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Stage M2: Numerical study of wave turbulence in partially-magnetized plasmas

Du 1 mars 2026 au 30 août 2026

Laboratoire de Physique des Plasmas, Ecole Polytechnique, Rte de Saclay, 91128 Palaiseau

Partially-magnetized E×B plasmas, where electrons are magnetized but ions are not, are key to technologies like Hall thrusters and ion sources for neutral beam injection for fusion. These plasmas host electrostatic instabilities (e.g., gradient-drift, lower-hybrid, electron cyclotron drift, modified two-stream) that can lead to wave turbulence. This project aims to study wave turbulence-driven transport with a pseudo-spectral solver. The focus is on understanding large-scale structure formation and the impact of parameters like gradients and boundaries. Results will be validated against kinetic simulations and will be used to assess the impact of the turbulent transport into macroscopic quantities as compared to experiments of electric propulsion thrusters.

Partially-magnetized plasmas are characterized by electrons that are magnetized whereas the ion Larmor radius remains larger than the typical length of the domain. These plasmas are widely used in technological applications such as Hall thrusters, ion sources for neutral beam injection for fusion, or Penning and magnetron discharges. In these applications, the electric and magnetic fields are mostly perpendicular to each other, hence called ExB configurations, where the electrons form a Hall current in the ExB direction and the ions are mostly accelerated by the electric field.

Partially-magnetized ExB plasmas can host a wide variety of electrostatic instabilities, such as gradient-drift, lower-hybrid, electron cyclotron drift, modified two-stream, etc (See [1, 2] for a recent review). These instabilities can lead to wave turbulence, which modifies the macroscopic properties of the discharge (e.g., the electric current, plasma density, etc). For this reason, a better understanding of the wave turbulence is fundamental for the characterization of ExB plasmas.

This project is developed in the frame of the ERC grant HiMomPlas on the theoretical study of electric propulsion plasmas. In this project, we propose to study wave turbulence transport in plasmas. The goal of the project is to extend a pseudo-spectral solver [3], currently developed at LPP to study turbulence in fusion plasmas. Based on the model proposed by previous works [4, 5], this project aims at analyzing the reasons for the observed tendency of formation of large structures as well as studying the impact of the different discharge parameters (e.g., gradients, boundaries, ions flows, etc). Comparison with kinetic simulations will be done. Similarly, the candidate will assess the impact of the turbulent transport into macroscopic quantities as compared to experiments of electric propulsion thrusters.

[1] Petronio et al. Phys. Plasmas 30, 012104 (2023)
[2] Boeuf & Smolyakov. Phys. Plasmas 30, 050901 (2023)
[3] Guillon & Gürcan Phys. Plasmas 32, 012306 (2025)
[4] Koshkarov Phys. Rev. Lett. 122, 185001 (2019)
[5] Smolyakov et al. Plasma Phys. Control. Fusion 59 014041 (2017)