1 西南科技大学 材料科学与工程学院，四川 绵阳 621000
2 中国工程物理研究院 激光聚变研究中心，四川 绵阳 621900
基于适用于整个克努森数范围的流动理论，建立了去除惯性约束聚变实验中靶丸内空气的理论模型，并设计实验验证了此模型的可靠性。物理实验要求靶丸内空气浓度低于10×10?6，数值模拟了去除靶丸内空气的过程，重点分析了靶丸内空气浓度、压力与除气时间的关系。计算并比较了单管路一次抽气法、单管路循环抽气法与双管路流洗法三种去除靶丸内空气方法的时间成本。数值计算结果表明：单管路一次抽气法中，靶丸上的微通道的存在对去除靶丸内空气所需时间的影响不可忽略，在考虑靶丸上微通道与充气管的情况下，需要1961.77 h才能使靶丸内的空气浓度达到标准。单管路循环抽气法中，抽气次数与单次抽气程度会影响去除靶丸内空气所需总时间，在单次抽气程度值取最优的情况下，采用充三次，抽四次的方案可使达标总时间减少至1 h左右，此方案下单次充气和抽气时间分别为6 min和10 min。而采用双管路流洗法则仅需11 min便可使靶丸内空气浓度达标。
抽气 充气 微管 自由分子流 数值模拟 evacuation gas filling microcapillary tube free molecular flow numerical simulation 强激光与粒子束
2021, 33(4): 042001
Author Affiliations
Abstract
1 Institute of Atomic and Molecular Physics, Jilin University, Changchun130012, China
2 Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang621900, China
In this paper, we report the study of degradation for a kind of ideal mandrel material called poly-α-methylstyrene based on theoretical and experimental methods. First-principles calculations reveal two types of process: depolymerization and hydrogen-transfer-induced chain scission. The energy barrier for the former (0.68–0.82 eV) is smaller than that for most of the latter (1.39–4.23 eV). More importantly, reaction rates suggest that the former is fast whereas the latter is mostly slow, which can result in a difference of 5–31 orders of magnitude at 550 K. Furthermore, a thermogravimetric experiment shows that the activation energy of 2.53 eV for degradation is between those of fast and slow processes, corresponding to the theoretical average value of multiple reaction paths. Thus, a mandrel degradation model combining fast and slow processes is established at the atomic level. Our work provides a direction for research into the key technology of target fabrication in inertial confinement fusion.
atomic level degradation first principles mandrel material thermogravimetric experiment High Power Laser Science and Engineering
2021, 9(1): 010000e1
强激光与粒子束
2020, 32(3): 032001
Author Affiliations
Abstract
1 Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, China
2 School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang, China
To improve the quality of deuterated polystyrene (DPS) shells, the synthesis and purification of DPS as well as the fabrication of DPS shells are investigated. The molecular weight and molecular weight distribution, measured by GPC-MALLS, are about 350 kg mol-1 and less than 2.0, respectively. The results of TG and GC-MS indicate that the residual solvent is almost completely removed. DPS shells with ～ 300 μm –2500 μm diameter and ～10 μm–100 μm wall thickness are successfully prepared by a microfluidic device. The monodispersity of the diameter is much better than that of the wall thickness in a batch of DPS shells. The vacuoles can be suppressed by both reducing hydrophilic residues in DPS and adding some salts into the outer water phase (W2). The defects appearing during the drying process decrease by heat treatment, ethanol exchange, and lowered drying temperature. The results presented in this work not only provide guidelines for the preparation of DPS shells of better quality, but also indicate challenges for the future.
Matter and Radiation at Extremes
2019, 4(1): 018401
1 西南科技大学 材料科学与工程学院, 四川 绵阳 621010
2 中国工程物理研究院 激光聚变研究中心, 四川 绵阳 621900
聚α-甲基苯乙烯(PAMS)是制备激光惯性约束聚变(ICF)用靶丸的重要芯轴材料之一。采用快速热解气相色谱-质谱法(Py-GC-MS)和热重分析技术(TG/DTG)分析了不同分子量PAMS的热降解产物和热降解温度, 并通过Arrhenius方程计算了不同分子量PAMS的等温热降解活化能。结果表明: 分子量对PAMS热降解产物的影响可忽略不计, 其热降解产物均为α甲基苯乙烯单体, 且产率均接近100%; 热降解温度随PAMS分子量的增加而降低, 其热降解温度介于240~450 ℃之间; 在相同降解率下, 随分子量的减小, PAMS的热降解活化能增加, 且PAMS的热降解活化能随着热降解率的增加而增加。
聚α-甲基苯乙烯 热降解 分子量 活化能 激光惯性约束聚变 poly-alpha-methylstyrene thermal degradation molecular weight activation energy inertial confinement fusion (ICF) 强激光与粒子束
2018, 30(11): 112001
1 中国工程物理研究院 激光聚变研究中心， 四川 绵阳 621900
2 西南科技大学 材料科学与工程学院， 四川 绵阳 621010
对空心玻璃微球(HGM)在高温充气过程中的表面形貌进行了研究。分析局部晶化出现的时间和条件，并通过其表面形貌、成分分析探究了其随时间的变化规律。研究结果表明：影响HGM高温充气后表面形貌的因素主要有充气温度和充气压力；充气温度越高、压力越大表面形貌发生变化所需时间越短。导致表面形貌变化的本质原因是结晶分相，结晶成分主要由Na,B等元素组成。HGM的表面结晶分相使其表面粗糙度大幅度升高，但随着脱离充气环境后放置时间的延长而又逐渐降低。其表面粗糙度降低的主要原因是Na,B等元素的逆向迁移。
空心玻璃微球 表面粗糙度 结晶 分相 hollow glass mircospheres surface roughness crystallization phase separation 强激光与粒子束
2018, 30(4): 042001
Author Affiliations
Abstract
1 School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China
2 Research Center of Laser Fusion, CAEP, P. O. Box 919-987, Mianyang, 621900, China
Hollow poly(alpha-methylstyrene) (PAMS) shows application in inertial confinement fusion experiments as the degradable mandrels of glow plasma polymer shells. However, the molecular weight of PAMS has great influence on the quality of mandrels. In this work, this influence was systematically studied using several PAMS samples with different molecular weights. For PAMS shells with 900 μm inner diameter and different wall thickness, when the molecular weight of PAMS is in the range of 300-500 kg·mol-1, perfect sphericity and good wall thickness uniformity can be obtained. In contrast, when increasing molecular weight to 800 kg·mol -1, the sphericity and the wall thickness uniformity become worse. Moreover, compared with the wall uniformity, the sphericity of PAMS shells was much less sensitive to the molecular weight. The results also showed that the stability of W1/O compound droplets of PAMS shells were less affected by the molecular weight. It was revealed that the wall uniformity and the sphericity of the PAMS shells were associated with the diffusion rates of fluorobenzene (FB).
Poly(alpha-methylstyrene) Poly(alpha-methylstyrene) Molecular weight Molecular weight Sphericity Sphericity Wall thickness uniformity Wall thickness uniformity Diffusion rate Diffusion rate Matter and Radiation at Extremes
2017, 2(4): 197
1 哈尔滨工业大学 机器人技术与系统国家重点实验室, 哈尔滨 150000
2 中国工程物理研究院 激光聚变研究中心, 四川 绵阳 621900
惯性约束聚变试验中,对大批量的聚变靶球的表面质量进行检测和分类是一项重要的工作。传统的人工检测分类方法效率低,精度差,难以满足实际需要。提出了一种基于计算机视觉的缺陷检测及分类方法。该方法在获取待测微球的显微图像之后,通过设置兴趣区域提取圆内部的像素点,并以此绘制灰度直方图。然后计算其累积分布函数,经归一化处理之后对分布函数进行分段线性拟合。最终根据拟合后的分布函数,提出均匀性和透光性两个参数用于定量表示微球的表面质量,很好地实现了光滑、粗糙和畸形三种类型的微球的分类。实验结果表明,该检测分类方法的准确率均在90%以上,处理1280×960分辨率的包含20个微球的图像平均只需300 ms,准确高效,可扩展性强。
计算机视觉 微球 缺陷检测 模式识别 分类器 computer vision microsphere defect detection pattern recognition classifier 强激光与粒子束
2017, 29(8): 084102
Author Affiliations
Abstract
1 Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900, China
2 School of Energy and Power Engineering, Yangzhou University, Yangzhou, Jiangsu, 225127, China
3 Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing,Jiangsu, 210096, China
Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion (ICF) experiments. Driven by the need to control the shape of water-in-oil (W1/O) compound droplets, the effects of the density matching level, the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed. The centering of W1/O compound droplets, the location and movement of W1/O compound droplets in the external phase (W2) were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field. Therefore, by optimizing the density matching level and rotation speed, the batch yield of polystyrene (PS) shells with high sphericity and uniform wall thickness increased. Moreover, the sphericity also increased by raising the oil/water (O/W2) interfacial tension, which drove a droplet to be spherical. The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases, while the concentric driving force, as a resultant force, is not only affected by the three phases, but also by the continuing fluid field. The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.Physics for financial support (2014B0302052) and National Natural Science Foundation of China (U1530260).
Compound droplet stability Compound droplet stability Compound droplet deformation Compound droplet deformation Sphericity Sphericity Wall thickness uniformity Wall thickness uniformity Interfacial tension Interfacial tension Density matching Density matching Matter and Radiation at Extremes
2016, 1(4): 213
中国工程物理研究院 激光聚变研究中心, 四川 绵阳 621900
为了改善臭氧处理聚苯乙烯(PS)单层球与聚乙烯醇(PVA)溶液生成的双层乳粒在油相中的分散性,提高大尺寸双层球的成活率,在双层球制备过程中采用了非离子型表面活性剂Tween 20 (T-20)来改性该种PS单层球。结果表明经表面活性剂T-20改性后显著降低了PS薄膜的亲水接触角,提高了PS与PVA间的相互作用,同时也大幅度提高了PS薄膜对PVA的吸附速率。红外光谱和紫外-可见分光光度计的测试结果证明：在PVA固化过程中,由于PVA与T-20的相比太大,PS表面吸附的表面活性剂T-20部分会被PVA置换、迁移至PVA溶液中。 T-20的迁移提高了制备双层球过程中水相与外油相的粘度比且显著降低PVA溶液表面张力,从而有利于实现双重乳粒在油相中的单分散。因此,T-20是制备大尺寸PS-PVA双层空心微球有效的表面活性剂。
惯性约束聚变 大尺寸双层空心聚合物微球 乳液微封装法 表面改性 PS-PVA双重乳粒 分散性 inertial confinement fusion large-diameter double layer hollow microspheres emulsion micropackaging surface modification PS-PVA double emulsion distribution 强激光与粒子束
2015, 27(12): 122007
