Suprathermal ion transport in turbulent magnetized plasmas

Résultats de recherche: Thèse externeThèse de doctorat


Inspired by suprathermal ion experiments in the basic plasma experiment TORPEX, the transport of suprathermal ions in ideal interchange mode turbulence is theoretically examined in the simple magnetized torus configuration. We follow ion tracer trajectories as specified by ideal interchange mode turbulence imported from a numerical simulation of drift-reduced Braginskii equations. Using the variance of displacements, σ2(t)∼tγ, we find that γ depends strongly on suprathermal ion injection energy and the relative magnitude of turbulent fluctuations. The value of γ also changes significantly as a function of time after injection, through three distinguishable phases: ballistic, interaction, and asymmetric. During the interaction phase, we find the remarkable presence of three regimes of dispersion: superdiffusive, diffusive, and subdiffusive, depending on the energy of the suprathermal ions and the amplitude of the turbulent fluctuations. We contrast these results with those from a “slab” magnetic geometry in which subdiffusion does not occur during the interaction phase. Initial results from TORPEX are consistent with data from a new synthetic diagnostic used to interpret our simulation results. The simplicity of the simple magnetized torus makes the present work of interest to analyses of more complicated contexts ranging from fusion devices to astrophysics and space plasma physics.
langue originaleAnglais
L'institution diplômante
  • Ecole Polytechnique Fédérale de Lausanne (EPFL)
  • Fasoli, Ambrogio F., Superviseur, Personne externe
  • Furno, Ivo, Superviseur, Personne externe
la date de réponse13 févr. 2015
Lieu de publicationLausanne
Les DOIs
Etat de la publicationPublié - 2015

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