[en] We have presented for the first time a set of coupled nonlinear equations that govern the dynamics of finite amplitude low-frequency electromagnetic fluctuations in non-uniform high-β plasmas. In the linear limit, these equations give a local dispersion relation which exhibits coupling between the magnetosonic, shear-Alfven, and electron drift waves

[en] It is shown that large amplitude shear waves can excite vortex-like dust fluid motions (or zonal winds) in strongly coupled dusty plasmas. For this purpose, we derive the governing equations for nonlinearly coupled transverse shear waves and zonal winds by employing the generalized hydrodynamic equations for the dust, and Ampere's law. The coupled mode equations are then used to investigate the parametric excitation of zonal winds by constant amplitude transverse shear waves. An explicit expression for the growth rate, which is of relevance to laboratory dusty plasmas, is derived

[en] The dispersion relation, which describes the nonlinear coupling of a large-amplitude electromagnetic pump wave with low-frequency collisional modes in the high-latitude ionosphere, is derived. In particular, it is pointed out that the nonlinearities in the electron-neutral collision term are important for the long-wavelength part of the spectrum. This fact has been overlooked by previous authors. 11 refs

No abstract available

[en] The generation of large scale zonal flows by flute-like wave modes in nonuniform rotating self-gravitating fluids is considered. In the geostrophic approximation, viz. when the mode frequencies are much smaller than the Coriolis frequency, the coupled mode equations are obtained by using the continuity, momentum and Poisson equations. The equations are then Fourier analyzed to obtain a nonlinear dispersion relation, which exhibits the parametric excitation of zonal flows by the nonlinear force of the flute-like wave modes. Nonlinearly excited zonal flows undergo further cascading and constitute a new turbulent state. They also contribute to the formation of large scale structures in astrophysical fluids

[en] It is shown that large scale zonal flows in a rotating fluid can be excited due to the Reynolds stresses of short scale Rossby waves. By employing the equations for a shallow rotating fluid in the geostrophic approximation, we obtain a Charney equation for nonlinearly coupled Rossby waves and zonal flows. The equation is then decomposed into two equations; one for short scale (comparable to the Rossby radius) Rossby waves in the presence of zonal flows, and another for zonal flows which are driven by the Reynolds stresses of the Rossby waves. Our pair of equations is then Fourier transformed to obtain a nonlinear dispersion relation, which admits the excitation of zonal flows due to the Rossby pumping energy. The present investigation thus provides a nonlinear mechanism for the energy transfer from short scale Rossby waves to large scale zonal flows

[en] A solution is obtained to the nonlinear MHD equations, which describe a helical magnetic field of arbitrarily large amplitude. The frequency and wave number of this field are not restricted by any particular relation. The stability properties of this large amplitude wave have been considered. This approach enables us to link together parametric instability theory with conventional MHD analysis of spatially varying magnetic fields. (author)

[en] The Vlasov description of the free electron laser is generalized in order to include in the formalism a nonzero static guide magnetic field as well as a finite frequency pump field. It then turns out that the coupling coefficients still are positive even if the amplitude of the helical wiggler field is arbitrarily large. (Auth.)

No abstract available

[en] The excitation of low-frequency electrostatic waves by a high-frequency electromagnetic wave is investigated analytically, considering the case of stimulated scattering in the ionosphere at auroral latitudes. It is shown that the two-stream Farley-Buneman and collisional-drift modes can be nonlinearly excited at these latitudes because particle drift motions lower the threshold fields, to below the level pump of the field of the EISCAT incoherent-scatter-radar facility, for example. Although it may be difficult to interpret the experimental data, at least some of the modes in the thermal-fluctuation spectrum should be identifiable using incoherent-scatter techniques. 16 references