Within the CEA-IRFU (Institut de Recherche sur les Lois Fondamentales de l'Univers), the DACM (Département des Accélérateurs, de Cryogénie et de Magnétisme) is a major player at national and international level in the field of particle accelerators. It has actively participated in most of the accelerator projects of the world's leading research centres over the last decades. An important part of these activities concerns the design of accelerators, linear or circular, for high energy physics or any other scientific application. The field of particle accelerator physics requires in-depth knowledge of the beam dynamics in order to control beams perfectly. In this discipline, the DACM has also turned to new laser-plasma acceleration techniques, with a view to designing laser-plasma wakefield accelerators (LWFA) that will make it possible to significantly reduce the size and cost of future accelerators. Collaborations with international (EuPRAXIA, CERN-AWAKE) or national (LPGP-CNRS, IJCLab-CNRS) partners have been initiated for the design of LWFAs in various configurations and applications. The DACM is currently involved in the design of a reliable and compact LWFA to serve as an electron source for the AWAKE collaboration. Such an accelerator would be a world first. In order to prove its viability, the LWFA must generate reproducible high-quality beams. Detailed physical and numerical optimisations from injection to the end user will have to be implemented. The candidate will also be involved in the other LWFA projects of the DACM.
The thesis will focus on the physical and numerical study of plasma acceleration stages and transport lines between plasma stages or to the end user. The core of the studies will be the control of the quality of the particle beam (size characteristics, divergence, energy spread, ...) that results from the laser-plasma interaction and the applied electromagnetic elements. The optimal integration of the acceleration and transport sections will then be determined. At each stage, the fundamental principles for obtaining the best beam parameters will be sought, and then applied to other ALP design projects in which DACM is involved. Optimizations using machine learning algorithms are also envisaged.
The success of these studies is strongly conditioned by a solid understanding of the physical phenomena in question (6D phase space of the beam, wakefields in plasmas subjected to ultra-intense lasers, multipolar field of electromagnets) and by a good use of the corresponding simulation codes.