Fine Structure of the Photoluminescence Spectrum of Diamond under the Multiple Emission of an Optical Phonon during the Autolocalization of Photoexcited Electrons

JETP Letters - The autolocalization of electrons photoexcited by laser pulses with a wavelength of 525 nm in the visible range and with a duration of 150 fs in an electron-hole plasma (density...     

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

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.     

The Diagnostic Probing of Laser Plasma with a Femtosecond Time Resolution Using a Three-Channel Polarization Interferometer

Physics of Atomic Nuclei - The possibility of modifying the scheme of the previously developed three-channel polarization interferometer and creating a device that allows laser probing of plasma...     

Modification of molybdenum disulfide (2H-MoS<Subscript>2</Subscript>) and synthesis of its intercalation compounds

We have shown that powdered molybdenum disulfide prepared as a result of the exfoliation (singlelayer dispersion) of a crystalline precursor (2H-MoS₂) and subsequent precipitation in an acid medium, is capable of forming intercalation compounds in reacting with salts of copper and tetramethylammonium, as well as diethylamine and triethylamine. We consider factors influencing the composition and type of the alternation of guest and host layers in the resulting layered compounds. Relationships between charge transfer to MoS₂ layers and the extraordinary reactivity of its modified species are discussed.     

Vacuum discharge instability at laser initiation of a cathode spot

The dynamics of fast (a current rise time of ≤10¹¹ A/s) laser-induced vacuum discharges with moderate amplitudes of the current (≤10 kA) and voltage (≤20 kV), as well as medium storage energy (20 J), is studied. It is shown experimentally that the initial conditions specified by the energy and duration of laser radiation are a decisive factor governing the discharge dynamics. Two types of beam-plasma instabilities separated in space and time are discovered, and their occurrence conditions are analyzed. The first type of instability, observed early in the discharge, is associated with pinch structures at the front of the cathode jet expanding into a vacuum. The second type arises either at the peak or at the trailing edge of the current pulse and is accompanied by generation of hard (with an energy of ≥100 keV) bremsstrahlung from the anode region. The increase of the hard component energy over the current source potential is attributed to breaking due to plasma erosion.     

Analysis of characteristic X-ray generation induced by laser plasma electrons accelerated by an electric field

The results of experiments devoted to the study of spectral, spatial, and time characteristics of a spectrally bright point x-ray source based on a vacuum diode with a laser-plasma cathode and a titanium needle anode with a photon energy approximately equal to 4.5 keV are presented. The experimental results revealed a considerable difference between the electron emission from laser plasma in a strong electric field and the explosive electron emission and demonstrated the effectiveness of laser plasma as an electron source. The optimization of the laser radiation power density, the accelerating voltage, and the interelectrode spacing made it possible to create a point x-ray source whose spectral brightness exceeds available sources in the class of small-size pulse x-ray instruments (tubes with explosive cathodes). It has been proved experimentally that the maximum contrast of the characteristic lines of the anode material is attained in the case of an optimal choice of accelerating voltage. The x-ray source has the following parameters: (1) spectral brightness of the K-lines of titanium of the order of 10²¹ photons/cm² s sr keV; (2) emitting region size of 250 mm; and (3) laser pulse duration less than 20 ns.     

Diagnostics of the temperature of a plasma created by a CO2 laser,from the UV radiation spectrum

Delivered at the Fifth All-Union Conference on Diagnostics of a High-Temperature Plasma (18–22 June, 1990, Minsk).     

Dynamics of plasma corona of laser-irradiated spherical targets

The paper is devoted to an investigation of the formation and spreading of an inhomogeneous dense plasma heated by high-power laser radiation. The present status of the experimental and theoretical research in this field is analyzed. The “Kal'-mar” facility is used to study the dynamics of the plasma corona (electron density n_e ~ 10¹⁸–10²⁰ cm^-3), the law of motion of the critical (n_e ~ 10²¹ cm^-3) region of the plasma is established, and the dependence of the rate of compression of the shell targets on the initial parameters is determined. The electron temperature of the corona is measured with high temporal resolution in the course of the compression. A jetlike expansion of the “fast” ions is observed and investigated.     

Formation of Nanogratings on the Surface of Nanoporous Glass Irradiated by Femtosecond Visible Laser Pulses

JETP Letters - Periodic nanostructures with a period of about 100–150 nm are formed on the surface of nanoporous silicate glass irradiated by sharply-focused laser pulses with a wavelength of...