Pseudo-classical transport II: A nonlinear theory of the ’’collisionless’’ drift instability

A self-consistent theory of the evolution of a plasma slab supporting a finite amplitude drift wave that has trapped the resonant electrons is presented. Previous work is extended to include the effect of particle trapping on the evolution of the finite amplitude wave. The connection between this theory and other works, using quasi-linear theory, on the anomalous transport associated with low frequency drift waves is considered. It is shown that, for parameters typical of tokamak plasmas, particle trapping may result in the nonlinear stabilization of the wave at amplitudes, (eΦ0/T) ≃10−2, that are of the same order as those observed in experiments. The application of this work to experiments is discussed, and it is found to be potentially useful in understanding the drift wave spectrum and transport rates observed in computer simulations, stellarators, and future tokamak experiments.