4 MV静电加速器调试中出现的问题及解决方案

 4 MV静电加速器由高压系统、离子源及束流系统、控制系统和气体系统四部分组成。调试中出现了离子源不起弧、加速管破裂、控制系统失灵和输电带输电能力降低等技术问题,分析了出现这些问题的原因,然后分别采取了相应的措施加以解决：变换工作流程,在每次关机前先把引出电压降为零,开机时等离子源起弧后再把引出电压升到预定值;对过渡法兰进行车加工,重新封装;对高压端的控制设备采取屏蔽措施,在输入、输出端使用TVS二极管,对控制软件进行抗干扰设计;对绝缘气体进行循环干燥等。调试出了流强为100 μA、能量在3 MeV以上的稳定质子流。     

厚翅片管内流体流动和传热的数值分析

本文应用Ｐａｔａｎｋａｒ等人［１］研究薄翅片管的湍流模型，对一种工业化的厚翅片管内的流体流动和传热进行了数值分析。计算范围包括了层流和湍流（Ｒｅ＝１０１～１０６），所得计算结果与较窄范围内实验所测的传热与阻力数据相当符合，本计算结果具有较大的推广价值。     

Transport phenomena in a plane shock wave

With the use of the nonpolynomial closure 1/ _z in the Mott-Smith approximation of the solution of the Boltzmann equation, we obtain a value of the density gradient in the limit of a very weak shock wave that is close to the correct value. For the determination of the transverse temperature gradient we calculated the _x ² / _z moment of the Mott-Smith collision integral. The effective values of viscosity and thermal conductivity in the limit of a very weak shock wave were calculated for inverse-power potentials and found to agree almost exactly with the Chapman-Enskog values. Such a comparison can serve as a criterion for the evaluation of different bimodal theories. Various bimodal theories give different values of viscosity and thermal conductivity, but all of them give 33 % too high a value of the Eucken ratio.     

微通道板真空体电阻与Ⅱ代倒象微光管匹配关系的研究

国内研制的20/30Ⅱ代倒象微光管经常出现微通道板真空体电阻偏高或偏低的问题,直接影响Ⅱ代倒象微光管荧光屏的亮度和目标分辨力,严重影响微光管的质量。经过对20/30Ⅱ代倒象微光管的研制和理论分析,证明英国马拉德公司对用于××1383Ⅱ代倒象微光管的H36微通道板技术条件中真空体电阻技术指标的规定也存在一定的问题。本文从目前国内外工艺水平和有关文献资料的分析出发,进行专题研究。本文中所推导的计算公式和对文献资料提供的技术数据的推导分析,同样适用于其他型号微通道板的真空体电阻与相应Ⅱ代、Ⅲ代微光管匹配关系的计算与研究。     

低喷淋密度超亲水表面水平管降液膜温度分布

水平管降液膜蒸发广泛应用在石油、化工、海水淡化等领域,对低喷淋密度温度演化规律的研究有助于拓宽其应用范围,理解其微观机理。本文在超亲水表面上结合红外热追踪技术,对水平管降液膜表面的温度演化规律进行了研究,分析了温度分区现象和温升规律。实验中首次发现了马鞍形液膜内部的高温环状结构,并结合三维数值模拟揭示了掺混作用导致的局部高温环状结构形成的内部机理。     

Ka波段螺旋波纹波导回旋行波管

螺旋波纹波导回旋行波管与采用圆波导的回旋行波管相比,有较大的带宽。介绍了它的线性注波互作用理论,并用该理论计算了不同的磁场与波导表面微扰幅度对Ka波段螺旋波纹波导回旋行波管线性增益的影响。计算结果与已报道的实验结果基本符合,说明该理论可以初步确定螺旋波纹波导回旋行波管的各项参数。     

高速摄影在流体动力学不稳定性研究中的应用

用高速摄影技术研究了高压气体膨胀驱动空气-水界面的瑞利-泰勒不稳定性,获得了空气-水界面的不稳定性清晰图像,得到气炮尖顶运动速度及湍流混合层高度增长速度与时间关系曲线。在横式激波管上用高速纹影诊断技术研究了激波作用空气-SF6界面的里克特迈耶-梅什科夫不稳定性,初步获得了实验图像,可清晰显示混合区变化过程。     

Spectroscopic Studies of Chemical Reactions in Strong Shock Waves

Shock tube provides a promising tool of studying high temperature chemical reaction in gases. The heating by shock wave is uniform, extremely fast and intense. So that the temperature may rise thousands of degrees in a fraction of a second. Observations of the effects of this heating on C₆H₆ has shown extensive decomposition into C₂ and CN.     

Ignition delay times of methane and hydrogen highly diluted in carbon dioxide at high pressures up to 300 atm

The need for more efficient power cycles has attracted interest in super-critical CO₂ (sCO₂) cycles. However, the effects of high CO₂ dilution on auto-ignition at extremely high pressures has not been studied in depth. As part of the effort to understand oxy-fuel combustion with massive CO₂ dilution, we have measured shock tube ignition delay times (IDT) for methane/O₂/CO₂ mixtures and hydrogen/O₂/CO₂ mixtures using sidewall pressure and OH* emission near 306?nm. Ignition delay time was measured in two different facilities behind reflected shock waves over a range of temperatures, 1045–1578?K, in different pressures and mixture regimes, i.e., CH₄/O₂/CO₂ mixtures at 27–286 atm and H₂/O₂/CO₂ mixtures at 37–311 atm. The measured data were compared with the predictions of two recent kinetics models. Fair agreement was found between model and experiment over most of the operating conditions studied. For those conditions where kinetic models fail, the current ignition delay time measurements provide useful target data for development and validation of the mechanisms.     

不同倾角的脉管制冷机内自然对流影响的研究

本文通过对脉管内自然对流的数值模拟，讨论了当脉管冷端处在不同方向时，脉管内的自然对流对脉管制冷机性能的影响．数值模拟结果表明，当冷端在下时获得的制冷温度最低；当热端在下并与重力方向成３０°时制冷温度最高．结论与实验测量结果定性一致．所做的理论分析对实现脉管制冷机的良好运行有指导意义。