Development of an electron-beam welding unit for small-size pieces

Requirements for equipment for electron-beam welding of small-size pieces are presented. Features of physical processes of the formation of low-power electron beams in process installations are shown. Mathematical simulation methods were used for the analysis of the operation of a three-electrode electron gun and for the choice of operation modes of power sources. The design and characteristics of the developed inverter power source for the electron-beam gun are described. The design of an electron-beam welding unit for small-size pieces is given.     

Dynamic processes in abnormal operating conditions of power supplies of welding electron-beam guns

The dynamic processes in power supplies of welding electron guns caused by abrupt change in the parameters of load, currents, and voltages have been considered. A mathematical model for the study of abnormal modes of power supplies that are part of the power unit of an electron-beam welding installation with regard to the mutual influence of their parameters has been proposed. Results of experimental studies of the operation of an inverter prototype have been compared with the simulation results.     

Modern principles for construction of power sources for electron-beam welding units

Modern requirements for power sources of welding electron guns are formulated. The electron-gun parameters are analyzed as the power source load, and main trends in electrical equipment for electron-beam welding are revealed. The modern principles for construction of power sources for electron-beam welding units are considered using the example of two schematic diagrams.     

The use of electron-beam technology to produce bimetallic contacts for electrical plants

The process of producing compounds of VM-80 tungsten–copper alloy with BrX1Tsr chrome–zircon bronze using the methods of electron-beam brazing, surfacing, and welding is considered as applied to creating billets for producing bimetallic electrical contacts. The structures of the bimetallic contact and the main processes of electron-beam brazing, surfacing and welding of the specified materials are studied; the microstructure and mechanical properties of joints produced by the methods of electron-beam brazing and surfacing are investigated; and practical recommendations are given for the performance of further thermal treatment so as to improve the mechanical properties of obtained compounds. The results of this work may be of interest for specialists in the area of electrical-equipment design.     

电子束曝光机束径和束流最佳配合研究

文中测量了电子束曝光机束斑直径和束流大小的测量方法,提出调整束斑直径的基本原理,设计了一种实现束径和束流最佳配合的自动测量和调整系统。     

Determination of the polarization distribution inelectron-beam-poled PVDF using heat wave and pressure pulse techniques

In the present paper, heat wave (LIMM) and pressure pulse measurements are reported of the polarization and electric field distribution in nonuniformly electron-beam poled PVDF. In order to obtain the spatial distributions from the LIMM spectra, the regularization technique is applied to the deconvolution. In this connection nonlinear grid distributions are discussed. The polarization profiles obtained by the two methods are compared over the whole thickness range, and a satisfactory agreement is found     

Current trends in development of electric equipment for electron-beam precision welding and dimensional machining

The article discusses the major trends in the development of power-supply sources for electronbeam industrial installations applied for precision welding and dimensional machining. Technical specifications are given, as well as general circuit approaches to the power-supply sources of triode thermionic electron-beam guns.     

Features of construction of manipulators for electron-beam welding installations

The features of the construction of multicoordinate manipulators for moving welded products in precision electron-beam welding installations are considered. The kinematic circuits of manipulators, the types of stepping motors, and the circuit of the control system over the multicoordinate moving of welded products are presented.     

电子枪高压放电的危害及其对策

介绍了电子束焊机运行过程中电子枪发生高压放电现象对焊机各部件产生的危害,并提出了抑制高压放电冲击电流的措施。     

An ultrahigh-voltage controllable power source based on an electron-beam valve

The construction feasibility of a modular ultrahigh-voltage power source with a voltage of 2.5 million V on the basis of EBV 2/200 electron-beam valves possessing a pentode volt-ampere characteristic a the voltage of up to 250 kV, is considered. The valve allows smooth control of the source high voltage values of every module up to 250 kV and maximal load breakdown current up to 1 A.     

Vacuum ultraviolet emissions from the ionic excimer molecules(KrCs)+ and (HeAr)+ by low-energy electron-beamexcitation

Vacuum ultraviolet fluorescence emissions from the ionic excimer molecules (KrCs)⁺ and (HeAr)⁺ were studied in detail by low-energy electron-beam excitation, measurements were performed as a function of gas composition, gas pressure, and deposited energy in order to investigate the kinetic mechanisms of these molecules. The rate constants of the formation and competitive reactions were determined from the observed fluorescence signal decay. Estimations of the total fluorescence yield and of the gain coefficient for these molecules are given     

Photonic Applications With the Organic Nonlinear Optical Crystal DAST

We review the recent progress in the development of photonic applications based on the organic crystal 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST). DAST is an organic salt with an extremely high nonlinear optical susceptibility chi⁽²⁾(-2omega,omega,omega)=580plusmn30 pm/V at 1.54 mum, a high electrooptic figure of merit n ³ r = 455plusmn80 pm/V at 1.54 mum, as well as a low dielectric constant epsiv = 5.2 . DAST is, therefore, very attractive for high-speed optical modulators and field detectors, as well as for frequency conversion and the generation of terahertz waves. Several techniques to microscopically structure this material have been developed recently; including modified photolithography, photobleaching, femtosecond laser ablation, graphoepitaxial growth, ion implantation, and direct electron-beam structuring, which open new perspectives of using this exceptional material for high-speed very-large-scale integrated photonics.     

Thyristor voltage pulse shapers for controlling high-voltage switching electronic elements

The efficiency of using switching high-voltage electron-beam valves (EBVs) in power-supply systems of electrophysical and other high-power units is shown. The novelty of the scientific and engineering solutions applied to design EBVs with high electric parameters is emphasized. The rationale for using single-operation SCR thyristors for EBV control is provided. The principles of constructing thyristor voltage pulse shapers are analyzed and generalized.     

A Method for the Removal of Sulfur Dioxide from Exhaust Gas Utilizing Pulsed Streamer Corona for Electron Energization

The performance of a new method using pulsed streamer corona for the removal of SO2 from humid air has been evaluated. The pulsed streamer corona produces energetic free electrons that excite, dissociate, and ionize gas molecules, forming radicals that enhance the gas-phase chemical reactions that convert SO2 to acid mist and/or particulate aerosols. The aerosols are then collected by conventional means, i.e., by electrostatic precipitator or bag filter. The SO2 removal efficiency was compared with that of the electron-beam and dc corona flue-gas treatment processes. The comparison demonstrates the advantage of the novel method.     

Thermal barrier coatings on gas turbine blades: Chemical vapor deposition (Review)

Schemes are presented for experimental setups (reactors) developed at leading scientific centers connected with the development of technologies for the deposition of coatings using the CVD method: at the Technical University of Braunschweig (Germany), the French Aerospace Research Center, the Materials Research Institute (Tohoku University, Japan) and the National Laboratory Oak Ridge (USA). Conditions and modes for obtaining the coatings with high operational parameters are considered. It is established that the formed thermal barrier coatings do not fundamentally differ in their properties (columnar microstructure, thermocyclic resistance, thermal conductivity coefficient) from standard electron-beam condensates, but the highest growth rates and the perfection of the crystal structure are achieved in the case of plasma-chemical processes and in reactors with additional laser or induction heating of a workpiece. It is shown that CVD reactors can serve as a basis for the development of rational and more advanced technologies for coating gas turbine blades that are not inferior to standard electron-beam plants in terms of the quality of produced coatings and have a much simpler and cheaper structure. The possibility of developing a new technology based on CVD processes for the formation of thermal barrier coatings with high operational parameters is discussed, including a set of requirements for industrial reactors, high-performance sources of vapor precursors, and promising new materials.     

Optimal control of steady-state modes of high-voltage electron-beam valves

The prospects for use of electron-beam valves (EBVs) in construction of high-voltage power supplies used in electrophysical, radiotechnical, and other types of high-power facilities are outlined. Observed dependences of EBV parameters are given. Various principles of EBV optimal control that are designed to permit minimal total power losses at the valve’s anode and control electrode are devised and synthesized.     

An analysis of approaches to developing converters for power engineering based on vacuum switching-type electronic devices

The technical feasibility of using electron-beam valves of the EBV 2/200, EBV 4/40, and EBV 50/100 types in power electronic engineering, including static reactive-power compensators or integrated power-flow controllers, was considered at line voltages of 20–35 kV without using high-voltage transformers. A physical analog of bridge and half-bridge inverters on the basis of the EBV 4/40 valve with pulse-width modulation with a sampling rate of 1–2 kHz was built.     

Complex design of electrical equipment for precision electron-beam welding

Results of analysis of electrical characteristics for precision electron-beam welding equipment in accordance with modern technological requirements are presented. A complex method of designing systems of this class that takes into account the relationship of characteristics of the elements and modes of operation and provides the composition and parameters of the equipment with their adjustment in the design process is proposed.     

Topping the 300-MW power unit at the GRES-24 district power station with a GTE-110 gas turbine unit. Technical solutions on the thermal circuit

We describe the outcomes from the development of a gas-turbine topping for the 300-MW power unit that was initially constructed as an attachment to an MHD-generator, which, however, has not been constructed. A 110-MW GTE-110 gas-turbine unit was used as a topping for this power unit. The topped power unit allows more than 9% of fuel to be saved as compared with the original one.     

Off-plane computer-generated waveguide hologram

We present the theory, design, fabrication and evaluation of off-plane computer-generated waveguide holograms (OP-CGWHs). The hologram structure is composed of an array of rectangular elements each containing a waveguide grating coupler. The function of the rectangular elements is twofold: outcoupling the guided optical wave, and introducing phase shift. The phase shift of each rectangular element can be determined by controlling the dislocation of the grating grooves along the guided wave propagation direction. In addition, the phase pattern of the OP-CGWH can be designed using many existing algorithms for computer-generated holograms (CGH), such as the iterative Fourier transform algorithm (IFTA). A design example is presented for a waveguide array generator, which outcouples a Gaussian-like incident guided wave and simultaneously produces an array of spots in free space. Such an OP-CGWH device, based on an AlGaAs-GaAs waveguide, was fabricated using electron-beam lithography and reactive ion beam etching. Experimental results are presented that demonstrate the effectiveness of the proposed idea. The uniformity error and the power efficiency of the fabricated OP-CGWH array generator were measured to be approximately 8% and 30%, respectively