An PBЕ-73C vacuum spark gap with a control circuit based on an inductive energy storage

The design and operating principle of a small (50 mm in diameter and 100 mm in height) РВЕ-73C vacuum spark gap are described. It is shown that it can be efficiently switched using a control circuit with a low (∼900 V) supply voltage, which is based on an inductive energy storage and a diode opening switch that forms a high-voltage igniting pulse with a rise time of nanosecond duration. The РВЕ-73C switching process is investigated at different rise times of igniting voltage pulses and different igniting current amplitudes. The results of tests of the spark gap operating in regimes of switching current pulses with an amplitude of 12 kA and a rise time of 800 ns are presented.     

Characteristics of MEDM for micro-holes with respect to circuit elements

Micro electrical discharge machining (MEDM) is a promising technology for fabricating micro-parts on a variety of materials. An RC circuit is suitable for MEDM because it produces low pulse width and relatively high peak current. However, it is not well understood how circuit elements affect machining characteristics of MEDM. In this paper, the effects of circuit elements on MEDM of micro-holes and the relation between characteristic variables of process and machining characteristics was investigated. Since the discharge inductance causes an increase in electrode wear and machining time, it should be minimized in MEDM. From this study, it should be less than a few μH. The machining time also increases with increasing the charging resistance. If the charging resistance is less than a few hundreds Ω, however, continuous arc discharge occurs and the machining speed is markedly reduced.     

Possibilities for reducing the duration of acoustic pulses generated by a piezoelectric plate using a damper or an electric <Emphasis Type="Italic">RL</Emphasis> circuit for a plate excited by electric pulses of different durations

Calculation formulas were obtained for determining the shape of an acoustic pulse radiated by a piezoelectric plate that has a mechanical damper and a correcting electric circuit and is excited by electric pulses with durations that are multiples of an integer number of half periods at the antiresonance frequency ω₀. Calculations were performed for particular cases when either an electric circuit or a damper is present. The optimal parameters of the electric circuit that provide the shortest duration of radiated signals were determined. The durations and amplitudes of radiated signals obtained using the damper or the electric circuit were compared. Conclusions concerning the degree of efficiency of applying an electric RL load were made.     

Photothermoplastic recording of contour holograms by means of inverted wave in brillouin scattering

Thermoplastic recording of contour holograms is based on the use of dual-frequency radiation comprising the pump-wave radiation (λ-0.694 μm) and radiation of the wave inverted relative to the pump wave in Brillouin scattering. Two possible arrangements for contour holograms recording are studied: an arrangement with additional amplification of the inverted wave radiation in the laser active medium, and an arrangement with isolation of the optical circuit of the laser from the inverted laser radiation. It is found that the reduced duration of the inverted wave pulse relative to the pump-pulse width, typical of Brillouin scattering, does not cause any loss of sensitivity of the photothermoplastic material. The proposed method of recording contour holograms ensures power stability of the output dual-frequency radiation with a changing frequency interval and makes it possible to study nonstationary objects.     

Automatic Determination of Resonance in Oscillatory Circuits

A method for tuning oscillatory circuits is described. The method consists in feeding the oscillatory circuit with rectangular current pulses of linearly varying frequency, isolating circuit oscillations with phases of ±45° (these phases correspond to the cutoff frequencies of the circuit passband), and calculating the resonance frequency by using the symmetry of the oscillatory circuit characteristics. The device ensures the control of the passband, resonance frequency, and the equivalent quality factor of an oscillatory circuit in a wide frequency range (from 0.1 to 60 MHz).     

High-frequency pulse generators based on SOS diodes with subnanosecond current cutoff time

Compact high-voltage generators with a pulse power of 100–500 MW, an output voltage of 150–400 kV, a pulse duration of 3–6 ns, and pulse repetition rates of 300–400 Hz and up to 5 kHz in a steady-state and a 30-s-long burst mode, respectively, are described. The output power-amplification unit is based on an inductive storage and SOS diodes with subnanosecond current cutoff time. Physical processes in the semiconductor structure of a SOS diode operating in the subnanosecond current cutoff mode are considered. The generator circuit designs and their test results are presented.     

用于闪电瞬态电场测量的高速采集系统设计

利用A/D转换芯片AD9057和基于Pockels效应的闪电电场传感器设计了一个闪电瞬态电场测量的高速采集系统,给出了高速采集系统的硬件电路和软件程序设计流程图。该系统主要包括:闪电电场传感、高速A/D转换、数据存储、数据处理。通过对闪电电场高速采集系统的硬件和软件设计,解决了数据采集过程中存在的高速A/D转换的速度与低速智能管理的速度不匹配问题,实现了带宽为0~10MHz的闪电瞬态电场信号采集。     

A discharge-based periodic pulse hollow-cathode generator and an antenna system for emitting high-power radio pulses

A discharge-based generator with a hollow cathode and an emitting system based on a corner antenna for emitting a periodic high-power high-frequency radio pulse train were developed and tested. The parameters of generated and emitted radio pulses are as follows: (i) the carrier frequency is 120 MHz, (ii) the peak power is 300 kW, (iii) the pulse duration is 1.2 μs, and (iv) the pulse repetition rate is 500 Hz.     

High immunity wafer-level measurement of MHz current

Wafer-level characterization of functional prototypes of solid state current sensors is usually the first step in the development stage, therefore a dedicated wafer-level measurement systems are required. Especially for MHz characterization, where electromagnetic interference issues became strongly relevant. Thus, for frequencies above 1 MHz, a sophisticated measurement techniques are needed, because parasitic couplings can significantly affect sensor response and other signal processing stages, causing errors or malfunction of the whole system. We propose technique for high immunity MHz current measurement by solid state sensor in wafer-level configuration. The system is especially well-suited for MHz characterization, where electromagnetic interference issues become highly relevant. We showed that balanced transmission provides possibility to reduce interference in the sensor biasing circuit of about 60 dB compared to single-ended method. The effectiveness of the proposed technique was tested in monitoring MHz current in the external line by single magnetoresistive sensors on wafer level.     

Research on Microelectromagnetic Relays

A new microelectromagnetic relay is presented and fabricated based on micromachining technology, aiming at the miniaturization and high manufacturing efficiency of electromagnetic relays. This microrelay is composed of a lower magnetic circuit, a planar exciting coil, and an upper magnetic armature. A complete magnetic circuit is composed, and the “ON” and “OFF” states are controlled by the current of the exciting coil. The dimension of this microrelay is 5 mm × 5 mm × 0.4–mm. The fabrication process mainly includes lithography, sputtering, electroplating, etching, sacrifice-layer technology, etc. Electromagnetic force is calculated theoretically. The calculation results are used for the optimization design of the armature and the number of turns of the exciting coil. A microelectromagnetic relay is fabricated and the initial test results are given. The resistance of the exciting coil is about 300 Ω. The switch-on state resistance is about 1.7 Ω at an exciting current of about 50–mA. Translated from Journal of Beijing University of Technology, 2004, 30(2) (in Chinese)     

Low power high-performance radio frequency oscillator for driving ion traps

We report a simple, efficient, high voltage radio frequency (RF) generator powered by a single voltage source (1.5-7 V) to resonantly drive ion traps or other capacitive loads. Our circuit is able to deliver RF voltages > 500?V(p-p) at frequencies ranging from 0.1 to 10 MHz. This RF oscillator uses low-cost, commercially available components, and can be easily assembled onto a circuit board of a few cm(2). Because of its simplicity and good efficiency, this circuit is useful in applications requiring small size and low power consumption such as portable ion trap systems where the duration of operation under battery power is of concern.     

Using single-photon detectors for quantum key distribution in an experimental fiber-optic communication system

This paper gives experimental results of quantum key distribution on a fiber-optic setup at a telecom wavelength of 1555 nm. A self-compensated two-channel optical circuit is used. Quantum key distribution was performed by coding the phase states of single photons radiated by a pulsed semiconductor laser in two alternative nonorthogonal bases. Specially developed single photon counters based on InGaAs: InP avalanche photodiodes were employed as high-sensitivity photodetectors. The results of investigation of the quantum efficiency, probability of afterpulses, and noise level for various operating modes of the detectors at temperatures from −40 to −60°C are given. A key distribution rate of 450 bit/s was obtained for a single-mode fiber-optic quantum communication channel between the receiver and sender 25 km long at a laser pulse clock frequency of 5 MHz and an average number of photons per pulse of about 0.2. For the achieved photodetector characteristics, the average number of errors in the quantum key did not exceed 3.7%.     

A study on the mirror surface machining by using a micro-energy EDM and the electrophoretic deposition polishing

In order to achieve a mirror-like workpiece surface by EDM, a micro-energy EDM or a manual lapping is normally used. However, both methods are time consuming and economically unattractive. To have better performance, a sinking EDM machine was first used in this research on SKD 61 for a micro-energy discharge process followed by the electrophoretic deposition (EPD) process to coat Al₂O₃ particles uniformly on a rotation electrode. The precision polishing process was then applied on the discharged workpiece with suitable parameters including the voltage, electrode rotating speed, pH value of electrolyte, and abrasive concentration. After the EDM process, the surface roughness and the recast layer thickness of a workpiece could also be reduced. The experimental data showed that when 0.3 μm of Al₂O₃ particles was used for the EPD polishing process, the initial roughness of a discharge surface could be improved from 0.52 μm Ra (6.50 μm Rt) to a mirror-like surface of 0.068 μm Ra (0.742 μm Rt). Also, the total working time could be reduced significantly to within the range of 5 to 10 min.     

A high-frequency semiconductor generator of high-voltage nanosecond pulses

A generator of high-voltage rectangular nanosecond pulses equipped with switches in the form of assemblies of deep-level dynistors connected in series is described. A control circuit for dynistors based on an assembly of inversely switched-off diodes connected in series is considered. The generator can operate at a frequency of 10 Hz and form (at a 20-pF load) rectangular voltage pulses with short (4 ns) leading and trailing edges and a short (25 ns) delay relative to an external control signal. The amplitude and duration of output pulses are controlled smoothly in the ranges 7–9 kV and 100–600 ns, respectively. The spread of moments of operation is within 0.5 ns.     

干式空心电抗器匝间短路故障暂态特性仿真研究

从理论上分析了干式空心电抗器从正常运行状态到匝间短路故障状态下的匝间短路动态过程,建立了暂态电路耦合计算模型,并利用ANSYS Maxwell软件模拟了匝间短路故障的暂态特性,提出了通过安装在电抗器封装上的检测线圈实现对电抗器短路位置引起的磁场突然变化的检测方法。通过实验研究表明,采用本文提出的方法可以在较早的故障期间检测到匝间短路故障。     

Improving bonding strength of tape-automated bonding technology by implementing statistical process control: a case study

The purpose of this paper is to improve the bonding strength of tape-automated bonding (TAB) technology in supertwisted nematic liquid crystal display (STN LCD) module manufacturing by double-process control. First, the quality characteristic – the output of the process – is monitored by control charts and the variation of the process is reduced. Later, it is found that the quality characteristic is affected by critical input process parameters. These critical input process parameters and the quality characteristic are therefore monitored simultaneously. By this double-process control, the deviation of the process is further reduced. The results show that process capability and yield rate are increased.     

800 MHz发射机带通滤波电路的优化容差设计

在考虑了电路元件容差的基础上，应用优化容差设计技术理论对用Bessel函数设计的800MHz无源LC带通滤波电路元件的参数值进行调整，以使其衰减特性在满足技术指标要求和低成本的条件下，同时使电路元件的参数值具有尽可能大的容差范围，从而使滤波系统具有较高的工作可靠性、稳定性和低成本。计算机仿真试验证明了本设计方案的优越性。在工程应用上极具理论指导意义和应用价值。     

Ultrasonic introscopy of welds of products in the nuclear industry

The parameters of ultrasonic testing equipment and techniques of producing 2D ultrasonic images of welds at frequencies of 10–50 MHz are given.     

A Self-Oscillatory Converter of Parameters of a Capacitive Sensor with High Losses

The converter is designed on the basis of a field-effect transistor with a balanced thermistor bridge connected to the drain circuit. The output of this thermistor bridge is connected to the transistor gate through a circuit specifying the operating frequency. The sensor is connected in parallel to the thermistor. The initial conversion frequency is 1 MHz, the range of measured capacitances is 5 × 10^–2–10^–3pF, and the error in the separability of converted parameters does not exceed 2% for conductances ranging from 0 to 2 × 10^–2S.