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ADVANCED CONCEPTS TEAM 1
ADVANCED CONCEPTS TEAM
P. Ben-Abdallah1, J.M. Llorens2, L. Bergamin2, and T. Vinko2
Esa 6th Round Table on MNTs
e
x
1 CNRS, Ecole Polytechnique, Laboratorie de Thermocinétique, Nantes, France2 Advanced Concepts Team, ESA (ESTEC), Noordwijk, The Netherlands
ADVANCED CONCEPTS TEAM 2
ACT AssessmentUniversities
• Informatics• Mission Analysis• Nanotechnologies• Propulsion
What is the ACT?
Who constitute the ACT?
How the ACT works?
• Loose ideas linked to space• First basic filtering of loose ideas linked to space• Preliminary ACT assessments - second filter• Academic assessment ARIADNA• Eventual transfer to ESA R&D programmes
Loose ideas linked to space
D/TEC - Programmes - GSP
filte
red,
ab
ando
ned
idea
s
filtered,
abandoned
ideas
Ariadna
Multidisciplinary research group:•Artificial Intelligence•Biomimetics•Energy Systems•Fundamental Physics
• 2 Staff • 6 Research Fellows• 5 Young Graduate Trainee
ADVANCED CONCEPTS TEAM 3
1.Introduction to directional
microstructured radiators
2.Reverse engineering strategy
3.Case studies:
•Quasi-isotropic radiator at room
temperature
•Directional radiator in the near
infrared
4.Conclusions and Outlook
ADVANCED CONCEPTS TEAM 4
1. Introduction to directionalmicrostructured radiators
1.Introduction to directional
microstructured radiators
2.Reverse engineering strategy
3.Case studies:
•Quasi-isotropic radiator at room
temperature
•Directional radiator in the near
infrared
4.Conclusions and Outlook
ADVANCED CONCEPTS TEAM 5
1. Introduction to directionalmicrostructured radiators
General Problem: Thermal control of Spacecraft
Solarradiation
Conduction
Convection
Radiation
XX
Proposal: Design surface finishes withspatially coherent thermal radiation
1.Polar materials + surface grating
2.Photonic band gap materials
3.Polar materials / metallic layer + photonic structures
4.Left-Handed material
ADVANCED CONCEPTS TEAM 6
1. Introduction to directionalmicrostructured radiators
General Problem: Thermal control of Spacecraft
Solarradiation
Conduction
Convection
Radiation
XX
Proposal: Design surface finishes withspatially coherent thermal radiation
1.Polar materials + surface grating
2.Photonic band gap materials
3.Polar materials / metallic layer + photonic structures
4.Left-Handed material
ADVANCED CONCEPTS TEAM 7
1. Introduction to directionalmicrostructured radiators
Polar material (SiC, GaN,…)
High and Low refractive indexPhotonicstructure
Schematic description of the concept:
Metalic layer (Ag, Al,…)ε(ω)
nH,L
Directionalradiation
Stop-band
λ
r
ReflectivityTransmitivityAbsorptivityEmissivity
t
r
eα
e
x
s, por
TE, TM
ADVANCED CONCEPTS TEAM 8
2. Reverse engineering strategy
1.Introduction to directional
microstructured radiators
2.Reverse engineering strategy
3.Case studies:
•Quasi-isotropic radiator at room
temperature
•Directional radiator in the near
infrared
4.Conclusions and Outlook
ADVANCED CONCEPTS TEAM 9
Objective of the study: For a given radiation distribution find the suitablemultilayer structure.
InputOptimization
process
Outputn(λ, z)
Optimization solver: Genetic Algorithm
Multilayer codification
Array element
Material layer
Initial random population
Evolution with genetic operators
Best solution
e(λ, θ) r(λ, θ)
ADVANCED CONCEPTS TEAM 10
Fitness function:
Physical model: Transfer matrix formalism
E+
E− E0−
E0+E0−
E0+E+
E−Transfermatrix
Reflection + Transmission
Energy conservation + Kirchhoff’s law
Emission
J =
Z λmax
λmin
Z θmax
θmin
(es − eTarget)2 + (ep − eTarget)2
+(rs − rTarget)2 + (rp − rTarget)2 dλ dθ
ADVANCED CONCEPTS TEAM 11
Implementation of the GA algorithm
Single CPU Distributed Computation (DC)
Single CPU evolves all the population
Each CPU evolves apart of the population
Physical DC platform:
Server
Client
Client
ClientClient
Population Initialization
+Sub-population
distribution
Population evolution
ADVANCED CONCEPTS TEAM 12
3. Case studies
1.Introduction to directional
microstructured radiators
2.Reverse engineering strategy
3.Case studies:
•Quasi-isotropic radiator at room
temperature
•Directional radiator in the near
infrared
4.Conclusions and Outlook
ADVANCED CONCEPTS TEAM 13
3. Case studies
Quasi-isotropic radiator at room temperature
λmax ≈ 10 μm
Radiation distribution T=300 K
Acording to Wien´s law:
•Polar Material: 3C-SiC (emission at 12.6 μm)•Low index material: CdTe nL=1.6•High index material: Ge nH=4.0
θ
Combination of materials
Parameters of the structure•50 layers => 350 (~7x1025) possible combinations•100 nm thickness
ADVANCED CONCEPTS TEAM 14
3. Case studies
Quasi-isotropic radiator at room temperature
Target Function
λ(μm
)
0 2 4 6 8 10
4
5
6
7
8
9
J (x
10-2
)Function Evaluantion (x104)
N. Generations ≡ 100 Function Eval.
Ge 3C-SiC CdTe
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70 80 90 12.2
12.3
12.4
12.5
12.6
12.7
12.8
θJ
(x 1
0-3 )
ADVANCED CONCEPTS TEAM 15
3. Case studies
Quasi-isotropic radiator at room temperatureE
mis
sion
0 10 20 30 40 50 60 70 80 12.2
12.3
12.4
12.5
12.6
12.7
12.8
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70 80 12.2
12.3
12.4
12.5
12.6
12.7
12.8
Ref
lect
ion
0 10 20 30 40 50 60 70 80 12.2
12.3
12.4
12.5
12.6
12.7
12.8
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70 80 12.2
12.3
12.4
12.5
12.6
12.7
12.8
s
s
p
p
λ
λ
λ
λ
θ
θ
θ
θ
ADVANCED CONCEPTS TEAM 16
3. Case studies
Quasi-isotropic radiator at room temperatureE
mis
sion
Ref
lect
ion
s
s
p
p
λ
λ
λ
λ
θ
θ
θ
θ
0 10 20 30 40 50 60 70 80 90 8
9
10
11
12
13
14
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70 80 90 8
9
10
11
12
13
14
0 10 20 30 40 50 60 70 80 90 8
9
10
11
12
13
14
0
0.1
0.2
0.3
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1
0 10 20 30 40 50 60 70 80 90 8
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14
ADVANCED CONCEPTS TEAM 17
3. Case studies
Quasi-isotropic radiator at room temperature
Run Details:1. Single CPU
• ESAGRID (Pentium Xeon2.40 GHz)
• Average functionevaluation time: ~ 2 s
2. DC• 12 Dell Desktops• Average function
evaluation time: ~ 5 s0 2 4 6 8 10 12
4
5
6
7
8
9
J (x
10-2
)
Function Evaluantion (x104)
SingleDC
Implementation into the DCJ
(x 1
0-3 )
6,700121,500
Outperformance ~ factor 18
ADVANCED CONCEPTS TEAM 18
3
4
5
6
7
8
9
100 1000 10000 100000
3. Case studies
Quasi-isotropic radiator at room temperature
SingleDC
Time reduction
J (x
10-
3 )
Time (s)
T=235,000 (2 d 17 h)
T=33,500 (9 h)
Outperformance ~ factor 7
ADVANCED CONCEPTS TEAM 19
3. Case studies
Directional radiator in the near infrared
Radiation distribution Working spectral range
[1.8 μm – 2.8 μm]
•Metal Layer: Ag (broad emission)•Low index material: SiO2 nL=1.45•High index material: Si nH=3.3
Combination of materials
Parameters of the structure•50 layers => 350 (~7·1025) possible combinations•50 nm thickness
e
x
ADVANCED CONCEPTS TEAM 20
0
0.1
0.2
0.3
0.4
0.5
0.6
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0.9
1
0 10 20 30 40 50 60 70 80 90 1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
3. Case studies
Quasi-isotropic radiator at room temperature
Target Function
θ
λ(μm
)
N. Generations ≡ 100 Function Eval.
0 2 4 6 8 103.75
4.00
4.25
4.50
4.75
5.00
J (x
10-2
)Function Evaluantion (x104)
Si Ag SiO2
J (x
10-
3 )
ADVANCED CONCEPTS TEAM 21
3. Case studies
Quasi-isotropic radiator at room temperatureE
mis
sion
Ref
lect
ion
s
s
p
p
λ
λ
λ
λ
θ
θ
θ
θ
0 10 20 30 40 50 60 70 80 90 1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
0 10 20 30 40 50 60 70 80 90 1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70 80 90 1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
0
0.1
0.2
0.3
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0.5
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0.8
0.9
1
0 10 20 30 40 50 60 70 80 90 1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
ADVANCED CONCEPTS TEAM 22
4. Conclusions and Outlook
1.Introduction to directional
microstructured radiators
2.Reverse engineering strategy
3.Case studies:
•Quasi-isotropic radiator at room
temperature
•Directional radiator in the near
infrared
4.Conclusions and Outlook
ADVANCED CONCEPTS TEAM 23
4. Conclusions and Outlook
Conclusions
•Development of a Reversal Engineering Tool for designing directional microstructured radiators •Proof their suitability for different types of radiators•Implementation of a distributed version of the GA solver•Distributed strategy shows an outperformance of factor 7
Outlook
• Asses the feasibility of the optimized structure (explore materials for the active layer)• Study the “control” over the reflectivity and emissivity features• Implement other GO solvers into the tool (DIGMO) • Combine this proposal with surface gratings to improve the directivity
ADVANCED CONCEPTS TEAM 24
Thank you for your attention !
More Information:• About the ACT: https://www.esa.int/act• About ARIADNA: http://www.esa.int/gsp/ACT/ariadna/index.htm• About Microstructured Radiators: Ariadna Final Report
http://www.esa.int/gsp/ACT/doc/ARI/ARI%20Study%20Report/ACT-RPT-NAN-ARI-069501-Micro_Radiators-Nantes.pdf
• About DIGMO: http://www.esa.int/gsp/ACT/inf/op/act-dc_digmo.htm