Particle Simulation of an Improved Axially Extracted Vircator

An axially extracted virtual cathode oscillator (vircator) with a feedback annulusis proposed and configured through particle-in-cell (PIC) simulation in Ref. [1]. In this paper,the effects of the feedback mechanism are studied through PIC method. The simulated results indicate that the improved new vircator can increase the output power twice large than that of the axially-extracted conventional vircator under the same condition. On the other hand, it can narrow the bandwidth and purify the modes.     

ns级快脉冲电源研制

高重复频率ns级快脉冲电源是粒子加速器超快kicker注入引出技术中有待攻克的关键技术难题。本工作利用计算机仿真和桌面实验等手段从理论上研究了感应叠加技术、射频MOSFET开关及驱动电路技术,并在此基础上设计研制了1台10级感应叠加的快脉冲电源性能样机。经初步测试,10级叠加性能样机在500 Hz低频工作条件下,输出脉冲幅度>4.3 kV,脉冲前沿<2.8 ns,脉冲宽度<9 ns,基本达到了预期目标。     

Discharge Characteristics of Series Surface/Packed-Bed Discharge Reactor Diven by Bipolar Pulsed Power

The discharge characteristics of the series surface/packed-bed discharge(SSPBD)reactor driven by bipolar pulse power were systemically investigated in this study.In order to evaluate the advantages of the SSPBD reactor,it was compared with traditional surface discharge(SD) reactor and packed-bed discharge(PBD) reactor in terms of the discharge voltage,discharge current,and ozone formation.The SSPBD reactor exhibited a faster rising time and lower tail voltage than the SD and PBD reactors.The distribution of the active species generated in different discharge regions of the SSPBD reactor was analyzed by optical emission spectra and ozone analysis.It was found that the packed-bed discharge region(3.5 mg/L),rather than the surface discharge region(1.3 mg/L) in the SSPBD reactor played a more important role in ozone generation.The optical emission spectroscopy analysis indicated that more intense peaks of the active species(e.g.N_2 and OI) in the optical emission spectra were observed in the packed-bed region.     

The Power Supply System for HL-2A Tokamak＇s Magnetic Field

The highpower pulsed power supply system for the magnetic field of the HL-2A Tokamak is described in this paper. The total output power of its eight magnetic field power supply units of nearly 250 MW. Their highest DC output voltage and current are 3510 V and 45 kA, respectively. All the units are operated in a pulsed mode. The pulse duration is 5 s, and the cyclic period is 15 min. The power supply system consists mainly of pulsed flywheel motor generators, rectifying transformers, thyristor converters, diode rectifiers and switches. The system incorporates many key technologies-supply equalization with two generators and four diode bridges, constant-angle phase triggers with a wide frequency range, current equalization, a status detector for the high current 6-phase converter, and advanced monitoring based on a programmable logic computer and engineering parameter measurement. The experimental results show that the performance of the power supply system satisfies the requirements of HL-2A experiments very well.     

Plasma Limiter Based on Surface Wave Plasma Excited by Microwave

A novel plasma limiter, in which the plasma is excited by surface wave, is presented. The breakdown time of some gases filled in the limiter were calculated as a function of gas pres- sure, ionization degree and density of seed electrons under low pressure （0.01 -1 Torr） and high pressure （10 -1000 Torr） cases. The results show that the limiter filled with Xe with a pressure of 0.9 Torr, seed electron density of 10^16 m^-3, and ionization degree of 10^-4, has a breakdown time of approximate 19.6 ns.     

脉冲萃取柱中正辛醇-硝酸体系流体力学性能研究

研究了喷嘴板脉冲萃取柱中正辛醇-0.5mol/L硝酸体系的液泛通量、分散相存留分数等流体力学特性.用改进的Pratt公式对两相流体力学参数进行了关联,得到水相连续时的n值为1.15,有机相连续时的K值为5.64.特性速度可用下述经验公式关联Vo(Vo′)=11.7e-0.693Af.有机相连续时柱内液滴以聚集为主,水相连续时柱内液滴以分散为主.在相同的脉冲强度下,该体系水相连续时液泛通量较小,有机相连续时液泛通量较大.经验公式计算得到的水相连续时的液泛通量与实验值的相对误差在±15%以内.     

The Propagation Characteristics of the Electron Beam with Initial Modulation

The propagation characteristics of the beam under various initial conditions are investigated by means of PIC method. The influences of density modulation and velocity modulation on the propagation characteristics are discussed and compared. The results reveal that by changing the amplitude of the two kinds of modulations and the phase difference between them, the distribution property of the first harmonic of the current density can be adapted along the beam propagating path, which is a feasible method to enhance the beam-wave interaction efficiency in Cerenkov HPM devices.     

The effect of the configuration of a single electrode corona discharge on its acoustic characteristics

A new sparker system based on pulsed spark discharge with a single electrode has already been utilized for oceanic seismic exploration. However, the electro-acoustic energy efficiency of this system is lower than that of arc discharge based systems. A simple electrode structure was investigated in order to improve the electro-acoustic energy efficiency of the spark discharge.Experiments were carried out on an experimental setup with discharge in water driven by a pulsed power source. The voltage–current waveform, acoustic signal and bubble oscillation were recorded when the relative position of the electrode varied. The electro-acoustic energy efficiency was also calculated. The load voltage had a saltation for the invaginated electrode tip,namely an obvious voltage remnant. The more the electrode tip was invaginated, the larger the pressure peaks and first period became. The results show that electrode recessing into the insulating layer is a simple and effective way to improve the electro-acoustic energy efficiency from 2% to about 4%.     

脉冲反应堆脉冲运行瞬态的子通道分析

为获得脉冲运行瞬态的堆芯温度场变化情况,本文开发了适用于低温、常压工况的脉冲反应堆瞬态热工分析子通道程序PRC-STAC。利用TRIGA MARKⅡ反应堆的瞬态参数对程序进行了验证,验证结果表明,二者符合较好。利用PRC-STAC程序计算了西安脉冲堆燃料元件和堆芯冷却剂的瞬态热工参数,并讨论了脉冲运行对燃料元件的安全影响。     

Electrical Characteristics of Pulsed Corona Discharge Plasmas in Chitosan Solution

Pulsed discharge plasma has exhibited active potential to prepare low molecular weight chitosan. In the present study, the viscosity of ehitosan solution was decreased noticeably after treated with pulsed corona discharge plasma. An experimental investigation on electrical characteristics of pulsed corona discharge plasma in chitosan solution was conducted with a view toward getting insight into discharge process. Factors affecting I-V curve, single pulse injec- tion energy and pulse width were studied. Experimental results showed positive effect of pulsed peak voltage on discharge plasma in chitosan solution. Pulse-forming capacitor greatly influenced the discharge form, and 4 nF was observed as a suitable value for efficiently generating stable discharge plasmas. As the electrode distance was larger than 10 ram, it had slight impact on dis- charge plasma due to the excellent conductive-property of chitosan solution. The injection energy significantly increased with air flow rate, while the pulse width hardly changed as the air flow rate increased from 0.5 m^3/h to 1.0 m^3/h. This study is expected to provide reference for promoting the application of pulsed corona discharge plasma to ehitosan solution treatment.     

西安脉冲堆方波运行功率调节方法研究

本文建立了数字化功率调节系统在方波运行下的自动控制方法,提出了新的功率调节系统投入时刻设计方案,给出了调节棒初始棒位和发射脉冲棒后堆芯正反应性大小的建议,设计了数字化系统的方波运行功率调节方法,使用西安脉冲堆仿真程序XPRSC对设计方法进行了优化和验证。结果表明,该方法可实现更宽定值功率范围内的方波运行,能为堆上试验提供理论指导。     

The Degradation of Organic Pollutants by Bubble Discharge in Water

Organic pollutants could be degraded by using bubble discharge in water with gas aeration in the discharge reactor and more plasma can be generated in the discharge process.When pulsed high voltage was applied between electrodes with gas aerated into the reactor,it showed that bubbles were broken,which meant that breakdown took place.It could also be observed that the removal rate of phenol increased with increasing discharge voltage or pulse frequency,and with reducing initial phenol concentration or solution electric conductivity.It could remove more amount of phenol by oxygen aeration.With increasing oxygen flow rate,the removal rate increased.There was little difference with air or nitrogen aeration for phenol removal.The solution temperature after discharge increased to a great extent.However,this part of energy consumption did not contribute to the reaction,which led to a reduction in the energy utilization efficiency.     

固态微波放大器的开发

2．5kW／352MHz无条件稳定的微波固态放大器在意大利Legnaro国家实验室研制成功并通过测试。该放大器由9个350W推挽工作方式的功率模块构成，每个模块采用1个环形器和1个终端电阻作为保护装置。该放大器为独立相位超导直线加速器的中β超导腔提供微波功率而开发，具有高效率、线性度好、可靠性高以及低成本的特点。文章介绍了该放大器的技术特点和测试结果。     

Characteristics of plasma in a novel laser-assisted pulsed plasma thruster

A novel laser-assisted pulsed plasma thruster (LA-PPT) is proposed as an electric propulsion thruster, which separates laser ablation and electromagnetic acceleration. It aims for a higher specific impulse than that achieved with conventional LA-PPTs. Owing to the short-time discharge and the novel configuration, the physical mechanism of the discharge is unclear. Time and spatial-resolved optical emission spectroscopy was applied to investigate the variation in the plasma properties in the thruster discharge channel. The plasma species, electron temperature, and electron density were obtained and discussed. Our investigation revealed that there were H_α, H_β, H_γ, H_ε atoms, C I, C II, C III, C IV, Cl I, Cl II particles, and a small amount of CH, C₃, C₂, H₂ neutral molecular groups in the plasma. The electron temperature of the discharge channel of the thruster was within 0.6–4.9 eV, and the electron density was within (1.1–3.0) $\times $ 10¹⁸ cm⁻³, which shows that the optical emission spectroscopy method is to measure the electron excitation temperature and electron density in heavy particles. But the Langmuir probe method is to measure the temperature and density of free electrons. The use of laser instead of spark plug as the ignition mode significantly changed the plasma distribution in the discharge channel. Unlike the conventional PPT, which has high electron density near the thruster surface, LA-PPT showed relatively large electron density at the thruster outlet, which increased the thruster specific impulse. In addition, the change in the ignition mode enabled the electron density in the LA-PPT discharge channel to be higher than that in the conventional PPT. This proves that the ignition mode with laser replacing the spark plug effectively optimised the PPT performance.     

基于脉冲功率装置的圆柱腔体系统电磁脉冲研究

通过在中国工程物理研究院流体物理研究所的脉冲功率装置上开展圆柱腔体X射线辐照实验,研究了腔体系统电磁脉冲（腔体SGEMP）效应。应用一种网拍天线进行了圆柱腔体中电场的测量。此外,通过时域有限差分（FDTD）和粒子模拟（PIC）的数值方法,进行了腔体内电磁场的计算。研究发现,腔体内的气体会显著降低电场强度,而电场强度也会随剂量率的增加而增加。     

脉冲强磁场探测系统的基本实现

简要介绍了电磁感应法测量脉冲强磁场的原理,并对基于此原理的探测系统进行了实现,最后对实验结果予以分析,给出了主要误差来源.     

Z-Pinch驱动的次临界包层的初步热工分析

Z-Pinch产生高能脉冲中子驱动以压水堆乏燃料或天然铀为燃料的次临界包层,以能源输出为主要目标,是实现能源可持续发展的可行途径.本文通过理论计算,分析了次临界包层在连续中子脉冲作用下的材料温度和输出功率随时间的变化规律.结果表明,通过合理的设计可以使材料温度在可接受的范围内波动,系统输出功率在时间轴上可以得到稳定.     

Influence of high-voltage pulse parameters on the propagation of a plasma synthetic jet

In this work, a typical pin-to-pin plasma synthetic jet in static air is excited by a pulsed DC power supply. The influences of the pulse rising time, the amplitude and the repetition frequency of the pulse voltage on the jet flow have been investigated. First, using a high-speed Schlieren imaging technique, the induced shock waves and the fast jet flow generated by the plasma synthetic jet are characterized. With a deposited energy of 44 mJ per pulse, the velocity of the shock wave and the maximum velocity of the jet flow reach 320 m s⁻¹ and 100 m s⁻¹, respectively. Second, when the applied voltage increases from 12.8 kV to 16 kV, the maximum jet velocity increases from 66 m s⁻¹ to 93 m s⁻¹. On the other hand, as the pulse rising time varies from 50 ns to 500 ns, or the pulse repetition frequency increases from 5 Hz to 40 Hz, the jet velocity induced by the plasma synthetic jet is weakly dependent. In addition, a comparative study of the plasma synthetic jets using three commercial pulsed power supplies (XJ-15, NPG- 18, and PG-30) is implemented. It reveals that the maximum jet velocity of 120 m s⁻¹ is obtained in the case of PG-30, with the longest pulse rising time and the lowest breakdown voltage, while the maximum velocity of 33 m s⁻¹ is detected in the case of NPG-18, even though it has the shortest pulse rising time and the highest breakdown voltage.