电离电流

Figure 2-11 illustrates guarding as applied to measuring the ion current from an ionization chamber.

图2-11说明保护技术应用于测量电离室的离子电流。

For the current in the ionization chamber is not amplified, so it is hard to collect the electric signal, in this paper, a direct I/F convertor is used to convert the electric current signal into frequent signal.

由于电离室本身不对电流放大，因此信号的采集较为困难，本文另外介绍了用I/F直接变换的电路以达到信号的转换。

Main contents and conclusions are: 1 The ionization current was measured continuously by a charge-integration method with a computer after the introduction of radon into the chamber.

主要内容及结论：1充氡后利用计算机连续进行电离电流累积测量，得到了精细的电流随时间的变化曲线，可清楚看出氡及其子体的生成衰变造成的电离电流的生长—稳定—衰减过程，与理论计算值进行了比较，由电离电流衰减速度的变化得出氡吸附作用的影响，并测量到电离室冲洗后氡的反扩散现象；2由已知活度的标准源定出相对测量的刻度系数K值，K=24.62 Bq／pA，对同一个监测源以半年为周期进行多次测量后得出稳定性符合要求；3通过测量电离电流和气压的关系曲线以及不同气压下的饱和曲线，确定了常规的工作条件；4测量了盐酸清洗电离室内表面降低本底的效果；5不确定度分析表明相对测氡的扩展不确定度(k=2)小于5％，由本底涨落得出探测下限为0.5 Bq；6理论上对壁损失修正进行了计算，实验上保持电离室工作在饱和区的情况下，测量了不同气压下电离电流的变化，从中得出了壁损失随气压变化的规律，可以看出，电离电流的实测值和计算值随气压变化规律基本一致；当气压大于125 kPa时，端效应等其它因素造成的影响不大于2％，因而在此工作条件下，测量电离电流后通过计算修正壁损失可以实现近似的绝对测氡，提出了进一步提高绝对测量准确度的方法。

In the current system of ED too will cause water ionization.

在ED系统中过大的电流会引起水的电离。

Carbon nanotubes are used to solve this problem effectively in this project. As controlled DC voltage is applied to the CNTs electrode, the sharp tips of CNTs can generate high electric fields, so it was easy to ionize gas and get larger current at lower voltages.

纳米碳管的出现有效地解决了该问题，在外加直流电压激励下，纳米碳管的尖端会形成很强的非均匀电场，在电压相对较低的情况下能很容易地电离气体且获得较大的放电电流。

A prediction model has been proposed to deal with threshold voltage shift as a function of 1MeV neutron flux and gate oxide thickness, and to deal with room-temperature annealing of threshold voltage shift induced-by 〓Coγ as a function of electric field and gate oxide thickness. The commonness and individuality of MOS device degradation between hot-carrier effect and ionizing radiation were investigated. The dependence of substrate current, gate current and threshold voltage shift due to hot-carrier on gate oxide thickness were simulated with MEDICI-2D simulator. The photocurrents of PN junction and bipolar transistor were studied. Their transient responses on varied bias voltages, pulse durations and absorbed doses were simulated. The influences of NPN base width on base and collector photocurrents were investigated. We also studied 1MeV neutron displacement damage in PN junction, and calculated reverse current leakage under the neutron flux of 2. 67×10〓 per square centimeter. 3 The study of nondestructive screening method for MOS radiation tolerance A theoretical and experimental study of nondestructive screening methods for radiation tolerance of nMOS and pMOS were firstly fulfilled. We determined the informative parameters pertinent to the method and proposed how to deal with experimental data and verify obtained results statistically, as well as make the required steps for nondestructive screening. Based on the experimental data of 180 samples of discrete pMOS devices, the relation between sample quantity and correlation coefficient, screening equation, and other significant results were obtained from the threshold voltage shifts of pre-and post-irradiation samples.

二、分立器件电离和位移辐射损伤响应研究在国内首次开展了电离辐射引起的氧化层阈值电压漂移和退火理论研究，编程计算了1MeV中子引起的MOS器件阈值电压漂移与中子通量及栅氧厚度的关系，计算了〓Coγ光子引起的阈值电压漂移及退火的时效曲线与纵向电场和栅氧厚度的关系等，对评估MOS型集成电路电离损伤和加固方法研究，以及论文中开展的MOSFETs无损筛选方法研究奠定了基础；分析了MOS器件热载流子损伤效应与辐射电离损伤效应之间的异同性，利用二维模拟软件MEDICI-2D模拟了衬底电流和栅电流，在不同栅氧厚度下随栅压的变化曲线，计算了热载流子效应造成的阈值电压漂移，研究结果对当前存在的以热载流子效应研究取代电离辐射损伤实验研究的设想，具有重要的参考价值；开展了PN结和双极晶体管电离光电流研究，计算了不同偏压、不同辐射脉宽和不同吸收剂量下PN结光电流的瞬时响应，计算了不同辐射脉宽下NPN晶体管基极电流和收集极电流的瞬时响应，以及基区宽度对NPN晶体管光电流的影响，研究结果对双极器件抗电离辐射损伤响应及加固方法研究具有重要意义；在国内首次开展了器件位移损伤的理论研究，分析了辐射产生的缺陷对电性能的影响，计算了注量为2.67×10〓cm〓的1MeV中子产生的缺陷对PN结反向电流的影响。

The difference of the structure, which influenced the light emission of porous, was the result of the competition between diffusion current and thermion current.

这主要是由于扩散电流和热电离电流的竞争，造成多孔硅形貌的多样性和孔隙度的变化。

2 The output of the general ignitor' Voltage and Current are fixed. Therefore it can not start up various

不同高压气体放电灯管其消激发与消电离过程均不同，一般IGNITOR 为输出固定电压、电流；能量太小

Spectrometer was adopted to measure the emission spectrum of argon plasma jet at the ignitor exit; boltzmann curve slope method was applied to caculate the jet electron temperature; ionization equilibrium equation was used to caculate jet temperature and measured a law that length, electron temperature and jet temperature of ignitor exit jet length changed with arc current and flowrate.

采用光谱仪测量了氩气等离子体射流在点火器出口的发射光谱，利用玻尔兹曼曲线斜率法计算了射流的电子温度，并通过电离平衡方程计算了射流气体温度，测得了点火器出口射流的长度、电子温度和射流温度随弧电流以及流量的变化规律。

When clean air particles of oxygen and nitrogen move through smoke detectors, the americium-241 ionizes them, which creates an electrical current.

当只含有氧气和氮气清洁的空气通过探测器时，镅241会产生一道电流，电离它们。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。