邳苍分洪道第一次砷超标事件解析

事件的基本情况 2009年1月7日,准委监测发现山东省临沂市邳苍分洪道出境断面砷超标.临沂市第一时间启动应急预案,1月9日锁定了肇事企业山东红日阿康化工股份有限公司,及时切断了污染源.同时向下游江苏省徐州市、邳州市通报有关情况,迅速同步开展应急处置工作,在邳苍分洪道东偏泓、城河、纲河等污染河段筑坝拦蓄,1月14日成功将污水拦截在江苏邳州境内,防止了事态的进一步扩大.     

大气压双频容性耦合Ar/O_(2)等离子体特性研究北大核心CSCD

文章利用二维流体模型对双频调制大气压Ar/O_(2)放电特性进行了研究,着重讨论高低频电压、低频频率等不同匹配方式对等离子体参数的影响,并且通过对电子加热模式、电子密度、中性粒子密度、正离子能量以及正离子总通量等分析了大气压Ar/O_(2)放电双频调控机制。结果表明,低频源电压的改变使得电子加热模式由α模式转变为DA/α混合模式,且等离子体密度、正离子总通量及离子能量均随着低频电压的升高而增大,发生了解耦现象。与低频源电压不同,高频源电压和低频源频率对电子加热模式不产生影响。此外,高频源电压对等离子体密度及正离子总通量影响较大,对刻蚀工业中易对材料造成损伤的离子能量影响很小;而低频源频率对工业中影响影响较大的离子能量和离子总通量影响较大,对等离子体密度影响较小,实现了等离子体密度和离子能量的独立控制。     

One-Dimensional Fluid Model of Pulse Modulated Radio-Frequency SiH4 /N2 /O2 Discharge

Driven by pulse modulated radio-frequency source,the behavior of SiH 4 /N 2 /O 2 plasma in capacitively coupled discharge are studied by using a one-dimensional fluid model.Totally,48 different species(electrons,ions,neutrals,radicals and excited species) are involved in this simulation.Time evolution of the particle densities and electron temperature with different duty cycles are obtained,as well as the electronegativity n SiH3 /n e of the main negative ion(SiH3).The results show that,by reducing the duty cycle,higher electron temperature and particle density can be achieved for the same average dissipated power,and the ion energy can also be effectively reduced,which will offer evident improvement in plasma deposition processes compared with the case of continuous wave discharge.     

Continuous wave and passively Q-switched Nd:Lu0.15- Y0.85VO4 laser with 885 nm direct pumping

The 885 nm direct pumping directly into the 4F3/2 emitting level of Nd3+ is applied on an Nd:Lu0.15Y0.85VO4 crystal. The maximum output power of 2.8 W for continuous wave (CW) operation is obtained. For Q-switched operation, the maximum average output power is 1.2 W with pulse repetition of 23.69 kHz and pulse width of 35 ns at the pump power of 27.9 W. The high-quality fundamental transverse mode can be observed owing to the reduction of thermal effect for Nd:Lu0.15Y0.85VO4 crystal by 885 nm direct pumping.     

Effect of gas flow on the nanoparticles transport in dusty acetylene plasmas

This article presents simulation results on the effects of neutral gas flow for nanoparticle transport in atmospheric-pressure, radio-frequency, capacitively-coupled, and acetylene discharge. The acetylene gas is set to flow into the chamber from the upper showerhead electrode. The internal energy of the gas medium therein is transferred into kinetic energy so the gas advection can be triggered. This is represented by the pressure volume work term of the gas energy converse equation. The gas adv...     

The effects of dilution gas on nanoparticle growth in atmospheric-pressure acetylene microdischarges

A two-dimensional multi-fluid model is developed to investigate the effects of dilution gas on microplasma properties and nanoparticle behavior in atmospheric-pressure radio-frequency acetylene discharges. The percentage of dilution gases (argon and helium) percentage varied from 0% to 90%, with the pressure kept constant. Simulation results show that the dilution gas percentage has a significant influence on the spatial distributions of the electron density and temperature, as well as on the formation of nanoparticles in acetylene microplasmas. With increasing dilution gas percentage, the electron density profile changes continuously from being high at the edge to high in the center. A mode transition from a mixed discharge mode with both α regime and drift-ambipolar regime into α regime occurs, which is associated with a sudden decrease in the electron density of the presheaths and an increase in the electron temperature of the bulk plasma. The mode transition point corresponds to the lowest number density ratio of hydrocarbon ions to acetylene. The highest number density ratio is observed at a dilution percentage of 90%, and causes more effective nucleation and coagulation of nanoparticles. Furthermore, owing to the high ionization potential of helium, the transition point moves to a larger dilution gas percentage in ${{\rm{C}}}_{2}{{\rm{H}}}_{2}$/He microplasmas. Finally, the growth of nanoparticles via coagulation is studied.