M. P. Kalashnikov

Investigation of anomalous generation of ω 0 and 2ω 0 harmonics of heating radiation in laser plasma corona by means of holographic gratings

The problems concerning the development of high f -number spectrographs with high spectral and spatial resolution using holographic reflecting gratings, for the study of processes of harmonic generation in laser plasmas are considered. The concave holographic gratings and spectrograph schemes used in the “Delfin-1” installation are described. The anomalous generation of ω 0 and 2ω 0 harmonics from the subcritical density plasma region has been observed experimentally. Possible interpretations of the observed effect are given.

The investigation of heating and compression of high-aspect ratio targets with ‘Delfin-1’

Experimental results on the compression of shell targets with aspect ratio A = 150–250 in the “Delfin-1” installation are reported. The absorbed laser energy was 0·3 to 0·5 kJ. The maximum compression was 3·5 × 10 3 , the velocity of target compression at the final stage was 2·6 × 10 7 cm/s, neutron yield was 10 6 to 10 7 D-D neutrons per laser shot. The appearence of plasma corona filamentation correlated with compression stability distruction.

Investigation of laser plasma dynamics using the X-ray spectra of multicharged ions☆

Abstract Results are reported on the study of the structure of optically thick laser plasmas from the intensity of X-ray spectral lines. The analysis of plasma images provides information about the average velocity of the plasma expansion, the hydrodynamic efficiency and the rate of the target evaporation.

Focusing crystal mirrors for X-ray diagnostics of laser-produced plasma

The paper describes an investigation of the characteristics of spherical focusing Bragg-reflection mirrors. The integral reflectivity of bent crystals at Bragg angles 80–90°, the width of the spectrum of the reflected x-rays, and the spatial resolution of the images formed by the focusing crystals are considered. Results are presented of the calculated integral reflectivity of bent silicon and quartz crystals of different orientation and in different orders of reflection. The feasibility is demonstrated of laser-plasma diagnostics using the images obtained with the aid of a multichannel x-ray microscope based on focusing crystals. Possible schemes of active diagnostics of a dense laser plasma using a monochromatic transilluminating x-ray beam are considered.

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.

System for nanosecond and picosecond laser synchronization using high-voltage semiconductor switches

Results are presented on the development and investigation of a system for the synchronization of the emission of a nanosecond laser, used for plasma heating, with the emission of a diagnostic picosecond laser. The system is based on the use of the fast-semiconductor-switch technology, and ensures a temporal synchronization instability not higher than 100 psec.