Plasma spread at irradiation of volume-structured materials

One of the main issues in investigation of laser interaction with inhomogeneous hot plasma is to study dynamics of expansion of heated matter. Region of the laser plasma with electron density ne ≤ nc is of great interest for research because the absorption and scattering of heating laser radiation occurs in this region. Nonlinear processes developing in this area determine the mechanisms of radiation interaction with matter. Such studies allow to determine the optimal conditions for laser heating of plasma, i.e. to identify the conditions under which the most efficient absorption of laser energy and the optimum coefficient of hydrodynamic transmission may be implemented. The nature and characteristics of plasma expansion are discussed in the report. Plasma was formed under the influence of the laser with a controllable degree of coherence to a volume structured targets at the flux density of heating radiation 1012-1014 W/cm2. In particular the results of experiments to study the radiation patterns of plasma flows at different angles of radiation incidence on the target are demonstrated. In addition image registration of the plasma produced in the interaction laser radiation with solid and low-density aerogel targets was carried out with high spatial resolution in different spectral ranges. Namely, the image of the plasma was registered in the visible and infrared spectral regions, and also in soft (180-200 Å) and hard X-rays (λ≤9Å). (author)