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.     

Properties of an intense 40-kV neutral beam injector

The properties of an intense neutral beam injector, the modified duoPIGatron ion source, are discussed and compared with other injectors. For this source (a) beam composition for hydrogen is approximately (85+/-5) % monatomic, (b) nucleon gas efficiency is 50%, (c) the electrical efficiency of ion generation is 1.1 A/kW, and (d) up to 52% of the input power is delivered in the ion and neutral beam to a target subtending a half angle of 1.8 degrees x1.4 degrees .     

A controlled stabilized high-voltage power supply for a photomultiplier tube

A small-size stabilized high-voltage power supply for a photomultiplier tube with remote digital and analog regulation of the output voltage is designed. The output voltage is smoothly regulated from 0.5 to 3 kV, the load current is 0–2 mA, and the ripple factor is 0.008%. The supply voltage is 12–16 V.     

高压双电源智能投切控制系统开发

供电的连续性是电力质量的一个重要方面,对于某些用电部门,如医院、机场、大型生产线等尤为重要。保证供电连续性的解决办法是给供电对象提供主、备2路独立的电源,对2路电源都进行实时监控。当一侧电源发生故障时,能根据设定的切换程序准确完成向另一侧电源的切换,最大限度地保证供电的连续性。     

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.     

The control system of the 1-MW TCV tokamak heating neutral beam injector

The control system of the neutral beam injector is presented that was designed and constructed at the Budker Institute of Nuclear Physics in Novosibirsk, for the TCV tokamak in Lausanne, Switzerland. The system hardware includes an industrial computer with reconfigurable PCI Express input–output boards, as well as interfacing electronics, which ensures galvanic isolation and electrical compatibility with the injector units. The software and firmware that implement the control system algorithm by means of both the industrial computer and the FPGAs of the reconfigurable boards are written using LabVIEW. The injection parameters are calculated using the beam-power model; the graphical representation and storage of the results are carried out in MATLAB. A communication interface with the tokamak control system is also provided for data exchange and synchronization of operation.     

Voltage holding study of 1 MeV accelerator for ITER neutral beam injector

Voltage holding test on MeV accelerator indicated that sustainable voltage was a half of that of ideal quasi-Rogowski electrode. It was suggested that the emission of the clumps is enhanced by a local electric field concentration, which leads to discharge initiation at lower voltage. To reduce the electric field concentration in the MeV accelerator, gaps between the grid supports were expanded and curvature radii at the support corners were increased. After the modifications, the accelerator succeeded in sustaining -1 MV in vacuum without beam acceleration. However, the beam energy was still limited at a level of 900 keV with a beam current density of 150 A∕m(2) (346 mA) where the 3 × 5 apertures were used. Measurement of the beam profile revealed that deflection of the H(-) ions was large and a part of the H(-) ions was intercepted at the acceleration grid. This causes high heat load on the grids and the breakdowns during beam acceleration. To suppress the direct interception, new grid system was designed with proper aperture displacement based on a 3D beam trajectory analysis. As the result, the beam deflection was compensated and the voltage holding during the beam acceleration was improved. Beam parameter of the MeV accelerator was increased to 980 keV, 185 A∕m(2) (427 mA), which is close to the requirement of ITER accelerator (1 MeV, 200 A∕m(2)).     

Beam optics in a MeV-class multi-aperture multi-grid accelerator for the ITER neutral beam injector

In a multi-aperture multi-grid accelerator of the ITER neutral beam injector, the beamlets are deflected due to space charge repulsion between beamlets and beam groups, and also due to magnetic field. Moreover, the beamlet deflection is influenced by electric field distortion generated by grid support structure. Such complicated beamlet deflections and the compensations have been examined utilizing a three-dimensional beam analysis. The space charge repulsion and the influence by the grid support structure were studied in a 1∕4 model of the accelerator including 320 beamlets. Beamlet deflection due to the magnetic field was studied by a single beamlet model. As the results, compensation methods of the beamlet deflection were designed, so as to utilize a metal bar (so-called field shaping plate) of 1 mm thick beneath the electron suppression grid (ESG), and an aperture offset of 1 mm in the ESG.     

基于ANSYS的中性束注入器主真空室结构力学分析

利用ANSYS软件建立了EAST中性束注入器样机主真空室的有限元模型,分析了主真空室的受力情况;主真空室由三段组装而成,依据实际的材料和受力情况,分别对三段放置于地面以及整体连接放置在导轨上两种工作状况下进行结构静力学分析,得到了相应工作状况下的结构应力分布和变形情况。分析表明主真空室在两种工作状况下最大Von-Mises等效应力值小于材料屈服强度,主真空室结构是安全和稳定的,分析结果给主真空室下一步的优化设计和结构选材提供了依据。     

Optical spectroscopy of plasma of the radio-frequency emitter of a powerful fast neutral beam injector

For studying entries of impurities into thermonuclear plasma, when injecting heated neutral beams, the spectroscopic diagnostics intended for promptly monitoring the plasma composition of the radiofrequency (RF) emitter of the powerful fast neutral beam injector is designed. The analysis of plasma radiation spectra allowed us to determine the rotational temperature of the neutral hydrogen and estimate the oxygen-to-carbon impurity ratio in the RF emitter. In this work, the long-term dynamics of the neutral oxygen line brightness is studied, and the influence of the discharge chamber ageing and warming-up on the impurity content is determined.     

A neutral beam sciopticon

A sciopticon based on the pinhole-camera effect is being used to determine individual beamlet contributions to the quality of neutral beams extracted from multiaperture ion sources. The technique outlined in this note can be used to study the effects on beam optics of nonhomogeneous source plasma density or acceleration gap nonuniformities, grid nonparallelism or aperture misplacement, and space-charge blowup or scattering in the neutralizer cell.     

Steady state performance test analysis of actively cooled extractor grids for SST-1 neutral beam injector

Neutral beam injection (NBI) system is a workhorse to heat magnetically confined tokamak fusion plasma. The heart of any NBI system is an ion extractor system. Steady State Superconducting Tokamak-1 (SST-1) needs 0.5 MW of hydrogen beam power at 30 kV to raise the plasma ion temperature to ~1 keV and 1.7 MW of hydrogen beam power at 55 kV for future upgradation. To meet this requirement, an ion extractor system consisting of three actively cooled grids has been designed, fabricated, and its performance test has been done at MARION test stand, IPP, Julich, Germany. During long pulse (14 s) operation, hydrogen ion beam of energy 31 MJ has been extracted at 41 kV. In this paper, we have presented detailed analysis of calorimetric data of actively cooled extractor grids and showed that by monitoring outlet water temperature, grid material temperature can be monitored for safe steady state operation of a NBI system. Steady state operation of NBI is the present day interest of fusion research. In the present experimental case, performance test analysis indicates that the actively cooled grids attain steady state heat removal condition and the grid material temperature rise is ~18°C and saturates after 10 s of beam pulse.     

Master controller of a high-voltage power unit source of an electron beam welding device

This paper describes the structure and control algorithms of a controller of a high-voltage source with an output voltage of 60 kV and a power of up to 30 kW. The source is designed to be used as part of a power unit of an electron-beam welding device developed at the Budker Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences (BINP SB RAS). High-quality welds require a stable electron beam energy. Herewith, a standard operation mode is quick and deep modulation of the electron current. The problem of achieving high-quality control and limiting the transient distortions of output voltage of the source is solved. The error of establishing and stabilizing the output voltage is 0.1%, which allows obtaining high-quality welding. Transient distortions at 100% modulation of the load current do not exceed the value of ±1%, which, along with fast reaction of the source to a load breakdown (energy released during breakdown is smaller than 15 J), protects the welded parts and elements of the gun from being damaged by an electron beam.     

Arc discharge regulation of a megawatt hot cathode bucket ion source for the experimental advanced superconducting tokamak neutral beam injector

Arc discharge of a hot cathode bucket ion source tends to be unstable what attributes to the filament self-heating and energetic electrons backstreaming from the accelerator. A regulation method, which based on the ion density measurement by a Langmuir probe, is employed for stable arc discharge operation and long pulse ion beam generation. Long pulse arc discharge of 100 s is obtained based on this regulation method of arc power. It establishes a foundation for the long pulse arc discharge of a megawatt ion source, which will be utilized a high power neutral beam injection device.     

First plasma of megawatt high current ion source for neutral beam injector of the experimental advanced superconducting tokamak on the test bed

High current ion source is the key part of the neutral beam injector. In order to develop the project of 4 MW neutral beam injection for the experimental advanced superconducting tokamak (EAST) on schedule, the megawatt high current ion source is prestudied in the Institute of Plasma Physics in China. In this paper, the megawatt high current ion source test bed and the first plasma are presented. The high current discharge of 900 A at 2 s and long pulse discharge of 5 s at 680 A are achieved. The arc discharge characteristic of high current ion source is analyzed primarily.     

Development of a low-energy and high-current pulsed neutral beam injector with a washer-gun plasma source for high-beta plasma experiments

We have developed a novel and economical neutral-beam injection system by employing a washer-gun plasma source. It provides a low-cost and maintenance-free ion beam, thus eliminating the need for the filaments and water-cooling systems employed conventionally. In our primary experiments, the washer gun produced a source plasma with an electron temperature of approximately 5 eV and an electron density of 5 × 10(17) m(-3), i.e., conditions suitable for ion-beam extraction. The dependence of the extracted beam current on the acceleration voltage is consistent with space-charge current limitation, because the observed current density is almost proportional to the 3∕2 power of the acceleration voltage below approximately 8 kV. By optimizing plasma formation, we successfully achieved beam extraction of up to 40 A at 15 kV and a pulse length in excess of 0.25 ms. Its low-voltage and high-current pulsed-beam properties enable us to apply this high-power neutral beam injection into a high-beta compact torus plasma characterized by a low magnetic field.     

基于单片机的脉宽可调低频高压脉冲电源

本文介绍了一种基于单片机的脉宽可调低频高压脉冲电源的设计.该电源输出电压的频率和脉宽可由用户自行设定,同时引入单相交流调压模块实现稳压输出,并使其输出电压在10KV～50KV范围内连续可调,利用单片机控制SG3525工作时间形成高压脉冲,并通过单片机的处理实时地将电源输出电压幅值、频率和脉宽显示在液晶屏幕上.     

A multichannel power supply for high power magnetrons

The paper describes characteristics and design principles of a multichannel power supply for CW magnetrons with RF power up to 3 kW. An advanced control system implemented in the power supply has resulted in its good operational properties as well as allowed providing adaptive procedures for the regulation of magnetron operation. A modular approach based on utilization of novel electronic components increases reliability and lowers weight and dimensions of the power supply.     

起重机械高压供电系统接地方式及单相接地选线分析

为满足特殊工程需要配备大量高压供电系统下的起重机械,针对此类供电系统的特点,结合不同小电流接地系统的特点,以及发生单相接地故障所采取的接地选线方式,对应用范围广、可靠性高的选线方式做了典型分析,有助于高压供电系统的起重机使用单位正确选择合适的接地接线方式.     

A pulse power supply of the linear induction accelerator

A pulse power system of the induction electron accelerator intended for parameters of 2 MeV, 2 kA, and operating in the double-pulse mode is presented. The schematic diagram and main elements of the pulse system are described, and the main technical solutions intended to produce a set of pulses with 21-kV peak voltages, peak currents of up to 8 kA, and 200-ns durations across a resistive-inductive load are indicated. The experimental data, which were obtained when separate units and the whole power system operated on the rated duty, are given.