Successive bifurcations to chaotic state in the nonlinear evolution of collisional drift wave

The successive bifurcations from a stationary state to a chaotic state in the nonlinear evolution of the collisional drift wave are studied on a set of model equations derived by Nishi-Kawa, Hatori and Terashima. A new truncation scheme is introduced to eliminate numerical instabilities observed by them. It is shown that a model system exhibits an inverted bifurcation as to the stability of a fixed point to the case of the 12-mode system and a normal bifurcation otherwise. All cases, though different in the type of bifurcations of fixed points, undergo a sequence of bifurcations, exhibiting single periodic and doubly periodic and aperiodic motions successively. The properties of stochastic states are also investigated. (author)