In the present work the generation of zonal flows in collisionless trapped electron mode (TEM) turbulence is studied analytically. A reduced model for TEM turbulence is utilized based on an advanced fluid model for reactive drift waves. An analytical expression for the zonal flow growth rate is derived and compared with the linear TEM growth, and its scaling with plasma parameters is examined f...

Relaxed state of a slightly resistive and turbulent magnetized plasma is obtained by invoking the Principle of Minimum Dissipation which leads to

G. G. PLUNK1,2,6 †, S. C. COWLEY3,4, A. A. SCHEKOCHIHIN5 AND T. TATSUNO6 Department of Physics, University of California, Los Angeles, CA 90095, USA Wolfgang Pauli Institute, University of Vienna, A-1090 Vienna, Austria EURATOM/UKAEA Fusion Association, Culham Science Centre, Abington OX 143DB, UK Plasma Physics, Blackett Laboratory, Imperial College, London SW7 2AZ, UK Rudolf Peierls Centre fo...

with τe being the electron collision time. nEQ is an equilibrium density associated with neoclassical fields and currents. K (nEQ) =−∇qJPS, which in turn is driven by the corresponding neoclassical potential JPS = 1 C (φPS). The contribution of impurities to the gross plasma density ni,0 is assumed to be negligible, i. e. ni = ni,0+nimp ≈ ni,0. For cold impurities the ion-drift velocity is give...

A calculation which describes the spin-up of toroidal plasmas by the radial propagation of turbulence fronts with broken parallel symmetry is presented. The associated flux of parallel momentum is calculated by using a two-scale direct-interaction approximation in the weak turbulence limit. We show that fluctuation momentum spreads faster than mean flow momentum. Specifically, the turbulent flu...

The bicoherence of fluctuations in a system of drift waves and zonal flows is discussed. In strong drift-wave turbulence, where broadband fluctuations are excited, the bicoherence is examined. A Langevin equation formalism of turbulent interactions allows us to relate the bicoherence coefficient to the projection of nonlinear force onto the test mode. The dependence of the summed bicoherence on...

The direct quantitative correspondence between theoretical predictions and the measured plasma fluctuations and transport is tested by performing nonlinear gyro-Landau-fluid simulations with the GRYFFIN ~or ITG! code @W. Dorland and G. W. Hammett, Phys. Fluids B 5, 812 ~1993!; M. A. Beer and G. W. Hammett, Phys. Plasmas 3, 4046 ~1996!#. In an L-mode reference discharge in the DIII-D tokamak @J....

A series of BOUT @X. Q. Xu et al., Phys. Plasmas 7, 1951 ~2000!# simulations is conducted to investigate the physical processes which limit the density in tokamak plasmas. Simulations of turbulence in tokamak boundary plasmas are presented which show that turbulent fluctuation levels and transport increase with collisionality. At high edge density, the perpendicular turbulent transport dominate...

The dynamo mechanism driven by weak plasma turbulence, called the p-ω dynamo, is studied. Under the assumption of the uniform rotation of a celestial body, a dynamo equation is derived from the magnetic induction equation based on mean field electrodynamics. It is well known that differential rotation is indispensable for an α-ω dynamo to be operative. In contrast to the α-ω dynamo model, no ma...