Том 82, № 4 (2018)

Experimental studies of carbides are briefly reviewed. The high-temperature properties of carbides used in nuclear power and aerospace engineering are considered. Temperature is measured from either plane surface emittance or the emittance of thin samples prepared in the form of a melting blackbody model. The following quantities are measured: Joule energy, heat capacity (predominantly С_p), electrical resistance, and phase-transition heat versus temperature (up to 5000 K). The pre-melting heat capacity exceeds the equilibrium value, but temperatures measured at the characteristic points of the phase diagram correspond to the design diagram.

Features of measuring the temperature of conducting materials (metals, carbide, graphite) with a brightness pyrometer upon heating with a microsecond pulse of electric current are considered. Problems of pyrometer calibration and developing a blackbody model for measuring true temperatures in solid and liquid phases are examined. Estimates of temperature field nonuniformity over a sample and errors of temperature measurement are given.

Since the first experiments with hybrid X-pinches (HXP), it has been shown that a short wire between two conical tungsten electrodes produces the same radiation as a standard X-pinch. Since HXP has a simple construction, it is commonly used in many laboratories instead of standard pinches. Although details of the HXP dynamics remain poorly studied, the main factors governing HXP formation are investigated experimentally in this work. It is shown that the process of the electrode plasma formation is one of the main factors that lead to single hot spot bursts. Experimental results allow the fitting of HXP parameters and determination of the size of the source of X-ray radiation. It is also shown the radiation of HXP can be used as a source for point projection radiography in the wavelength range of soft to hard X-rays. Such sources can be also used for absorption spectroscopy and even electron beams.

The scheme and parameters of the upgraded RS-20E electron beam generator on the basis of a plasma opening switch (POS) are presented. The output unit of the POS is modified to allow the use of optical diagnostics in investigating wave processes generated in transparent targets by the electron beam of the accelerator. A new optical diagnostic system is also presented. Its scheme allows the four-frame electron-optical registration of a sample in both its own glow and in the laser shadow during propagation of the shock wave generated by the electron beam.

Scintillation detectors for detecting X-ray, gamma, and neutron radiation with time resolutions of 3–4 ns and having high noise stability have been developed. The detector housings are shielded from the strong electromagnetic interference produced at the moment of discharge. The detector design features an original voltage divider. With these detectors, the parameters of the high-energy radiation from a megavolt atmospheric nanosecond discharge can be studied at the limit of sensitivity of this class of devices.

GaAs/Ge/GaAs heterostructures with sublattice reversed GaAs on Ge epilayers grown via molecular beam epitaxy (MBE) for periodic domain inverted structures are presented. For the first time, such structures are grown in separate MBE machines for GaAs and Ge with atmospheric wafer transfer. The high quality of the heterostructures is confirmed via X-ray diffraction and photoluminescence. It is proposed that the surfactants (Bi, Sb) be used to control the nucleation of GaAs epilayers on a Ge epilayer.

The plasmonic enhancement of four-particle emission from SiGe layer occurring in the yellow–green spectral region is accomplished using a quasi-two-dimensional electron–hole liquid localized in SiGe/Si quantum well and coupled with gold nanoparticles placed on the top of a quantum well cap layer. This emission is a result of the simultaneous recombination of two holes and two electrons from opposite valleys, accompanied by the transfer of energy to a single photon.

Measurements of low-temperature (5 K) microphotoluminescence reveal the existence of isolated (quantum) emitters in ZnSe/ZnMgSSe quantum well with a radiation line experiencing abrupt displacements of its spectral position by several meV within 1–10 min. The unusual properties of the detected emitters are explained on the basis of a system with a large dipole moment in its ground state, e.g., a single donor–acceptor pair.

High-production laser ablation is used to prepare nano-ink that is colored colloidal solutions of nanoparticles in water, characterized by a variety of physicochemical properties. Using the nano-ink, singleand multi-layered nanocoatings are printed by a jet technique and studied in detail.

The effects of plasmon-exciton interaction on the spectra of light absorption by hybrid systems of two- and three-layer nanoparticles that consist of a metallic nucleus, the outer shells of ordered molecular dye J-aggregates, and an intermediate passive organic spacer between them is analyzed theoretically. It is established that the type of the absorption spectra and the efficiency of a near-field electromagnetic coupling between the particles in the system depends largely on the distance between the centers of concentric spheres and the direction of light polarization.