大面积PIN探测器性能参数实验测量

利用CFC-67型三通道γ源加速器测量了Ф50mm,Ф60mmPIN探测器的时间响应、线性电流及相对灵敏度,并与理论计算结果进行了比较,验证了实验结果的可靠性。Ф60 mm silicon PIN detector is a large area and high sensitive one which has been developed in near years. Using the type CГC-67 γ accelerator, the parameters of PIN detectors such as time response, linear current and relative sensitivity are measured. The experiment results are compared with the theory calculation. The PIN detector can reach high γefficiency of up to 10^-14-10^-16 C·cm2, the rise time is about 10 ns and the FWHM of the time pulse is about 35 ns. The γ efficiency of the PIN detector may provide the sensitive range between 10^-14-10^-16 C·cm^2 that scintillator ＋ photo tubes detecting system and scintillator ＋ photomul tiplier tubes detecting system is not developed.     

Electrical instability in a semiconductor gas discharge system

Electrical instability in a SI GaAs plates of the semiconductor gas discharge gap system (SGDGS) is studied experimentally in a wide range of the gas pressures, interelectrode distances and different diameters of the cathode areas. While being driven with a stationary voltage, it generates current and discharge light emission (DLE) instabilities with different amplitudes of the oscillation. It is shown that under the experimental conditions the interelectrode distance played only a passive role and was not responsible for the appearance of the DLE instability. At the same time for different diameters D of the GaAs plate areas the expanded range of current and DLE oscillations are observed. SGDGS with an N‐shaped CVC was analyzed using both the current and DLE data showing the electrical instability in the GaAs cathode. It was found that application of high feeding voltage to this cathode give rise to non‐uniform spatial distribution of the DLE, which disturbed the operation of the system. The experiment presents also a new metod to study and visualization of the electrical instabilities in high‐resistivity GaAs plates of large diameter. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

涡流损耗对爆炸去磁脉冲发生器输出性能的影响

 为了提高爆炸去磁脉冲发生器的输出能量,设计了绝缘层截断涡流回路磁体结构,以减小冲击去磁过程中磁体内产生涡流造成的能量损耗。把圆柱形钕铁硼磁体切分成4块,在块与块之间增加聚脂绝缘层,再组合成一个圆柱形整体,形成截断涡流回路的磁体结构。采用Maxwell 3D电磁场有限元分析软件,对未切分和切分后的钕铁硼磁体进行了静磁场计算,分析了两种结构下的磁感应强度分布。对这两种磁体结构的脉冲发生器进行了爆炸实验,测量了脉冲发生器输出的感生电动势,分析了涡流损耗对发生器输出电流的影响。结果表明：磁体中截断涡流回路的脉冲功率发生器涡流损耗较小,能够输出更大的电能。     

H=B0／μ0的判据与静磁场的两种物理图象

本指出：在均匀介质情况下Ｈ＝Ｂ０／μ０的判据可简化为Ｂｎ＝０；在介质图象下，“Ｈ仅与自由电流和介质的分布有关，而与磁化电流无关”的结论并不错。本还举例说明了静磁场中两种物理图象的应用。     

基于改进射影控制的降阶高压直流附加控制器设计

针对电力系统控制器设计中,控制器阶数过高且影响控制品质的问题,提出一种基于射影定理的降阶控制器设计新方法,并对射影定理做出改进,实现抑制低频振荡的高压直流附加阻尼控制.通过总体最小二乘-旋转不变技术分析系统振荡特性并辨识出相关模型,再基于极点配置得到状态反馈矩阵,最后利用改进的射影控制理论设计输出反馈降阶控制器,同时将控制器与传统的带观测器的极点配置控制方法进行比较.仿真验证表明,基于射影控制理论的控制器效果较好,控制器阶数较低,鲁棒性强,便于工程实现.     

Synthesis of transparent BaTiO3 nanoparticle/polymer composite film using DC field

Transparent BaTiO₃ nanoparticle/polymer composite films were synthesized from titanium-organic film and barium ion in aqueous solution under direct current (DC) field. Titanium-organic precursor was synthesized from titanium isopropoxide, acetylacetone and methacrylate derivative. The UV treatment was effective to increase the anti-solubility of the titanium-organic film during DC processing. BaTiO₃ nanoparticles were crystallized in the precursor films on stainless substrates without high temperature process, as low as 40°C. The crystallite size of BaTiO₃ increased with increasing reaction temperature from 40 to 50 °C at 3.0 V/cm. BaTiO₃ nanoparticles also grew in size with increasing reaction time from 15 min to 45 min at 3.0 V/cm and 50 °C. Transparent BaTiO₃ nanoparticle/polymer films were synthesized on stainless substrates at 3.0 V/cm and 50°C for 45 min.     

Recent R&D towards Aqueous Reprocessing of FBR Fuels

The mixed Pu-rich carbide spent fuel with a burn up of 155 GWd/t from the Fast Breeder Test Reactor is being reprocessed in a hot-cell facility by PUREX process. Based on the input from the operation of this facility, R&D activities were carried out to improve the recovery, decontamination factors, economy and to reduce the waste volumes. Reduction of uranyl ions in a continuous flow electrochemical reactor and electrolytic as well as chemical reduction of 4M HNO₃ from liquid waste could be accomplished in continuous mode. Using the optimized parameters, suitable electrolytic cells/experimental setups were designed for the plant capacity of 6 L/h. Studies on the extraction kinetics of Ru with 30% TBP in NPH revealed that better decontamination factor with respect to Ru can be achieved using fast contactors like centrifugal extractors (CEs). Towards developing a spent solvent recovery system to reduce organic waste volumes, a pilot plant was set up, which could recover diluent as top product of distillation column and 40% TBP as bottom product from inactive degraded solvent. A solvent recovery system using short path distillation was also developed for installation in hot cells.     

Rapid separation of polysaccharides using a novel spiral coil column by high‐speed countercurrent chromatography

The separation of polysaccharides is time consuming. We developed and optimized a type‐J counter‐current chromatography system with a novel tri‐rotor spiral coil column for the rapid separation of polysaccharides. The optimal composition of an aqueous PEG1000/K₂HPO₄/KH₂PO₄ system was found to be 14:16:14 w/w/w where the lower phase was the mobile phase. Optimal performance was achieved at a column rotational speed, temperature, and flow rate of 1200 rpm, 45°C, and 3.0 mL/min, respectively. The mobile phase was pumped from the inner terminal in a ‘‘head‐to‐tail’’ elution mode. Polysaccharide LCP‐1 (10.7 mg) was successfully obtained in high purity in one step from 50.0 mg of a crude polysaccharide extracted from the lychee fruit (Litchi chinensis) within 100 min. LCP‐1 possess a number‐average molecular weight and weight‐average molecular weight of 1.05 × 10⁵ and 1.59 × 10⁵ kDa, respectively. The monosaccharide composition consists of the molar ratio of glucose, galactose, and arabinose of 1.3:3.5:1.     

甚长波量子阱红外探测器的暗电流特性研究

基于载流子在量子结构中的输运理论研究了甚长波量子阱红外探测器(峰值响应波长15μm，量子阱个数大于40)的载流子的输运性质.研究结果表明，在甚长波量子阱红外探测器中，电流密度一般很低，暗电流主要来源于能量高于势垒边的热激发电子.通过薛定谔方程和泊松方程以及电流的连续性方程的自洽求解，发现外加偏压下电子浓度在甚长波器件各量子阱的分布发生较大变化，电场在整个器件结构上呈非均匀分布，靠近发射极层的势垒承担的电压远远高于均匀分布的情形.平带模型假定电压在器件体系上均匀分布，导致小偏压下的理论计算值远远低于实验值. 关键词： 甚长波量子阱红外探测器 量子波输运 暗电流