Generation of droplets emitted by pool explosive-emission cathodes

The velocity spectrum of droplets emitted by a pool explosive-emission cathode was studied. Relation between sizes of droplets and its maximal velocities over the range of 10³−18×10⁴ cm/s have been found. The dependence obtained confirms the mechanism found earlier for the droplet emission under high pressures developed in explosive emission centers. Institute of High Current Electronics. Siberian Division of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 105–109, March, 1999.     

Investigation of the erosion drop fraction for liquid-metalexplosive-emission cathodes

The velocity spectrum of drops emitted by a liquid-metal explosive-emission cathode has been investigated. A relation between the sizes of the drops and their maximum velocities has been found for the velocity range 10³-8×10⁴ cm/s. The relation obtained supports the earlier established mechanism for the emission of drops under the action of high pressures developing in explosive emission centers. The possibilities of an additional acceleration of drops due to the explosion of necks formed on breaking the drops off the cathode surface and at the expense of the kinetic energy of the ions of the expanding cathode plasma have been discussed     

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     

Investigation into the formation of X-ray photopolymer lenses

Two nondestructive methods of X-ray lens testing—X-ray microtomography and phase contrast introscopy—are analyzed and compared. Refractive lenses fabricated via laser stereolithography are used as a comparative object. The first samples of photopolymer lenses have been created via the rotation method, in which a capillary filled with a Dikhrom Lyuks liquid photopolymer is exposed to UV radiation during centrifuge rotation. Lens samples have been fabricated at the centrifuge’s angular velocities lying in the range from 3000 to 5000 rpm. The features of photopolymer transition from the liquid state into the solid phase under UV irradiation have been investigated to estimate their influence on the formation of the required shape of a refractive profile.     

光栅扫描光谱仪参数的研究

光栅扫描光谱仪的入射光线和出射光线的方向是固定的,在光栅转动下进行分光,这与光栅不动而入射光方向改变的分光方法不同。由光栅方程出发,计算出电脑自动控制多光栅转动的光谱仪测试系统的角色散率、线色散率和分辨本领,得出光栅扫描光谱仪的角色散率、线色散率和分辨本领等参数公式。所得结果与光栅不动而入射光方向改变的光谱仪的角色散率、线色散率和分辨本领不同。这为光栅扫描光谱仪的使用和研究提供了理论依据。     

Investigation into the power-law dependence of fibre Bragg grating growth

We have undertaken a detailed experimental and numerical investigation of fibre Bragg grating growth rates over relatively long timescales, in which we consider the influence of zero-order UV irradiation, jitter and drift. In contrast to other studies, our results show that measurements of grating growth dynamics are in good agreement with numerical expressions describing exponential decay of a population of defect sites if the influence of small lateral displacements between the optical fibre and the modulated UV beam (jitter) are accounted for.     

关于音乐厅响度评价的研究

该文回顾并综述了对音乐厅(包括西洋交响乐厅及中国民族音乐厅)响度评价的研究历程,指出采用乐队齐奏强音标志乐段的平均声压级L_pF作为评价音乐厅响度客观指标的合理性与可行性。文中给出L_pF的计算方法以及对若干厅堂计算值与实测值的比较,并通过主观评价,给出L_pF的初步优选值域。采用L_pF作为响度评价指标的好处不仅在于它能表征听众听到的绝对响度的感受,还在于能预判何种规模的乐队适于在多大规模的音乐厅中演出,以便达到较佳响度效果的问题。     

Investigation on ultrasonic cavitation erosion of TiMo and TiNb alloys in sulfuric acid solution

Two kinds of Ti-alloys, i.e., TiMo and TiNb alloys are manufactured in this paper, and their ultrasonic cavitation erosion behaviors in 0.1 M H₂SO₄ solution are evaluated by the mean depth erosion (MDE), SEM and white light photograph. The results show that MDE of TiMo and TiNb alloys obviously increase with increasing the cavitation erosion time, however, they evidently decrease with the increment of Mo or Nb content at each fixed cavitation erosion time, and even some large blank areas (uneroded areas) still exist on the sample surface after ultrasonic cavitation erosion for 2 h in the case of Ti10Mo and Ti20Nb samples, implying the enhanced anti-cavitation erosion property of Ti-alloy by adding Mo or Nb element. The MDE of Ti10Mo or Ti20Nb sample is lower than that of TC4 sample in the case of each cavitation erosion time, indicating the better cavitation erosion resistance of of Ti10Mo or Ti20Nb sample. The influences of Mo and Nb on the passivity of TiMo and TiNb alloys during the ultrasonic cavitation erosion are detected by potentiodynamic curves. The results display that Ti, TC4, TixMo (x = 1, 5, 10) and TixNb (x = 5, 10, 20) samples are all almost in the passive state within the potential region from 0V_SCE to 1.5V_SCE during ultrasonic cavitation erosion, and the passive current density evidently decreases with increasing Mo or Nb content, indicating the enhanced passive characteristic by adding Mo or Nb alloys during the ultrasonic cavitation erosion.     

Investigation into the kinetics of ordering of the Au4Zn alloy

The kinetics of ordering of the Au₄Zn alloy is investigated using X-ray diffractometry. It is established that the ordering and growth of domains inside the ordered phase are multistage processes. These processes are characterized by nucleation and growth of the ordered phase. The kinetics of growth of domains involves the nucleation and growth stages, as well as stages in which the crystal lattice axes have preferred or equally probable directions. The stages are more pronounced at low annealing temperatures. The duration of particular stages of the evolution of antiphase domains and their sizes depend on the annealing temperature.     

Experimental Investigation into the Low-Molecular-Weight Fluoropolymer for the Storage of Ultracold Neutrons

The experimental setup for examining the low-molecular-weight CF₃(CF₂)₃–O–CF₂–O–(CF₂)₃CF₃ fluoropolymer, which is a promising coating material for the walls of storage chambers for ultracold neutrons, is described. The results are detailed. The measurement data are interpreted in the model of a multilayer complex quantum-mechanical potential of the chamber walls.     

Investigation into the rotational bands of 185Pt with the particle-rotor model

Theoretical calculations have been performed for the ν9/2⁺[624](i _13/2) and ν7/2⁻[503]( f _7/2) bands of ¹⁸⁵Pt in the framework of particle-rotor model. The band properties of signature splitting and configuration mixing have been analyzed. The level energy and signature splitting before the band crossing can be well interpreted by introducing triaxiality. The positive-parity yrast band is proposed to be dominated by the ν9/2⁺[624](i _13/2) component, while the negative-parity band shows strong mixing of ν7/2⁻[503](f _7/2) and ν9/2⁻[505](h _9/2) configurations.

     

Investigation into the dielectric relaxation of vinylidene fluoride copolymers with hexafluoropropylene

Four relaxation processes and one ferroelectric-paraelectric phase transition are revealed in vinylidene fluoride-hexafluoropropylene copolymers with different ratios of the components in the temperature range from ?100 to 150°C. The relaxation process occurring at the lowest temperature is associated with the local mobility of the chains, whereas the relaxation process at a higher temperature is due to micro-Brownian motion of segments in the amorphous phase in the glass transition range. A smeared relaxor phase transition from the polar modification of the α phase of vinylidene fluoride units to the paraelectric phase is observed in the temperature range 50–70°C. At higher temperatures, there occurs an intensive relaxation process that can be attributed to space-charge relaxation or manifestation of the normal relaxation mode.     

Investigation into the structural and electrical properties of silver-intercalated zirconium diselenide

Silver-intercalated zirconium diselenides of the general formula Ag_xZrSe₂ are synthesized for the first time. The phase diagram of the Ag_xZrSe₂ compound is determined in the temperature range 423–523 K and at room temperature. An analysis has revealed the coexistence of two compounds, namely, Ag_0.125ZrSe₂ and Ag_0.25ZrSe₂, of which only the latter compound is stable at room temperature. The structural and electrical properties of Ag_xZrSe₂ diselenides are investigated. The results obtained indicate a polaron nature of charge-carrier localization. A comparison with isostructural intercalation compounds shows that free charge carriers play a dominant role in screening of the impurity potential.     

Investigation into the improved axial compressibility of a spinning non-ideal gas

Using theoretical analysis and numerical calculation method, the axial adiabatic compression of a spinning non-ideal gas in a cylinder with a smooth surface is investigated. We show that the axial pressure of a spinning gas will gradually become lower than that of a stationary gas during continuous compression, even though the initial axial pressure of the spinning gas is larger than that of the stationary gas at the same initial temperature and average density. This phenomenon indicates that the axial compressibility of gas is improved in a rotating system. In addition, the effect of different forms of virial coefficient B(T) on pressure and temperature changes in spinning and stationary gases are investigated. Research on the axial compressibility of spinning non-ideal gas can provide useful references for fields that require high compression of gases, such as laser fusion, laboratory astrophysics, and Z-pinch experiments.