Alignment techniques for DRAGON-Ⅰ LIA

DRAGON-Ⅰ designed and manufactured by CAEP is a linear induction accelerator which can produce a 20 MeV-3 kA-60 us electron beam. The high performance required for the machine is determined by the beam quality and thus is greatly dependent on the accelerator alignment. In order to reduce the chromatic effect of the beam, the stretched wire technique has been developed to measure magnetic axes of the cells precisely, and the dipole steering magnets have been equipped into each cell to correct its magnetic axis misalignment. Finally, the laser tracker has been used to examine the installation error of the accelerator. In this paper, different alignment techniques and the primary results are presented and discussed.     

铝丝阵Z箍缩辐射产生机理初步研究

利用一维非平衡辐射磁流体力学程序研究了铝丝阵内爆过程中的能量转化规律和辐射产生机理.细致讨论了Z箍缩过程中脉冲功率驱动器电磁能馈入等离子体,等离子体动能转化为内能以及通过一系列原子过程电子内能转化为X射线辐射的能量转化机理.结合离子布居信息深入分析了Z箍缩过程中的辐射产生机理.结果表明,在内爆压缩阶段,电离和激发过程占优,线辐射占据总辐射的绝大部分.在滞止时,离子大都处于裸核离化度,连续谱辐射达到峰值.在滞止附近,线辐射出现两个峰值.在膨胀过程中,光电复合过程优于三体复合,线辐射占总辐射的份额逐渐下降.     

Development of a portable and fast wire tension measurement system for MWPC construction

In a multi-wire proportional chamber detector(MWPC), the anode and signal wires must maintain suitable tension, which is very important for the detector's stable and accurate performance. As a result, wire tension control and measurement is essential in MWPC construction. A high pressure3 He MWPC detector is to be used as the thermal neutron detector of the multi-functional reflectometer at China Spallation Neutron Source, and in the construction of the detector, we have developed a wire tension measurement system. This system is accurate,portable and time-saving. With it, the wire tension on an anode wire plane has been tested. The measurement results show that the wire tension control techniques used in detector manufacture are reliable.     

箍缩背光照相

利用PPG-Ⅰ脉冲功率装置（500 kV,400 kA,100 ns）驱动X箍缩负载,得到了μm量级的亚纳秒脉冲X射线辐射点源。在阴阳极轴线和回流柱上同时安装X箍缩负载,前者可作为背光照相的X射线点源;后者可作为被拍照的目标X箍缩。获得了X箍缩发展过程不同时刻的时间序列图像,在背光照相的图像中可以清晰观察到X箍缩交叉点处等离子体的外爆、箍缩以及最终的崩溃阶段。将阴阳极轴线上的X箍缩负载用Z箍缩丝阵负载代替,实现了对丝阵负载Z箍缩放电起始阶段的X射线背光照相,观察到了最初的各单丝电爆炸、等离子体膨胀及融合过程,同时观察到了双丝Z箍缩发展过程中的等离子体不稳定性。实验结果有助于深入理解Z箍缩发展的物理过程,同时可为有效的模拟建模分析提供基本的实验数据。     

热核聚变实验堆中超导母线绝缘层的红外热波检测

本项研究的目的在于探索热核聚变实验堆中超导母线绝缘层的主动式 红外热波检测方法.文中用装有热水的薄膜袋对预埋脱黏缺陷的试件表面进行接触热激励; 给出了在面热源作用下长圆柱内一维瞬态导热的近似理论模型;通 过对理论模型的模拟和分析,发现对热波降温信号进行微分处理可有效提高缺陷和 非缺陷信号对比度;与闪光灯激励的结果进行比较,显示接触热激励的检测深度优于 闪光灯脉冲热激励.     

复合绝热低温容器真空丧失后抗热冲击分析

真空丧失对低温容器的安全性是一大威胁,可能会造成严重后果。文中通过实验,利用氮气为破空介质,对比了高真空多层绝热结构与真空复合多层绝热结构低温容器在真空丧失情况下的排放率和漏热。结果表明,复合绝热结构在真空破坏时能较好的保护低温容器,大大降低了低温储罐真空丧失后的热冲击。     

Radiation characteristics and implosion dynamics of tungsten wire array Z-pinches on the YANG accelerator

We investigated the radiation characteristics and implosion dynamics of low-wire-number cylindrical tungsten wire array Z-pinches on the YANG accelerator with a peak current 0.8-1.1 MA and a rising time ～ 90 ns.The arrays are made up of(8-32)×5 μm wires 6/10 mm in diameter and 15 mm in height.The highest X-ray power obtained in the experiments was about 0.37 TW with the total radiation energy ～ 13 kJ and the energy conversion efficiency ～ 9%(24×5 μm wires,6 mm in diameter).Most of the X-ray emissions from tungsten Z-pinch plasmas were distributed in the spectral band of 100-600 eV,peaked at 250 and 375 eV.The dominant wavelengths of the wire ablation and the magneto-Rayleigh-Taylor instability were found and analyzed through measuring the time-gated self-emission and laser interferometric images.Through analyzing the implosion trajectories obtained by an optical streak camera,the run-in velocities of the Z-pinch plasmas at the end of the implosion phase were determined to be about(1.3-2.1)×10 7 cm/s.     

Studying the Suitability of Nineteen Lignins as Partial Polyol Replacement in Rigid Polyurethane/Polyisocyanurate Foam

In this study, nineteen unmodified lignins from various sources (hardwood, softwood, wheat straw, and corn stover) and isolation processes (kraft, soda, organosolv, sulfite, and enzymatic hydrolysis) were used to replace 30 wt.% of petroleum-based polyol in rigid polyurethane/polyisocyanurate (PUR/PIR) foam formulations. Lignin samples were characterized by measuring their ash content, hydroxyl content (Phosphorus Nuclear Magnetic Resonance Spectroscopy), impurities (Inductively Coupled Plasma), and pH. After foam formulation, properties of lignin-based foams were evaluated and compared with a control foam (with no lignin) via cell morphology, closed-cell content, compression strength, apparent density, thermal conductivity, and color analysis. Lignin-based foams passed all measured standard specifications required by ASTM International C1029-15 for type 1 rigid insulation foams, except for three foams. These three foams had poor compressive strengths, significantly larger cell sizes, darker color, lower closed-cell contents, and slower foaming times. The foam made with corn stover enzymatic hydrolysis lignin showed no significant difference from the control foam in terms of compressive strength and outperformed all other lignin-based foams due to its higher aliphatic and p-hydroxyphenyl hydroxyl contents. Lignin-based foams that passed all required performance testing were made with lignins having higher pH, potassium, sodium, calcium, magnesium, and aliphatic/p-hydroxyphenyl hydroxyl group contents than those that failed.     

DESIGN AND PHOTOFUNCTIONS OF DENDRIMER-ENCAPSULATED POLY(PHENYLENEETHYNYLENE)S

A series of dendrimer-encapsulated poly(phenyleneethynylene)s 4～6 were Synthesize d. The light-harvesting antenna functions of dendrimer frameworks together with the blue-light emitting activities of 4～6 were highlighted.     

利用手持技术探究加热过程中石棉网上表面的温度

利用手持技术实时精确测量加热中石棉网上表面不同位置的温度,采用独立样本t检验比较石棉网上表面无铁丝点和有铁丝点间的温度差异与温差差异,通过回归分析探究石棉网上表面温度与其主要影响因素间的关系。研究表明：同等条件下加热中的石棉网上表面无铁丝点与有铁丝点存在显著温度差异,而无铁丝点间的单位距离温差与有铁丝点间的单位距离温差无显著差异;石棉网升温阶段上表面温度与时间、位置的关系可拟合为二元一次线性方程,恒温阶段上表面温度与位置的关系可拟合为一元三次曲线方程;石棉网上表面温度从中心向边缘小幅递减,均匀分布,最大温差小于玻璃仪器的耐热骤变温差。研究结果为化学教育实践中科学使用石棉网以及化学实验教材的编写提供参考依据。