Transport properties for Warm Dense Matter
Transport properties in the warm dense matter regime are crucial for the modelling of planetary physics and inertial confinement fusion.
We have an opening position for a Post Doctoral Research staff member in the field of plasma physics. You will be integrated in to a team of theoretical physicist conducting Density Functional Theory (DFT)_based simulations to address problems at the edge of warm dense matter. The research aims to advance the understanding of electronic transport properties of warm dense metal in expanded regime through a combination of DFT-based simulations performed on supercomputers and on-site experiment at CEA/DAM Ile de France. Using numerical simulations and analysis tools, you will contribute tothe interpretation of experiments conducted on high-power facility, thereby advancing the understanding of electronic transport properties.
A Functional Renormalization Group Approach to Nucleon-Nucleon Interactions and the Critical End Point
This research project seeks to bridge the gap between fundamental Quantum Chromodynamics (QCD) and nuclear structure by establishing a unified framework based on the Functional Renormalization Group (FRG). By moving beyond the limitations of Chiral Effective Field Theory (?EFT) and phenomenological Energy Density Functionals (EDF), the project aims to derive nucleon-nucleon (NN) interactions directly from the underlying SU(3)c? dynamics. A pivotal feature is the implementation of a dynamic baryonization scheme, where baryonic fields emerge naturally from quark degrees of freedom as the RG scale flows from the ultraviolet to the infrared. This approach allows for an in-medium treatment of NN kernels, where coupling constants evolve as scale-dependent functions of temperature and density. The ultimate goal is to provide a consistent description of the QCD phase diagram, specifically linking the nuclear liquid-gas instability to the chiral critical end point (CEP). By tracking how baryon fluctuations drive these transitions, the work provides a first-principles theoretical counterpart to heavy-ion collision experiments, replacing empirical models with QCD-anchored functionals.
Development of an electromagnetic jet material characterization probe
The subject falls within the scope of non-destructive testing of the electromagnetic properties of materials.
The aim is to upgrade an existing experimental device based on the use of a radiofrequency probe that extracts the magnetic permeability of the material covering an object from the measured reflection coefficient. Solving the direct problem using numerical simulations allows us to establish charts that are used to solve the inverse problem. The sensitivity to material properties, spatial resolution, and measurement uncertainties of the current device are limited by the antenna. Recent studies have demonstrated the value of using an electromagnetic jet-based probe for characterization with sub-wavelength resolution. Based on this work, the objective is to design and build a new probe that meets the desired performance requirements. The candidate will be responsible for the design and simulation work and then for monitoring the production of the prototypes. He/she will also be responsible for testing these prototypes on reference objects to demonstrate their advantages over the current solution. The new probe will then be integrated into the current measurement system and process
The postdoctoral research will proceed in three main stages. The first will consist of studying the principle of electromagnetic jet antennas and proposing a probe design suitable for the measurement method. Commercial simulation software will be used for the design, followed by internal codes for the validation of the selected prototype. The second stage will involve the manufacture of the prototype, followed by tests with reference samples to validate the concept. Finally, the probe will be integrated into the test bench and the calculation and extraction chain..
In-situ 4D tracking of microstructural evolution in atomistic simulations
The exponential growth of high-performance computing has enabled atomistic simulations involving billions or even trillions of particles, offering unprecedented insight into complex physical phenomena. However, these simulations generate massive amounts of data, making storage and post-processing increasingly restrictive. To overcome this limitation, on-the-fly (in-situ) analysis has emerged as a key approach for reducing stored data by extracting and compressing relevant information during runtime without significantly affecting simulation performance.
In this context, tracking the four-dimensional (space and time) microstructural evolution of materials under extreme conditions is a major scientific challenge. Atomistic simulations provide a unique spatial resolution to analyze crystalline defects such as dislocations, twinning, vacancies and pores, which govern dynamic phase transformations, melting, damage and mechanical behavior. By capturing their spatio-temporal evolution, it becomes possible to study their statistics, correlations and collective effects in out-of-equilibrium regimes, leading to more accurate predictive material models.
This project builds on advances of the exaNBody high-performance computing platform and a recently developed in-situ clustering method in the ExaStamp molecular dynamics code at CEA. This method projects atomic information onto a 3D Eulerian grid to perform real-time clustering. The objective is to extend this approach to full 4D tracking, enabling the time-resolved monitoring of clusters. This will allow dynamic graph-based analysis of their evolution, including changes in size, shape and temporal behavior, providing new insights into microstructural dynamics at the atomic scale.
Spin-lattice interactions in Machine Learning assisted ab initio simulations
The scientific field addressed by this postdoctoral project lies at the intersection of ab initio molecular dynamics, machine learning, and the thermodynamic characterization of materials under extreme conditions. Traditional AIMD simulations are a powerful tool to study temperature- and pressure-dependent properties from first principles, but their high computational cost limits their widespread use. By developing and applying machine learning-assisted sampling techniques like MLACS, this postdoc aims to drastically reduce the computational burden while retaining ab initio accuracy. This enables the efficient exploration of phase diagrams in high-pressure and high-temperature conditions. This research contributes to both fundamental understanding and practical modeling of materials, offering high-impact tools for the scientific community.
Simulation of landslides and the associated water waves by a 3D code
Until now, tsunamis generated by underwater landslides were modelled at the CEA using a 2D long wave code (Avalanche) that was adapted to the computing resources available at the time but now seems obsolete in the literature. An initial post-doctoral study (2023-2025) showed that the 3D OpenFoam tool could accurately simulate a landslide and the associated waves in the generation zone. During this post-doctoral fellowship, a coupling between the CEA's ‘2D’ propagation code (Taitoko) and the 3D code was developed in order to propagate waves over long distances. The work carried out will be continued. The first objective will be to familiarise with the tools developed and to publish the work carried out on the 80 Mm3 collapse that occurred in Mururoa in 1979. The main objective is then to carry out simulations of potential collapses in the northern zone, bearing in mind that the main difficulty lies in defining the geometry of these potential collapses. The propagation of waves over long distances is simulated by a ‘2D’ tsunami code coupled with the OpenFoam code.
Preparation and characterization of an oxide/oxide composite
Fiber-reinforced ceramic matrix composites (CMCs) are a class of materials that combine good specific mechanical properties (properties relative to their density) with resistance to high temperatures (> 1000 °C), even in oxidizing atmospheres. They are typically composed of a carbon or ceramic fiber reinforcement and a ceramic matrix (carbide or oxide.
The proposed study focuses on the development of a low-matrix oxide/oxide CMC with suitable dielectric, thermal, and mechanical properties.
This study will be conducted in collaboration with several laboratories at CEA Le Ripault.
Influence of laser bandwidth and wavelength on laser plasma instabilities
As part of the Taranis project initiated by Thales and supported by BPI France and in collaboration with numerous scientific partners such as CEA/DAM, CELIA and LULI, work on target design and definition of the laser intended to energy production in direct drive will take place. A prerequisite for this work is to understand the laser-plasma interaction mechanisms that will occur when the laser is coupled with the target. These deleterious mechanisms for the success of fusion experiments can be regulated by the use of so-called “broadband” lasers. In addition, the choice of the laser wavelength used for the target design and the laser architecture must be defined. The objective of the postdoctoral position is to study the growth and evolution of these instabilities (Brillouin, Raman) in the presence of “broadband” lasers both from an experimental and simulation point of view, and thus to be able to define the laser conditions making it possible to reduce these parametric instabilities.