一种小型空间反射镜支撑结构的设计与分析

为了确保成像质量,空间光学遥感器反射镜既要满足在重力和温度耦合的复杂工况下面形误差的要求,同时还应具有良好的动态特性.设计了一种圆形小型反射镜,并类比反射镜径向挠性安装原理设计其柔性支撑结构.采用CAE有限元分析软件对该反射镜的柔性支撑结构的参数进行了优化,最终确定了一种合理的柔性支撑结构.经过分析计算,该柔性支撑结构...     

SSC-LINAC重离子RFQ动力学模拟与研究

采用多粒子跟踪程序BEAMPATH 对SSC-LINAC 重离子RFQ 直线加速器进行动力学模拟,分别对RFQ 的接受度、高频特性、束流稳定性、空间电荷效应等进行了分析。该RFQ具有很大的纵向接受度,有利于束流在RFQ中的传输;高频特性研究表明,翼间电压设定在理论值以上时,该RFQ都能保持较好的束流特性;束流稳定性分析结果表明,该RFQ具有很大的束流失配容忍度;空间电荷效应研究表明,当束流强度低于0.5 mA时,束流传输不受影响。综合研究结果表明,53.667 MHz重离子RFQ具有较好的动力学特性,满足SSC-LINAC直线加速器的设计要求。The RFQ beam dynamics of a heavy ion linac was investigated in this paper and the BEAMPATH code was employed in this study. The main research was focused on the beam performances depending on longitudinal acceptance, RF properties, beam instability and space charge effect. The RFQ has large longitudinal acceptance in design, which brings the beam performances well. In the RF parameter study, the beam can keep good transmission in the acceleration even the vane voltage is larger than the theoretical value. It is also shown that the RFQ has a large robustness for the mismatch of the input beam by the analysis of the beam instability.Furthermore, the beam evolution is independent on the space charge effect when the beam current is less than 0.5 emA. The preliminary analysis of the beam dynamics shows that the 53.667 MHz heavy ion RFQ has a promising performance, which meets the requirements of SSC-LINAC.     

在聚合物表面刻写方格子的新方法及理论研究

为了提高制作偶氮苯微结构的实验技术,在偶氮苯聚合物的光致异构和光致取向特性的基础上,利用两激光束的新实验方案,运用比较简便的分步制作的方法,成功的在偶氮苯功能化聚合物薄膜表面“刻写”出二维的正方格子结构。提出了一个新的光异构取向场理论：在两束偏振方向互相垂直的偏振光照射下,偶氮苯聚合物表面光栅的形成是光异构取向场的干涉的结果,并对实验现象进行了解释。用计算机对实验结果进行了模拟,将模拟结果与实验结果进行了比较,结果表明计算机模拟将会更加有利于偶氮苯聚合物微结构的设计和制作。     

激光烧蚀-双光束二极管激光原子吸收光谱法测定固体样品中的铀同位素比

以两个二极管激光作为光源 ,采用激光烧蚀 双光束二极管激光原子吸收光谱法测定了2 3 5U/ 2 3 8U同位素比。实验对用于样品烧蚀的Nd :YAG激光聚焦点位置进行了优化 ,在同时满足一定原子化程度和较高2 3 5U 6 82 6 736nm信背比的原则下 ,选择了聚焦点位置低于样品表面 0 4cm作为分析条件。测量2 3 5U/ 2 3 8U同位素比的精密度和准确度分别为 5 %和 2 % ,2 3 5U检测限为 18μg·g-1。结果表明 ,双光束检测法能消除激光烧蚀脉冲间信号波动对测量重现性的影响 ,比早先报道的单光束检测法在精密度和准确度上有了很大的改善     

大鼠急性缺血心肌31P磁共振波谱的基础研究

利用³¹P磁共振波谱（MRS）检测了急性缺血心肌组织提取物中高能磷酸化合物的变化. 方法：成年SD大鼠在心肌梗塞后0、5、 20、45 min后进行取材,梗塞区、边缘区及正常区的心肌组织经高氯酸萃取后进行高分辨MRS检测. 结果：梗塞区,缺血5 min PCr/Pi比值下降到对照组的12 ％;20 min ATP/Pi 比值下降至0.05,Pi/EPP比值上升至0.8;45 min 梗塞区PDE/ATP上升至1.93,与45 min心肌的不可逆损伤超微结构相吻合. 边缘区各代谢产物出现改变的程度要小于梗塞区,大于正常区. 正常区也有能量代谢的改变. 结论：心肌组织的³¹P MRS能够反映心肌缺血后心肌不同部位的动态能量代谢改变. PDE/ATP是判断心肌不可拟性损伤的可靠指标.     

Zn-Cr整体催化剂中Ce-Zr溶胶涂层的制备、表征及对甲醇自热重整反应的影响

 以溶胶-凝胶法制备出粒子尺度均一的Ce-Zr溶胶. TEM和XRD结果表明, 1073 K焙烧后, Ce-Zr复合氧化物的粒径仍保持在20～50 nm. 将Ce-Zr溶胶作为甲醇自热重整制氢Zn-Cr整体催化剂的涂层,考察了溶胶在涂层多次重复过程中的稳定性和干燥方式对Ce-Zr涂层龟裂程度的影响. 结果表明,对多次使用后的溶胶进行胶溶处理可以有效控制涂层制备过程中胶体粒子的大小; 微波干燥更加有利于蜂窝陶瓷载体各通道中Ce-Zr涂层的均匀干燥; Ce-Zr涂层的引入显著提高了甲醇自热重整Zn-Cr整体催化剂的稳定性,这归因于Ce-Zr涂层提高了催化剂的氧化还原活性,使其能量匹配更好,避免了热点的产生,从而抑制了催化剂的烧结与失活.     

HIAF-BRing的双向涂抹注入模拟

BRing是HIAF工程的主加速器,其设计流强为每个脉冲内的粒子数1×1011个（238U34+）,为了达到此设计流强,注入增益应达到88倍以上。BRing采用了双向涂抹注入方案,其满足BRing的注入增益要求,同时具有注入时间短和累计束分布较均匀而减小了空间电荷效应的特点。双向涂抹注入方案利用水平和垂直两组凸轨磁铁以及倾斜的静电偏转板,在水平相空间和垂直相空间内同时进行涂抹。为了检验双向涂抹注入方案能否达到BRing的设计要求,利用ORBIT程序对双向涂抹注入过程进行了模拟,模拟结果显示,在单次双向涂抹注入113圈的情况下,注入效率为97.7%,注入增益达到110.3倍,满足了BRing流强要求。累积束的分布相对均匀,空间电荷效应引起的工作点漂移约为-0.02,粒子因共振损失风险很小。针对注入束流偏角、切割板角度、工作点偏差和Bump延时等不同注入参数进行了误差分析,结果显示BRing的双向涂抹注入效率对注入参数偏差的容忍度较高。BRing is the main accelerator of High Intensity heavy Ion Accelerator Facility(HIAF) and its design current is 1×1011 particles per pulse (238U34+). To accumulate beams up to the design current, the injection gain has to reach 88. Two planes painting injection scheme is proposed for BRing. This scheme uses a tilted electrostatic septum and 8 bump magnets to paint beams into horizontal and vertical phase space simultaneously. It can inject enough beams into the ring in a short time and paint beams uniformly. The injection process is simulated using ORBIT code and 113 turns is injected into BRing with an injection efficiency of 97.7% which meets the requirement for beam current of BRing. The accumulated beams are distributed uniformly in transverse and hence have a little tune shift of -0.02 which reduces the risk of beam loss due to the resonance. Errors of injection parameters are analysed and the result shows two planes painting injection scheme has a high tolerance for errors of injection parameters.     

CSR-LINAC IH-RFQ的高频电磁设计

中国科学院近代物理研究所在CSR-LINAC项目中设计了一台108.48 MHz的IH型RFQ直线加速器。该RFQ可以将质荷比为3~7的离子从4 keV/u加速到300 keV/u。在完成束流动力学设计的基础上,主要针对RFQ腔体的高频电磁设计展开了研究,同时利用了电磁场仿真和束流动力学模拟来研究腔体的四极场不平整度和二极场及其动力学影响。未经调谐的情况下,腔体的谐振频率为108.15 MHz,腔体空载品质因子Q₀为5 910,腔体功耗为123 kW。通过在支撑板两端增加底切的设计,将腔体的四极场不平整度由-21%~ 12%优化至±2.5%,满足了束流动力学要求。腔体的二极场为-3%~ -2.2%,使得束流在垂直方向小幅振荡,RFQ的垂直方向接受度减小5%。为了保证功率馈入时反射较小,将耦合器设置在临界耦合状态,耦合面积为940 mm2。为了补偿腔体的频率偏差和漂移,设计了调谐量分别为707和132 kHz的固定调谐器和可动调谐器。The 108.48 MHz IH type RFQ for CSR-LINAC project is under design at Institute of Modern Physics, Chinese Academy of Sciences. This RFQ can accelerate heavy ions with mass to charge ratio of 3~7 from 4 keV/u to 300 keV/u. According to the beam dynamics requirement, the RF structure design has been finished. The quadrupole field unflatness and dipole field of the cavity were studied by electromagnetic simulation and beam dynamics simulation. The frequency of the cavity without tuning is 108.15 MHz, the Q₀ of the cavity is 5910, and the RF power loss is 123 kW. The quadrupole field unflatness of ±2.5%,which was -21%~12% before optimizing, is achieved to meet dynamics requirement through the undercuts in cavity supporters. The dipole field of -3%~ -2.2% causes the oscillation of the beam center and acceptance reduction of 5%. The power coupler must be in critical coupling state with the coupling area of 940 mm2 for minimum reflection coefficient. The tuners, consist of coarse and fine tuners with frequency shift of 707 and 132 kHz respectively, is used for tuning of frequency deviation of the cavity.     

AOTF在光谱分析中的应用研究——3.AOTF在原子发射光谱分析中的应用

本文报道了一台以声光可调滤光器(AOTF)为分光元件的自装ICP原子发射光谱仪.其硬件及软件系统均为自行设计.采用的TeO2晶体为Brimrose TEAF5-0.36-0.52-S.波长校正采用了Ca,Y,Li,Eu,Sr和Ba等六个元素的十四条谱线,经十次拟合后波长值误差小于0.1 nm.不同PMT电压下测定的峰值偏差小于0.04 nm.Ba,Y,Eu,Sc和Sr等五个元素的校正曲线平均相关系数为0.999 1,检出限在0.051～0.97 μg*mL-1范围. 在488 nm处半峰高宽度约为2.1 nm,如不采取增强分辨率的措施,该仪器在原子发射光谱分析中的应用有一定的局限性.