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217 personnes travaillent au LJLL

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Chiffres janvier 2014

 

2015-GdT ITER - S. Kobayashi

2/12/2015 Sumire Kobayashi

Séance du 2 Décembre 2015 à 11h00.

SUMIRE KOBAYASHI,

LPP, Ecole Polytechnique.

 

TITRE,

The predator-prey interaction between zonal flows and turbulence in gyrokinetic simulations.

Résumé,

The zonal flow generation within turbulence is ubiquitous in 2D fluid
and plasma turbulence, for example, as seen in the atmosphere of Jupiter
and Saturn, Earth’s jet streams, and in various magnetically confined
fusion experiments. One of the biggest challenges in magnetic fusion is
the loss of plasma and heat due to turbulent transport. Because of its
ability to suppress turbulence, recent studies in magnetic fusion
community have focused on untangling the dynamics of zonal flow and
turbulence. However, the detailed mechanisms are still not very well
understood. During this talk, I will discuss the predator-prey-like
dynamics between zonal flows (predator) and turbulence (prey) observed
in gyrokinetic simulations. In particular, we show the emergence of
characteristic turbulent spectrum in the presence of zonal flows, which
is compared with a simple theoretical model. Also, we demonstrate some
results of dynamical fitting between nonlinear gyrokinetic simulations
and a simple Lotka-Volterra type predator-prey model. This type of
analysis allows us to extract the model coefficients that are usually
difficult to measure. The result might gives us some clues about the
underlying physics, as well as some potential of applying such analysis
in actual experimental data.