Turbulence and Turbulent transport are ubiquitous in nature. There are a number of mechanisms by which this transport can be changed. These include turbulent amplitude and the phase between the advecting and advected quantities. We will discuss the basic mechanismss and then we will talk about a new effect the might play an important role in controlling the phase and therefore the transport in some of these sytems.
As an application of these we note that over the last 2 decades, simple dynamical models for fusion plasmas have been able to capture a remarkable amount of the dynamics of the core and edge transport barriers found in many devices. Further adding to this model a simple model for the phase effects, due to multiple instabilities, between the transported fields such as density and temperature, we can investigate whether the dynamics of more continuous transitions such as the I-mode can be captured and understood. If so, what can the model tell us about control knobs for these promising regimes?