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See detailThermal Balance Test of Solar Orbiter EUI Instrument Structural and Thermal Model with 13 Solar Constants
Jacques, Lionel ULg; Halain, Jean-Philippe ULg; Rossi, Laurence ULg et al

Scientific conference (2015, March 26)

Developed by a European consortium led by the Centre Spatial de Liège in Belgium, the Extreme Ultraviolet Imager (EUI) is an instrument onboard the Solar Orbiter ESA M-class mission. At its 0.28AU ... [more ▼]

Developed by a European consortium led by the Centre Spatial de Liège in Belgium, the Extreme Ultraviolet Imager (EUI) is an instrument onboard the Solar Orbiter ESA M-class mission. At its 0.28AU perihelion, the spacecraft will be exposed to a 13 solar constants solar flux. EUI is protected behind the spacecraft heat shield but for three apertures for its telescopes looking at the Sun in the Extreme-UV. To better reject the unwanted visible light and protect 150nm thick EUV filters, Aluminum coated carbon-fiber-reinforced plastics entrance baffles are located at the front of the instrument. The residual absorbed heat by the entrance filters and baffles is evacuated through heat pipes to a dedicated spacecraft thermal interface. To verify its thermal design, the instrument structural and thermal model has been tested in a vacuum chamber with a solar simulator providing the 13 solar constants solar flux at the three entrance apertures and dedicated heaters to model the spacecraft heat shield feedthroughs. To assess the off-pointing performance of the entrance baffles, the instrument was mounted onto a rotating structure inside the chamber. The test setup, results and the thermal model correlation will be presented as well as the calibration of the solar simulator divergence and intensity. [less ▲]

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See detailFinite Element Model Reduction of Thermal Systems with Conductive and Radiative Heat Transfers
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

Scientific conference (2015, March 24)

The Lumped parameter method (LPM) is the main method used for space structures thermal design. It is very versatile and allows easy integration of user-defined components but the computation of the ... [more ▼]

The Lumped parameter method (LPM) is the main method used for space structures thermal design. It is very versatile and allows easy integration of user-defined components but the computation of the conductive links is error-prone and still too often computed by hand. Widely used in structural design, the finite element method (FEM) is however not yet often used for thermal analysis. One of the main reasons is that the radiative exchange factors, usually computed through Monte Carlo ray tracing, are extremely expensive to compute due to the large number of elements composing a FE model. A new global approach for FE model reduction of thermal systems is presented. The method is based on an automated FE mesh partitioning leading to super-faces and super-nodes. It is tailored for radiative exchange factors computation, taking into account selected quadric recognition and material constraints. The method also provides accurate conductive links computation and enables a direct mapping of the reduced temperatures back onto the detailed FE mesh (for e.g. thermo-elastic analyses). The application to two instruments developed at the Centre Spatial de Liège in Belgium will be presented, namely the Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter and the Back Telescope Assembly (BTA) onboard Meteosat Third Generation. [less ▲]

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See detailEnhancement of ray tracing method for radiative heat transfer: application to EUI space instrument
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Proceedings of the 15th International Heat Transfer Conference, IHTC-15 (2014, August)

The finite element method (FEM) is widely used in mechanical engineering, in particular for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, in particular for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the lumped parameter method is still dominant. Radiative exchange factors (REFs), used to calculate radiative thermal exchanges in space, are usually computed through Monte Carlo ray tracing. Due to the large number of elements composing a FE model, the computation of the REFs is prohibitively expensive. The isocell method aims at reducing the computational effort of the REFs with FEM, by decreasing the number of rays required to achieve a given accuracy. Based on Nusselt’s analogy, the ray direction sampling is carried out by sampling the unit disc to derive the ray directions. The isocell method is a special case of stratified sampling. It divides the unit disc into cells of almost same area and shape from which random points are generated. This enhances the uniformity of the ray directions and leads to faster convergence. This isocell method is associated with different surface sampling to derive the REFs. The method is benchmarked against ESARAD, the standard thermal analysis ray tracing engine used in the European aerospace industry. One entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developedat the Centre Spatial de Liège in Belgium is used as benchmarking case. Solar Orbiter is an European Space Agency mission to be launched in a Sun-centered 0.28 perihelion orbit. [less ▲]

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See detailEnhancement of ray tracing method for radiative heat transfer with new isocell quasi-monte carlo technique and application to EUI space instrument
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Proceedings of the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, HEFAT2014 (2014, July)

Monte Carlo ray tracing method for thermal analysis. The rationale for this research is the speed-up of radiative heat transfer computation with the Finite Element Method, widely used in mechanical ... [more ▼]

Monte Carlo ray tracing method for thermal analysis. The rationale for this research is the speed-up of radiative heat transfer computation with the Finite Element Method, widely used in mechanical engineering especially for space structure design but not yet often for thermal analysis of these structures. Based on Nusselt’s analogy, the ray direction sampling is done by sampling the unit disc to derive the ray directions. Stratified sampling is applied to the unit disc that is divided into cells or strata into which random points are generated. The isocell method relies on cells that have the particularity of presenting almost the same area and shape. This enhances the uniformity of the generated quasi-random sequence of ray directions and leads to faster convergence. The isocell method is associated with different surface sampling to derive REFs. The method is benchmarked against ESARAD, the standard ray tracing engine of the thermal analysis software used in the European aerospace industry. Various geometries are used. In particular, one entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developed at the Centre Spatial de Liège in Belgium is presented. The EUI instrument of the Solar Orbiter European Space Agency mission and will be launched in a 0.28 perihelion orbit around the Sun in 2018. [less ▲]

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See detailSpace radiation parameters for EUI and the Sun Sensor of Solar Orbiter, ESIO and JUDE instruments
Rossi, Laurence ULg; Jacques, Lionel ULg; Halain, Jean-Philippe ULg et al

in Proceedings of SPIE (2014, June 18)

This paper presents predictions of space radiation parameters for four space instruments performed by the Centre Spatial de Liège (ULg – Belgium); EUI, the Extreme Ultra-violet Instrument, on-board the ... [more ▼]

This paper presents predictions of space radiation parameters for four space instruments performed by the Centre Spatial de Liège (ULg – Belgium); EUI, the Extreme Ultra-violet Instrument, on-board the Solar Orbiter platform; ESIO, Extreme-UV solar Imager for Operations, and JUDE, the Jupiter system Ultraviolet Dynamics Experiment, which was proposed for the JUICE platform. For Solar Orbiter platform, the radiation environment is defined by ESA environmental specification and the determination of the parameters is done through ray-trace analyses inside the EUI instrument. For ESIO instrument, the radiation environment of the geostationary orbit is defined through simulations of the trapped particles flux, the energetic solar protons flux and the galactic cosmic rays flux, taking the ECSS standard for space environment as a guideline. Then ray-trace analyses inside the instrument are performed to predict the particles fluxes at the level of the most radiation-sensitive elements of the instrument. For JUICE, the spacecraft trajectory is built from ephemeris files provided by ESA and the radiation environment is modeled through simulations by JOSE (Jovian Specification Environment model) then ray-trace analyses inside the instrument are performed to predict the particles fluxes at the level of the most radiation-sensitive elements of the instrument. [less ▲]

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See detailSolar simulation test up to 13 solar constants for the thermal balance of the Solar Orbiter EUI instrument
Rossi, Laurence ULg; zhukova, Maria; Jacques, Lionel ULg et al

in Proceedings of SPIE (2014, June 18)

Solar Orbiter EUI instrument was submitted to a high solar flux to correlate the thermal model of the instrument. EUI, the Extreme Ultraviolet Imager, is developed by a European consortium led by the ... [more ▼]

Solar Orbiter EUI instrument was submitted to a high solar flux to correlate the thermal model of the instrument. EUI, the Extreme Ultraviolet Imager, is developed by a European consortium led by the Centre Spatial de Liège for the Solar Orbiter ESA M-class mission. The solar flux that it shall have to withstand will be as high as 13 solar constants when the spacecraft reaches its 0.28AU perihelion. It is essential to verify the thermal design of the instrument, especially the heat evacuation property and to assess the thermo-mechanical behavior of the instrument when submitted to high thermal load. Therefore, a thermal balance test under 13 solar constants was performed on the first model of EUI, the Structural and Thermal Model. The optical analyses and experiments performed to characterize accurately the thermal and divergence parameters of the flux are presented; the set-up of the test, and the correlation with the thermal model performed to deduce the unknown thermal parameters of the instrument and assess its temperature profile under real flight conditions are also presented. [less ▲]

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See detailRay tracing enhancement for space thermal analysis: isocell method
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Sarler, Bozidar; Massaroti, Nicola; Nithiarasu, Perumal (Eds.) Third International Conference on Computational Methods for Thermal Problems (2014, June 02)

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the lumped parameter method is still dominant. Radiative exchange factors (REFs) are usually computed through Monte Carlo ray-tracing. Due to the large number of elements composing a FE model, the computation of the REFs is prohibitively expensive. The developments of the new Isocell quasi-Monte Carlo ray tracing method are presented. The Isocell method enhances the uniformity of the generated quasi-random sequence of ray directions and leads to faster convergence. It is associated with different surface sampling to derive the REFs. The method is benchmarked against ESARAD, the standard ray-tracing engine for thermal analysis used in the European aerospace industry. Various geometries are used. In particular, one entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developed at the Centre Spatial de Liège in Belgium is used. The EUI instrument of the Solar Orbiter European Space Agency mission and will be launched in a Sun-centered 0.28 perihelion orbit in 2018. [less ▲]

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See detailThe dual-gain 10 µm back-thinned 3k x 3k CMOS-APS detector of the Solar Orbiter Extreme UV Imager
Halain, Jean-Philippe ULg; Debaize, Arnaud ULg; Gillis, Jean-Marie ULg et al

in Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, (2014), SPIE 9144-126

The Extreme Ultraviolet Imager (EUI) on-board the Solar Orbiter mission will provide image sequences of the solar atmosphere at selected spectral emission lines in the extreme and vacuum ultraviolet. For ... [more ▼]

The Extreme Ultraviolet Imager (EUI) on-board the Solar Orbiter mission will provide image sequences of the solar atmosphere at selected spectral emission lines in the extreme and vacuum ultraviolet. For the two Extreme Ultraviolet (EUV) channels of the EUI instrument, low noise and radiation tolerant detectors with low power consumption and high sensitivity in the 10-40 nm wavelength range are required to achieve the science objectives. In that frame, a dual-gain 10 µm pixel pitch back-thinned 1k x 1k Active Pixel Sensor (APS) CMOS prototype has been tested during the preliminary development phase of the instrument, to validate the pixel design, the expected EUV sensitivity and noise level, and the capability to withstand the mission radiation environment. Taking heritage of this prototype, the detector architecture has been improved and scaled up to the required 3k x 3k array. The dynamic range is increased, the readout architecture enhanced, the power consumption reduced, and the pixel design adapted to the required stitching. The detector packaging has also been customized to fit within the constraints imposed by the camera mechanical, thermal and electrical boundaries. The manufacturing process has also been adapted and back-thinning process improved. Once manufactured and packaged, a batch of sensors will undergo a characterization and calibration campaign to select the best candidates for integration into the instrument qualification and flight cameras. The flight devices, within their cameras, will then be embarked on the EUI instrument, and be the first scientific APS-CMOS detectors for EUV observation of the Sun. [less ▲]

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See detailThe Extreme UV Imager of Solar Orbiter – From detailed design to Flight Model
Halain, Jean-Philippe ULg; Rochus, Pierre ULg; Renotte, Etienne ULg et al

in Proceedings of SPIE - The International Society for Optical Engineering - Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray (2014), SPIE 9144-7

The Extreme Ultraviolet Imager (EUI) on-board the Solar Orbiter mission will provide full-sun and high-resolution image sequences of the solar atmosphere at selected spectral emission lines in the extreme ... [more ▼]

The Extreme Ultraviolet Imager (EUI) on-board the Solar Orbiter mission will provide full-sun and high-resolution image sequences of the solar atmosphere at selected spectral emission lines in the extreme and vacuum ultraviolet. After the breadboarding and prototyping activities that focused on key technologies, the EUI project has completed the design phase and has started the final manufacturing of the instrument and its validation. The EUI instrument has successfully passed its Critical Design Review (CDR). The process validated the detailed design of the Optical Bench unit and of its sub-units (entrance baffles, doors, mirrors, camera, and filter wheel mechanisms), and of the Electronic Box unit. In the same timeframe, the Structural and Thermal Model (STM) test campaign of the two units have been achieved, and allowed to correlate the associated mathematical models. The lessons learned from STM and the detailed design served as input to release the manufacturing of the Qualification Model (QM) and of the Flight Model (FM). The QM will serve to qualify the instrument units and sub-units, in advance of the FM acceptance tests and final on-ground calibration. [less ▲]

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See detailRay tracing enhancement for space thermal analysis: isocell method
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

Conference (2013, December 04)

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the lumped parameter method is still dominant. Radiative exchange factors (REFs), used to calculate radiative thermal exchanges in space, are usually computed through Monte Carlo ray-tracing. Due to the large number of elements composing a FE model, the computation of the REFs is prohibitively expensive. In the frame of a global approach, several research axes will be investigated to reduce the computational effort of the REFs with FEM. The first one focuses on accelerating the convergence and enhancing the accuracy of the ray-tracing process to decrease the number of rays required to achieve a given accuracy. The developments of the new Isocell quasi-Monte Carlo ray tracing method are presented. Based on Nusselt’s analogy, the ray direction sampling is carried out by sampling the unit disc to derive the ray directions. The unit disc is divided into cells into which random points are then generated. The cells have the particularity of presenting almost the same area and shape. This enhances the uniformity of the generated quasi-random sequence of ray directions and leads to faster convergence. This Isocell method has been associated with different surface sampling to derive the REFs. The method is benchmarked against ESARAD, the standard thermal analysis software used in the European aerospace industry. Various geometries have been used. In particular, one entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developed at the Centre Spatial de Liège in Belgium is used. The EUI instrument of the Solar Orbiter European Space Agency mission and will be launched in a Sun-centered (0.28 perihelion) orbit in 2018. [less ▲]

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See detailPerformance of Solmacs, a High PV Solar Concentrator With Efficient Optics
Thibert, Tanguy ULg; Hellin, Marie-Laure ULg; Loicq, Jerôme ULg et al

in AIP Conference Proceedings, , Volume 1477 (2012, October 05)

A new solar panel with high concentration photovoltaic technology (x700) has been designed, prototyped and tested in the SOLMACS project. The quality of concentrating optics is a key factor for high ... [more ▼]

A new solar panel with high concentration photovoltaic technology (x700) has been designed, prototyped and tested in the SOLMACS project. The quality of concentrating optics is a key factor for high module efficiency. Therefore new dedicated PMMA Fresnel lenses were studied and produced by injection molding. Lens design, material and production process were optimized to achieve a high optical yield of 86%. Thorough lens performance assessment in optical laboratory was completed with lifetime UV aging tests. Another important aspect is the thermal control of the hot spot created under the solar cell that receives the concentrated flux of 700 Suns. A dedicated heat spreader was developed to achieve passive thermal control with minimum mass and cost. This was supported by thermal models and tests at both cell and module level. 35% triple junction cells were implemented in the module. Micro-assembly technologies were used for the cell packaging and electrical connections. In support to the research, a continuous solar simulator was designed and built to assess the system performance, both at component and module level. The concentrator developments were integrated in a prototype and tested both indoor with the simulator and outdoor on the CSL solar test platform. The overall efficiency of the PV concentrator module is 28.5%. [less ▲]

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See detailUltrathin EUV Filters Testing and Characterization under High Flux (13 SC) for Solar Orbiter EUI Instrument
Jacques, Lionel ULg; Halain, Jean-Philippe ULg; Rossi, Laurence ULg et al

Conference (2011, October 07)

The test setup and characterization parameters of ultrathin EUV filters under high solar flux are presented. These 150nm thick aluminium filters are used at the entrance of the Extreme Ultraviolet Imager ... [more ▼]

The test setup and characterization parameters of ultrathin EUV filters under high solar flux are presented. These 150nm thick aluminium filters are used at the entrance of the Extreme Ultraviolet Imager (EUI) payload, which is developed at the Centre Spatial de Liège for the Solar Orbiter ESA M-class mission. The solar flux that they shall have to withstand will be as high as 13 solar constants when the spacecraft reach its 0.28AU perihelion. A specific design based on additional ribs has therefore been developed to enhance the thermal behaviour and heat evacuation while preserving its optical properties. It is essential to assess the design performances under the Solar Orbiter high solar flux. Therefore, thermal vacuum test under 13 solar constants will be performed. The filters temperature profiles will be measured during the tests through infrared imaging. A thermal correlation of the test will then be performed to deduce the filters actual thermal properties to be used in the global instrument geometrical and thermal mathematical models. [less ▲]

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See detailProspects for space solar power in Europe
Summerer, Leopold; Jacques, Lionel ULg

Conference (2011, October 04)

In 2002, a phased, multi-year approach to space solar power has been published. Following this plan, several activities have matured the concept and technology further in the following years. Despite ... [more ▼]

In 2002, a phased, multi-year approach to space solar power has been published. Following this plan, several activities have matured the concept and technology further in the following years. Despite substantial advances in key technologies, space solar power remains still at the weak intersections between the space sector and the energy sector. In the 10 years since the development of the European SPS Programme Plan, both, the space and the energy sectors have undergone substantial changes and many key enabling technologies for space solar power have advanced significantly. The present paper attempts to take account of these changes in view to assess how they influence the prospect for space solar power work for Europe. [less ▲]

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See detailThe technical challenges of the Solar-Orbiter EUI instrument
Halain, Jean-Philippe ULg; Rochus, Pierre ULg; Renotte, Etienne ULg et al

in Proceedings - Society of Photo-Optical Instrumentation Engineers (2010), 7732(26),

The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide EUV and Lyman-α images of the ... [more ▼]

The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide EUV and Lyman-α images of the solar atmospheric layers above the photosphere. The EUI instrument is based on a set of challenging new technologies allowing to reach the scientific objectives and to cope with the hard space environment of the Solar Orbiter mission. The mechanical concept of the EUI instrument is based on a common structure supporting the HRI and FSI channels, and a separated electronic box. A heat rejection baffle system is used to reduce the Sun heat load and provide a first protection level against the solar disk straylight. The spectral bands are selected by thin filters and multilayer mirror coatings. The detectors are 10µm pitch back illuminated CMOS Active Pixel Sensors (APS), best suited for the EUI science requirements and radiation hardness. This paper presents the EUI instrument concept and its major sub-systems. The current developments of the instrument technologies are also summarized. [less ▲]

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See detailThermal Design of the OUFTI-1 nanosatellite
Jacques, Lionel ULg

Master's dissertation (2009)

OUFTI-1 is the first nanosatellite developed at the University of Liège and even the first one ever made in Belgium. This student project takes place within the framework of a long-term goal program ... [more ▼]

OUFTI-1 is the first nanosatellite developed at the University of Liège and even the first one ever made in Belgium. This student project takes place within the framework of a long-term goal program called LEODIUM (Liège in Latin). The goal of this program is to provide hands-on experience to engineering students through the development of a series of nanosatellite for scientific experiments in cooperation with space industries of the region of Liège. OUFTI-1 will be the first satellite ever equipped with one of the latest digital amateur radio communication protocol : the D-STAR protocol. This technology represents one of the three payload of OUFTI-1, since one target of the mission is to test this new protocol in space. The two other payloads are high efficiency solar cells provided by Azur Space and an innovative electrical power system developed with Thales Alenia Space ETCA. OUFTI-1 will hopefully be launched on the new European launcher Vega with eight other student nanosatellites. This present thesis focuses on the thermal design of OUFTI-1 whose goal is to guarantee all components are functioning within their allowable temperature range. With this in mind, different thermal model of increasing complexity are developed within both Matlab/Simulink and ESATAN/ESARAD environments. based on their results, proper measures will be taken to ensure all the components works indeed in their allowable range of temperatures. [less ▲]

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