Thermal Balance Test of Solar Orbiter EUI Instrument Structural and Thermal Model with 13 Solar Constants

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Thermal balance test of Solar Orbiter EUI

instrument Structural and Thermal Model

with 13 Solar constants

L. Jacques, J.-P. Halain, L. Rossi, M.-L. Hellin, P. Jamotton, S. Liebecq, A. Mazzoli, E. Renotte, P. Rochus

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Outline

What we do at CSL? Solar Orbiter

EUI

Test setup presentation Test results

Test correlation Conclusions

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Outline

What we do at CSL?

Solar Orbiter EUI

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Space Center in Liège, Belgium

University of Liège Research Center (since 1959) Test facility for ESA:

– Class 10000 & class 100 cleanrooms

– 5 Vacuum chambers with optical bench (1.5 to

6.5m Ø)

– 2 shakers in cleanroom (also cryo-vib)

– Planck S/C, Herschel mirror, GAIA (PLM), XMM

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Space instruments developed at CSL

EIT (SOHO), OM (XMM), FUV/SI (IMAGE), Sun baffle (CoRoT), HI

(STEREO), PACS grating & DEC/MEC (Herschel), MIRI (JWST), UVS

SMA (JUNO), SWAP & LYRA (PROBA-2), EUI (Solar Orbiter), ASPCIIS

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Outline

What we do at CSL?

Solar Orbiter

EUI

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Solar Orbiter key figures

ESA M-Class mission S/C currently in CDR Oct-2018 launch

0.28AU perihelion (17.5kW/m²), 1.47AU aphelion 6 remote sensing instruments

4 in-situ instruments

~1800kg S/C (~190kg payload) ~1kW

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Outline

EUI

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The

E

xtreme-

U

ltraviolet

I

mager

Remote sensing instrument with 3 channels

2 High Resolution Imagers (100km resol.)

– HRI_Lya at Lyman-α _{line (1216Å)}

– HRI_EUV at 174Å

1 dual-band Full Sun Imager at 174Å and 304Å (900km resol.)

FSI channel

HRI_Lyachannel

HRI_EUV channel

HRI_EUV entrance baffle HRI_Lyaentrance baffle FSI entrance baffle

HRIs Focal Plane Assembly FSI Focal Plane Assembly

(detector + Front End Electronics) FSI filter wheel

FSI primary mirror

HRIs primary mirror

HRIs secondary mirror

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EUI in a nutshell

860 x 450 x 360 mm, ~15kg, 28W

CFRP-Alu honeycomb-CFRP sandwich structure

Ultrathin HRI_EUV & FSI entrance filters (150nm thick Al.)

MgF₂ coated HRI_Lya entrance filter

Al. coated CFRP entrance baffles

Heat-pipes to cool down entrance filters, baffles and doors

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S/C thermal interfaces

S/C -y panel (conductive environment) S/C Heat Shield S/C heat shield Feedthrough Honeycomb bench HRI FPAs FEE detector HE CE_HRIs ME_HRIs

HRIs entrance baffle, door, filter assembly

FSI FPA CE_FSI ME_FSI Radiative environment Q_S Q_B FEE detector

HE: Hot Element interface (+50°C) CE: Cold Element Interface (-50°C)

ME: Medium Element Interface (+20°C)

Q_B: IR load from S/C heat shield feedthroughs at ~300°C

Q_S: Solar heat flux (17.5kW/m² at 0.28AU)

T_R: S/C cavity radiative environment (+50°C) T_SRP: S/C conductive environment (+50°C)

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HRIs heat pipes

Conducts heat from HRIs filters, baffles & doors to HE Two redundant heat-pipes

Al-NH₃ heat pipes with H-shaped copper brazed interfaces

Copper goggles connecting doors, baffles, filters to HP Instrument orientation in TB test (also at S/C level)

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Ultrathin HRI

_EUV

entrance filter

108 _{rejection of visible part of Solar spectrum}

Twice reinforced for structural & thermal

– Local Nickel mesh grown onto Al foil – Clamped between Al. frames

Ni mesh Frame cell Aluminium frame 2mm thick Aluminium frame ~30µm thick Ni mesh Frame pattern matching 150nm thick Aluminium foil

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Detector &

F

ocal

P

lane

A

ssembly

3k x 3k Active Pixel Sensor (developed for EUI)

Aluminum nitride package (T° _{uniformity + CTE matching)}

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Outline

EUI

Test setup presentation

Test results

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Thermal balance test setup overview

Instrument STM upside-down 3 Xe lamps

3 feedthroughs 220 sensors

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Illumination setup

3 elliptical Cermax Xe arc-lamp + parabolic folding mirror Lamp spectrum + mirror spectral reflectivity

Instrument coating absorptance adjusted

400 600 800 1000 1200 1400 1600 1800 2000 0 0.5 1 Wavelength [nm] re la ti v e s p e c tr a l in te n s it y [ A U ] 400 600 800 1000 1200 1400 1600 1800 2000 0 50 100 Wavelength [nm] In te g ra te d i n te n s it y [ % ] ∫E_Cermax(λ)dλ ∫E_Sun(λ)dλ

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Illumination setup callibration

Profile measured with picture & photodiode mapping Intensity measured with pyranometer

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17.5kW/m² @ 1.5m

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 5 10 15 20 25 30 35 40 Ir ra d ia n c e [ k W /m ²]

Distribution over a 50mm diam area

Avg Max Min 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 5 6 7 8 9 10

distance from mirror [m]

N o n u n if o rm it y w rt a v e ra g e [ % ] (Max-Avg)/Avg (Avg-Min)/Avg

Distance from folding mirror [m] Distance from folding mirror [m]

17.5

Irradiance [kW/m²]

Non-uniformity

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Divergence from pinhole spot size

0 50 100 150 200 250 300 350 400 0 50 100 150 200 250 300 350 50mm 50 100 150 200 250 0.2 0.4 0.6 0.8 1 X: 35.63 Y: 0.278 X: 41.8 Y: 0.2815 M1 Array of pinholes screen penumbra atan Δ 2 atan 2 1.4 . . deg

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Thermal IF setup

LN₂ panel + straps with heaters to provide CE, ME & HE temperatures

S/C cavity conductive environment

S/C heat shield

representative feedthrough (hot & cold) with ceramic heaters & LN₂ lines

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Outline

EUI

Test setup presentation

Test results

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Test sequence & results overview

01/09 01/10 01/11 01/12 01/13 01/14 -200 -100 0 100 200 300 400 500 Time T e m p e ra tu re [ °C ] Baffle_EUV_front_-Y THERMAL_IF_PANEL_1 Feedthrough_EUV_heater1_north FPA_FSI_APS_1 08-Jan-2014 12:00:00 14-Jan-2014 00:00:00 close vacuum chamber and pumping

Thermal shroud PID tuning

Start hot case - 1 Fuse broke up - 1 S/C Heater lost

Switch ON lamps to 17.5kW/m²

Switch to LN2 on radiator and wait stabilization

- ≠_{OP cases}

- Rotation of the instrument:

Heat pipe stall

- Hot NOP case - 3SC case

- Start cold OP case

- ≠_{OP cases}

- Start cold NOP case

Back to ambient P and T

HRI_EUVentrance baffle Thermal IF panel HRI_EUVfeedthrough FSI detector

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Outline

EUI

Test correlation

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Thermal model description

Semi-transparent screen to model lamp flux non-uniformity

Actual divergence Actual absorption 5219 nodes

HRI_Lya flux Solar transmissivity

0 0.65

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Thermal model correlation

RMS error (93 sensors): 1.2K (4.8K before correlation) Error max: 2.8K

Hot OP case results:

Temperature [°C] 88 45 63 75 200

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Test heat balance

14.0W environment input, 10W dissipation

QSRP = 0.0 W QS [W] QB [W] pupil 1.0 baffle 1.0 7.7 W VIS filter 3.4 1.0 W IR QR = 3.9 W door housing 2.3 QI 10.0 W pupil 0.7

baffle 0.4 3.7 W VIS QCE,HRIs = 4.8 W

filter 1.7 0.5 W IR

door housing 0.9 QS+QB Q TOT

14.0 W 24.0 W

pupil 0.4

baffle 0.0 0.5 W VIS

filter 0.0 0.0 W IR QME,HRIs = 2.9 W

door housing 0.0

Stru (goggles) & MLI 0.3 0.3 0.6 W Total 12.1 W + 1.8 W = 14.0 W QHE = 8.7 W 1.0 HRI EUV 8.7 W QME,FSI = 1.4 W HRI Lya 4.2 W QCE,FSI = 2.3 W FSI 0.0 0.5 W 0.5 IN OUT

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Outline

EUI

Test correlation

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Conclusions

Model correlated

Ultrathin filters survived

Hot & cold thermo-elastic measurement performed & correlated

Lessons learned for QM and FM thermal tests Further unit dedicated test:

– Focal plane assemblies QM – Doors QM

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Thank you for your attention…

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Contact

Lionel Jacques, [email protected] Thermal Engineer & PhD student

Centre Spatial de Liège Liège Science Park

Avenue Pré-Aily

B-4031 Angleur Belgium http://www.csl.ulg.ac.be University of Liège

Space Structures and Systems Lab 1, Chemin des Chevreuils (B52/3) Liege, B-4000, Belgium