Chaos control and taming of turbulence in plasma devices

Abstract

Chaos and turbulence are often considered as troublesome features of plasma devices. In the general framework of nonlinear dynamical systems, a number of strategies have been developed to achieve active control over complex temporal or spatio-temporal behavior. Many of these techniques apply to plasma instabilities. In the present paper we discuss recent progress in chaos control and taming of turbulence in three different plasma “model” experiments: (1) Chaotic oscillations in simple plasma diodes, (2) ionization wave turbulence in the positive column of glow discharges, and (3) drift wave turbulence in a magnetized plasma column. Depending on the physical mechanism of the specific instability in each case, an appropriate control strategy is chosen out of a variety of different approaches; in particular discrete feedback, continuous feedback, or spatio-temporal open-loop synchronization. Electric control fields are externally applied to the plasma device and the chaotic or turbulent state is stabilized by only weak perturbations of the plasma equilibrium. The success of this approach is demonstrated in both experiment and numerical simulation and the actual effect of the applied control fields is investigated.