Analyses of Nonlinear Coupling for Turbulent Structural Formation in Magnetized Cylindrical Plasmas

Turbulent plasmas form a variety of meso-scale structures such as a zonal flow and a streamer, which regulates micro-scale fluctuations. The mechanism of nonlinear structural formation has been studied with a three-field (density, potential and parallel velocity of electrons) reduced fluid model, which describes the resistive drift wave turbulence in magnetized cylindrical plasmas. The turbulent structure, streamer, is selectively formed by changing the ion-neutral collision frequency, which is the damping parameter of the zonal flow, in the target plasma. The turbulent structures are formed by nonlinear wave coupling of eigenmodes. The possible coupling can be controlled by restricting some modes in numerical simulations, and it is found that the same structural formation mechanism is dominant within several kinds of coupling paths.