Development of a predictive power model for a photovoltaic device under spatial constraints
CEA is developing new cell and module architectures and simulation tools to assess the electrical performance of photovoltaic (PV) systems in their operating environment. One of these models, called CTMod (Cell To Module), takes into account not only the different materials making up the module, but also the different cell architectures. For space applications, the community wants to use terrestrial silicon-based technologies that can be integrated on flexible PVAs (Photovoltaic Assembly). The space environment imposes severe constraints. A relevant evaluation of performance at the start and end of a mission is therefore essential for their dimensioning.
The aim of this thesis is to correlate physical models of radiation-matter degradation in space with electrical models of photovoltaic cells. Performance degradations linked to the various electron, proton and ultraviolet (UV) irradiations of the space environment will be evaluated and validated experimentally. Linked to the CTMod Model, this new approach, never seen in the literature, will able to get a more accurate understanding of interactions between radiations and PVAs. These degradations result from non-ionizing energy deposition phenomena, quantified by the defect dose per displacement, and ionizing ones quantified by the total ionizing dose for protons and electrons. In the case of UV, the excitation of electrons in matter generates chain breaks in organic materials and colored centers in inorganic materials. Initially, the solar cell used in the model will be a Silicon cell, but the model can be extended to include other types of solar cell under development, such as perovskite-based cells.
Multiphe hydrogen injection at anode side of PEMFC
The alternating feeding architecture (known as Ping-Pong) was developed by the CEA. This architecture emerged in 2013 and has been implemented in several fuel cell systems. Following the latest tests on this architecture, questions remained unanswered. First, it is a question of understanding how species (hydrogen, nitrogen, liquid and gaseous water) move in cells operating with alternating feeding. Control laws influences these movements, it will be necessary to identify the levers to make the most out of it and then to propose methods to promote the evacuation of water and nitrogen while avoiding the evacuation of hydrogen.
The thesis work will aim to optimize the anode architecture with alternating feeding and to bring this architecture to maturity. The key points are the search for an optimum control of this architecture, the achievement of a hydrogen rejection rate of less than 1%. Finally, this optimization will also have to maximize the durability of the stack.
The doctoral student will have to model the movements of species at different time scales (10ms to 10 minutes), understand the mechanisms, adapt the control laws and validate the new control laws on a test bench.
This work will identify solutions to efficiently evacuate liquid water and nitrogen and minimize H2 rejection and then obtain superior performance compared to conventional architectures.
Dynamic clamping of hygrogen fuel cells: experimental and numerical simulation approach
The impact of the clamping of PEMFC stacks has been demonstrated by the publication of numerous experimental measurements. Passive clamping systems were developped to garantee the minimum elasticity necessary notably during temperature changes or to improve the stress distribution. The new components are finer and finer presenting a reduced elasticity range, moreover latest publications demonstrate the impact of clamping on the deformation and performance of few microns thick active layers and it should be a major improvement to integrate an accurate dynamic clamping.
The first aim of the phD is to study experimetally the impact of the dynamic control of the clamping on the performances of stacks. These tests will be performed with stacks integrating either stamped metallic bipolar plates: the reference technology, or printed cells: the new technology in development at CEA. In parallel, the candidate will learn the model, actually under development thanks to a phD, simulating stresses and deformations, and the associated multiphysic parameters such as porosity or electric resistance, in function of clamping.
Thanks to the synthesis of these experimental and numerical results the candidate will improve the undertanding of the impact of the clamping and will propose solutions to improve notably the durability which is a critical point for our ongoing european or industrial projects.
In function of the phD progress, vibratory tests could be performed to evaluate the potential input of mechanical spectroscopy, notably for diagnosis.
Secure and Agile Hardware/Software Implementation of new Post-Quantum Cryptography Digital Signature Algorithms
Cryptography plays a fundamental role in securing modern communication systems by ensuring confidentiality, integrity, and authenticity. Public-key cryptography, in particular, has become indispensable for secure data exchange and authentication processes. However, the advent of quantum computing poses an existential threat to many of the traditional public-key cryptographic algorithms, such as RSA, DSA, and ECC, which rely on problems like integer factorization and discrete logarithms that quantum computers can solve efficiently. Recognizing this imminent challenge, the National Institute of Standards and Technology (NIST) initiated in 2016 a global effort to develop and standardize Post-Quantum Cryptography (PQC). After three rigorous rounds of evaluation, NIST announced its first set of standardized algorithms in 2022. While these algorithms represent significant progress, NIST has expressed an explicit need for additional digital signature schemes that leverage alternative security assumptions, emphasizing the importance of schemes that offer shorter signatures and faster verification times to enhance practical applicability in resource-constrained environments. Building on this foundation, NIST opened a new competition to identify additional general-purpose signature schemes. The second-round candidates, announced in October 2024, reflect a diverse array of cryptographic families.
This research focuses on the critical intersection of post-quantum digital signature algorithms and hardware implementations. As the cryptographic community moves toward adoption, the challenge lies not only in selecting robust algorithms but also in deploying them efficiently in real-world systems. Hardware implementations, in particular, must address stringent requirements for performance, power consumption, and security, while also providing the flexibility to adapt to multiple algorithms—both those standardized and those still under evaluation. Such agility is essential to future-proof systems against the uncertainty inherent in cryptographic transitions. The primary objective of this PhD research is to design and develop hardware-agile implementations for post-quantum digital signature algorithms. The focus will be on supporting multiple algorithms within a unified hardware framework, enabling seamless adaptability to the diverse needs of evolving cryptographic standards. This involves an in-depth study of the leading candidates from NIST’s fourth-round competition, as well as those already standardized, to understand their unique computational requirements and security properties. Special attention will be given to designing modular architectures that can support different signatures, ensuring versatility and extensibility. The proposed research will also explore optimizations for resource efficiency, balancing trade-offs between performance, power consumption, and area utilization. Additionally, resilience against physical attacks (side-channel attacks and fault injection attacks) will be a key consideration in the design process. This PhD project will be conducted within the PEPR PQ-TLS project in collaboration with the TIMA laboratory (Grenoble), the Agence nationale de la sécurité des systèmes d’information (ANSSI) and INRIA.
Distributed Passive Radar
Our objective is to detect and locate drones entering an urban area to be protected by observing the signals emitted by cellular stations. Studies have shown that it is possible to locate a drone if it is close to the listening system and the cellular station (i.e. the base station). When the situation is more complex (i.e. there is no direct path between the cellular station and the radar or in the presence of several transmitting cellular stations causing a high level of interference), a single listening system called passive radar cannot correctly detect and locate the drone. To overcome these difficult conditions, we wish to distribute or deploy in the area to be protected a set of low-complexity passive radars which optimally exploit the signals emitted by these cellular stations. A distribution and deployment strategy for passive radars must then be considered by taking into account the positions of the transmitting cellular stations. The possibility of exchanging information between passive radars must also be considered in order to better manage interference linked to cellular stations.
Software support for sparse computation
The performance of computers has become limited by data movement in the fields of AI, HPC and embedded computing. Hardware accelerators do exist to handle data movement in an energy-efficient way, but there is no programming language that allows them to be implemented in the code supporting the calculations.
It's up to the programmer to explicitly configure DMAs and use function calls for data transfers and do program analysis to identify memory bottleneck
In addition, compilers were designed in the 80s, when memories worked at the same frequency as computing cores.
The aim of this thesis will be to integrate into a compiler the ability to perform optimizations based on data transfers.
EM Signature Modeling in Multi-path Scenario for Object Recognition and Semantic Radio SLAM
Context:
The vision for future communication networks includes providing highly accurate positioning and localization in both indoor and outdoor environments, alongside communication services (JCAS). With the widespread adoption of radar technologies, the concept of Simultaneous Localization and Mapping (SLAM) has recently been adapted for radiofrequency applications. Initial proof-of-concept demonstrations have been conducted in indoor environments, producing 2D maps based on mmWave/THz monostatic backscattered signals. These measurements enable the development of complex state models that detail the precise location, size, and orientation of target objects, as well as their electromagnetic properties and material composition.
Beyond simply reproducing maps, incorporating object recognition and positioning within the environment adds a semantic layer to these applications. While semantic SLAM has been explored with video-based technologies, its application to radiofrequency is still an emerging area of research. This approach requires precise electromagnetic models of object signatures and their interactions with the surrounding environment. Recent studies have developed iterative physical optics and equivalent current-based models to simulate the free-space multistatic signature of nearby objects.
PhD Thesis:
The objective of this thesis is to study and model object backscattering in a multi-path scenario for precise imaging and object recognition (including material properties). The work will involve developing a mathematical model for the backscattering of sensed objects in the environment, applying it to 3D SLAM, and achieving object recognition/classification. The model should capture both near- and far-field effects while accounting for the impact of the antenna on the overall radio channel. The study will support the joint design of antenna systems and the associated processing techniques (e.g., filtering and imaging) required for the application.
The PhD student will be hosted in the Antenna and Propagation Laboratory at CEA LETI in Grenoble, France. The research will be conducted in partnership with the University of Bologna.
Application:
The position is open to outstanding students with a Master of Science degree, “école d’ingénieur” diploma, or equivalent. The student should have a specialization in telecommunications, microwaves, and/or signal processing. The application must include a CV, cover letter, and academic transcripts for the last two years of study.
Advanced RF circuit design in a system and technology co-optimization approach
This thesis addresses the two major challenges facing Europe today in terms of integrating the communication systems of the future. The aim is to design RF integrated circuits using 22nm FDSOI technology in the frequency bands dedicated to 6G, which will not only increase data rates but also reduce the carbon footprint of telecoms networks. At the same time, it is essential to consider the evolution of silicon technologies that could improve the energy efficiency and effectiveness of these circuits. This work will be carried out with an eye to the design methodology of radio frequency systems.
Within the framework of the thesis, the objective will be broken down into three phases. Firstly, simulation tools will be developed to predict the performance of Leti's future 10nm FDSOI technology. The second stage will involve identifying the most relevant architectures available in the literature for the application areas envisaged for the technology. A link with upstream telecoms projects will be systematically established to ensure that the candidate understands the systems' challenges.
Finally, in order to validate the concepts developed, the design of an LNA and a VCO as part of an ongoing project in the laboratory will be proposed.
The candidate will join a large team that works on new communication systems and addresses aspects of architectural study, modeling and design of integrated circuits. The candidate must have serious skills in the design of integrated circuits and radio frequency systems as well as good ability to work in a team.
Scalable thermodynamic computing architectures
Large-scale optimisation problems are increasingly prevalent in industries such as finance, materials development, logistics and artificial intelligence. These algorithms are typically realised on hardware solutions comprising clusters of CPUs and GPUs. However, at scale, this can quickly translate into latencies, energies and financial costs that are not sustainable. Thermodynamic computing is a new computing paradigm in which analogue components are coupled together in a physical network. It promises extremely efficient implementations of algorithms such as simulated annealing, stochastic gradient descent and Markov chain Monte Carlo using the intrinsic physics of the system. However, no clear vision of how a realistic programmable and scalable thermodynamic computer exists. It is this ambitious challenge that will be addressed in this PhD topic. Aspects ranging from the development computing macroblocks, their partitioning and interfacing to a digital system to the adaptation and compilation of algorithms to thermodynamic hardware may be considered. Particular emphasis will be put on understanding the trade-offs required to maximise the scalability and programmability of thermodynamic computers on large-scale optimisation benchmarks and their comparison to implementations on conventional digital hardware.
Towards a multimodal photon irradiation platform: foundations and conceptualization
Photonic irradiation techniques exploit the interactions between a beam of high-energy photons and matter to carry out non-destructive measurements. By inducing photonuclear reactions such as photonic activation, nuclear resonance fluorescence (NRF) and photofission, these irradiation techniques enable deep probing of matter. Combining these different nuclear measurement techniques within a single irradiation platform would enable precise, quantitative identification of a wide variety of elements, probing the volume of the materials or objects under study. The high-energy photon beam is generally produced by the Bremsstrahlung phenomenon within a conversion target of a linear electron accelerator. An innovative alternative is to exploit the high-energy electrons delivered by a laser-plasma source, converted by Bremsstrahlung radiation or inverse Compton scattering. A platform based on such a source would open up new possibilities, as laser-plasma sources can reach significantly higher energies, enabling access to new advanced imaging techniques and applications. The aim of this thesis is to establish the foundations and conceptualize a multimodal photonic irradiation platform. Such a device would aim to be based on a laser-plasma source and would enable the combination of photonic activation, nuclear resonance fluorescence (NRF) and photofission techniques. By pushing back the limits of non-destructive nuclear measurements, this platform would offer innovative solutions to major challenges in strategic sectors such as security and border control, radioactive waste package management, and the recycling industry.