Design and Development of a Power Supply System for NBI Test Stand of EAST

A neutral beam injector (NBI) test stand was constructed to develop a multi-megawatt prototype ion source as an auxiliary heating system on experimental advanced superconducting tokamak. A power supply system for the NBI test stand components such as a set of dc power supplies for plasma generator, a dc high voltage power supply of a tetrode accelerator, a transmission line and a surge energy suppressor. Stable arc discharges of the plasma generator with hydrogen gases for 100 s long pulse have been produced by six Langmuir probes feedback loop regulation mode to control the arc power supply. The 4 MW hydrogen ion beam of 1 s is extracted with beam energy of 80 keV and the beam current of 52 A. The dc high voltage power supply for the plasma grid of the prototype ion source was designed to contribute maximum voltage of 100 kV and current of 100 A. The high voltage power output is continuously adjustable to satisfy with plasma physics experiment in operation frequency of 10 Hz. To prevent damage of the beam source at high voltage breakdown, core snubber using deltamax soft magnetic materials have been adopted to satisfy the input energy into the accelerator from the power supply can be reduced to about 5 J in the case of breakdown at 80 kV. For the transmission line, a disc shape multi cable coaxial configuration was adopted and which the dimension of the diameter is 140 mm at the core snubber. The major issues of discharge characteristics with long pulse and beam extraction with high power for the prototype ion source were investigated on the NBI test stand.     

EAST强流离子源电源系统的初步测试运行

测试NBI大功率强流离子源的综合测试台正在建设,已研制了离子源等离子体发生器电源系统、等离子体电极高压电源及梯度极分压器、抑制极负高压电源等电源系统,以及高压传输线及缓冲器,在测试台上开展了对EAST中性束注入器第一台兆瓦级强流离子源样机进行整体电源系统测试和离子源起弧放电的初步测试,完成了离子源电源系统初步性能测试及...     

Characteristic Analysis of AC Plasma Arc in Water

An experimental system of AC arc discharge in water was designed with pole-pole electrodes and a peak voltage of 1500 V and a test circuit was set up using virtual instrument technology. The mechanism of an AC plasma arc generated in water was analyzed. The voltage- current characteristic of the AC plasma arc was obtained from the waveform. The temperature characteristic was tested with a spectrum diagnosis system, and the effect of different electrode materials on the striking voltage and peak current was analyzed. The results show that when a power supply of 6 KW is applied on electrodes with a gap of 2 mm in water, the striking voltage is from 900 to 1300 V, the arc voltage is from 40 to 100 V, the arc current is from 2 to 7 A, and the zero rest period is from 1 to 2 ms. In addition, the arc voltage and current are different for electrodes in aluminum, copper and stainless steel. The arc voltage is lower and the current is higher for an aluminum electrode than those for copper and stainless steel ones. The highest temperature of the arc is 7643 K.     

基于Saber的5MW中性束注入弧电源仿真设计

强流离子源是HL-2M装置5 MW中性束注入加热系统的核心部件,离子源通过弧电源加速初级电子至高能态,碰撞气体分子,产生等离子体。所以,弧电源对于离子源维持稳定的弧放电非常重要。本文利用Saber软件建立了弧电源的主电路模型,设计并仿真了弧电流的恒流控制、打坑控制以及超级电容的恒流充电控制、恒功率放电控制等。这种方法不仅提高了弧电源电路的分析和设计效率,缩短了系统研制的周期,还可用于实际系统的故障分析和控制参数的整定,降低实验风险。实验结果表明,弧电源的真实输出与仿真输出结果相符。     

数字化X荧光仪电源的最优化设计

针对数字化X荧光仪的低功耗、低噪声等要求进行了电源最优化设计。文中对数字梯形滤波器进行了Simulink仿真,根据仿真结果得到最佳的M,N系数,由此确定微分电路的时间常数,最后确定高压电源的最佳开关频率点,降低了高压偏置电源噪声对系统的干扰。还分析了数字梯形滤波器及高速ADC采样的特点,设计了最优化的低压供电系统,进一步降低低压电源对系统的干扰。为了提高Si-Pin探测器制冷电源的供电效率,采用了高效率DC-DC、LDO芯片与检流芯片完成高效率恒流源的设计。实测高压电源的交流纹波小于3.5 mV,带载功耗小于70 mW,恒流源的带载转换效率83%,纹波电压小于12 mV,相同条件下采用文中电源系统可提高谱线的能量分辨率。     

Simulation,Design, Construction of Duoplasmatron and Diagnostic Neutral Beam System for Alborz Tokamak

Diagnostic Neutral Beam (DNB) has been used for measuring plasma parameters of tokamaks such as ion and electron temperature, safety factor, impurity concentration and etc. Ion source and electrical power supply specification are the main part of DNB. Arc discharge current value is affected by filament current and anode voltage. Beam current changes with arc current signal in our experiment that agree with theoretical relations. Sixty milli-ampere (60 mA) pulse beam current is because of arc current of about 40 A and extraction voltage of about 20 kV. The increase of beam current with arc current has been reported experimentally and effect of arc current on beam current has been investigated for several high extraction voltages. Optimum condition, which means having a telescopic beam (minimum divergence) for specific parameters of duoplasmatron, has been simulated and verified with experimental test. The best extraction voltage for these parameters has been found to be about 16-kV. The ratio of the perpendicular velocity to parallel velocity has been calculated to be about 0.012. It has been shown experimentally with optical emission spectroscopy that increase in arc current and magnetic current increase proton content of beam.     

PIG Ion Source with Permanent Magnets: Model Based Anode Current Return Circuit

Ion sources are widely used in fusion technologies. A new high voltage pulsed power supply for use in penning ion gauge ion sources is proposed in this paper. To use discharge current, a diode-capacitor bank is included. The power supply is composed of 3 stages. A fast switching transistor is used as a single switch which is trigged by a pulse generator. A transformer is used to level up the voltage up to 2?kV without power loss. It is also used to isolate input and high voltage output. Also; the proposed high voltage power supply implementation uses a diode-capacitor bank whose capacitors are charged during plasma discharge. This system structure gives compactness and easiness to implement the total system which in combination with inexpensive commercially available components, makes the unit versatile and inexpensive.     

Analysis of Effects of the Arc Voltage on Arc Discharges in a Cathode Ion Source of Neutral Beam Injector

A hot cathode bucket ion source is used for the EAST(experimental advanced superconducting tokamak)neutral beam injector.The thermal electrons emitted from the surface of the cathode are extracted and accelerated by the electric field formed by the arc voltage,which is applied between the arc chamber of the ion source and the cathode.This paper analyzes the effects of arc voltage on the arc discharge in a hot cathode high current ion source.     

Experimental Results of Ion Beam Extraction of High-Current Ion Source for EAST Neutral Beam Injector

The first campaign of ion beam extraction tests are completed for EAST NBI high current ion source. The hydrogen ion beam with beam voltage of 80 keV is extracted from tetrode accelerator system. During the experiment, the characteristics of arc discharge and ion beam extraction are studied. The arc power reaches 120 kW and the extracted ion beam power reaches 3 MW. The relationship of some key parameters of arc and beam are investigated, and the details are described in this paper.     

Duoplasmatron Ion Sources

A survey on questions related to the production of multiply charged ions with the Duoplasmatron ion source is given. In spite of differences of the multiply charged ion source and the mass separator type, design considerations show that high containment is a common feature to be attained in both subjects. Multiply charged metal ions are produced by material evaporation into the magnetically confined anodic plasma and auxiliary gas feed into the cathode discharge regions. Energy spreads of ion beams from the low and the high arc current source are compared. The Duoplasmatron ion source proves to be a hygieneous source of high containment that permits the production of medium charge states up to 9+ for xenon at modest energy spread and good brilliance of the extracted ion beam in a high current-low voltage discharge mode.     

低能高束流氩离子源的结构及性能

离子源技术是等离子体研究中的一项重要内容,而低能大束流源则是离子源技术研究中的一个重要方向,因为这样的源在离子束刻蚀、离子束溅射镀膜以及荷能粒子与物质相互作用方面都有广泛的应用;本文采用空心阴极空心阳极结构,用热阴极电子发射弧放电驱动并用磁场约束产生等离子体,用曲面发射引出离子束,研制成了氩气放电溅射离子源;研究了灯丝加热电流、弧压对弧流的影响和弧流与工作气体压力对离子束引出的影响规律.离子源的引出电压在0-4.0 kV之间连续可调,最大引出束流为100 mA,束斑面积为φ6.0 cm,以Ti为溅射靶时的最大溅射沉积率为0.45 nm/s,离子源可连续工作160 h.     

Hot Cathode’s Working Voltage Impacts on the Operation of High Current Ion Source

High power ion source is one of the important parts of the neutral beam injection. It produces high energy beam by extracting and accelerating ions from its arc chamber. The hot cathode (filaments) in the arc chamber of the ion source operates in two modes. Operation mode of the cathode has great effect on the stable operation of the ion source. Based on the theory of hot cathode and experimental results, this paper presents the operation results (beam current, arc efficiency) of an ion source with various cathode temperatures (controlled by voltage applied to the cathode).     

Long-pulse power-supply system for EAST neutral-beam injectors

The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP (Institute of Plasma Physics,Chinese Academy of Sciences):one for the neutralbeam test stand and two for the EAST neutral-beam injectors (NBI-1 and NBI-2,respectively).Each power supply system consists of two low voltage and high current DC power supplies for plasma generation of the ion source,and two high voltage and high current DC power supplies for the accelerator grid system.The operation range of the NB power supply is about 80 percent of the design value,which is the safe and stable operation range.At the neutral-beam test stand,a hydrogen ion beam with a beam pulse of 150 s,beam power of 1.5 MW and beam energy of 50 keV was achieved during the long-pulse testing experiments.The result shows that the power-supply system meets the requirements of the EAST-NBIs fully and lays a basis for achieving plasma heating.     

EAST-NBI抑制极电源IGBT串联技术的研究

中性束注入器(Neutral Beam Injector,NBI)是东方超环(Experimental Advanced Superconducting Tokamak,EAST)核聚变实验装置辅助加热的重要组成部分。目前NBI离子源引出系统采用四电极结构,即加速电极、梯度电极、抑制电极和地电极。抑制极电源是为其中的抑制电极提供负电位的高压直流电源。根据抑制极电源输出特性的要求,输出端采用串联绝缘栅双极型晶体管(Insulated Gate Bipolar Transistor,IGBT)作为调制开关。为研究IGBT串联技术对均压效果和抑制极电源输出特性的影响,采用PSpice软件对IGBT开关进行了建模,并进行了不同电路参数下的仿真。仿真表明:一定条件下,电阻电容二极管(Resistance Capacitance Diode,RCD)缓冲电路中电容参数对动态均压效果和电源关断特性具有决定性影响,缓冲电阻影响电容的放电时间及放电电流峰值。最后给出了相应的实验测试结果。该研究结果可以明确缓冲电路参数与均压效果以及抑制极电源开关特性之间的定量关系,为抑制极电源开关特性的进一步优化及其与加速极电源的特性匹配提供数据指导,对于NBI离子源的安全稳定运行具有重要意义。     

Production of Multiply-Charged Ions of Ne, Ar, Kr and Xe by the Electron-Bonbarded Hot Cathode IoN Source of IPCR

Production of multiply-charged ions of Ne, Ar, Kr and Xe has been studied by use of an electron-bombarded hot cathode type ion source of the IPCR 160cm cyclotron, which is similar to Morozov's source. These multiply-charged ions were accelerated by a 3rd harmonics acceleration mode in the cyclotron and detected with a beam probe fixed at the radius of 55cm. Observed multiply-charged ions are Ne2+, Ne3+, Ne4+, Ne5+, Ar3+, Ar4+ Ar5+, Ar6+, Ar7+, Ar8+, Kr6+, Kr7+, Kr8+, Kr9+, Xe9+, Xe10+ and Xe11+. Relative abundance of each charge state of four elements were measured. In case of Kr and Xe , the intensity of observed multiply-charged ions decreased to 1/3 or 1/4 when the charge number is increased by one. Intensities of Ar4+, Ar6+, Ar8+, Kr6+ and Kr8+ were measured as a function of the operation conditions of the ion source, such as arc voltage, arc power and gas flow rate. It was found that a smaller gas flow and a higher arc power brought about a higher yield in all the measured ions. Obtained current intensities of ion source output are 40?A Ar8+, 600?A Kr6+, 40?A Kr9+, 150?A Xe9+ and 10?A Xe11+ respectively.     

Performance and modelling of 70kVdc power supply with solid-state crowbar

The experimental activities of tokamak research involve development of high power RF and microwave sources for fusion related heating and current drive applications. High power RF and microwave tubes like Klystron, Gyrotron and Tetrode are in general operated with high voltage DC power supplies. These HVDC power supplies of the order of 70 kVdc, must be equipped with necessary arc fault protection in addition to general over current and over voltage protection.The arc fault protection must act within few microseconds to prevent permanent damage to the RF tube, window, etc. When an arc fault is detected, output voltage of the DC power supply is short circuited using a crowbar device (generally Ignitron, Thyratron, thyristor, rail-gap, etc.) that operates in few microseconds. This diverts the fault current from the load to crowbar device, thereby protecting the load. This is necessary as conventional protection in the power supply input takes ～100 ms to switch-off. The crowbar device must be able to take the fault current till the circuit breaker placed at power supply input is switched off.The arc fault protection is tested for its effectiveness by “wire-burn” test. Full power short circuit of ～1.5 MW DC power supply puts enormous stress on the power supply, utility and the crowbar, therefore frequent wire-burn testing is to be avoided.This report presents simulation of wire-burn test using PSIM software. Optimization of the component values without conducting actual wire-burn test could be achieved.     

Electrical Parameter Measurement System of the Ion Source for EAST Neutral Beam Injector

Neutral beam injection (NBI) is recognized as one of the most effective means of plasma heating. A virtual instrument (VI) has been designed to provide electrical parameter measurement for the ion source of EAST-NBI. The VI is written using the National Instruments LabVIEW graphical programming language. All data acquisition (DAQ) is accomplished using ADLINK DAQ hardware interface and Task-oriented DAQ Driver. The VI can measure filament voltage, filament current, arc voltage, arc current and accelerating voltage etc. The data obtained from the VI are feedback of the ion source operation state and helpful to direct the operation parameter optimization of the ion source.     

基于超级电容储能的中性束注入系统弧电源设计

弧电源是中性束注入加热系统中最关键的设备之一,它的性能决定了弧放电的稳定性及束流引出的品质。为提高弧放电稳定性,降低电网容量,减少对电网的冲击,弧电源拓扑设计采用了基于超级电容储能和开关电源技术的DC/DC变换器结构。利用多个IGBT功率模块并联工作,可提高电源工作频率,实现更快的动态响应速度。在详细分析电源工作过程的基础上,设计了滤波电路和电流快速转移电路,根据电源的要求和具体参数,由一阶RL电路的电流响应特性,精确计算出滤波电感的最小值。最后,利用Matlab对电源性能指标进行了仿真验证,结果表明电源性能完全符合设计要求。