pacs ihdr 12/13 nov 2003 overview and mechanical/thermal ifs to fpu 1 mpe j. schubert pacs ihdr

Overview and Mechanical/Thermal IFs to FPU 1

PACS IHDR 12/13 Nov 2003

Overview and Mechanical/Thermal IFs to FPU

MPEJ. Schubert

PACS IHDR



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 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 (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)



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



PACS Thermal I/Fs to SC

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

Ge:Ga Level 0

GeGa Level 0

PhFPU Level 0

Level 1

Level 1

Level 1

Level 1 I/F (3x)

Thread distance changed from 33 mm to 37 mm

PhFPU/Cooler Level 0 I/F (2x)



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



• 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

Engineering Change at PACS Thermal Cooler L0 I/F

New Design Old Design



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 ?

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

PhFPU Cooling Strap to Bolometer

S/C Cooling Strap Evaporator

PhFPU Baffles

PhFPU Feed Through

S/C Temp. Sensors



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



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.



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,

Tan

k

0) K

apit

za

1) In

tern

Po

d

2) K

on

takt

HT

T In

tern

3) H

TT

Ski

n

4) C

on

tact

ct

HT

T e

x.

5) E

xter

n P

od

6) C

on

t. P

od

./Fle

x L

ink

7) F

lexi

b. L

ink

8) C

on

tact

Inst

r. I/

F

Te

mp

era

ture

[K]

1.65

1.70

1.75

1.80

1.85

1.90

1.95

2.00

Upper Temperature Limitfor Evaporator Switch 1.85K

1.97K @ 15 mWHeat Flow: 15 mW (end of condensation phase)Tank: 1.7KPods: Al 1050Load on I/F ~100 gram

Data from Lo Thermal Links, Thermal AnalysisHP-2-AIRL-0005, Issue 3

1.85K @ 15 mW

Open TankClose Tank



Estimation of PACS Level 0 I/F Temperatures in Orbit

HERSCHEL Tank Temperature: 1.7K Material Pods: Al 1050Open Pods: Open Tank Solution for the Evaporator I/F

Conductance data taken from AIR LIQUIDE analysis HP-2-AIRL-AN-0004

I/F Total Conductanc

e [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.

0.06110

~ 500 2

1.869.91.73

N/A105

-YesYes

Cooler Evaporator Condensation End of Cond. Low Temp.

0.10150 15 1

2.191.851.71

2.81.851.85

YesYesYes

*) Can be tuned at the I/F



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 !!!



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



Estimation of PACS Level 0 I/F Temperatures IMTTank Temperature: 1.75KThermal radiation environment: 8K-10K, not taken into accountLevel 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


e [W/K]

Max Heat Flux [mW]


at IF [K]


[K]

OK


Red Detector 0.043 0.8 1.77 1.75 (No)


0.03610

500 2

2.0215.51.81

N/A105

-NoYes


0.035 20 deg tilt80 (TBC) 35 (TBC)

1

4.042.751.78

2.81.851.85

NoNoYes




Estimation of PACS Level 0 I/F Temperatures EQM

Tank Temperature: unknown, used also 1.65KThermal radiation environment: unknown, should be 5KLevel 1 temperature unknown: unknown, should be around 4K to 5K

Conductance data taken from AIR LIQUITE analysis HP-2-AIRL-AN-0004


e [W/K]

Max Heat Flux [mW]


at IF [K]


[K]

OK


Red Detector 0.212 0.8 1.65 1.75 Yes


0.10610

1000 2

1.7411.11.67

N/A105

-NoYes


0.093 20 deg tilt80 (TBC) 35 (TBC)

1

2.512.031.66

2.81.851.85

YesNoYes




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.

pacs ihdr 12/13 nov 2003 overview and mechanical/thermal ifs to fpu 1 mpe j. schubert pacs ihdr

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