Nonlinear mechanisms for drift wave saturation and induced particle transport

Drift wave test particle transport in reversed shear profile

Drift wave maps, area preserving maps that describe the motion of charged particles in drift waves, are derived. The maps allow the integration of particle orbits on the long time scale needed to describe transport. Calculations using the drift wave maps show that dramatic improvement in the particle confinement, in the presence of a given level and spectrum of E3B turbulence, can occur for q(r...

Nonlinear Self-Sustained Drift-Wave Turbulence.

Numerical simulations of 3D collisional drift-wave turbulence in a sheared magnetic field are presented which demonstrate that fluctuations are self-sustaining even though the linear eigenmodes of the system are all damped. An analytic calculation reveals that the source of the turbulence is a nonlinear streaming instability in which radial flows extract energy from the ambient density gradient...

Nonlinear Simulation of Drift Wave Turbulence

In a two-dimensional version of the modified Hasegawa-Wakatani (HW) model, which describes electrostatic resistive drift wave turbulence, the resistive coupling between vorticity and density does not act on the zonal components (ky = 0). It is therefore necessary to modify the HW model to treat the zonal components properly. The modified equations are solved numerically, and visualization and a...

Extremal Bounds on Drift Wave Growth Rates and Transport

Spiral wave drift induced by stimulating wave trains.

We investigate the drift of a spiral wave core in a homogeneous excitable medium under the influence of a periodic stimulation by wave trains close to the core. Two important results were found. First, as opposed to existing theories of spiral wave drift, we observe drift induced by wave trains with periods larger than the period of the freely rotating spiral wave. Second, when investigating th...