Development of discharge plasma waveguide with external magnetic field for laser plasma acceleration

To improve the acceleration length in laser plasma acceleration, we investigate the discharge plasma waveguide with a magnetic field. The discharge circuit consists of two pulsed‐power circuits for preionization and main discharge. Discharges were repeated through the circuit using high‐power semiconductor switches. Laser propagation characteristics of discharge plasma waveguide with the external magnetic field were observed. The results show that the reproducibility of waveguide with the external magnetic field is relatively high compared to that without magnetic field. The laser intensity gradually decreases with the strength of external magnetic field. These results suggest that the electron density profile is possible to control using the discharge plasma waveguide with an external magnetic field.     

自动清洗纽带入口反旋强化的动力矩计算方法研究及其应用

运用动量矩定理建立了入口反旋强化纽带的自动清洗动力矩计算式。应用该计算式进行了以自转动力矩强化为目标的结构设计和优化试验及其工程应用研究,获得了重要的结果。其中2030型反旋强化轴承座的冲推力矩使2 000 mm长的纽带自转力矩增大235%,能够显著地降低纽带自转流速要求,并且阻力只有1.5 kPa,结构简单,成本低廉。该技术适于在0.9 m/s左右流速的传热设备中推广应用,尤其在传热管长度不大时效果更为显著。     

Numerical study of the oscillation characteristics of a surface wave oscillator

The oscillation characteristics of a surface wave oscillator is analyzed numerically. The oscillation frequency due to Cherenkov instability can be controlled by the electron beam energy though the alteration of the accompanying temporal growth rate. The growth rate increases exponentially with the proximity of the beam to a corrugated metal plate. The oscillation frequency is not changed by this proximity. The peak of the growth rate of the Cherenkov instability is one or more orders higher than that of a Smith–Purcell type instability. Moreover, in frequency and wavenumbers, the difference of two instabilities is enlarged by the increase in the growth rate. Therefore, the influence of the Smith–Purcell type instability on the Cherenkov instability is decreased. IEEJ Trans 2010 DOI: 10.1002/tee.20611     

An analysis of the field acceleration method and of vector control of induction motors

The two-axis theory and vector control based on this theory are well known. On the other hand, Yamamura has proposed the phase segregation method (spiral vector method) for the analysis of induction motors along with the field acceleration method (FAM). In this paper these analytical and control methods are compared. We begin by analyzing the equations for phase segegation, which contain information derived from the three-phase stator and rotor equations. We next demonstrate that the vector control system for constant rotor flux is obtained from the type T-I type field acceleration method when the transient term is zero. By By using the equivalent circuit for a T-I transient, we readily obtain the desired vector control system, because the circuit is identical to the steady-state circuit when the rotor flux is constant. An analytical solution of the transient response for the vector control system is obtained for arbitrary initial conditions. Finally, the stability of type T-II FAM is discussed, with special emphasis on the effect of changes in stator resistance, by computing the torque transfer function. When the stator resistance is correctly estimated, pole-zero cancellation occurs on the imaginary axis.     

一种数字式单片加速度传感器的原理与应用

本文首先简单介绍了一种高精度、数字式单片加速度传感器的工作原理;然后阐述了其校准方法及典型应用;重点给出了一种利用纯硬件将脉冲宽度信号转换成模拟电压信号的电路,利用AD转换芯片ICL7106将模拟电压信号转换成数字信号,并利用液晶屏直接显示结果;最后给出了一组实测数据.该加速度计可广泛用于地震监测、汽车安全报警、双轴线倾斜角测量等领域.     

基于MEMS惯性传感器的波浪测量系统设计与实现

波浪测量系统能够在固定海域、全天候、全天时地自动监测海洋的波高、周期和波向。设计了基于STM32F429处理器和MTI-3-8A7G6T惯性传感器的波浪测量系统。完成波浪测量系统的算法及软件设计,其中波高和波周期的测量采用在频域内对加速度进行二次积分,可以有效避免直流分量对积分结果的影响,同时在频域内进行数字滤波,滤除加速度计零偏误差和低频随机噪声;波向的测量是利用水平合成加速度与磁航向的夹角获得。通过软件设计将测波算法成功移植到STM32F429处理器中,实现波浪测量功能。经实验验证,针对不同波高和波周期的波浪,波浪测量系统的测量误差都在规定范围内。系统对波浪特征值解算准确,长时间运行稳定,满足高精度和高可靠性的测量要求。     

托卡马克等离子体电子密度测量与处理研究

等离子体电子密度是托卡马克物理研究中一个重要的物理量,它是表征等离子体特性的一个重要参数。本文介绍J-TEXT托卡马克装置中HCN激光干涉仪测量等离子体电子密度的基本原理,并采用软件相位差法获得等离子体电子密度,详细叙述该软件算法流程。该算法采用傅里叶变换法获得HCN相位差值,用数字滤波器对信号进行去噪处理,该算法能够准确地去除零漂,有效的进行信号翻转处理,实现对等离子体电子密度的准确测量。该系统已在J-TEXT装置实验中成功应用,获得了高精度低噪音的等离子体电子密度值,为相关物理研究提供了重要的数据。     

风、浪对海上风电机组振动特性的影响及控制策略

建立了波浪模型,分析了风力机气动载荷和气动转矩中与水动频率相关的脉动分量产生的原因,并基于GH Bladed平台仿真验证了这种脉动的存在性。为减小这种脉动以及风切变和塔影效应对风力机产生的影响,将积分后的塔顶振动加速度信号与统一变桨距参考信号叠加,减小统一变桨距信号,结合风力机输出功率的3倍频风轮旋转频率(3P)脉动分量以及每支叶片的方位角将其转换为该叶片的桨距角调节信号,实现变桨距控制。仿真结果表明,所提变桨距控制策略不仅能有效平缓风、浪引起的海上风力机叶根挥舞载荷的脉动,还能明显减小其气动转矩以及输出功率的波动,在减小风轮疲劳载荷的同时提高了海上风力机的输出电能质量。     

Three‐dimensional numerical analysis on discharge properties of microwave excited ring dielectric line surface wave processing plasma device

A three‐dimensional simulation code with the finite difference time domain (FDTD) method combined with the electron fluid model has been developed for the microwave excited surface wave plasma in the RDL‐SWP device. This code permits the three‐dimensional numerical analysis of the spatial distributions of electric field, power absorption, electron density, and electron temperature. At a low gas pressure (about 10 mTorr), the numerical results were compared with the experimental measurements that show the validity of this 3D simulation code. A simplified analysis assuming that the electron density is spatially uniform has also been studied and its applicability is evaluated by the comparison of the 3D simulation and the analytical solutions. The surface wave eigenmodes are determined by the electron density, and it is found that the structure of the device strongly influences the spatial distribution of the electric fields of surface waves in a low‐density area (n_e < 3.0 × 10¹¹ cm^?3). A method to irradiate by microwave the whole surface area of the plasma is proposed. The method is found to be effective in obtaining a high uniformity distribution of electron density. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 150(4): 1–12, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10333     

Measurements of electron density profile characteristics in various kinds of plasma configurations in the TS‐3 plasma merging device

Measurements and a comparative study have been performed on electron density profiles, focusing on the electron density gradient near the magnetic separatrix in various kinds of plasma confinements such as the ST, spheromak, and RFP in the TS‐3 device. A CO₂ laser interferometer using a glass tube to clear the path for the laser was introduced in order to measure the electron density profile with time resolution. It was shown that ST with a high q value at the plasma edge (q: safety factor) has a larger electron density gradient than low‐q plasma confinements such as the spheromak and RFP. In particular, the ST with edge q value greater than about 2 showed a large electron density gradient at the edge. The idea that the j × B force profile of the higher‐q ST could sustain the higher thermal pressure supports these results. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(2): 35–41, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10158     

特高压直流极母线避雷器污秽状况下内外部电场分布的仿真研究

由于直流电场对污秽颗粒的吸附作用,使直流避雷器相对于交流避雷器的积污更加严重。且特高压直流极母线避雷器在绝缘外套内部还有3柱并联的电阻片柱,污秽分布对绝缘外套表面电场以及电阻片柱与绝缘外套之间的径向电场的改变,都将会对避雷器的运行状况造成一定的影响。文章结合直流场中污秽的分布特点,建立了特高压直流极母线避雷器污秽状况下的电场仿真模型,对避雷器在整体湿污秽以及出现局部干燥带时的伞裙表面电场和电阻片柱与绝缘外套间的径向电场进行了计算分析,结果表明：避雷器整体污秽会导致绝缘外套表面场强与内部径向场强的增大,但数值较小尚且不会引起电晕及闪络现象;而局部干燥带的出现,则会在伞裙表面和电阻片与绝缘外套间的空气间隙形成局部过高的表面场强和径向场强,导致绝缘外套表面闪络,以及电阻片柱与绝缘外套间的贯穿性放电等现象,严重危害避雷器的安全稳定运行。     

Development of a switching and focusing mechanism of shock wave and expansion wave using the discharge phenomena of electrically induced microbubbles

A novel needle‐free injection system by electrically induced microbubbles has been developed. First of all, we evaluated the depth of injected reagent for evaluating injection performance. Then, the cavitation‐induced shock wave has been focused to magnify the injection performance by semispherical reflector. We successfully visualized the shock wave by the schlieren method and succeeded in measuring the pressure of focused shock wave and expansion wave by hydrophone.     

凝汽器采用螺旋槽铜管强化传热的试验研究

本文对水平螺旋槽管凝结放热进行了实验研究,并在电厂凝汽器上进行了工业试验。结果表明,螺旋槽管换热器总体传热系数比光管换热器提高约23％～48％,凝汽器采用螺旋槽管后,使N25—3.43/435汽轮机背压降低1.16kPa,因而具有显著的经济效益。     

Comparative study of electron density profiles in compact torus plasma merging experiments

Following two previous papers on comparative studies of the electron density distributions for a single compact torus (CT) and a spherical tokamak (ST), and for a single ST and a merged ST, a comparative study on the dynamics of the electron density profile during and after the CT and ST plasma merging process was performed. The sharpness of the peak in the electron density profile around the midplane just after the merging of CT with a low safety factor (q value) such as RFP or spheromak is found to be related to the speed of the magnetic axis during the plasma merging process. It is also found that the electron density gradient near the plasma edge in a high‐q ST is larger than that of a low‐q CT. High‐q ST is found to have a magnetic structure which is able to sustain a large thermal pressure by a strong j × B force. Despite these differences in the electron density profile between CT and ST during merging, the confinement characteristics evaluated from the number of electrons confined within the magnetic separatrix after the completion of the merging are almost similar between the merging CT and the merging ST. For all configurations, the electron density profiles after the completion of the merging are analogous to those of the corresponding single configuration produced without the merging process. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(2): 14–21, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10312     

电网谐波的产生、危害及抑制措施

论述了电力系统中谐波的产生,危害及抑制措施,只有真正有效地抑制谐波,才能确保电力系统安全稳定运行。     

大坝电厂三期“3.13”机组故障录波异常分析

对大坝三期＂3.13＂事故中机组故障录波器录波波形进行分析,发现了录波波形异常,对波形异常产生原因进行了分析和验证,提出了整改措施和建议。     

飞机驾驶杆(盘)力系统现场测试校准技术研究

面对飞机上测试环境和测试要求的改变,力参数的实验室测试校准方法已无法满足当下的要求。本文首先对驾驶杆(盘)力现场联机测试校准进行了需求分析,找出了其中的关键点和难点,最后采用了通过飞机驾驶杆(盘)专用夹具对标准力传感器和驾驶杆(盘)同时施加拉压力、同时进行数据采集的方法,并通过试验结果分析,能够满足测试需求,从而论证了该测试方法的可行性和正确性。     

局部同塔双回直流线路故障行波传播特性及其对行波保护的影响研究

局部同塔双回直流线路分界点各侧的线路段具有不同的耦合特性,结合分界点各侧线路段的相模变换,得到了不同线路段入射分界点时各电压模量行波的交叉折射系数。在此基础上,对局部同塔双回线路不同线路区段发生单极接地故障时的故障行波传播特性及其行波保护动作量进行了定量分析,并比较了其与单回线路及完全同塔双回线路的差异。结果表明:同塔双回线路段的线模1分量与单回线路段的地模分量之间的交叉折射是造成局部同塔双回线路的故障行波传播特性与单回线路及完全同塔双回线路不同的主要原因;就基于模量的行波保护判据而言,局部同塔双回线路行波特性的影响主要体现在线模波变化率,其大小介于完全同塔双回线路和单回线路之间,且与单回线路段的总长度有关。     

风浪扰动下海上风电机组塔架载荷与输出功率的协同优化控制

风浪扰动导致海上风电机组响应特性复杂,控制器需要综合处理多种外源扰动。此外,气动力造成风轮旋转与塔架运动的耦合作用,增加了变桨控制器设计的难度。首先,通过动力学分析建立合适的海上风电机组低阶数学模型。然后针对风浪扰动,提出了随机干扰调节控制器(SDAC)。最后协同输出功率控制与塔架载荷控制,设计含线性二次型调节器的变桨控制器。基于GH Bladed软件的仿真结果表明,相较于传统控制器,SDAC能够优化机组输出功率波动,降低塔架载荷,实现塔架载荷与输出功率的协同优化。     

电网谐波分析及其对策

介绍电力网谐波的产生机理及产生谐波的谐波发源地，特别指出谐波对电力系统所产生的危害，提出减小谐波影响的技术措施和管理措施。