A high-voltage power supply of the diagnostic neutral beam injector of the Alcator-Cmod tokamak

A diagnostic neutral beam injector for ensuring the active spectroscopic diagnostics of plasma parameters in the Alcator-Cmod tokamak (Massachusetts Institute of Technology (MIT), Boston, United States) is designed and manufactured at the Institute of Nuclear Physics (Novosibirsk). The energy of fast atoms of the diagnostic injector is determined by the output voltage level of the high-voltage power supply and can vary from 20 to 55 keV. The ion source of the diagnostic neutral beam injector generates proton beams with an equivalent current of up to 7 A. The accelerated protons after the neutralization on a gas target produce streams of neutral particles—fast atoms with an equivalent current of up to 4 A. The diagnostic neutral beam injector is capable of producing 100% energy-modulated fast hydrogen atomic beams, and this is ensured by operation of the high-voltage power supply under the corresponding law. The high-voltage power supply is based on modules consisting of high-frequency transformers and diode rectifiers placed in a sealed tank filled with insulating gas SF₆. The output voltage is smoothly regulated from 20 to 55 kV by IGBT inverters with a pulse-width control energizing the primary windings of the step-up high-frequency transformers. The high-voltage power supply allows the multiple-breakdown operation mode of the load with voltage recovering as the specified time passes after the breakdown. The rated power of the high-voltage power supply is 450 kW. A functional diagram and design of the high-voltage power supply are given.     

A solid-state generator with pulsed excitation of the oscillating circuit

A solid-state high-frequency damping oscillation pulse generator based on a pulsed excitation circuit is designed. The frequency of high-frequency oscillations reaches units of megahertz with a pulse repetition rate in the continuous mode of up to 1 kHz. The frequency of output pulses determines the power consumption from the supply mains that does not exceed 700 W. In this case, the peak power of output pulses reaches hundreds of kilowatts with a generator efficiency of up to 65%, if the optimal resistive load is used. The main area of the generator application is the generation of low-temperature atmospheric-pressure plasma.     

A high-voltage power supply based on a distributed capacitive energy storage

For the corpuscular plasma heating in the MST plasma device (Madison, United States), an injector of hydrogen atoms with 25-keV energy, equivalent at omic current of >45 A, and 20-ms pulse duration was designed and put into operation at the Budker Institute of Nuclear Physics (Novosibirsk, Russia) in 2009. The pulse repetition rate is 5 min. The output current of the ion source in the atomic injector exceeds 50 A. A high-voltage source with a 1.5-MW power was design ed for the high-voltage powering of the atomic injector. The run duration of the power supply with rated characteristics is >20 ms. The power supply is based on a distributed capacitive energy storage, which allows the power consumption from the industrial network to be reduced down to 10 kW at a pulsed load power of 1.5 MW. The high-voltage power supply smoothly regulates the output voltage from 0 to 30 kV and is capable of being quickly deenergized if high-voltage breakdown of the load takes place. The diagram and structural components of the high-voltage power system of the atomic injector are described, and its test results are given.     

Use of the focusing multi-slit ion optical system at RUssian Diagnostic Injector (RUDI)

The upgrade of the diagnostic neutral beam injector RUDI in 2010 was performed to increase the beam density at the focal plane in accordance with the requirements of charge-exchange recombination spectroscopy diagnostics. A new focusing ion-optical system (IOS) with slit beamlets and an enlarged aperture was optimized for 50% higher nominal beam current and reduced angular divergence with respect to the previous multi-aperture IOS version. The upgraded injector provides the beam current up to 3 A, the measured beam divergence in the direction along the slits is 0.35°. Additionally, the plasma generator was modified to extend the beam pulse to 8 s.     

A nanosecond SOS generator with a peak power of 4 GW

A high-current nanosecond generator with a peak power of up to 4 GW, an output voltage of 0.4–1 MV, a pulse duration of 8–10 ns, and pulse repetition rates of 300 Hz in a continuous mode and up to 1 kHz in the burst mode is described. The average output power at a pulse repetition rate of 1 kHz reaches 30 kW. The generator has an all-solid-state energy-switching system. A semiconductor opening switch on SOS diodes forms output pulses. The electric circuit and design of the generator are described, and the experimental results are presented. A device for eliminating prepulses across the load is proposed. The results of its testing and numerical simulation are presented.     

用于金属拔丝的调频调幅大电流窄脉冲电源

介绍了一种将电流脉冲的电塑性效应应用于金属拔丝的调频调幅大电流窄脉冲电源系统。电源初级储能环节采用常规三相桥式整流和LC滤波;中间二次储能电路采用Buck变换器,利用全控型功率开关器件IGBT调节电热电容的充电电压,进而控制输出脉冲电流的幅值;而窄脉冲的形成则由电热电容、输出回路电感和等效负载电阻决定,由高频晶闸管进行控制。电源输出脉冲电流的频率和幅值可实时调节、数字显示。运行及测试结果表明,电源系统工作稳定,脉冲电流幅值和频率调节方便,控制准确。     

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 SOS-Generator for technological applications

A solid-state nanosecond SOS-generator for electrophysical technology applications is described. In the input part of the generator, the energy arrives at the high-voltage magnetic compressor through IGBT modules and a step-up pulse transformer. The input part of the generator is equipped with an unused energy recuperation circuit, and, when the output pulse is formed, the microsecond pumping mode of the semiconductor opening switch (SOS) is realized. As a result, the complete efficiency of the generator operating into a matched load is increased from ∼40 to 60–62%. The other characteristics of the generator are as follows: the peak voltage is up to 60 kV, the current is up to 6 kA, the pulse duration is about 40 ns, the pulse repetition rate in the continuous mode is 1 kHz, and the average output power is up to 9 kW.     

Linear induction accelerators made from pulse-line cavities with external pulse injection

Two types of linear induction accelerator have been reported previously. In one, unidirectional voltage pulses are generated outside the accelerator and injected into the accelerator cavity modules, which contain ferromagnetic material to reduce energy losses in the form of currents induced, in parallel with the beam, in the cavity structure. In the other type, the accelerator cavity modules are themselves pulse-forming lines with energy storage and switches; parallel current losses are made zero by the use of circuits that generate bidirectional acceleration waveforms with a zero voltage-time integral. In a third type of design described here, the cavities are externally driven, and 100% efficient coupling of energy to the beam is obtained by designing the external pulse generators to produce bidirectional voltage waveforms with zero voltage-time integral. A design for such a pulse generator is described that is itself one hundred percent efficient and which is well suited to existing pulse power techniques. Two accelerator cavity designs are described that can couple the pulse from such a generator to the beam; one of these designs provides voltage doubling. Comparison is made between the accelerating gradients that can be obtained with this and the preceding types of induction accelerator.     

A generator of high-power nanosecond pulses based on a modular two-level summator

A modular approach to designing generators of high-power high-voltage nanosecond pulses on the basis of a two-level wave summator and transistor formers of partial pulses is considered. The design and parameters of the modules that are oriented at the development of generators of voltage pulses of up to 300 kV at a current of up to 4 kA are described. The capabilities of these modules are demonstrated based on the example of a pulse generator with a power of 10 MW, a varied pulse duration of 50–150 ns, and a pulse repetition rate of up to 2 kHz.     

Synchronous extraction of the microwave energy from two resonators through a waveguide bridge

Results of the experimental investigation of the resonant microwave pulse compression system operating in a 10-cm wavelength region are presented. The system contains two multimode resonators for storing high-frequency energy and a waveguide bridge for the fast and synchronous energy extraction. When powered from a magnetron generator having a radiation power of 5 MW and pulse duration of 4 μs, microwave pulses with an output power of ～0.8 GW, duration of ～5 ns, and pulse repetition rate up to 100 Hz were obtained in this compression system.     

Features of application of PBY-47 controlled vacuum switches in high-current pulsed installations

The time parameters of PBY-47 controlled vacuum spark-gap switches (CVSSs), which are high-current pulse switches that can pass pulse currents with amplitudes of up to several hundred amperes, were investigated. When using CVSSs, it is necessary to know their time parameters, such as the operation delay time and its spread (jitter). To study these parameters, a run of experiments was performed on a laboratory test bench with sinusoidal discharge-current pulses with an amplitude of 120 kA and a period of 17 μs. When multimodule power-supply systems are developed, special attention is drawn to the agreed parallel operation of the switches of discharge modules. To determine the main requirements that are imposed on the operation stability of multimodule power-supply systems, a criterion was developed that relates the inductance of the load to the inductance of discharge modules and the number of modules to such a property of the used switches as a wide range of the operating voltages.     

磁力调频压电电磁复合发电设计与实验

开展了基于环境振动发电作为微电源弥补传统化学电池供能缺陷的研究。基于非线性磁力调频开发了低宽频振动能采集压电电磁复合发电系统。介绍了发电装置工作原理;利用ANSYS和Ansoft Maxwell有限元分析软件仿真分析了压电和电磁发电的输出特性;最后,搭建了压电电磁复合宽频发电装置实验测试系统,测试了发电系统在磁力自调过程中的输出特性。实验结果显示:复合发电系统在谐振频率60Hz时输出开路电压峰值为5.8V,高于压电系统(5.5V)和电磁系统(410mV)独立发电的开路电压峰值。施加磁力拓宽装置后,当压电悬臂梁沿竖直方向上下移动0~15mm时,系统适应谐振频带拓宽为45~76Hz;悬臂梁沿水平方向平移0~30mm时,谐振频带拓宽为51~70 Hz。结果表明仿真分析与实验测试结果吻合很好。该宽频带能量采集技术可用于低频振动环境的能量采集,可在频变环境中为微型低功耗系统提供低电能。     

A high-current nanosecond electron accelerator with a semiconductor opening switch

A compact nanosecond electron accelerator with an output energy of up to 4000 keV, a pulsed power of 100–180 MW, a beam current of 0.25–1.1 kA, and a pulse energy of 5–7 J is described. The accelerator operates with a pulse repetition rate of 200 Hz and ensures an average beam power of up to 1 kW. A nanosecond generator with a solid-state switching system, which is based on magnetic stages of pulse compression and a semiconductor opening switch, is used as a supplying device. The design and electric circuit of the accelerator are described, and test results are presented.     

A compact repetitive high-voltage nanosecond pulse generator for the application of gas discharge

Uniform and stable discharge plasma requires very short duration pulses with fast rise times. A repetitive high-voltage nanosecond pulse generator for the application of gas discharge is presented in this paper. It is constructed with all solid-state components. Two-stage magnetic compression is used to generate a short duration pulse. Unlike in some reported studies, common commercial fast recovery diodes instead of a semiconductor opening switch (SOS) are used in our experiment that plays the role of SOS. The SOS-like effects of four different kinds of diodes are studied experimentally to optimize the output performance. It is found that the output pulse voltage is higher with a shorter reverse recovery time, and the rise time of pulse becomes faster when the falling time of reverse recovery current is shorter. The SOS-like effect of the diodes can be adjusted by changing the external circuit parameters. Through optimization the pulse generator can provide a pulsed voltage of 40 kV with a 40 ns duration, 10 ns rise time, and pulse repetition frequency of up to 5 kHz. Diffuse plasma can be formed in air at standard atmospheric pressure using the developed pulse generator. With a light weight and small packaging the pulse generator is suitable for gas discharge application.     

A Megavolt Nanosecond Generator with a Semiconductor Opening Switch

A high-current nanosecond-pulse generator with a pulse power of up to 1.6 GW, an output voltage of 0.5–1 MV, pulse duration of 40–60 ns, and repetition rates of 300 Hz (in a steady-state mode) and up to 850 Hz (in a burst mode) is described. Its average output power is 30 kW at a pulse repetition rate of 500 Hz. The energy-switching system of the generator fully consists of solid-state elements: a thyristor, magnetic switches, and a semiconductor-opening switch based on SOS diodes.     

中频逆变高频PWM电子束焊机高压电源

设计一种中频逆变高频PWM电子束焊机高压电源装置,装置将由高频PWM脉冲驱动的逆变器产生的中频交流电送入中频高压变压器,通过高压整流滤波器、高压放电扼流电路后得到纹波系数小、运行稳定的高压输出,同时故障判别电路对高压电源实时监控,当出现异常时,实现快速截止保护。实验结果表明,这是一种调节速度快、效率较高的电子束焊机高压逆变电源装置。     

Studying the effect of adsorbed molecules on the operation of a diode with an explosive-emission cathode

The results of an experimental study of the effect of an adsorbed gas and surface contaminations of an explosive-emission cathode on the operation of a diode during generation of a high-current electron beam of nanosecond duration are presented. The effect of contaminations was revealed from the change in the rate of expansion of the planar-diode cathode plasma for cathodes of different designs manufactured from different materials and different initial anode-cathode gaps. The plasma velocity was calculated from the experimental perveance of the diode with a resolution of 0.2 ns. Experiments were performed on a ТЭУ-500 pulsed electron accelerator (350–450 kV, 100 ns, and 250 J/pulse) in a mode of matching the diode impedance to the output impedance of the nanosecond generator. It has been found that the velocity of cathode plasma is constant for 70–90 ns after applying voltages to different cathodes at different anode-cathode gaps. The velocities were 2.0 ± 0.5 cm/ μs for carbon cathodes (of different diameters), 3 ± 0.5 cm/μs for multispike tungsten cathodes, and 4.0 ± 0.5 cm/μs for copper (solid or multispike) cathodes. An appreciable dependence of the plasma velocity on the cathode material shows an insignificant influence of the adsorbed gas and cathode surface contaminations on the expansion velocity of the explosive-emission plasma in a planar diode during generation of the electron beam (10–15 ns after a voltage is applied).