Hyperdiffusion of dust particles in a turbulent tokamak plasma - Aix-Marseille Université Access content directly
Journal Articles Physics of Plasmas Year : 2021

Hyperdiffusion of dust particles in a turbulent tokamak plasma


The effect of plasma turbulence on the trajectories of dust particles is investigated for the first time. The dynamics of dust particles is computed using the ad-hoc developed Dust Injection Simulator code, using a 3D turbulent plasma background computed with the TOKAM3X code. As a result, the evolution of the particle trajectories is governed by the ion drag force, and the shape of the trajectory is set by the Stokes number St ∝ a d /n 0 , with a d the dust radius and n 0 the density at the separatrix. The plasma turbulence is observed to scatter the dust particles, exhibiting a hyperdiffusive regime in all cases. The amplitude of the turbulent spread of the trajectories ∆r 2 is shown to depend on the ratio Ku/St, with Ku ∝ u rms the Kubo number and u rms the fluctuation level of the plasma flow. These results are compared with a simple analytical model, predicting ∆r 2 ∝ (Ku/St) 2 t 3 , or ∆r 2 ∝ (u rms n 0 /a d) 2 t 3. As the dust is heated by the plasma fluxes, thermionic emission sets the dust charge, originally negative, to slightly positive values. This results in a substantial reduction of the ion drag force through the suppression of its Coulomb scattering component. The dust grain inertia is then no longer negligible, and drives the transition from a hyperdiffusive regime towards a ballistic one.
Fichier principal
Vignette du fichier
dust_turbulence_V3 (11).pdf (1.11 Mo) Télécharger le fichier
Origin : Files produced by the author(s)

Dates and versions

hal-03663972 , version 1 (10-05-2022)



F. Nespoli, I. Kaganovich, A. Autricque, P. Tamain, Y. Marandet. Hyperdiffusion of dust particles in a turbulent tokamak plasma. Physics of Plasmas, 2021, 28 (7), pp.073704. ⟨10.1063/5.0051332⟩. ⟨hal-03663972⟩
29 View
19 Download



Gmail Facebook X LinkedIn More