  The competition between drift wave and interchange physics in general
E-cross-B drift turbulence is studied with computations in three dimensional
tokamak flux tube geometry. For a given set of background scales, the parameter
space can be covered by the plasma beta and drift wave collisionality. At large
enough plasma beta the turbulence breaks out into ideal ballooning modes and
saturates only by depleting the free energy in the background pressure
gradient. At high collisionality it finds a more gradual transition to
resistive ballooning. At moderate beta and collisionality it retains drift wave
character, qualitatively identical to simple two dimensional slab models. The
underlying cause is the nonlinear vorticity advection through which the self
sustained drift wave turbulence supersedes the linear instabilities, scattering
them apart before they can grow, imposing its own physical character on the
dynamics. This vorticity advection catalyses the gradient drive, while
saturation occurs solely through turbulent mixing of pressure disturbances.
This situation persists in the whole of tokamak edge parameter space. Both
simplified isothermal models and complete warm ion models are treated.
