Statistical properties of transport in plasma turbulence

Abstract

The statistical properties of the $E \times B$ flux in different types of plasma turbulence simulations are investigated using probability density distribution functions (PDF). The physics included in the models ranges from two dimensional drift-wave turbulence to three dimensional MHD simulations. The PDFs of the flux surface averaged transport are in good agreement with an extreme value distribution (EVD). This is interpreted as a signature of localized vortical structures dominating the transport on a flux surface. Models accounting for a local input of energy and including the global evolution of background profiles show a more bursty behavior in 2D as well as 3D simulations of interchange and drift type turbulence. Although the PDFs are not Gaussian, again no algebraic tails are observed. The tails are, in all cases considered, in excellent agreement with EVDs.Comment: 16 pages and 11 figure

Convective transport by intermittent blob-filaments: Comparison of theory and experiment

“…The characteristics of PDF tails in various edge turbulence models, and some of the subtleties in their interpretation, are discussed further in Ref. 251.…”

Non-Gaussian properties of global momentum and particle fluxes in a cylindrical laboratory plasma

“…Non-Gaussian properties of C and P have been studied theoretically 5,13,14 and experimentally. [4][5][6][15][16][17] Global transport phenomena are determined by the flux events averaged over the flux surface and=or over the full azimuthal direction.…”

Uncertainty propagation by using spectral methods: A practical application to a two-dimensional turbulence fluid model

“…In fact, models similar the the one used to investigate the SMT plasma dynamics have been used also for the tokamak SOL (see, e.g., Refs. [16,17]). …”

“…In Fig. 4 we present the distributions of η obtained at x = 40 (first row) and x = 60 (second row) with the spectral code for (K, L, M, N ) = (1, 12, 9, 1), (2,14,11,2), (3,16,13,3) (left, middle, and right columns, respectively). We observe that the distributions slightly depend on the number of spectral terms used in the simulations and that η does not depend linearly on…”

“…We apply the proposed methodology to a two-dimensional fluid model used to investigate the plasma dynamics in basic plasma physics experiments, such as linear devices [12] and simple magnetized torus (SMT) [13][14][15], and in the tokamak scrape-off layer (SOL) [16,17].…”