M. V. Osipov

Combination scattering as a method for laser plasma diagnostics

Abstract The combination scattering of the probing radiation in laser spherical heating experiments performed with the Kalmar laser system was investigated. The second harmonic of an Nd laser was used for plasma probing. The frequencies 3 2 ω 0 , 5 2 ω 0 and 3ω 0 (where ω 0 is the frequency of the Nd laser) in the plasma radiation spectrum were measured. The possibility to determine the plasma turbulence spectrum from the scattered light is demonstrated.

Nonlinear optical conversion of Nd:glass laser multimode radiation into the second harmonic in KDP crystal

The second-harmonic generation (SHG) of Nd:glass multimode laser radiation in a 3?cm long KDP crystal has been studied both experimentally and theoretically for type I doubling at power densities of up to 2.5 GW cm?2, radiation divergence of 0.5?3.5 mrad and between 100?1000 transverse modes. The theoretical calculations of SHG were performed in the fixed-field approximation, fixed-intensity approximation and in the nonlinear regime. The maximum experimental conversion efficiency of 52% was obtained for the case of partially polarized radiation with divergence of 0.5 mrad and 100 transverse modes.

Aerogel foil plasma: Forward scattering, back scattering, and transmission of laser radiation

Experimental results obtained with “Kanal-2” facility under the study of powerful laser pulse interaction with the low density microstructure media are presented and discussed in this paper. Forward scattering, back scattering, and transmission of laser radiation by aerogel foil plasma have been investigated. The temporal, spectral, and energy characteristics of both the radiation scattering in the direction of heating radiation beam and the back scattering radiation were studied; the directional diagrams of forward and back scattering radiation were obtained for ω 0 and 2ω 0 frequencies. Analysis of intensity redistribution on the heating beam cross-section after passing through a polymer microstructure target was carried out.

Measurement of the dynamics of the compression of high aspect-ratio shell targets in the “Delfin-1” installation

Abstract With the help of a specific diagnostic system designed for the “DELFIN-1” installation we have measured implosion velocities ≳ 250 km/s, which are record values for experiments on compression at sufficiently high hydrodynamic efficiency of ablative shell targets. An empirical scaling is shown to agree well with the measured compression velocities.

Interaction of partially coherent laser radiation with matter

A new approach to the problem of IFE laser driver based on generation and amplification of radiation with controllable coherence proposed and realized at P.N. Lebedev Physical Institute of the RAS had initiated the studies of an interaction efficiency of a partially coherent radiation with matter. Recent results of experiments carried out with the aim to study of the physical processes in targets under illumination by the laser with controllable coherence of radiation are presented and discussed, especially such important laser-matter interaction phenomena as absorption and scattering of laser radiation, the laser radiation harmonic generation, X-ray generation, crater formation and plasma expansion under laser pulse, conversion of laser radiation by means of nonlinear crystals, influence of coherence degree on the processes mentioned above.

Stimulated Raman scattering in a laser-produced plasma heated by laser at wavelength of 0.53 /spl mu/m

Stimulated Raman scattering (SRS) has been studied in a plasma produced by a second harmonic Nd-glass laser irradiating a limited mass target, which does not burn through during the interaction time. It is assumed that flat density regions form and move through an expanding plasma, and the SRS results have been analyzed on that basis. The SRS spectrum cut-offs are discussed, as well as features of time-integrated and time-resolved SRS spectra.

Laser plasma diagnostics in the critical density region by means of the method of combination scattering

Abstract For the first time the method of combination scattering of the probing radiation has been used in studying a plasma in the critical density region ( n c ≈ 10 21 cm −3 ) for heating radiation produced by an Nd laser. Nonlinear processes in the plasma in the near-critical region have been identified on the basis of studying the scattered spectrum of the probing wave. The possibilities of the application of this method for the determination of the spectral distribution of the plasma wave energy for the mentioned plasma density region are shown.