Importance of the plasma motion on wave propagation properties

Importance of the plasma motion on wave propagation properties

Context – The properties of wave propagation in a moving medium differ from those in a medium at rest. In the case of a rotating medium, rotation leads to circular birefringence, and thus to a rotation of the polarization of a linearly polarized wave propagating along the rotation axis of this medium. In plasmas, it has recently been uncovered that this mechanical effect might be at play in the rotating magnetosphere that surrounds pulsars, possibly affecting galactic magnetic field measurements in astrophysics. The same mechanical effect in plasmas may also enable new means to manipulate light in laboratories on Earth. Furthermore, beyond affecting wave polarization, which is the spin component of the wave’s angular momentum, it has just been found that plasma rotation can also affect the wave’s orbital angular momentum in a phenomenon known as image rotation. This is the manifestation of the beam drag induced by the medium’s motion. Beyond fundamental questions, this new effect in plasmas may hold promise for rotation diagnostics, notably in magnetic confinement fusion experiments.

Objectives – The effect of motion on plasma waves remains largely unexplored and is not currently accounted for in models. The Warp project, funded through ANR and started in 2022 in collaboration with specialists in astrophysics and high–energy density plasma experiments, aims to systematically study these effects. Two PhD theses are developing models to capture the effect of rotation on plasma waves beyond the simple models available to date. The postdoctoral project will apply these new models to practical rotating plasma configurations to quantify the importance of rotation effects in experiments or natural environments. Depending on the candidate’s skills and interests, this could be in astrophysics or magnetic confinement fusion, ultimately leading to ways to account for or leverage these effects.

Candidate education – PhD in plasma physics or wave physics.

Candidate profile : Strong analytical skills, good physical intuition, curiosity and resourcefulness are essential assets for this project. Knowledge of and experience with wave physics in magnetic confinement fusion and/or space physics will be helpful.

Keywords – Electrodynamics / electromagnetism & optics / plasma physics.

Supervisor & contact – Renaud Gueroult – , +33 (5) Preferred start date – Summer–Fall 2024, until filled.

References:

• 1 R. Gueroult et al. (2019), Nat. Commun., 10, 3232
• 2 R. Gueroult, J.-M. Rax and N. J. Fisch (2020), Phys. Rev. E, 102, (R)
• 3 J.-M. Rax and R. Gueroult (2021), J. Plasma Phys., 87,
• 4 R. Gueroult, J.-M. Rax and J. J. Fisch (2023), Plasma Phys. Control. Fusion, 65, 34006
• 5 J. Langlois and R. Gueroult (2023), Phys. Rev. E, 108,
• 6 J. Langlois and R. Gueroult (2024), arXiv: