Influence of super-strong magnetic field on the electron chemical potential and β decay in the stellar surroundings

In this paper, considering the quantum effect of electrons in a super-strong magnetic field, the influence of a super-strong magnetic field on the chemical potential of a non-zero temperature electron is analyzed, the rates of β decay under the super-strong magnetic field are studied, and then we compare them with the case without a magnetic field. Here, the nucleus ^63Co is investigated in detail as an example. The results show that a magnetic field that is less than 1010 T has little effect on the electron chemical potential and β decay rates, but the super-strong magnetic field that is greater than 1010 T depresses the electron chemical potential and improves the β decay rates clearly.     

国际未来直线对撞机(ILC)阻尼环Lattice设计

为了使国际未来直线对撞机达到高的亮度, 对撞机的阻尼环必须要有很小的自然发射度. 同时, 阻尼环要有很大的接收度来接受来自正电子注入系统的大能散、大发射度的正电子束团. 对于磁聚焦结构的设计来说, 同时达到以上要求是一件很有挑战性的工作. 为了降低ILC阻尼环的造价采用修正的FODO结构设计了可以满足ILC要求的阻尼环备用Lattice, 并使四极磁铁的数量比起ILC阻尼环BCD设计减少了一半.     

为提高BEPCⅡ亮度进行的一些研究

BEPCⅡ是BEPC的升级工程, 它被设计工作在亮度为1×10³³cm^－2.s^－1的τ-charm能区. 根据用几个不同的程序进行的束--束相互作用的模拟结果, BEPCⅡ的亮度较设计亮度有不同程度的下降. 其中一个程序的计算结果表明, 在原设计对撞模式下运行, BEPCⅡ的运行亮度只能达到0.50×10³³cm^－2.s^－1. 为了提高BEPCⅡ的运行亮度, 研究了小动量压缩因子的对撞模式, 亮度可以提高到0.54×10³³cm^－2.s^－1. 相应的束长由1.5cm减小到1.2cm. 为了和1.2cm的束长相匹配, 又研究了对撞点垂直β函数等于1.2cm的对撞模式. 根据束--束相互作用的模拟结果, 选择了几个高亮度的工作点, 对它们的线性lattice和动力学孔径等进行了研究和优化. 其中, 最高的亮度可以达到0.828×10³³cm^－2.s^－1.     

无基底焦平面阵列的红外成像性能分析

利用提出的光学读出非制冷红外成像系统,先后制作了单元尺寸各不相同的单层膜无基底焦平面阵列(focal plane array,FPA),获得了室温物体的热图像.分析发现,当FPA的单元尺寸从200μm逐渐减小到60μm时,基于恒温基底模型的理论响应与实验结果的偏差逐渐增大.通过有限元分析方法,模拟分析了不同尺寸的微梁单元在无基底FPA中的热学行为,发现了当单元尺寸逐渐减小时恒温基底模型偏差逐渐增大的原因,即无基底FPA的支撑框架不满足恒温基底条件,受热辐射后支撑框架的温升从基底上抬高了单元的温升.论文还分 关键词： 光学读出 非制冷红外成像 焦平面阵列 无基底     

Analytical treatment of the nonlinear electron cloud effect and the combined effects with beam-beam and space charge nonlinear forces in storage rings

In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC II. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations.     

“金属的电化学腐蚀与防护”的探究教学设计

以“暖宝宝”为情境素材,以实验探究和小组讨论为主要活动方式,设计并实施了“金属的电化学腐蚀与防护”的探究教学.在教学设计中,详述了2个核心探究: “暖宝宝”发热原理的探究和金属电化学防护原理的探究,分析了核心探究活动在培养学生高级思维和创新能力方面的功能价值,反思了教学素材的选取和整合、情境创设的全程性及哲学思想的渗透对激发学生学习兴趣、培养学生的创新动机情感和创造力等方面的重要意义.     

高三化学专题复习的新型探究教学设计——以“高考题是怎样炼成的”为例

针对北京市高考化学对学生能力的考查要求,结合高三学生化学学习的实际情况,围绕"铁及其化合物"的核心知识设计新型探究教学专题。引导学生在课堂解决实际问题的过程中,体会高考"考什么-怎样考-怎样答",体现高考题的生成性和问题解决的策略性,提高学生解决问题的能力,提升学生的思维水平。     

交变磁场中硅熔液的电磁力有限元分析

从电磁场的基本理论出发,本文利用ANSYS软件数值模拟了片状加热器硅晶体生长炉中的磁场和电磁力情况,采用有限元法对三相交流电产生的电磁场进行了三维数值求解,并进行了实验验证.结果表明:硅熔液在交变磁场下所受电磁力的空间分布呈周向性,且硅熔液边角处的电磁力最大,而不同电压相序下的电磁力方向是相反的,从而也导致了硅熔液的不同流动,最终模拟结果与实验现象符合良好.本文为进一步研发铸锭方式下进行的硅晶体生长技术提供了有价值的借鉴.     

无基底焦平面阵列结构优化设计及性能分析

基于光学读出非制冷红外成像技术,本文作者提出并成功设计制作了无基底焦平面阵列结构(Focal Plane Array,FPA),不仅简化了制作工艺,而且大幅提升了成像性能。但由于其为单层膜结构,固有频率值低,可能会引起热机械振动噪声(NETDTM),导致噪声等效温度差(NETD)上升。为解决这一问题,本文提出两种改进的加强梁结构,借助有限元简化模型和激光位移传感器,通过数值模拟和实验验证,证实这两种结构可以大幅度提高FPA固有频率值(分别从74Hz提升至835Hz和404Hz),NETDTM降低约两个数量级,从而实现了对FPA的优化设计。     

International Linear Collider damping ring lattice design with two wiggler sections

The International Linear Collider (ILC), which is based on super-conducting RF acceleration technology, requires the damping rings to provide beams with extremely small equilibrium emittance, and large acceptance to ensure good injection efficiency for high-emittance, and high-energy spread beam from the positron source. In order to reduce the cost for ILC damping rings, an alternative lattice which is different from the baseline configuration design has been designed with modified FODO arc cells, and the total quadrupole number has been reduced by half. At the same time, to decrease the total cost involved in constructing access shafts needed to supply power, cryogenics etc. for the wigglers and other systems, the number of wiggler sections is decreased from 8 to 4, and further to 2. This new lattice has been optimized to have a good dynamic aperture. This alternative ILC damping ring lattice design will reduce the cost largely as compared with the baseline design.