Drift wave vortices in inhomogeneous plasmas

The effects of density and temperature gradients on drift wave vortex dynamics are studied using a fully nonlinear model with the Boltzmann density distribution. The equation based on the full Boltzmann relation, in the short wavelength (∼ρs) region, possesses no localized monopole solution, while in the longer wavelength [∼(ρsrn)1/2] region the density profile governs the existence of monopolelike solutions. In the longer wavelength regime, however, the results of analysis show that due to the inhomogeneity of the plasma the monopoles cannot be localized sufficiently to avoid coupling to propagating drift waves. Thus, the monopole drift wave vortex is a long-lived coherent structure, but it is not precisely a stationary structure since the coupling results in a ''flapping'' tail. The flapping tail causes energy of the vortex to leak out, but the effect of the temperature gradient-induced nonlinearity is to reduce the leaking of this energy