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Overview and Mechanical/Thermal IFs to FPU PACS IHDR MPE J. Schubert 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

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overview and mechanical thermal ifs to fpu

Overview and Mechanical/Thermal IFs to FPU

PACS IHDR

MPE

J. Schubert

Overview and Mechanical/Thermal IFs to FPU

content
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

overview pacs fpu
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

overview cont
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

pacs mechanical i f to s c
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

pacs thermal i fs to sc
PACS Thermal I/Fs to SC

Ge:Ga 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

Overview and Mechanical/Thermal IFs to FPU

mechanical loads to level 0 ge ga detectors i f
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

engineering change at pacs thermal cooler l0 i f
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
    • 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 -> ~ 30% gained in thermal conductivity to the cooler I/F

New Design

Old Design

Overview and Mechanical/Thermal IFs to FPU

mechanical design at l0 cooler i f after ecp
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 Evaporator

S/C Temp. Sensors

S/C Cooling Strap to Pump (cut in drawing, shown partly only)

Overview and Mechanical/Thermal IFs to FPU

mechanical loads to level 0 cooler i f
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

mechanical loads to level 0 cooler i f cont
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

herschel l0 i f temperature to the cooler evaporator
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

Overview and Mechanical/Thermal IFs to FPU

estimation of pacs level 0 i f temperatures in orbit
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

*) Can be tuned at the I/F

Overview and Mechanical/Thermal IFs to FPU

difference between ground and orbit
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

difference between ground and orbit cont
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

estimation of pacs level 0 i f temperatures imt
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

*) Can be tuned at the I/F

Overview and Mechanical/Thermal IFs to FPU

estimation of pacs level 0 i f temperatures eqm
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

*) Can be tuned at the I/F

Overview and Mechanical/Thermal IFs to FPU

summery on pacs level 0 i f temperatures
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