PINCH EFFECT IN 2-DIMENSIONAL TURBULENCE

A two-dimensional model describing the nonlinear evolution of pressure driven flute modes in an inhomogeneous magnetic field is derived. The model couples fluctuations in ion and electron temperatures and densi ties with the fluctuations in the electrostatic potential. The well kn own Rayleigh-Taylor instability is recovered by linear stability analy sis based on a local approach in the long-wave limit. This mode is uns table when the pressure profile is more peaked than the profile of the square of the magnetic field. Using a quasi-linear approach it is rev ealed that the turbulent fluctuations driven by this instability may g ive rise to up-gradient transport, a 'pinch flux', of either heat or p articles.