A Unified Theory of Toroidal Momentum Transport and Momentum Transport Bifurcations by Drift Wave Turbulence*

We present a unified theory of toroidal momentum transport, treating both resonant and non-resonant particle contributions. A general momentum conservation theorem is proved, which relates momentum density evolution to the resonant particle momentum flux, the wave momentum flux and a refractive force due to straining of wave packets. The wave momentum flux is calculated using a Chapmen-Enskog like expansion of the wave kinetic equation. The results are used to explain a new class of momentum transport bifurcation. Possible origins of hysteresis are discussed.