Post-doc (M/F) in Laser-Plasma Acceleration

Job Description

Missions

Laser-plasma accelerators (LPAs) are a compact alternative to conventional accelerators and can generate ultra-relativistic electron beams over centimeter-scale distances thanks to extreme accelerating fields. A key limitation for beam energy is the dephasing between accelerated electrons and the plasma wake: electrons eventually outrun the accelerating phase, which caps the effective acceleration length and final energy. We explore a dephasing-free concept based on superluminal laser pulses, where the focal point can be made to propagate through the plasma at an arbitrarily controlled velocity, including faster than the speed of light in vacuum. This is achieved by combining an axiparabola, which focuses each annular portion of the near-field at a different longitudinal position, with a controlled radial delay introduced via spatiotemporal couplings (STC). Experimentally, these STC can be implemented using a lens doublet that introduces a tunable radial delay. A more advanced, programmable method would be to use a large-aperture spatial light modulator (SLM) to impose tailored spectral phase and space-dependent delay. This added programmability would enable greater control on the laser propagation to implement flying-focus.

The postdoctoral researcher will lead the experimental implementation of a flying-focus laser pulse for laser wakefield acceleration on LOA's 100 TW-class laser and extend the approach to the Apollon petawatt facility. The work will focus on creating and tuning the spatiotemporal couplings required for controlled focal-velocity propagation, with a particular emphasis on exploring the possibility of using large-aperture spatial light modulators to imprint programmable, radius-dependent spectral phase and delay. The postdoc will develop the associated spatiotemporal metrology, integrate the flying-focus optics into high-intensity beamlines and carry-out laser-plasma acceleration experiments. A key research direction will be to explore new designs using flying-focus to improve LWFA-based X-ray sources. Although this is primarily an experimental position, we also encourage applications from motivated candidates with a strong simulation and/or theoretical background; the project scope can be adapted to the successful applicant's expertise and interests.

Activity

- Design, preparation, and participation in laser-plasma acceleration experimental campaigns
- Design of diagnostics for spatiotemporal couplings and measurement of these couplings on laser systems
- Analysis of experimental data
- Numerical simulations with optical propagation and Particle-in-Cell codes
- Scientific communication: writing scientific articles and presenting at conferences

Your Profil

Skills

- PhD in Physics with strong interest for experimental physics.
- Expertise in one of the followings: laser-plasma accelerators, high-intensity lasers, laser-plasma interaction, optics.
- Ability to work in team, coordinate with PhD students and staff and lead experimental campaigns.
- Good communication skill, oral and written in order to write scientific articles and present result in international conferences.
- Experience with one of the following would be a plus: optical design software (Zemax), Particle-in-Cell simulations, Spatial light modulators (SLMs).

Your Work Environment

The Laboratoire d'Optique Appliquée (LOA) is a joint research unit of the CNRS, École Polytechnique, and ENSTA Paris, located on the École Polytechnique campus in Palaiseau. A pioneer in laser-matter interaction and plasma physics for more than 30 years, the laboratory's research spans a broad range of topics in ultrafast science, including the development of ultra-intense femtosecond laser systems, the physics of laser filamentation in air, and the development of compact sources of radiation and energetic particles for academic, societal, and industrial applications. The selected candidate will join the Ultrafast Particle and X-ray Sources group (UPX).

Compensation and benefits

Compensation

Between 3131€ et 4143€ gross per month depending on experience.

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions