Behavior of a zonal flow near the threshold

Numerical solutions of the model equation describing nonlinear dynamics of a zonal flow near marginal stability [Phys. Rev. Lett. 89, 185002 (2002)] are presented for different parameter regimes. The present simulations confirm the conclusion that below certain critical values of the drift wave to zonal flow growth rates ratio the system bifurcates from the stationary state to limit cycle behavior. Well below the bifurcation point, oscillations of the zonal flow amplitude become chaotic. (C) 2003 American Institute of Physics.