Theoretical and experimental study of electron-optical systems in low-energy wide-aperture electron accelerators

A large-area electron accelerator based on filament cathodes that operates in a continuous mode is described. The results of calculations of electron-optical systems of triode- and tetrode-type accelerators in accordance with the proposed engineering approach are considered, and experimental and calculated parameters of the accelerator are compared.     

New principles of designing multibeam electron-optical microsystems for diagnostics of semiconductor structures

A new approach to fabrication of diagnostic electron-optical systems of high (10–30 nm) and ultrahigh (to 2 nm) resolution for defect inspection of large-diameter semiconductor wafers is proposed. Electron optical calculation of electron-optical systems with different configurations is performed. The efficiency of using thin films for increasing quality of electron-optical systems is estimated.     

A simple model for magnetism in itinerant electron systems

A new lattice model of interacting electrons is presented. It can be viewed as a classical Hubbard model in which the energy associated to electron itinerance is proportional to the total number of possible electron jumps. Symmetry properties of the Hubbard model are preserved. In the half-filled band with strong interaction the model becomes the Ising model. The main features of the magnetic behavior of the model in the one-dimensional and mean-field cases are studied.     

Open-type image tubes for plasma research

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 3, pp. 518–520, September, 1991.     

Determination of limiting parameters of multiple-beam electron-optical systems for diagnostics of semiconductor structures

The factors limiting the possibilities of electron probe systems for diagnostics of semiconductor structures are discussed. Their effect on instrument characteristics, i.e., efficiency, resolution, and data quality, are determined. The correlation between these characteristics is considered to develop an electron probe system for a particular application, i.e., defect detection with a set of characteristics best corresponding to this specific problem, is determined.     

Numerical analysis and synthesis of electron-optical systems of complex structure

The problem of the numerical analysis of the electrostatic field of individual elements in complex three-dimensional electron-optical systems is considered. Zh. Tekh. Fiz. 68, 97–103 (February 1998)     

Analytical method for designing dispersion-managed fiber systems

Using the equations of motion of pulse width and chirp, we present an analytical method for designing dispersion-managed (DM) fiber systems without optical losses. We show that the initial Gaussian pulse considered for the analytical design of periodically amplified DM fiber systems with losses will propagate as a proximity fixed point. Then averaging the DM soliton fields obtained from the slow dynamics of the proximity fixed point will yield the exact fixed point.     

Numerical analysis and synthesis of electron-optical systems of complex structure. II

The numerical analysis and synthesis of intrinsically three dimensional electron-optical systems with complex structures are examined. Zh. Tekh. Fiz. 68, 126–129 (July 1998)     

Thermal analysis of electron gun for travelling wave tubes

Thermal analysis of a pierce type electron gun using the FEM software ANSYS and its experimental validation are presented in this paper. Thermal analysis of the electron gun structure has been carried out to find out the effect of heater power on steady state temperature and warm-up time. The thermal drain of the supporting structure has also been analyzed for different materials. These results were experimentally verified in an electron gun. The experimental results closely match the ANSYS results.     

数码相机CMOS图像传感器的特性参数与选择

介绍了数码相机的核心器件———CMOS图像传感器的特性参数和在数码相机设计过程中CMOS图像传感器的选择。选择CMOS图像传感器,不仅需要考虑包括传感器的尺寸、像素总数和有效像素数、最小照度、动态范围、灵敏度、分辨力、光电响应不均匀性以及光谱响应等在内的特性参数,而且还要考虑电源管理和功耗、模数转换位数、开发的简便性以及成本等因素。     

A generalized scheme for designing multistable continuous dynamical systems

In this paper, a generalized scheme is proposed for designing multistable continuous dynamical systems. The scheme is based on the concept of partial synchronization of states and the concept of constants of motion. The most important observation is that by coupling two m-dimensional dynamical systems, multistable nature can be obtained if i number of variables of the two systems are completely synchronized and j number of variables keep a constant difference between them i.e., their differences are constants of motion, where i + j = m and 1 ≤ i, j ≤ m?1. The proposed scheme is illustrated by taking coupled Lorenz systems and coupled chaotic Lorenz-like systems. According to the scheme, two coupled systems reduce to single modified system with some initial condition-dependent parameters. Time evolution plots, phase diagrams, variation of maximum Lyapunov exponent and bifurcation diagrams of the systems are presented to show the multistable nature of the coupled systems.     

Dynamics and instability of electron phase-space tubes

Two-dimensional simulations of beam-driven turbulence in the auroral ionosphere have shown the formation and instability of phase-space tubes. These tubes are a generalization of electron phase-space holes in a one-dimensional plasma. In a strongly magnetized plasma, such tubes vibrate at frequencies below the bounce frequency of the trapping potential. A theory for these vibrations yields quantitative agreement with kinetic simulations. Furthermore, the theory predicts that the vibrations can become unstable when resonantly coupled to electrostatic whistlers-also in agreement with simulations.     

A simple method for designing structural models with closely spaced modes of vibration

Vehicle structures often have closely spaced modes of vibration within the frequency spectrum of applied loads. Such modes are important since they tend to be the source of vibration problems. In order to study the effects that closely spaced modes have on structural response in such situations as modal testing and self-excited vibrations, it is useful to be able to design a mathematical structural model having closely spaced modes. In this paper, a method for designing such a model is presented and illustrated with examples. Given a reference model with specified geometry and degrees of freedom, the lumped inertias and stiffnesses of the model are perturbed in such a manner as to force together two of its natural frequencies. With a slight alteration, the method is also applicable to the inverse problem of separating undesirable closely spaced modes which appear in a structural design.     

Aged skin: detection of alterations of major collagen types ratio by image processing of electron-optical data

Automated algorithms are developed in this paper based on digital signal processing to correlate electron-optical data from skin collagen fibrils with known sequence data. In particular, they detect alterations on the ratio of major collagen types in skin upon age.     

A physical basis for designing integrated acoustic network systems for underwater observations

A concept for designing network systems for underwater observations based on the joint development of hydroacoustic radiating and receiving elements integrated with different channels of communication is discussed. The main requirements for such systems, principles, and algorithms of their operation under nonstationary conditions of actual marine waters are formulated. The results from several numerical and field experiments demonstrating the performance of certain elements of such systems in typical shallow water basins are presented.     

Droplet traffic in microfluidic networks: a simple model for understanding and designing

We propose a simple model to analyze the traffic of droplets in microfluidic "dual networks." Such functional networks which consist of two types of channels, namely, those accessible or forbidden to droplets, often display a complex behavior characteristic of dynamical systems. By focusing on three recently proposed configurations, we offer an explanation for their remarkable behavior. Additionally, the model allows us to predict the behavior in different parameter regimes. A verification will clarify fundamental issues, such as the network symmetry, the role of the driving conditions, and of the occurrence of reversible behavior. The model lends itself to a fast numerical implementation, thus can help designing devices, identifying parameter windows where the behavior is sufficiently robust for a device to be practically useful, and exploring new functionalities.     

Magneto-electric response functions for simple atomic systems

We consider a simple atomic two-body bound state system that is overall charge neutral and placed in a static electric and magnetic field, and calculate the magneto-electric response function as a function of frequency. This is done from first principles using a two-particle Hamiltonian for both an harmonic oscillator and Coulomb binding potential. In the high frequency limit, the response function falls off as 1/ω ² whilst at low frequencies it tends to a constant value.