Description du sujet de thèse

Laser-plasma accelerators can generate electric fields of several hundred GV/m, a thousand times greater than those of conventional radiofrequency accelerators. They can thus produce high-energy electrons over extremely short distances. The maximum energy of these so-called wakefield accelerators is ultimately limited by the dephasing between the electron beam and the accelerating field, generated by the plasma waves. This dephasing comes from the velocity difference between the accelerated particles, which quickly ramp up to almost the light speed in a vacuum, and the driver laser pulse that gets slower in plasmas. This limitation could, in principle, be removed by controlling the velocity of the accelerating plasma waves, which requires that the laser pulse propagates in a vacuum at a superluminal velocity (larger than c). We recently produced such a pulse experimentally, using a Bessel laser beam having spatio-temporal couplings, and showed numerically that it could dramatically increase the energy of the electrons produced through laser-plasma acceleration. However, many questions remain open: how to inject electrons into such accelerator, or how to ensure that the laser keeps its special properties in the plasma over long distances, and what is the energy efficiency of this accelerator?
The project aims at studying numerically and theoretically this new acceleration scheme

Contexte de travail

The thesis will take place at Laboratoire d'Optique Appliquée (LOA) in Palaiseau.
Member of the Institut Polytechnique de Paris (IP-Paris), the Laboratoire d'Optique Appliquée has played a pioneer role on laser-matter interaction and plasma physics for more than 30 years. The research activity covers a broad spectrum of topics in ultrafast laser science including the development of ultra-intense femtosecond laser systems, the physics of laser filamentation in air and the realization of compact sources of ultrafast energetic radiation and particles for societal, academic and industrial applications.

The PhD is funded by a Marie Curie fellowship, which includes two secondments of 2 weeks each at DESY in Germany.