Electro-optical probes design for impulse fields characterization

Characterization methods for LMJ’s layered cryogenic targets

Inertial Fusion on the Laser Megajoule facilty requires to form a spherical DT layer at cryogenic temperature. A major topic of interest for fusion experiments is the characterization of the layer quality and thickness. The characterization will be done using two technics : optical shadowgraphy and X-ray phase contrast analysis. A cryostat developed by CEA is already available to work on future target designs and layer characterization.
The objectives of the PhD are to understand and model (theorically and numerically) the physics of the layer observation and to develop the characterization test bench in the cryostat’s environment and the image analysis for the 3D description of the layer.
The student will have to learn to use the cryostat, its command system and its simple actual characterization system. After a bibliography research, he will have to study the physics governing the characterization (multiple reflections, refractions, phase contrast, …) and develop the acquisition and image analysis system allowing the 3D description of the layer using images obtained during experiments with the cryostat. Lastly, the coupling between the command of the cryostat and the characterization will be developed. For all these developments, the student will have access to extensive bibliographical data and the expertise of the host team

Multiscale overlay measurements

In the microelectronics industry, the lithography step is monitored using image-based overlay (IBO) or diffraction-based overlay (DBO) measurement techniques. These techniques are relatively simple to implement, fast and their specifications meet the needs of mature technologies (CMOS20nm and earlier). To exploit these techniques, dedicated metrology structures need to be integrated into specific areas. These structures have a specific design that differs from the product being manufactured. This raises the question of the representativeness of the overlay measurement resulting from these metrology techniques compared with the overlay in the product. New methods such as scanning electron techniques (SEM) are currently being developed, the major advantage of which is their ability to measure at any point in the product and in a repeatable manner. However, this technique deteriorates certain materials. Further studies must therefore be carried out to find the best conditions for using this technique in order to establish the link between misalignment in the product and comparison with measurements using conventional techniques (IBO and DBO). Other techniques, such as X-ray techniques or other methodologies will be investigated (defect analysis method, machine learning, etc.). This work will enable us to address more effectively the new technological nodes currently being developed at LETI.

Propagation of uncertainties for nuclear electromagnetic pulses measurement