Diagnostic of capacitively coupled radio frequency plasma from electrical discharge characteristics: comparison with optical emission spectroscopy and fluid model simulation

The capacitively coupled radio frequency(CCRF)plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma.In this paper,a glass vacuum chamber and a pair of plate electrodes were designed and fabricated,using 13.56 MHz radio frequency(RF)discharge technology to ionize the working gas of Ar.This discharge was mathematically described with equivalent circuit model.The discharge voltage and current of the plasma were measured atdifferent pressures and different powers.Based on the capacitively coupled homogeneous discharge model,the equivalent circuit and the analytical formula were established.The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation.The experimental results show that when RF discharge power is 50–300 W and pressure is 25–250 Pa,the average electron temperature is about 1.7–2.1 e V and the average electron density is about 0.5?×?10~(17)–3.6?×?10~(17)m~(-3).Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.     

6 kA镨钕电解槽不同阴极直径下的 电热场耦合模拟

以6kA镨钕电解槽为研究对象,运用多物理场有限元分析软件COMSOL对不同阴极直径下的6kA镨钕电解槽电解过程进行电热场耦合数值模拟,分析阴极直径对槽内电热场的影响。结果表明,随着阴极直径的改变,电解槽内的电场与温度场均发生变化并且相互影响,结合实际生产经验和模拟仿真研究,认为阴极直径为80mm时,可使6kA镨钕电解槽产生足够电解反应发生的焦耳热,电解效率良好。     

Temperature gradients drive radial fluid flow in petri dishes and multiwell plates

Liquid in a Petri dish spontaneously circulates in a radial pattern, even when the dish is at rest. These fluid flows have been observed and utilized for biological research, but their origins have not been well‐studied. Here, particle‐tracking to measure velocities of radial fluid flows, which are shown to be linked to evaporation, is used. Infrared thermal imaging was used to identify thermal gradients at the air‐liquid interface and at the bottom of the dish. Two‐color ratiometric fluorescence confocal imaging was used to measure thermal gradients in the vertical direction within the fluid. A finite‐element model of the fluid, incorporating the measured temperature profiles, shows that buoyancy forces are sufficient to produce flows consistent with the measured particle velocity results. Such flows may arise in other dish or plate formats, and may impact biological research in positive or negative ways. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2227–2233, 2016     

磁选机典型开放式磁路分析与仿真

开放式磁路是一种应用最早、广泛、成熟且仍不断创新的磁路形式,对该磁路的深入研究可为目标磁路设计、工艺流程优化及工程设备选型提供有益指导。借助于COMSOL Multiphysics软件,仿真并研究若干种典型的开放式磁路,并分析磁源、磁极深度、配比、辅助极、磁化方向等相关因素对磁路的影响,之后给出几种磁路下磁性颗粒的运动轨迹。     

外界供给参数对PEMFC输出性能及水热平衡的影响

为了改善质子交换膜燃料电池(PEMFC)内部的水热平衡,从而进一步改善PEMFC的输出性能,文章建立了PEMFC的三维模型,通过改变PEMFC的外界供给参数(进气速度、加湿率以及冷却水流速),应用COMSOL模拟仿真得到了PEMFC的极化曲线和功率曲线、流道和气体扩散层(GDL)的水浓度分布情况,以及冷却水流速对PEMFC温度的影响。研究结果表明:随着进气速度和加湿率的逐渐增加,PEMFC的输出性能均逐渐提升,但是,过高的加湿率可能导致电极水淹;随着冷却水流速的增加,PEMFC温度加速下降,膜内温度分布变得更均匀。     

基于ZnO/Si结构的声表面波器件设计研究

微机电系统(MEMS)工艺已被广泛用于制造各种硅基薄膜器件.声表面波(SAW)器件是性能优良的MEMS器件.该文利用多物理耦合场软件COMSOL Multiphysics仿真了氧化锌/硅(ZnO/Si)结构SAW谐振器,并得到其S11参数.对应于仿真,该文制造了该种结构的SAW器件.实验所用的ZnO通过射频磁控溅射制备,所制备的ZnO具有良好的(002)取向.实验测得的ZnO/Si结构SAW器件的中心频率为111.6 MHz,与仿真结构接近.     

基于ADμC812的芯片温度控制系统的研究

介绍了一种以PID增量算法为核心,以812为硬件基础的温度控制系统,并给出了硬件电路和软件设计的总体结构。采用模拟软件COMSOL Multiphysics3.2分析控制对象的温度分布能够使控制结果与实际要求更为符合,满足芯片培养细胞的需要。     

基于动态数据的端面摩擦热-力耦合分析

为了更加准确地探索端面摩擦过程中的温度分布情况,使用端面摩擦过程中的实时动态摩擦因数和红外探头实测温度作为边界条件,在多场耦合软件COMSOL Multiphysics中进行热-力直接耦合分析,并利用红外热像仪对计算结果进行检验。结果表明:实时边界条件与数值计算相结合的方法可以准确地模拟出端面摩擦瞬态温度场;摩擦副之间的转速、载荷、摩擦因数是影响温度场分布的主要因素。     

光纤传感电流监测中光纤套筒周围的电磁场分布研究

介绍了一种用COMSOL软件模拟大电流磁场的方法,并提供了光纤电流传感器中传感元件所放置的套筒的材料的选择依据,本方法具有实用性及可靠性。根据法拉第电磁感应定律,通过COMSOL软件,建立了大电流直导线模型,利用所建立的模型,分别用理论和实验模拟了大电流周围磁场分布。由光纤传感器中不同套筒材质导线周围的磁场分布情况对比表明:磁场对材料镍制作的套筒的置入不敏感。     

不同流场的PEMFC性能研究

改进了一个耦合气体流道和气体扩散层的两相、三维和多组分质子交换膜燃料电池(PEMFC)模型,研究4种流道形式对PEMFC输出性能的影响。设定温度为70℃,有效面积为3.61 cm~2的情况下,发现单边交指单蛇形流道的性能最好,单蛇形流道的性能最差。阳极流场的形状对PEMFC性能的影响不大。单边交指单蛇形流道的阴极氧气浓度分布最均匀,浓度差值为6.41 mol/m~3,同时排水性能最好,阴极流道内水浓度差值为10.25 mol/m~3。