Selecting, characterizing, and acting on drift waves and flute modes turbulence in a low-β magnetized plasma column

We report on experiments performed on the low-beta plasma device MIRABELLE. Using a limiter, we recently observed [1,2] that when increasing the magnetic field strength transitions between various gradient driven instabilities occur. New thorough measurements allow to identify unambiguously three instability regimes. At low magnetic field the strong E(r)xB velocity shear drives a Kelvin-Helmholtz instability, whereas at high magnetic field drift waves are only observed. A centrifugal (Rayleigh-Taylor) instability is also observed in between when the poloidal velocity field is shearless and strong enough. A close connection is made between the ratio rho(s)/L-perpendicular to of the drift parameter to the radial density gradient length and each instability regime. The transition scenario from regular waves to turbulence was experimentally investigated. As for drift waves the transition from regular state to spatio-temporal chaos and turbulence follows the quasi-periodicity (or Ruelle-Takens-Newhouse) route. Eventually we present new results on the efficiency of control and synchronization methods on Kelvin-Helmholtz and Rayleigh-Taylor spatio-temporal chaos in comparison with drift waves.