Ensuring uniform thickness of the conductive coating on the inner surface of the hemispherical resonator by magnetron sputtering

The possibilities of technological ensuring of the uniformity of thickness distribution of a thin-film metal coating produced by magnetron sputtering on the inner surface of a thinwalled silica resonator made in the shape of a hemisphere are considered. The possibility of minimizing the thickness of the coating by optimizing the diameter of the annular magnetron emission zone in combination with the distance from the resonator to the target made of sprayed material is shown. A further increase in the evenness of thickness of the coating is possible on the basis of the use of a fixed screen with a hole, the shape and location of which are calculated analytically, and the final configuration of the contour is specified empirically

Mesa-structures and Focal Plane Arrays based on epitaxially grown InSb layers

Aspects of epitaxially grown indium antimonide (InSb) on InSb substrates (InSb-on-InSb) by molecular beam epitaxy (MBE) for the 2D focal plane arrays fabrication process have been described. The epitaxial growth offers possibility for complex structure production, and then such structures suppose more effective control of the thermal generation charge carriers as the detector temperature is raised above 80 K. Investigations of mid-wave infrared (MWIR) 320256 FPAs with 30 μm pitch and 640512 FPAs with 15 μm pitch based on InSb-on-InSb layers have shown high performance: the average detectivity at T = 77 K more than 21011 cmW-1Hz1/2, the average value of noise equivalent temperature difference (NETD) with a cold aperture of 60o at T = 77K was in the range of 10–20 mK. High quality thermal imaging images were obtained in real time mode.

SWIR Photosensory

In this paper, we report on the design, the fabrication, and performance of SWIR photomodules using sensitive two-dimensional arrays based on InGaAs-heterostructures. The de- sign of suggested InGaAs-heterostructure includes InAlAs wideband barrier layer and high sensitive absorber InGaAs layer which are increasing the uniformity and operability of focal plane array (FPA), so the number of defect elements are less than 0.5 %. The possibilities of spectral range expanding into short-wavelength to 0.5 μm and into long-wavelength to 2.2 μm regions have been considered. The operation principals of active-pulse system for 0.9–1.7 μm spectral range based on InGaAs 320256 FPA with 30 μm pitch have been presented. The investigations showed that the infrared gated-viewing system based on the InGaAs 320256 FPA provided a spatial resolution of 0,6 m.

Distinctive features of the structure of current sheets formed in plasma in three-dimensional magnetic configurations with an X line (a review)

A review is presented on experimental results related to investigation of distinctive features of the structure and evolution of plasma current sheets formed in three dimensional (3D) magnetic configurations with an X line, in the presence of a longitudinal magnetic field component (guide field) directed along the X line. It is shown that formation of a plasma current sheet results in enhancement of the guide field within the sheet. The excessive guide field is maintained by plasma currents that flow in the transverse plane relative to the main current in the sheet. As a result, the structure of the currents becomes three-dimensional. Increasing the initial value of the guide field brings about a decrease of compression into the sheet of both the electric current and plasma. This effect is caused by changing the pres- sure balance in the sheet when an excessive guide field appears in it. Deformation of plasma current sheets in 3D magnetic configurations, namely, an appearance of asymmetric and tilted sheets, results from excitation of the Hall currents and their interaction with the guide field. It is shown that the formation of current sheets in 3D magnetic configurations with an X line is possible in a relatively wide, but limited range of initial conditions

Current state and prospects of detectors in the terahertz range. Part 2. Heterodyne detection of terahertz radiation

The paper discusses the problems associated with the development of technology for terahertz radiation detectors. The main physical phenomena and recent progress in various methods of detecting terahertz radiation (direct detection and heterodyne detection) are considered. Advantages and disadvantages of direct detection sensors and sensors with heterodyne detection are discussed. In part 1, a number of features of direct detection are considered and some types of terahertz direct detection detectors are described. Part 2 will describe heterodyne detection and continue to describe some types of modern photonic terahertz receivers.

The characteristics of microplasma discharge propagation over the titanium surface covered with a thin oxide film

The propagation and structure of a microplasma discharge initiated in vacuum by a pulsed plasma flow with a density of 1013 cm–3 on the surface of a titanium sample covered with a thin continuous dielectric titanium oxide film with a shickness of 2–6 nm were studied experimentally when the electric current of the discharge changes from 50 A to 400 A. It was found that the microplasma discharge glow visually at the macroscale has a branched structure of the dendrite type, which at the microscale consists of a large number of brightly glowing “point” formations – cathode spots localized on the metal surface. The resulting erosion structure on the titanium surface is visually “identical” to the structure of the discharge glow and consists of a large number of separate non-overlapping microcraters with characteristic sizes from 0.1–3 μm, which are formed at the sites of localization of cathode spots at distances of up to 20 μm from each other. It was found that the propagation of a single microplasma discharge over the titanium surface covered with a thin oxide film a thickness of 2–6 nm occurs at an average velocity of 15–70 m/s when the amplitude of the discharge electric current changes in the range of 50–400 A. In this case, the microplasma discharge propagation on the microscale has a “jumping” character: the plasma of “motionless” burning cathode spots, during their lifetime 1 μs, initiates the excitation of new microdischarges, which create new cathode spots at localization distances of 1–20 μm from the primary cathode spots. This process repeated many times during a microplasma dis- charge pulse with a duration from 0.1 ms to 20 ms.

Increasing the energy of the initiating spark discharge in order to reduce and stabilize the delay time in a compact vacuum breaker

The similarity of the switching mechanisms of compact vacuum spark breakers and spark breakers with laser ignition is established at a comparable level of energy flux density in the ignition node–ionization of the residual gas by a stream of short-wave radiation and fast electrons from the cathode spot plasma or laser plasma. This mechanism allows you to effectively reduce the delay in triggering the spark gap by increasing the ignition energy. An experimental study of the advantages of using an ignition circuit with increased energy for controlling small-sized vacuum spark breakers is carried out. There is a steady decrease in the delay time of the spark gap and an increase in the level of delay stability. From the point of view of minimization and stability of the delay time of the spark gap, the energy investment in the formation of the initiating plasma occurs most effectively at the spark stage of the auxiliary discharge along the surface of the dielectric in the ignition node.

MWIR optoelectronic module based on the Russian 640512 InSb photodetector

Consideration is given to the results of the development of an optoelectronic module based on a Russian cooled matrix photodetector of 640512 elements format, operating in the spectral range of 3.6–4.9 microns, based on InSb. The paper describes the basic algorithms used for video image processing, describes the main blocks of the developed device, describes the methods for measuring NETD and spatial resolution, and gives the characteristics of the device.

Theoretical analysis of the factors, influencing composition uniformity of the cadmium zinc telluride substrates grown by THM

The effect of the sample composition, variation of the temperature field and the feed material non-homogeneity on uniformity of the growing crystal is considered. It is shown that optimization of the solvent composition makes it possible to minimize the jump of the ZnTe concentration at the seed/crystal boundary. The composition fluctuations at variation of the thermal field during crystal growth are smooth enough and relatively non-significant. The feed composition distribution has, as a rule, a random character. Different harmonics of composition distribution non-uniformity in the feed material differently affect the homogeneity of the growing crystal. Longwave non-uniformities in the feed transform into the growing crystal almost completely. At the wavelength equals to a half of the solvent length or shorter, the perturbations of the growing crystal composition are relatively small. Evidently, the cause of the local composition variations, found in real crystals, is, basically, the feed composition non-uniformities

Lasers developed in the Institute of Atmospheric Optics of the SB RAS (a review)

The results of research on the development of the first electric discharge lasers on active media N2, CO2, Cu, CuBr and excimer molecules at the Institute of Atmospheric Optics named after V. E. Zueva SB RAS are given. It created one of the world's first Cu-lasers with a pulse production of copper vapors due to the explosion of conductors and a transverse excitation discharge. For a copper laser, record specific generation parameters were obtained almost equal to the limit: radiation energy 2.4 J/l, peak power 120 MW/l with an efficiency of 0.16 %. For the CuBr laser operating in frequency mode, for the first time, an average radiation power of more than 100 W was obtained. In the dual pulse excitation mode, conditions were found that limit the growth of the efficiency of the CuBr laser. For him, a record efficiency of 2.7 % was obtained. For the first time, a nitrogen laser was developed with a maximum efficiency of 0.27 % with an energy of 0.8 mJ, a peak power of 160 kW. For the first time, a miniature XeCl laser with a longitudinal excitation discharge was developed, which worked both with and without buffer gases He, Ne and Ar.