An ultrawideband Gigawatt pulse generator

An ultrawideband pulse generator consists of a bipolar voltage pulse generator, a four-channel power divider, and a flat (2×2) equally spaced equal-amplitude antenna array. Characteristics of the ultrawide-band radiation at the excitation of the antenna array by bipolar pulses with a±200-kV voltage amplitude, ≈3.5-ns duration, and 100-Hz pulse repetition rate are given. The peak power of the vertically polarized radiation is 1.3 GW.     

A magnetic-thyristor pulse generator for electric-discharge technologies

A generator is described that is intended for operation in the area of electric-discharge technologies. Depending on the electrical strength of the load, the generator produces voltages of up to 50 kV, the dissipated energy of the pulse is up to 200 J, and the pulse repetition rate is up to 100 Hz. The generator is based on the direct discharge of capacitors to a discharge gap through a coaxial cable with a length of up to 200 m and without additional switching components. The circuit stabilizing the pulse energy due to recuperation of the unused energy in the filter capacitor of the power supply is used to stabilize the energy dissipated by the load.     

A compact nanosecond pulse generator

A compact high-current pulse generator with the amplitude of the load current up to 140 kA and rise time below 200 ns is designed. The basic element of the pulse generator design is the HCEIcap 100–0.2 capacitor switch assembly. The capacitance value of the capacitor switch assembly is 200 nF, the charging voltage is 100 kV, the energy storage is 1000 J, and the full inductance value is 20 nH. The sizes of the active part of the capacitor are 80-mm inner diameter ×160-mm outer diameter ×160 mm. A multigap spark-gap is used as a switch. The rise rate of the current through the load (X-pinch, 2 molybdenum wires with a 25-μm diameter) is 1.3 kA/ns, and the soft X-ray pulse duration is 2.0–3.5 ns.     

A pulsed electromagnetic stimulator for bone-growth studies

A variable-pulse electromagnetic pulse generator has been developed to study the effect of the magnetic field on bone growth. The unit's repetition frequency can be varied from 2 to 200 Hz, and the peak current that it can drive is 10 A. The duty cycle of the pulse can be varied in steps of 10, 12.5, 17, 25, 50, 75, 83, 87.5, and 90% and is independent of the repetition frequency. The trailing edge of the output pulse can be controlled to produce any desired voltage-time pulse characteristic. This decay adjustment makes it possible to generate a variable-pulse frequency spectrum.     

A Programmable Pulse Sequence Generator for High Temperature Low-Field NMR Apparatus

The stable operation of pulse sequence generators at high temperatures (200°C) has been an important issue for some time in the application of nuclear magnetic resonance (NMR) apparatus for oil exploration. The application of system-in-package (SiP) technology was used to improve the temperature-resist grade of the hardware platform. A pulse sequence generator that meets the requirements of accurate phase and adjustable frequency during NMR apparatus in high temperature environments was designed and implemented. At ambient temperatures of up to 200°C, experimental results show that the delay times of the rising and falling edges of the pulse are 3.2 and 3.35 ns. respectively. The eye diagram Q factor of the critical path is not less than 15, and the Bit Error Rate (BER) is not more than 10^–50. The experimental results show that a pulse sequence generator can meet the requirements of high temperature NMR apparatus, and can also provide a template for the design of an NMR pulse sequence generator for special fields of application, such as deep sea surveys and aviation.     

A high-voltage stable-pulse generator

A high-voltage pulse generator producing pulses with a stable flat top is described. It is based on a multistage amplitude discriminator with inductance coils. The generator produces pulses with an amplitude of up to ?20 kV, a top width of up to 200 μs, and a pulse repetition rate of up to 50 Hz at a 20-kΩ load. The top width voltage instability does not exceed ±20 V. The generator is used in the power supply system of the INR linac H^? injector-based ion source.     

A current source with an inductive energy storage for measuring pulse impedances of grounding connections

A pulse generator with an inductive energy storage for measuring pulse impedances of grounding connections is developed. The generator produces current pulses with a rise time of 200–300 ns and an amplitude of up to 8 A. In contrast to the capacitive storage sources, it is fully controllable, allows one to adjust the amplitude, and ensures a constant current-pulse shape regardless of the load parameters. The different operation modes of the source are described. The experimental load-current waveforms are presented.     

A high-current pulse generator for gas discharge pumping

A generator has been designed for pumping a pseudospark gas discharge in xenon with the aim of generating UV radiation at a wavelength of 13.5 nm. The output parameters of the generator are as follows: the pulse energy is 10 J, the voltage is 6 kV, the peak current when short circuited is 40 kA, the base current pulse duration is 200 ns, and the frequency is as high as 500 Hz.     

基于FPGA的脉冲信号发生器设计

基于FPGA并运用DDS技术的相关理论,通过模块化设计,使标准脉冲信号发生器达到较高的性能指标,能够产生1~100kHz线性可调的脉冲,脉冲分辨率达100Hz,上升沿及下降沿为2.5ns,脉冲宽度从200ns~5μs可调,脉宽分辨率50ns,满足集成电路的脉冲驱动要求。     

YPT-0.5 repetitive-pulse nanosecond electron accelerator

An YPT-0.5 repetive-pulse nanosecond electron accelerator designed according to the thyratron-pulse transformer-semiconductor opening switch scheme is described. Its accelerating voltage reaches 0.5 MV, the FWHM pulse duration is 50 ns, and the pulse repetition rate is 200 Hz. A metal-dielectric cathode allows for obtaining an electron beam with a diameter of 30–100 mm at a maximum pulse current density of 40 A/cm². Operating in the bremsstrahlung generator mode, the accelerator provides an absorbed dose rate of 30.4 Gy/min at a distance of 5 cm from the target.     

A compact, low jitter, nanosecond rise time, high voltage pulse generator with variable amplitude

In this paper, a compact, low jitter, nanosecond rise time, command triggered, high peak power, gas-switch pulse generator system is developed for high energy physics experiment. The main components of the system are a high voltage capacitor, the spark gap switch and R = 50 Ω load resistance built into a structure to obtain a fast high power pulse. The pulse drive unit, comprised of a vacuum planar triode and a stack of avalanche transistors, is command triggered by a single or multiple TTL (transistor-transistor logic) level pulses generated by a trigger pulse control unit implemented using the 555 timer circuit. The control unit also accepts user input TTL trigger signal. The vacuum planar triode in the pulse driving unit that close the first stage switches is applied to drive the spark gap reducing jitter. By adjusting the charge voltage of a high voltage capacitor charging power supply, the pulse amplitude varies from 5 kV to 10 kV, with a rise time of <3 ns and the maximum peak current up to 200 A (into 50 Ω). The jitter of the pulse generator system is less than 1 ns. The maximum pulse repetition rate is set at 10 Hz that limited only by the gas-switch and available capacitor recovery time.     

Development of a plasma generator for a long pulse ion source for neutral beam injectors

A plasma generator for a long pulse H(+)/D(+) ion source has been developed. The plasma generator was designed to produce 65 A H(+)/D(+) beams at an energy of 120 keV from an ion extraction area of 12 cm in width and 45 cm in length. Configuration of the plasma generator is a multi-cusp bucket type with SmCo permanent magnets. Dimension of a plasma chamber is 25 cm in width, 59 cm in length, and 32.5 cm in depth. The plasma generator was designed and fabricated at Japan Atomic Energy Agency. Source plasma generation and beam extraction tests for hydrogen coupling with an accelerator of the KSTAR ion source have been performed at the KSTAR neutral beam test stand under the agreement of Japan-Korea collaborative experiment. Spatial uniformity of the source plasma at the extraction region was measured using Langmuir probes and ±7% of the deviation from an averaged ion saturation current density was obtained. A long pulse test of the plasma generation up to 200 s with an arc discharge power of 70 kW has been successfully demonstrated. The arc discharge power satisfies the requirement of the beam production for the KSTAR NBI. A 70 keV, 41 A, 5 s hydrogen ion beam has been extracted with a high arc efficiency of 0.9 -1.1 A/kW at a beam extraction experiment. A deuteron yield of 77% was measured even at a low beam current density of 73 mA/cm(2).     

A high-voltage nanosecond pulse generator based on a barrier discharge

One of the specific features of the barrier electric discharge is the short duration of microdischarge processes that last about tens of nanoseconds. A high-voltage nanosecond pulse generator based on a barrier electric discharge is presented. A voltage of tens of kilovolts is usually applied to electrodes of the discharge cell. The peak values of the current pulse may be very high (from a few amperes to several tens of amperes). The presented high-voltage nanosecond pulse generator, having a sufficiently simple design, ensures quite good pulse repetition stability, and, when necessary, allows one to easily tune characteristics of pulses and their repetition rates by changing the geometrical, electrical, and physical-chemical parameters of the setup.     

小孔加工电火花脉冲电源实验研究

针对传统脉冲电源普遍存在的电能利用率低、电阻发热严重、散热设备庞大等问题,提出了一种取消限流电阻的电火花脉冲电源结构。电源由PWM控制器、DC/DC变换器、加工脉冲时序发生器等组成。电源本身具有自动调节输出电压的功能,可实现空载击穿电压、脉冲宽度、脉冲间隔独立可调,取消了体积庞大的工频变压器。通过多次小孔加工实验获得了脉冲电源加工过程中电极损耗率、小孔椭圆度以及单边放电间隙等和电源稳定性相关参数的数据曲线,所得数据表明电源具有较好的加工稳定性和可靠性。     

Machining characteristics of micro EDM in water using high frequency bipolar pulse

Micro EDM using conventional pulse generators such as the RC type or transistor type with water as the dielectric fluid suffers from poor accuracy of machined structures due to electrolytic corrosion. In this study, a new high frequency bipolar pulse generator for micro EDM in water was developed in order to prevent electrolytic corrosion. The new pulse generator produced a high frequency bipolar pulse possessing a positive pulse duration of several hundred nanoseconds with a high repetition rate provided to the machining gap. Discharge characteristics of micro EDM using the new pulse generator were investigated. Machining characteristics were also investigated according to machining conditions such as the repetition rate, positive voltage, capacitance and resistivity. Using the new pulse generator, micro holes without electrolytic corrosion were successfully fabricated in deionized water and tap water. Machining time, tool wear and clearance using the new pulse generator in deionized water decreased compared with those using the RC circuit in kerosene.     

程控高压脉冲发生器

介绍一种程控高压脉冲发生器,主要由高压电源、储能电容器组、氢闸流管和控制电路等组成,可以输出一个负极性的高压脉冲,脉冲幅度为10～15kV。程控高压脉冲发生器采用模块化设计结构,将通用的构建于模拟电路基础之上的高压脉冲发生器与数字控制技术相结合,通过触摸屏、可编程控制器PLC加以控制,实现仪器的智能化。     

A high-voltage semiconductor rectangular-pulse generator for powering a barrier discharge

A semiconductor rectangular-pulse generator with smoothly controlled output parameters for powering a barrier discharge was developed and investigated. The generator allows the formation of voltage pulses with the smoothly regulated amplitude (0–16 kV) and duration (600 ns–1 ms) across the discharge gap. The pulse rise and fall times can be varied from 40 ns to 1 μs. The generator pulse repetition rate can be smoothly varied from 0 to 50 kHz. The generator can operate in the manual-triggering mode and in the mode of pulse trains with an effective frequency of up to 500 kHz. The generator is intended for initiating and investigating a barrier discharge in millimeter-wide air gaps at the atmospheric pressure.     

A small low-inductance capacitor charged with 200-kV pulses

A small low-inductance PC 200-1.5 capacitor with pulsed charging to 200 kV has been developed. In this capacitor, which has an inductance of 1.5 nF, a combined paper-film insulator impregnated with castor oil is employed. To reduce the edge effect in the capacitor, a method of splitting the insulator into thin layers in the region of the plate’s sharp edge by way of mutually shifting the capacitor’s plates. PC 200-1.5 devices were used as peak capacitors at the LTD-100R stage of a high-power pulse generator and allowed the output power to be increased by ～25%. The service life of these capacitors exceeded 2 × 10³ pulses.     

An Analysis of Excitation Pulse Adjustable Signal of Ultrasonic Flaw Detection

This research focuses on the influence of the ultrasonic flaw detection circuit on the ultrasonic emission. A software simulation and the super-exploration test are adopted. The characteristics of the transmitting circuit, the spike wave pulse generator and the square wave pulse generator are analyzed by simulating the pulse amplitude, the square wave pulse width and the transmitting pulse damping of the pulse generator. On the basis of simulations and experiments the fact that the best pulse effect relies on a reasonable coordination of pulse width and damping resistance is further verified. By using double-high-speed output power switch, appropriate adjustments on square wave pulse generator help to excite twice the charge voltage than the spike pulse generator can stimulate.     

A scheme of a modular plasma-opening-switch-based generator of megaampere currents for experiments with Z-pinches

A modular scheme of a megaampere current pulse generator on the plasma opening switch (POS) basis with insulation of the POS interelectrode gap by a magnetic field created by an external source is proposed for experiments with wire liners and other applications. The POS is fed from independent modules that are switched on in parallel. On the basis of an НК-50-3 (50 kV, 3 μF) capacitor, a supply module with a current through the equivalent part of the POS of up to 200 kA is designed and tested. The limiting POS parameters and the maximum permissible number of modules are determined, and circuit designs of the basic units of the generator are presented.