9,063 research outputs found
Transition Probability to Turbulent Transport Regime
Transition phenomena between thermal noise state and turbulent state observed
in a submarginal turbulent plasma are analyzed with statistical theory.
Time-development of turbulent fluctuation is obtained by numerical simulations
of Langevin equation which contains hysteresis characteristics. Transition
rates between two states are analyzed. Transition from turbulent state to
thermal noise state occurs in entire region between subcritical bifurcation
point and linear stability boundary.Comment: 9 pages, 6 figures, to be published in Plasma Phys. Control. Fusio
Stochastic Transition between Turbulent Branch and Thermodynamic Branch of an Inhomogeneous Plasma
Transition phenomena between thermodynamic branch and turbulent branch in
submarginal turbulent plasma are analyzed with statistical theory.
Time-development of turbulent fluctuation is obtained by numerical simulations
of Langevin equation which contains submarginal characteristics. Probability
density functions and transition rates between two states are analyzed.
Transition from turbulent branch to thermodynamic branch occurs in almost
entire region between subcritical bifurcation point and linear stability
boundary.Comment: 10 pages, 8 figures, to be published in J. Phys. Soc. Jp
Coherent Structure of Zonal Flow and Onset of Turbulent Transport
Excitation of the turbulence in the range of drift wave frequency and zonal flow in magnetized plasmas is analyzed. Nonlinear stabilization effect on zonal flow drive is introduced, and the steady state solution is obtained. The condition for the onset of turbulent transport is obtained and partition ratio of fluctuation energy into turbulence and zonal flows is derived. The turbulent transport coefficient, which includes the effect of zonal flow, is also obtained. Analytic result and direct numerical simulation show a good agreemen
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