Main objectives and applications

The ITFIP team activity covers fundamental and exploratory research, making use of large scale facilities, to perform experimental and theoretical studies of laser-plasma interaction in the strong field regime, and of laser propagation and guiding at ultra-high intensity in plasma media.

 The main application domains are the acceleration of particles to ultra-relativistic energy in under-dense plasmas, the development of new coherent, soft X-ray sources created by short pulse lasers and inertial fusion.

Research topics

ITFIP is actively pursuing modelling and experimental studies of electron acceleration driven by laser wakefield in plasmas. Several key issues for the development of future accelerators are being studied, such as intense laser guiding inside waveguides, the design of new plasma cells providing tailored density profiles, physical mechanisms for trapping and accelerating electrons in a plasma wave for multi-stage laser plasma accelerators.

This work is undertaken in the frame of the electron acceleration scientific programme of the Apollon Facility and contributes to the design and commissioning of the long focal area. The ITFIP team is involved in the coordination of working groups of the European projects EUPRAXIA (Design Study and Preparatory Phase) and ARIES up to 2022.

The ITFIP team uses Particle in Cell (PIC) numerical codes such as WAKE, FBPIC and Smilei and actively contributes to the development of Smilei. Experiments are performed using French (UHI100) and European (LLC, Lund Sweden, HZDR Dresden, Germany) laser facilities in the frame of LaserLab transnational access.


3D view of a simulation performed with Smilei illustrating laser wakefield acceleration of ionisation injected electrons.
Violet: enveloppe of the laser electric field;
blue: electron density; white: electrons trapped after ionisation in the plasma cavity.

Simulation of laser wakefield acceleration of electrons with ionization injection, F. Massimo


An intense laser pulse (red) propagates through a partially ionised hydrogen-nitrogen plasma and drives a nonlinear plasma wave (electron density in blue) in the laser's wake. The laser pulse further ionises the plasma nitrogen, releasing electrons (in white) from its inner energy levels. Some of these electrons are trapped in the plasma wave, where they are subject to a strong electric field that accelerates them up to a relativistic energy level.

Modelling activities

Modelling activities are strongly coupled to the experimental programme of the team on laser driven acceleration in plasmas.

Smilei and FBPIC PIC codes are mainly used to describe laser propagation in underdense plasmas, injection and acceleration of electron bunches in plasma cavities. In particular, F. Massimo contributes to the development of the open source code Smilei, in collaboration with several teams from the plateau de Saclay laboratories, LULI, LLR and la Maison de la Simulation of CEA. F. Massimo is also involved in the development of physical models and numerical techniques to make PIC simulations and their analysis faster.

Gas flow modelling to design plasma targets is performed using fluid simulation codes such as COMSOL Multiphysics and OpenFOAM. The comparison of these results with gas and plasma density measurements inside the target is crucial for the comparison with experiments and as input for PIC simulations, as the plasma density profile ionised by the laser is directly related to gas distribution.

Fluence measurements in experiments provide only a partial description of the laser field, which imperfections impact significantly the mechanisms of electron injection and acceleration in plasmas. To improve our understanding of these mechanisms, the team is developping fast techniques to reconstruct the laser electric field distribution from measured fluence data. This allows us to use a realistic laser distribution as input to PIC simulations and improve significantly the agreement with experimental results concerning electrons distributions in energy and in space, leading to a better understanding of observations.
Realistic simulations are also of interest to better characterise the laser beam properties and evaluate the sensitivity of electron properties to specific parameters.

The team develops numerical tools for experiments, for example modules using machine learning techniques to explore rapidly the large parameter space controlling acceleration mechanisms, and improve the properties of accelerated electron beams

On the long term, the team is aiming at designing complex experiment using "ab initio" simulations, including the design of an injector based on laser wakefield acceleration for the AWAKE experiment at CERN and future multi-stage laser plasma experiments. The objective is to simulate the various components of these experiments, ranging from plasma creation in gas target, to the transport of the electron beam to the user.


European Plasma Research Accelerator with eXcellence In Applications (EuPRAXIA) project

The ITFIP team is actively involved in the EUPRAXIA European project which preparatory phase project started in November 2022, following the inclusion of EUPRAXIA on the ESFRI roadmap. The team is involved in the simulation programme that will define global parameters and the technical design of the facility, following leardership of the work package « high accelerating gradient plasma structures » during the Design Study of EuPRAXIA.

The team has been strongly involved for more than 10 years in the coordination of national and European projects  scientifically (CILEX, EUPRAXIA, ARIES) and at the management level (Labex PALM, département PHOM de l’Université Paris Saclay, international strategy for accelerator development ALEGRO, GdR APPEL).

The team has been strongly involved for more than 10 years in the coordination of national and European projects scientifically (CILEX, EUPRAXIA, ARIES) and at the management level (Labex PALM, département PHOM de l’Université Paris Saclay, international strategy for accelerator development ALEGRO, GdR APPEL).

B. Cros is the spoke person of ALEGRO (Advanced LinEar Collider study GROup), which brings together at the international level about 80 scientists from high energy physics, accelerator physics, laser and plasma physics. The objective of ALEGRO is to coordinate international efforts to define a road map for future high gradient accelerators for particle physics, and propose joint efforts for the design of large scale facilities. This work is endorsed by the ICFA, the international committee for future accelerators.

At the national level, B. Cros has lead the  GdR Accélérateurs Plasma pompés par laser, funded by  CNRS IN2P3 from 2019 to 2023, continuing in the GdR Science of Particle Accelerators since the end of  2023.

Thesis prepared in the team

• Lewis Dickson: Accélération d'électrons par sillage laser-plasma (29 mars 2023)
• Patrick Lee: Modélisation d'un injecteur laser-plasma pour l'accélération multi-étages (11 juillet 2017)
• Thomas Audet: Développement d'un injecteur pour l'accélération laser plasma multi-étages (10 novembre 2016)
• Frédéric Desforges: Injection induite par ionisation pour l'accélération laser-plasma dans des tubes capillaires diélectriques (10 juillet 2015)
• Jean-Sébastien Macé: Modélisation du fonctionnement d’un gyrolaser He-Ne de très haute précision (21 juillet 2014)
• Jinchuan Ju: Electron acceleration and betatron radiation driven by laser wakefield inside dielectric capillary tubes (27 juin 2013)
• Amar Boudaa: Optimisation de sources XUV générées par l'interaction d'un laser sub-picoseconde avec un gaz rare (25 novembre 2010)
• Bruno Robillart: Modélisation de la physique atomique et du transfert radiatif pour le laser X-UV (29 octobre 2010)
• Franck Wojda: Mesure de l'amplitude d'une onde de plasma créée par sillage laser guidé (6 mai 2010)
• Daniel Zimmer (co-tutelle GSI): A new double laser pulse pumping scheme for transient collisionally excited plasma soft x-ray laser (6 juillet 2010)

Thesis defended before 2010

• Jamil Habib: Etude et développement d'un laser XUV à haute cadence pour la station LASERIX. Application à la radiobiologie (21 décembre 2009)
• Kamel Bennadji: Effets des corrections de champ local sur les propriétés thermodynamiques et de transport dans les plasmas corrélés (28 mai 2009)
• Romain Popoff: Diffusion multiple et ralentissement d'un ion basse vitesse dans un plasma de fusion (18 décembre 2008)
• Flavien Lambert (co-tutelle CEA-DAM): Approche sans orbitale des plasmas chauds et denses (6 juillet 2007)
• David Patin : Chauffage stochastique dans l'interaction laser-plasma à très haut flux (15 mars 2006)
• Antoine Bret : Ralentissement d'agrégats chargés et de charges non ponctuelles dans la matière dense et chaude (1994)

Organisation of events

• Workshop ALEGRO 2024, 19-22 March, IST Lisbon(Portugal)
• Workshop ALEGRO 2023, 22 - 24 Mach DESY, Hambourg (Allemagne)
• Journées Accélérateurs 2017 du 4 au 6 octobre 2017 à Roscoff
• Advanced an Novel Accelerators for High Energy Physics Roadmap workshop 2017, ANAR2017, du 25 au 28 avril 2017 au CERN
• Journées Accélérateurs 2015 du 4 au 7 octobre à Roscoff.
• European Conference on Laser Interaction with Matter: ECLIM2014, Septembre 2014 à Paris.
• Journées Accélérateurs de la SFP à Roscoff en 2009, 2011 et 201", qui réunit la communauté accélérateur française tous les deux ans.
• «International Workshop on High Energy Electron Acceleration Using Plasma» en juin 2005 à Paris.
• «16th International Symposium on Heavy Ion Inertial Fusion » qui a rassemblé plus de 80 spécialistes internationaux à St Malô en juillet 2006.