title: System size effects on gyrokinetic turbulence.
abstract: The scaling of turbulence-driven heat transport with system size in magnetically confined plasmas is reexamined using first-principles based numerical simulations. Two very different numerical methods are applied to this problem, in order to resolve a long-standing quantitative disagreement, which may have arisen due to inconsistencies in the geometrical approximation. System size effects are further explored by modifying the width of the strong gradient region at fixed system size. The finite width of the strong gradient region in gyroradius units, rather than the finite overall system size, is found to induce the diffusivity reduction seen in global gyrokinetic simulations.
authors.affiliation: Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne, PPB, 1015 Lausanne, Switzerland.
authors.forename: B F
authors.initials: BF
authors.lastname: McMillan
authors.forename: X
authors.initials: X
authors.lastname: Lapillonne
authors.forename: S
authors.initials: S
authors.lastname: Brunner
authors.forename: L
authors.initials: L
authors.lastname: Villard
authors.forename: S
authors.initials: S
authors.lastname: Jolliet
authors.forename: A
authors.initials: A
authors.lastname: Bottino
authors.forename: T
authors.initials: T
authors.lastname: Görler
authors.forename: F
authors.initials: F
authors.lastname: Jenko