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We report a model of nanosecond laser ablation of compound semiconductors taking into account stoichiometry loss as a result of different volatilities of the material components. The model is based on the heat-flow equation for the bulk material and the diffusion equation for its atomic constituents and takes into account variations of material properties as functions of temperature and composition. Changing the optical response which results from stoichiometry violation is described within the concept of an effective medium and a multi-layer reflection model is applied. For cadmium telluride, as an example, the processes of ablation, melting, and resolidification under the action of a KrF laser have been studied in dynamics for particular experimental conditions in a wide range of laser fluences from the ablation threshold to the plasma shielding regimes described by the effective plasma plume representation. Multi-shot irradiation regimes have been investigated and the mechanism of the irradiation-controlled stoichiometry reversal has been elucidated.

To describe the effect of significant enhancement in thermal energy retained in metal targets following femtosecond laser ablation in a gas environment, we develop a combined model based on both 2D thermal modeling of laser-induced target heating and dynamics of the ambient gas perturbed by multiphoton absorption of laser energy in close proximity to the target. Using our model, we find that thermal energy coupling to the sample is significantly enhanced due to laser-induced gas-dynamic motion in plasma. Another finding is that total thermal energy coupled to the sample due to gas-dynamic energy transfer and thermal energy conduction is close to that measured in our experiment.

Dynamics of the plasma in open magnetic traps with an electron beam, in particular, in a GOL-3 trap, is studied. The possibility of the formation of a resonant surface of the magnetic field and the development of helical instability caused by the presence of this surface is studied numerically.

The specific features of the density and total pressure (the sum of magnetic and gas-kinetic pressures) behavior in the process of forced (by the example of propagation of a magnetic acoustic wave in the vicinity of the X-point) and spontaneous (by the example of development of a helical Thirring mode) reconnection are considered. It is shown that the total pressure distribution depends weakly on the initial value of the gas-kinetic pressure, the strength of the z-component of the magnetic field, and the thermal conductivity in a wide range of parameters. The character of density distribution is determined only by the thermal conductivity. It is also shown that the behavior of the total pressure and density in the case of spontaneous reconnection weakly depends on the thermal conductivity, in contrast to the forced case.

With reference to the problem of the development of tiring instability in a helical geometry it is shown that, as distinct from traditional gas dynamics, in plasma dynamics the incompressibility approximation cannot generally be used for describing slow flows. This is associated with the fact that several types of disturbances whose interaction results in possible density variations of the order of unity can propagate in plasma.

The development of the tearing instability is studied in the presence of a high toroidal magnetic field and a high plasma conductivity. The variation of the plasma density is shown to be significant in this case.

In this article we demonstrate that turbulent stress contributions which depend on the rotation of the frame of reference (and therefore are system dependent) give rise to the inverse energy cascade, and thus introduce an ordering in the structure of turbulence.

Linear equations of turbulent convection in the presence of rotation are derived within the framework of a phenomenological approach. It is shown that the amplification of large-scale disturbances is possible only for the essentially inhomogeneous problem when the dimensions of the large-scale disturbance exceed the characteristic scale of density variation.