Bulletin of the Lebedev Physics Institute最新文献

The survival efficiency of dust during the interaction of dusty interstellar clouds with shock wave was studied. We have found that in the adiabatic destruction of small clouds, the dust grains belonging to the cloud are separated by size along the cloud motion: large dust grains remain far behind the gaseous clumps of the cloud, and small grains are entrained by the cloud. In large radiatively cooled clouds, a significant part of dust is contained and saved inside dense cold clumps of the cloud independently of the grain size.

We report investigation of the resonant process of electron impact induced charge transfer in the inert gas systems Ar + Xe⁺ and Kr + Xe⁺. Along with this, the reaction of the formation of charge-transfer ions XeRg⁺ in triple collisions Rg + Xe⁺ + e, occurring due to nonadiabatic transitions, is studied. These processes are compared with the efficiency of dissociative electron impact excitation of ArXe⁺ and KrXe⁺ ions, accompanied by the formation of Ar⁺ and Kr⁺ ions, under conditions of plasma equilibrium in nuclear motion.

The transformation of elliptical polarization in a layer of azobenzene-containing amorphous polymer is calculated. The dependences of the Stokes parameters for the propagation of a light wave deep into the layer are obtained. It is shown that the light-induced change in absorption leads to a decrease in the ellipticity of the light wave, which, in turn, slows down the rotation of the polarization ellipse. The obtained results are important for optical writing of phase structures in polymers.

The radio emission of the electron charge excess from an extensive air shower (EAS) is calculated taking into account the geomagnetic field in a kinetic model. Unlike the previous macroscopic models, the emission of each excess electron of the shower disk is calculated taking into account their longitudinal and transverse current caused by the Lorentz force. The spatial distribution of excess electrons in the disk, their energy spectrum, multiple scattering, and evolution of the disk along the EAS track is taken into account.

A laser ablation method for the formation of light-trapping pyramidal microstructures on the surface of monocrystalline silicon is considered. The optimal parameters for obtaining such structures were determined, their chemical composition was investigated, and measurements of the specular reflection and transmission in the spectral range of 700–5000 cm^–1 were performed.

We report the results of the dissolution dynamics of germanium nanoparticles synthesized by laser ablation in distilled water and isopropanol. It is shown that germanium nanoparticles dissolve almost completely in distilled water within 24 h. A comparative experiment is performed on laser heating of distilled water and an aqueous germanium nanoparticles solution with an average nanoparticle size of ~130 nm and a concentration of 0.8 mg/ml, which makes it possible to construct heating and cooling curves. Under conditions of the experiment, the heating of the nanoparticle solution increased by 36% compared to distilled water. The obtained results can be used in photohyperthermia technologies for the treatment of cancer tumors.

Under the action of multipulse (≈40‒100 pulses per point) laser radiation at a wavelength of 532 nm and a pulse duration of 10 ns in an atmosphere of SF₆ gas, structures doped with a sulfur donor impurity are fabricated on the silicon surface. The topography of the laser-structured surface is characterized by scanning electron microscopy (SEM). Energy-dispersive X-ray microanalysis of the surface layer is indicative of the presence of up to ≈2 at % of the doping donor sulfur impurity. Fourier-IR spectroscopy shows broadband absorption for the structured samples. Using the Raman spectroscopy data, the appearance of an amorphous phase in structured silicon is demonstrated and the sizes of nanocrystallites are estimated to be ~4‒20 nm.

Based on a presentation at the 48th Vavilov Readings (Lebedev Physical Institute of the Russian Academy of Sciences, April 17, 2024), a review is given of current issues in laser-plasma high energy physics associated with self-trapping of light pulses in relativistic plasma. An analysis is made of electron acceleration in this regime by relativistically intense laser pulses up to sub-GeV energies with multi-nanocoulomb charge carried by the accelerated electron bunch and their possible radiation/nuclear applications. The discussion of the latter includes generation of synchrotron-type secondary radiation from laser-irradiated transparent targets or converter targets in the range from hard X-rays to gamma-rays; generation of terahertz pulses, including unique half-cycle/unipolar pulses; generation of neutrons and positrons; possible deep radiography of strongly shielded objects based on laser-induced ultrabright gamma-ray bursts; an all-optical inverse Compton source for high spatial resolution radiography; and radiation FLASH therapy using laser-accelerated ultrahigh energy electrons.

We report the results of experimental and computational studies on the formation of electron beams by ultrashort terawatt laser pulses. Various acceleration regimes—direct laser acceleration (DLA), laser wake field acceleration (LWFA), and hybrid variants—are discussed. A possibility of controlling the processes occurring during such interactions with an additional nanosecond laser pulse is demonstrated: formation of a plasma with the required density and profile, change in the electron beam emission direction, and improvement of the beam emittance. Possible applications of such tabletop accelerators in the study of photonuclear processes, for the generation of unipolar pulses of extreme amplitude in the terahertz range of the spectrum, etc., are discussed.

The development of laser and accelerator technologies has made it possible to generate extremely strong electromagnetic (EM) fields with a strength several orders of magnitude higher than that of the atomic field. The review discusses the processes that play a key role in extremely strong EM fields, and new “quantum-electrodynamic” plasma states. Schemes aimed at generating extremely strong EM fields in laboratory conditions are described. These schemes can be conditionally divided into three groups: (i) all-optical schemes, (ii) laser-beam schemes, and (iii) schemes based on the interaction of charged particle beams. Much attention is paid to the XCELS project, the main objective of which is to study both fundamental processes of extremely high-intensity laser interaction with matter and possible applications associated with this interaction.