超短脉冲激光与乙醇微滴相互作用中超热电子的双叶状角分布

测量了聚焦光强为1016W/cm2的超短脉冲激光与乙醇微滴相互作用中产生的能量大于50?keV的超热电子的角分布和电子能谱.观察到的超热电子角分布明显依赖于激光的偏振特性，在与激光偏振平面平行的平面上超热电子相对于激光入射方向呈对称的双叶状分布.超热电子的能谱显示超热电子的最大能量大于750?keV.以上超热电子的角分布可用一个基于共振吸收机制的模型加以解释. 关键词： 超短脉冲激光 超热电子 微滴 共振吸收     

Generation of high-power electron beams by magnetron injection guns with secondary-emission cathodes

The generation of high-power electron beams by magnetron injection guns using a secondary-emission cold cathode is studied experimentally. Stable operation at an output power of up to 8 MW is achieved.     

Generation of high-power electron beams in magnetron guns with secondary-emission cathodes

High-power electrons beams generated in a single injection magnetron gun with secondary-emission cathodes and in a set of such guns are studied. Hollow electron beams of current 50–100 A, electron energy 30–100 kV, and peak power 1–5 MW are obtained. The beams can be used as electron sources in accelerators and ordinary and multibeam high-power microwave devices.     

Investigation into the erosion of explosive-emission liquid-metalcathodes

The erosion rate has been measured for capillary-type and needle-type liquid-metal cathodes. The erosion drop fraction composition and percentage have been determined. For the needle-type liquid-metal cathodes, the erosion of the core has been discovered and investigated. To describe this erosion, a simple analytical model has been proposed     

Generation of electron beams in high-aspect-ratio magnetron guns with secondary emission cathodes

The generation of electron beams in high-aspect-ratio magnetron guns with cold metallic secondary-emission small-diameter cathodes is discussed. The parameters of the beams as functions of the electric and magnetic fields are studied for various ways of generating voltage pulses needed for the secondary emission multiplication of the electrons and the beam generation.     

Generation of high-power electron beams in magnetron guns with cold secondary-emission cathodes

The generation of powerful electron beams in a single magnetron gun and in a set of magnetron guns with cold secondary-emission cathodes is studied. The possibility of generating tubular electron beams of current 50–100 A, particle energy 30–100 kV, and pulse power 1–5 MW is shown. Such beams can be used as electron sources in the technology of accelerators, as well as in ordinary and multibeam high-power microwave devices.     

From quantum light emitted by single molecule to classical light emitted by molecular ensemble

Fluorescence from an ensemble of noninteracting molecules excited by continuous laser radiation is considered as a glow of M individual molecules. The expression that governs the autocorrelation function (ACF) of fluorescence from M molecules is derived based on the theoretical expression that governs the ACF of fluorescence from a single-molecule. Fluctuations of blinking fluorescence and its statistical properties are analyzed using a computer simulation. The results of statistical analysis of the computer experiment are in good agreement with the derived formula that governs the ACF of fluorescence from several molecules.     

Noise emitted by water supply installations

This work deals with the problem of noise generated by water supply systems in homes. Measurements were made in situ to determine normal conditions of installations and noise levels generated in different rooms in the home. In order to determine the sources of noise and the best construction methods to minimise noise generation, a laboratory was also built to reproduce the conditions of this type of installation in homes. Tests were carried out in this laboratory on different configurations of type of tap, installation material, walling and fastening of the installation, to allow quantitative determination of the differences in noise generation between the various configurations used in households.     

利用分幅相机测量铋球表面发射X射线图像

设计了一种塑料靶表面涂铋(Bi)的靶丸替代常规内爆靶,利用分幅相机获取辐射驱动内爆替代靶丸Bi等离子体再发射X射线的2维图像。实验时,从主激光中分出一束光信号,经光电转换后作为分幅相机的触发信号,以激光直接驱动金球靶建立相机的时标。根据分幅相机的时标可确定每幅X射线图像相对于主激光的时间延迟。分析Bi球靶的X射线分幅图像,得到夹持内爆靶丸的CH膜的烧蚀时间及Bi球靶半径的变化关系。通过X射线图像还可反推出诊断孔的大小和CH膜支撑靶丸的对称性。     

Effect of the expanding explosive-emission centers plasma on theimpedance of a high-current diode

Formulas for the space-charge-limited electron current in a planar diode with a small hemispherical or hemi-cylindrical plasma emitter have been obtained theoretically and by a numerical simulation. For a periodic cathode structure of hemispherical emitters, an approximate expression for current is derived. Based on these results, the increase in current with time in high current explosive-emission diodes is explained. A condition has been found under which the expanding cathode plasma has no effect on the diode impedance. This is related to the electric field pressure on the cathode. A configuration of the cathode surface has been proposed which provides realization of this condition     

Polychromatic Gaussian beams emitted by dispersive laser resonators

In-vacuum propagation of a polychromatic Gaussian beam emitted by a dispersive laser resonator and its passage through thin plates are studied under following assumptions: optical fields are stationary and plane-polarized, the paraxial wave equation is valid for each monochromatic component of the beam, the waist position and the Rayleigh range depend on wavelength and diffraction edge effects are negligible. Mathematical expressions for beam radius, divergence, beam parameter product and beam propagation factor are obtained. The use of thin plates for waist position achromatization is analyzed.     

The number of photons emitted by a channeled electron

A discussion is presented of the influence of photon multiplicity in the emission from channeled electrons on the radiation spectrum measured by a total-absorption spectrometric device. It is shown that as the maximum in the spectrum shifts with increasing crystal thickness, in the absence of further information it is impossible to determine the multiplicity of the emission. A method is proposed for determining the presence of multiple emission from channeled electrons with a total-absorption spectrometer by using an absorber covering a specified portion of the -ray aperture. The presence of multiplicity is identified in emission from channeled electrons with energy E₀=900 MeV in a tungsten single crystal of 1.18 mm. Previously the presence of multiplicity in the radiation from channeled electrons had been detected for electron energies above 4.5 GeV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 88–105, June, 1991.     

Aerosols emitted by the combustion of polymers containing nanoparticles

The fire behavior and the characterization of solid and gaseous fire effluents of polymers [polymethyl methacrylate (PMMA) and polyamide-6 (PA-6)] filled with nanoparticles (silica, alumina, and carbon nanotubes) used to improve their flame retardancy were investigated. To determine the impact of these composites on the emission of airborne particles produced during their combustion in accidental fire scenarios, an experimental setup was developed to measure the mass distribution in the 30 nm–10 μm range, and the concentrations of submicrometric particles in the aerosol. Comparisons were made between unfilled and filled polymers, and the influence of filler surface treatments (silane-based), as well as combinations with a flame retardant [ammonium polyphosphate (APP)], was investigated. The presence of nano-oxides in PMMA shows a significant effect on the rate of particle emission with a decrease in the concentration of the emitted submicrometric particles. APP in PMMA led to a decrease in the mass fraction of ultrafine particles and an increase in the rate of submicrometric particle emission compared to filled compositions with nano-oxides. Atomic force microscopy was used as a complementary tool for the characterization of the particles emitted during combustion, allowing direct observation of nanoparticle morphology, detection of carbon nanotubes in the aerosol, and visualization of the effect of APP on nanoparticle morphology.     

Stark broadening of isolated lines emitted by singly-ionized tin

Calculations have been performed on the electron impact broadening of isolated lines from singly-ionized tin from a cool plasma. These have been compared with results of measurements recently performed by Miller, Roig, and Bengtson on a plasma produced by a conventional shock tube, and satisfactory overall agreement has been obtained. Our method is similar in procedure to that of the semi-empirical approximation of Griem, but we take into account the details of the radiator structure, including configuration interaction for two of the terms. We propose a new expression from which the relevant effective Gaunt factors for singly-charged ions can be calculated for incident energies above threshold. In some cases, a significant variation of line width within multiplets is noted. Some difficulties have been experienced with transitions to states involving equivalent electrons.