Transition in multiple-scale-lengths turbulence in plasmas

Statistical theory of strong turbulence in inhomogeneous plasmas is extended to the state where fluctuations with different scale lengths, micro and semi-micro modes, coexist. Their nonlinear interactions give several states of turbulence: in one state, the micro mode is excited while the semi-micro mode is quenched; in another state, the latter is excited while the micro mode is suppressed. A new turbulence transition with a hard bifurcation was obtained. A phase diagram was obtained. A new insight is given for the physics of internal transport barrier. (author)