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Abstract— The design of a subnanosecond accelerator composed of three sections and a gas-filled diode and results of its testing are presented. The three sections of the accelerator are a double forming line, a ferrite line, and a line with a variable wave impedance. A beam current amplitude of ≈2.7 kA has been measured behind the anode foil at a pulse width at half-maximum of ≈370 ps. Using this accelerator and a standard spectrometer, Cherenkov radiation and pulsed cathodoluminescence have been investigated in KU-1 fused silica, polymethyl methacrylate, and KBr crystal samples.

Recommendations are given on designing thermosiphons (TS) prepared on the basis of the experience that the authors gained in designing more than 4000 TSs for heat-recovery steam generators and the results of long-term investigations and tests carried out to study thermohydraulic and corrosion processes in vertical and inclined TSs filled with steam-water mixture. The results of similar studies performed by other authors are analyzed. References are given to the regulations on the design of heat transfer equipment for thermal and nuclear power stations. The requirements for TS construction materials, the degree of TS filling with water, and the TS vacuum level are outlined. Whether the evacuation of TS may be abandoned was assessed. Measures are proposed to prevent depressurization on water freezing in TSs. Recommendations are given on the calculation of thermohydraulic characteristics and steam-and-gas distribution in vertical or inclined TSs. The conditions of displacement by a steam flow of noncondensable gases, including air, to the top of the condensation zone in a thermosiphon are considered. Various regimes of axial heat transport and heat transfer are described for pure steam condensation (including film condensation, bubble condensation, distribution of different regimes of steam condensation, and condensate cooling along the height of the condensation zone during “flooding”). Heat transfer in the steam condensation from an air-steam mixture (the diffusion component of thermal resistance), maximum power, and the conditions for poorer cooling of the TS heating zone (“flooding,” steam separation at the upper generatrix of the heating zone in an inclined thermosiphon) are examined. Thermosiphons feature a countercurrent flow of steam and its condensate in a single flow with the same mass flowrates. Hence, a special case of “flooding” affecting the maximum power of the thermosiphon, the effect of the incoming steam flow on the heat transfer rate during film condensation, steam-and-gas distribution in a top-plugged channel, corrosion processes in thermosiphons, and hydrogen diffusion through the thermosiphon wall should also be studied.

—This paper describes the design and parameters of a nanosecond accelerator with an additional transmission line that has variable wave impedance and a gas-filled diode. The possibility of controlling the beam current parameters by changing the air pressure in the diode is shown. Behind the anode foil, at a half-maximum pulse width of ≈1.3 ns and an electron energy of up to 350 keV, the beam current amplitude was ≈700 A. Vavilov–Cherenkov radiation spectra and oscillograms were recorded when were excited by the electron beam of this accelerator. quartz, sapphire, and synthetic diamond were excited by the electron beam of this accelerator.

Представлены результаты имитационного моделирования , иллю стрирующие влияние законов движения самолетов - носителей РСА ( активного и пассивного ) относительно исследуемого участка поверхности Земли на разре шающую способность результирующей бистатической радиолокационной систе мы . Изложены методы расчета вторичных информационных массивов для син теза изображения , включая семейство опорных функций , на основе первичной навигационной информации , представлены как формулы , так и результаты моде лирования . Выявлены специфические черты бистатических обзоров общей кон фигурации по сравнению с моностатическими . Проиллюстрирована процедура синтеза применительно к самолетной бистатике .

Cherenkov radiation is widely used to register charged particles with high energy. This paper describes the design and parameters of an electrons accelerator, as well as the results of studies of the spectra and amplitude-time characteristics of sapphire and quartz KU1 radiation under the excitation of electrons with an energy of up to 350 keV. It was shown that in the UV and visible spectral regions a wide band is recorded, the intensity of which increases with decreasing wavelength. It was established that the duration and shape of the radiation pulse of this band coincides with the pulse of the electron beam. All this allows us to attribute the registered emission to the Cherenkov radiation.

Results of experimental determination of the average heat transfer coefficient upon condensation of pure steam αc and steam from air–steam mixture αas.m in tubes of a large-scale model of the emergency cooling heat exchanger in the system of passive heat removal through steam generators of AES-2006 project at Leningrad II NPP are presented. The model contained 16 parallel tubes with a diameter of 16 × 2 mm and a length of 2.9 m connected to the upper steam distributing and lower condensate gathering horizontal collectors; the distance between their axes was 2.28 m. The tube segments were vertical, horizontal, or inclined. The internal diameter of the collectors was 40 or 60 mm. The model was placed in the lower part of a tank with a height of 6.5 m and a volume of 5.85 m3 filled with boiling water at atmospheric pressure. The experimental parameters were as follows: pressure range 0.43–7.77 MPa, condensate Reynolds number Ref = (0.87–9.3) × 103, and average air volume fraction at the segment with air–steam mixture 0.18–0.85. The studies showed that nonuniformity of static pressure distribution along the steam-distributing collector strongly influences the reduction of αc value (ejecting effect). The agreement between experimental and calculated according to statutory guidelines values of αc for vertical tubes is achieved if the dynamic head of the steam flow at the input of the steam-distributing collector does not exceed 1 kPa. Equations for calculation of the diffusion heat transfer coefficient at steam condensation from the air–steam mixture αas.m on the internal tube surface are proposed. In the considered conditions, air is completely displaced by steam flow from the upper to the lower part of the tubes. The boundary between these regions is characterized by an average reduced steam velocity through this cross section of 1.6 ± 0.4 m/s. Above the boundary cross section, it is recommended to calculate αc. according to [1].