cont. Pod./Flex Link
                                                                                                  1) Intern Pod




                                                                                                                                                                                                                          7) Flexib. Link
                                                                              Tank




                                                                                                                                          3) HTT Skin




                                                                                                                                                                                                                                               8) Contact Instr. I/F
                                                                                     0) Kapitza




                                                                                                                  2) Kontakt HTT Intern




                                                                                                                                                        4) Contact ct HTT ex.

                                                                                                                                                                                5) Extern Pod
    Overview and Mechanical/Thermal IFs to FPU                                                                                                                                                                                                      12
PACS IHDR                                                                         12/13 Nov 2003

  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     Max Heat Flux      Calculated          Max.      OK
                        Conductance      [mW]          Temperature at   Temperature
                           [W/K]                           IF [K]        allowed [K]
   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            0.061
    Condensation                         10               1.86            N/A         -
    End of Cond.                         ~ 500              9.9            10          Yes
    Low Temp.                             2               1.73             5          Yes
   Cooler Evaporator      0.101
    Condensation                          50               2.19             2.8        Yes
    End of Cond.                          15              1.85            1.85        Yes
    Low Temp.                            1                1.71            1.85        Yes

                                                      *) Can be tuned at the I/F

 Overview and Mechanical/Thermal IFs to FPU                                                  13
 PACS IHDR                                                             12/13 Nov 2003


                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 !!!




  Overview and Mechanical/Thermal IFs to FPU                                        14
PACS IHDR                                                                                   12/13 Nov 2003

             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 -> ~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


    Overview and Mechanical/Thermal IFs to FPU                                                               15
PACS IHDR                                                                         12/13 Nov 2003

     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     Max Heat Flux      Calculated          Max.       OK
                        Conductance      [mW]          Temperature at   Temperature
                           [W/K]                           IF [K]        allowed [K]
   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            0.036
    Condensation                        10                2.02            N/A         -
    End of Cond.                         500              15.5            10          No
    Low Temp.                            2                1.81             5          Yes
   Cooler Evaporator      0.035        20 deg tilt
    Condensation                       80 (TBC)            4.04             2.8        No
    End of Cond.                          35              2.75            1.85        No
    Low Temp.                            (TBC)             1.78            1.85        Yes
                                          1
                                                      *) Can be tuned at the I/F

 Overview and Mechanical/Thermal IFs to FPU                                                   16
PACS IHDR                                                                         12/13 Nov 2003

     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     Max Heat Flux      Calculated          Max.      OK
                        Conductance      [mW]          Temperature at   Temperature
                           [W/K]                           IF [K]        allowed [K]
   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            0.106
    Condensation                        10                1.74            N/A         -
    End of Cond.                        1000              11.1            10          No
    Low Temp.                           2                 1.67             5          Yes
   Cooler Evaporator      0.093        20 deg tilt
    Condensation                       80 (TBC)            2.51             2.8        Yes
    End of Cond.                          35              2.03            1.85        No
    Low Temp.                            (TBC)             1.66            1.85        Yes
                                          1
                                                      *) Can be tuned at the I/F

 Overview and Mechanical/Thermal IFs to FPU                                                  17
PACS IHDR                                                     12/13 Nov 2003


         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.



 Overview and Mechanical/Thermal IFs to FPU                                18

				
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