Current Ramp-up by Microwave Power in the LATE Device

In the low aspect ratio torus experiment （LATE） device, plasma current is initiated and ramped up to 20 kA solely by microwave power at the electron cyclotron （EC） range of frequency with a ramp of the external vertical field By for the radial equilibrium of plasma torus at larger currents. Measurements suggest that an energetic electron tail in the energy range of about 200 keV carries the current. The line averaged electron density is higher than the plasma cutoff density, suggesting that tail electrons might be driven by electron Bernstein waves modeconverted from the launched electromagnetic waves.

Two Dimensional Density FlUCtuation Measurements During the Non-Inductive Current Ramp-up Phase in the Compact Plasma Wall Interaction Experimental Device CPD

Two-dimensional structure of density fluctuations is examined during the current jump phase, indicating a change from the open magnetic fields to the closed ones. During the smooth current ramp-up phase the two-dimensional contour of the LiI intensity shows vertically alignment, consistent with the magnetic surfaces. At the inflection point in Ip ramp-up the LiI intensity contour becomes flat in the observation regime and then suddenly a steep gradient and higher intensity regime are formed in the vertical direction. This higher intensity corresponds to a burst of LiI waveform. According to these changes in the contour, it is found that, within ~1 ms around the burst of LiI, a low frequency coherent wave with a long wavelength rapidly grows. The relations with other signals （magnetic flux and microwave stray power） are discussed with respect to the topological change in the magnetic configuration and mode conversion of the incident electromagnetic waves.

新型整平剂对电镀铜填通孔的影响及机制探究

针对目前国内电子电镀专用化学品瓶颈问题,合成了一种由含氮杂环与含氧碳链组成的新型整平剂分子SC-21。通过哈林槽实验、循环伏安法(CV)、计时电位法(CP&CPCR)和电化学交流阻抗谱(EIS)对比,研究了常见整平剂健那绿(JGB)、聚乙烯亚胺烷基盐(PN)与新型整平剂SC-21在电镀铜填充通孔过程中的作用差异。结果表明:以一定浓度SC-21为整平剂时可出现“蝴蝶填充”现象,进而实现对深径比2∶1通孔的无空洞填充;与JGB和PN相比,此浓度下的SC-21在较宽的电流密度范围内具有动态吸附行为,可产生“负微分电阻效应”,使得通孔内呈现与“蝴蝶填充”形状相匹配的沉铜速率梯度,最终实现对通孔的无空洞填充。

Discharge simulation and volt-second consumption analysis during ramp-up on the CFETR tokamak

The plasma current ramp-up is an important process for tokamak discharge,which directly affects the quality of the plasma and the system resources such as volt-second consumption and plasma current profile.The China Fusion Engineering Test Reactor(CFETR)ramp-up discharge is predicted with the tokamak simulation code(TSC).The main plasma parameters,the plasma configuration evolution and coil current evolution are given out.At the same time,the volt-second consumption during CFETR ramp-up is analyzed for different plasma shaping times and different plasma current ramp rates dIP/dt with/without assisted heating.The results show that the earlier shaping time and the faster plasma current ramp rate with auxiliary heating will enable the volt-second to save 5%-10%.At the same time,the system ability to provide the volt-second is probably 470 V·s.These simulations will give some reference to engineering design for CFETR to some degree.

Dynamics and stabilization of peak current-mode controlled buck converter with constant current load

The discrete iterative map model of peak current-mode controlled buck converter with constant current load（CCL）,containing the output voltage feedback and ramp compensation, is established in this paper. Based on this model the complex dynamics of this converter is investigated by analyzing bifurcation diagrams and the Lyapunov exponent spectrum. The effects of ramp compensation and output voltage feedback on the stability of the converter are investigated. Experimental results verify the simulation and theoretical analysis. The stability boundary and chaos boundary are obtained under the theoretical conditions of period-doubling bifurcation and border collision. It is found that there are four operation regions in the peak current-mode controlled buck converter with CCL due to period-doubling bifurcation and border-collision bifurcation. Research results indicate that ramp compensation can extend the stable operation range and transfer the operating mode, and output voltage feedback can eventually eliminate the coexisting fast-slow scale instability.

Effects of Linear Falling Ramp Reset Pulse on Addressing Operation in AC PDP

The effects of linear falling ramp reset pulse related to addressing operation in an alternating current plasma display panel （AC PDP） were studied. The wall charge waveforms were measured by the electrode balance method in a 12-inch coplanar AC PDP. The wall charge waveforms show the relationship between the slope ratio of the falling ramp reset pulse and the wall charges at the end of the falling ramp reset pulse which influences the addressing stability. Then the effects of the slope ratio of the linear falling ramp reset pulse on the addressing voltage and addressing time were investigated. The experimental results show that the minimum addressing voltage increases with the increase of the slope ratio of the falling ramp reset pulse, and so does the minimum addressing time. Based on the experimental results, the optimization of the addressing time and the slope ratio of the falling ramp pulse is discussed.

500 kV限流器高温超导磁体的制作与测试

超导限流器是对超高压输电线路短路故障电流实现快速、有效限制的一种新型电力装置。近年来随着国民经济的发展,用电负荷增长和供电可靠性需求增加,电网短路电流水平已经逼近甚至超过传统开关设备的开断能力,成为超高压电网发展和安全、稳定运行的重要制约因素之一。然而,电网结构调整等传统限流措施降低了电网的安全性和灵活性,亟需研制适用于超高压电网的限流装置。超导限流器集短路故障检测、触发和限流功能于一身,是电力系统最理想的限流装置。依托高电压等级限流器用超导磁体系统的研制项目,完成500 kV限流器用高温超导磁体系统制作与测试工作。该超导磁体的室温孔径为1660 mm,总高度为1960 mm,液氮量为2000 L,中心最大磁场为0.45 T,额定励磁安匝数为468000安匝,由3组线圈共计88个双饼组成,运行电流分别为220 A(YBCO线圈)/1000 A(Bi2223线圈)/220 A(YBCO线圈),杜瓦注入液氮后抽空减压至72 K稳定运行。经过绕制、接线、组装、焊接、检测等工序,完成磁体系统集成,降温后进行整体测试,一次性励磁成功,没有失超。整个系统绝缘等级大于10 kV、真空漏率优于10^(-6)(Pa·L)/s、液氮蒸发量小于70 L/d,指标均达到设计目标。

斜阶跃电流激励下多匝小回线瞬变电磁场延时特征

采用Duhamel积分对斜阶跃电流激励的瞬变电磁场进行直接计算,应用叠加原理得到了多匝小回线全域瞬变电磁响应.研究了多匝小回线的早、晚延时临界条件以及等磁矩单匝大回线与多匝小回线的延时和关断时间特征,分析了电阻率、厚度等参数变化时斜阶跃电流对层状模型瞬变响应的影响特征,最后采用实测数据验证了关断效应的校正效果.结果显示,回线边长越小或表层电阻率越大,瞬变响应越早离开早期并进入晚期.多匝小回线的关断时间远大于等磁矩的单匝大回线,但由前者激发的瞬变响应进入晚期的时间却大幅提前,更有利于晚期条件下各种理论公式的使用.斜阶跃影响校正结果显示,增加多匝小回线的匝数可以扩展反演深度的范围,减少匝数则可以提高反演电阻率的精确性;实测数据处理结果显示校正方法产生了一定的效果.本研究补充了多匝小回线瞬变电磁理论内容,研究结果可以为复杂环境中小尺寸多匝线圈的工作参数选择提供参考.

电磁轨道炮轨道电阻率和轨道高度对电流上升沿阶段电枢边沿熔蚀的影响

在固体电枢电磁轨道炮系统中,保持电枢轨道界面良好的电接触至关重要。在电流处于上升沿的发射起始阶段,往往可以观察到电枢材料熔化沉积集中在轨道的外侧,这表明该阶段电流在电枢边沿集中的特性。为此,利用ANSYS软件,在改变轨道电阻率和高度的条件下,对电枢电流密度的分布进行了数值仿真,仿真结果表明:1)电流集中在电枢尾翼边沿;2)通过提高轨道电阻率或者(同时)减小轨道高度可以减小电枢尾翼边沿的电流密度。在20 mm方口径轨道炮上进行了实验,研究了不同电阻率的轨道材料(如98%铜-1%锆-1%铬合金,黄铜和非磁性不锈钢)和不同轨道高度(50、30 mm)对电枢熔化的影响。实验结果表明,在电流上升沿,更高的轨道电阻率和更低的轨道高度时有相对较小的电枢边沿熔蚀。基于数值分析和实验结果,提出了电磁轨道炮起始阶段(电流上升沿阶段)减小电枢边沿熔蚀的轨道结构改进方案。

串联锂离子电池斜坡电流均衡器

针对串联锂离子单体电池在充、放电过程中存在荷电状态(SOC)不一致的情况,提出了一种斜坡电流均衡器。均衡时能量直接由电池组中的高电压单体电池向低电压单体电池转移。此均衡方案以电感和电容为储能元件,通过开关器件的占空比控制均衡电流,均衡电流为可控的斜坡电流。同时对两串联锂离子电池进行了仿真和实验,实验结果证明了此均衡方案的有效性。

浅层瞬变电磁法中全程瞬变场的畸变研究

浅层瞬变电磁法中,由于发射线圈为感性负载,实际激励信号是斜阶跃波,采用常规的后沿校正方法,探测时近地表仍然存在盲区,直接影响浅层探测的精度和分辨率。针对这一问题,研究了全程瞬变电磁场与斜阶跃波的关断时间与接收探头频率特性之间的关系,揭示了早期瞬变电磁场信号发生畸变和影响浅层瞬变电磁探测的根本原因,提出了当瞬变电磁测量系统在电流关断开始时刻记录全程瞬变响应和发射电流波形时,并且接收探头的位置和谐振频率已知,就可以通过数值计算方法从根本上剔除接收探头对早期瞬变信号的影响,从而实现浅层近地表探测,缩短探测盲区。通过对浙江舟山连岛工程的野外勘探数据进行数值剔除,验证算法的有效性。

Breakdown Voltage and Charge to Breakdown Investigation of Gate Oxide of 0.18μm Dual Gate CMOS Process with Different Measurement Methods

Breakdown voltage （Vbd） and charge to breakdown （Qbd） are two parameters often used to evaluate gate oxide reliability. In this paper,we investigate the effects of measurement methods on Vbd and Qbd of the gate oxide of a 0.18μm dual gate CMOS process. Voltage ramps （V-ramp） and current ramps （J-ramp） are used to evaluate gate oxide reliability. The thin and thick gate oxides are all evaluated in the accumulation condition. Our experimental results show that the measurement methods affect Vbd only slightly but affect Qbd seriously,as do the measurement conditions.This affects the I-t curves obtained with the J-ramp and V-ramp methods. From the I-t curve,it can be seen that Qbd obtained using a J-ramp is much bigger than that with a V-ramp. At the same time, the Weibull slopes of Qbd are definitely smaller than those of Vbd. This means that Vbd is more reliable than Qbd, Thus we should be careful to use Qbd to evaluate the reliability of 0.18μm or beyond CMOS process gate oxide.

托卡马克等离子体电流爬升阶段逃逸电子行为

分析了电流爬升阶段等离子体密度和电流爬升率对逃逸电子行为的影响,研究了低杂波辅助电流驱动条件下的逃逸电子辐射行为。结果发现:电流爬升阶段等离子体密度的大小严重影响了电流爬升阶段甚至电流平顶阶段逃逸电子的行为,较低的等离子体密度将会导致放电过程中比较强的逃逸电子辐射;低能逃逸电子辐射随着电流爬升率的增大而增强;低杂波辅助电流爬升可以有效地节约装置的伏秒数;降低放电过程中的环电压,可有效抑制逃逸电子的产生。

DC-DC转换器高集成度片上软启动电路

提出了一种可片内集成的软启动电路,电路由斜坡电压产生电路和带软启动功能的误差放大器组成。斜坡电压产生电路采用脉冲吞咽和窄脉冲充电技术,以小电容实现了缓慢上升的斜坡电压信号,便于片内集成;软启动完成后斜坡电压产生电路自动关闭,节省了功耗。在传统误差放大器的基础上只增加两个晶体管便实现了软启动过程控制,启动阶段误差放大器输出电压跟随斜坡信号上升,控制转换器输出电压和电感电流缓慢上升;在软启动结束时自动平滑地过渡到稳定工作状态,避免了开关切换方法产生的电感电流扰动。该软启动电路集成到一款峰值电流模升压型DC-DC转换器电路中,采用CSMC 0.5μm BCD工艺实现。仿真结果表明,软启动电路有效地消除了浪涌电流,实现了输出电压平稳上升无过冲,并能自动平滑地过渡到稳定工作状态。电路简单易实现,便于片内集成。

峰值电流控制模式BOOST DC-DC变换器的斜坡发生器的设计

该文简要分析了峰值电流控制模式中斜坡补偿的基本原理和设计问题,对基本的充放电振荡器电路进行了改进和优化设计,设计了适用于恒频峰值电流模式BOOSTDC DC变换器斜坡补偿电路中的CMOS定时斜升波发生器电路.

电流模式PWM升压DC-DC变换器斜升波发生器的设计

简要分析了峰值电流控制模式升压变换器的不稳定性及其原因,阐述了斜坡补偿的基本原理和设计问题。对基本的多谐振荡器电路进行了改进和优化设计,设计了适用于峰值电流模式PWM升压型DC-DC变换器斜坡补偿电路中的CMOS斜升波发生器电路。该电路基于UMC BiCMOS工艺设计,经HSpice仿真验证达到了设计目标,性能有很大改善,满足了芯片的需要。

基于电流跟踪控制的三电平DSTATCOM装置的控制方法

指出了在配电网静止同步补偿器(DSTATCOM)中应用直接电流控制方式能够有效地防止装置过流,从而提高其安全可靠性,降低开关器件所需的容量裕度,提高性能价格比。并针对DSTATCOM广泛应用的三电平三单相桥结构,提出了一整套三电平变流器电流跟踪与直流电压平衡控制方法。仿真和实验结果表明采用该控制方法后,DSTATCOM响应迅速,工作稳定可靠,对负荷冲击具有很好的补偿效果。

TETB中的低混杂波电流驱动

本文对低混杂波电流驱升和充电过程进行了理论描述和分析。考虑了低混杂波电流驱动时非线性效应的波谱展宽、附加电导率以及电子和离子的温度变化。将此理论模型应用于托卡马克工程试验混合堆(简称TETB)中的低混杂波电流驱升和充电过程,数值计算和折衷考虑后,给出了一组优化的物理参数。

峰值电流模式控制BoostPFC变换器斜波补偿设计

峰值电流模式控制Boost PFC变换器中存在着丰富的非线性行为,为了控制以削弱不稳定现象的范围,工程上通常采用斜波补偿的方法,但完全靠设计经验。以非线性系统理论的分叉控制观点给出了系统稳定性的临界参数条件及判据,推导了斜波补偿法的参数选择公式,为设计电路时的参数选择提供了理论依据,对实际产品开发具有一定的指导意义。

混合能量存储系统中直流变换器在峰值电流控制下的混沌问题

由于超级电容的工作电压范围广,直流变换器在无电流补偿的峰值电流控制下出现分岔,甚至产生混沌现象。本文中研究了双向直流变换器在超级电容和电池主动并联混合能量存储系统应用中的控制问题,确定了发生分岔时电池和超级电容的工作电压关系。结果表明,采用电流斜坡补偿方法,可使直流变换器在电池和超级电容的工作电压范围内不发生分岔和混沌现象,改善了控制质量。