10 MeV质子等时性回旋加速器的设计研究

给出10MeV质子等时性回旋加速器的等时性磁场设计,中心区的设计以及加速后最终的束流品质,该加速器可作为正电子断层扫描装置的配套设备,用于生产中短寿命放射性同位素等.它沿半径方向只用一套线圈励磁,等时性磁场的建立完全由磁极形状决定.中心区的设计满足了轨道中心化的要求,并给出较大的横向和纵向接受度,以获得足够的束流强度. 经过172圈加速后,最终的束流品质满足要求.     

储存环HIAF-SRing等时性模式的非线性磁场影响研究

高精度环形谱仪SRing（Spectrometer Ring）是强流重离子加速器装置（HIAF）的重要组成部分,其等时性模式为远离β稳定线的短寿命原子核质量和寿命的精确测量提供国际领先的科研条件。为了扩大短寿命原子核质量测量精度和范围,SRing等时性模式设计了两种光学:γ_t=1.43和1.67。质量分辨是衡量等时性储存环的最重要参数。二极磁铁的高阶场以及磁铁的边缘场能强烈地引起束流光学高阶畸变,对质量分辨产生影响,因此需要高极磁铁对其进行校正。介绍了SRing等时性模式的线性计算,对非线性磁场的影响进行了详细研究。应用六极磁铁和八极磁铁对非线性场和发射度的影响进行了校正后,离子的循环时间标准偏差σ（T）/T达到3.5×10-7,质量分辨△m/m达到1×106。The isochronous mode of the Spectrometer Ring at the High Intensity heavy-ion Accelerator Facility (HIAF) project in China offers the capacity of measuring the mass and half-life of short-lived nuclides. The transition energy settings of the SRing are 1.43 and 1.67, which have been calculated in the same injection scheme. The resolution of mass or revolution time is the most important parameter of the isochronous mode design of a storage ring. The nonlinear magnetic field errors, including high-order magnet field of dipole, fringe field of magnets, have strongly effect to the resolution of revolution time. High-order corrections are required to improve the resolution of revolution time and mass. In this paper, the SRing linear isochronous optical were shown. The influence of nonlinear magnetic field errors on the revolution time resolving power were investigated. With 3 sextupole families and 1 octupole family corrections, the relative variation of revolution time reaches 4.6×10-7 with the momentum spread of ±0.2%. The relation of the relative standard revolution time deviation σ(T)/T and revolution turns was researched. With corrections of high-order isochronous condition and emittance influence by 3 sextupole families and 1 octupole family, one can reach a resolution of up to σ(T)/T=3.5×10-7, which corresponds to the mass resolution of △m/m=1×106.     

圆滚线运动的等时性

当一圆轮沿一直线做纯滚动时，轮缘上任一点在空间的运动轨迹就是圆滚线，或称旋轮线．在经典力学中这是一条既有趣又有用的曲线．借助于它来讨论圆轮沿直线做纯滚动时轮缘上任一点的速度和加速度就不需要考虑两个运动的叠加．有趣的是质点沿圆滚线运动具有等时性，     

圆滚线摆的等时性研究

介绍一种具有真正等时性的Cycloid摆－圆滚线摆，通过计算机测量进行了验证。     

HIRFL-CSR上等时性质量测量进展

基于兰州重离子研究装置冷却储存环(HIRFL-CSR)发展了等时性质谱术(Isochronous mass spectrometry,IMS),高精度测量了一批短寿命原子核的质量并研究了核结构和核天体领域的相关物理问题。本文综述了IMS实验的原理和步骤,重点介绍了目前正在发展的双TOF探测器谱仪。利用双TOF质量谱仪在测量离子回旋周期的同时测量了离子的速度,用来修正实验结果,可以在很宽的动量接收度内实现高质量分辨,并消除离子动量分散带来的系统误差。双TOF等时性质谱术是全新的概念,需要针对性开发相关实验技术。我们建立了基于CSRe的模拟平台,研制了高性能TOF探测器并安装在CSRe直线段,进行了在线束流测试,发展了新的束流光学设置并进行优化,开发了实验数据处理方法并在做进一步优化,并对下一步工作进行了展望。     

圆滚线运动的等时性

当一圆轮沿一直线作纯滚动时,轮缘上任一点在空间的运动轨迹就是圆滚线,或称旋轮线.在经典力学中这是一条非常有趣又非常有用的曲线.借助于它来讨论圆轮沿直线作纯滚动时轮缘上任一点的速度和加速度就不需要考虑两个运动的迭加.有趣的是质点沿圆滚线运动具有等时性,惠更斯并据此做成了理想摆.所以圆滚线又称为最落每项线或摆线.     

HIAF-SRing的等时性模式光学设计

高精度环形谱仪SRing作为HIAF装置的核心之一,是获取高品质放射性次级束,并将束流用于加速器技术研究、原子物理及核物理实验的关键设备。SRing有三种运行模式:等时性模式、正常模式与内靶模式。等时性模式下,SRing运行在特殊线性光学设置下,可以精确测量寿命低至几十微秒的原子核的质量。介绍SRing等时性模式的线性光学及高阶项校正的设计方案。在使用程序GICOSY进行等时性高阶项校正数值计算后,将得到的光学传输矩阵输入到程序MOCADI进行粒子跟踪模拟。以γ_t=1.43的等时性模式为例,SRing的动量接收度为±0.20%,粒子跟踪结果显示,在仅满足一阶等时性条件时SRing的质量分辨能力R=1.6×104。在保证动量接收度不变的前提下,考虑了等时性高阶项校正后SRing的质量分辨能力提高到R=1.2×106,达到设计要求。The Spectrometer Ring, as the most important experiment terminal of the High Intensity heavy-ion Accelerator Facility (HIAF) project, is a key device to obtain high-quality radioactive ion beams (RIBs) for atomic physics, nuclear physics experiments and accelerator technology researches. Three operation modes including the isochronous mode, the normal mode and the internal target mode, have been designed for the SRing. In the isochronous mode, the SRing operates under a special ion optics and could be used for precision mass measurement of short-lived nuclei with half-life shorter than several tens of microseconds. This study aims to design the ion optics for the isochronous mode and improve the mass resolving power of the SRing with higher-order ion-optical correction scheme for isochronism while preserve a large momentum acceptance of SRing. The ion optics and the higher-order correction for the isochronous mode are calculated with the code MAD-X and GICOSY respectively. Three ion optics with γ_t=1.43, 1.67, 1.83 settings have been calculated. The code MCOADI which utilizes the matrixes generated by the code GICOSY is used for particles tracking to verify the correction results. For the ion-optical setting of γ_t=1.43 with a momentum acceptance of ±0.20%, the mass resolving power of the SRing could be improved from R=1.6×104 to R=1.2×106, after isochronous higher-order corrections.     

一种新的消色差等时性磁偏转系统

描述了一种新的消色差等时性磁偏转系统。它由二个反对称的预偏磁铁和一个主偏磁铁构成。根据六维传输矩阵导出了系统的消色差和等时性关系式。该系统具有优良的消色差性、等时性和良好的聚焦特性。这种结构紧凑的三磁铁偏转系统适用于自由电子激光器的束流传输。     

如此证明"等时性"合理吗

人教版高一物理教材《必修2》第五章第二节“质点在平面内的运动”，以蜡块的运动为例，讲述合运动与分运动的概念以及介绍一种处理复杂运动的方法——运动的合成与分解．在讨论合运动与分运动的“等时性”时，有些教师试图给出一个让学生信服的理由．但笔者认为其做法有些不妥，在此提出质疑．     

质点沿可自由移动的光滑凹槽的运动分析

分析了质点在可自由移动的凹槽上运动的运动平面与凹槽的交线是一般曲线的情况,给出了质点在静止参考系中运动的轨迹方程和严格等时振动的条件,求出了质点沿几种常见曲线运动的周期.     

圆柱面波的复惠更斯源展开

本文提出一种分析波场问题的新方法——复惠更斯源展开法,它用具有复数坐标的次波源代替普通的次波源,根据复射线理论求解各次波源的贡献,并按叠加原理而构成初波源的场.文中讨论了二维波场的这种展开.只要适当选择展开参量,该方法相对于严格理论解的误差不大于1%.     

惠更斯对离心力公式的证明过程

惠更斯在1673年发表的《Horologium Oscillatorium》附录中提出了离心力的概念和计算方法,但没有给出相关的证明过程.在惠更斯去世之后的1703年,惠更斯对离心力计算公式的证明过程才被后人整理发表出来.本文主要介绍惠更斯的这个证明过程.     

蛇摆的研究与制作

蛇摆以其简单的原理和奇妙的现象向人们展示了物理独特的美.本文全面地介绍了蛇摆的现象、原理、制作方法和研究心得.     

惠更斯次波法在遥感图像去云和云影中的应用

针对在遥感图像中有云和云影的区域无法获取信息的情况，提出一种对遥感图像局域增强的新方法，即采用惠更斯次波法寻找遥感图像中有云覆盖的区域和有云阴影的区域，进而采用邻域平均法，将有云覆盖的区域和云阴影区域与大尺寸的平滑卷积核进行卷积得到具有较宽的渐变边缘，再对原图像中有云覆盖的区域和云阴影区域的亮度进行补偿，从而获得原图中被云覆盖的区域和云阴影区域的信息。这种半自动提取地物的方法，对在有云和有云影的遥感图像中提取地物信息具有辅助作用。     

计算机辅助单摆实验

讨论了计算机辅助单摆实验的方法,并结合阻尼摆给出了数值解和实验结果比较曲线。     

一种具有异常透射功能的新型惠更斯超表面

提出了一种具有独立调控透射幅值与相位能力的新型惠更斯单元结构,能够实现透射幅值在0～0.9、透射相位在0～2π的任意调控.基于广义斯涅耳定理对惠更斯单元进行排列,设计并制备出具有异常透射功能的超表面结构.全波仿真结果表明超表面能够使频率为10 GHz的正入射电磁波产生约60°的偏折.近场测试结果与仿真结果基本一致,进一...     

Independent controls of orthogonally polarized transmitted waves using a Huygens metasurface

An ultrathin Huygens metasurface is proposed to manipulate orthogonally polarized transmitted waves independently. The Huygens metasurface consists of two layers of dielectric substrates and three layers of artificial metallic structures with ultrathin electric thickness. In physics, two orthogonal electric dipoles and two orthogonal magnetic dipoles are supported by each unit cell of the metasurface, which enable the complete control of phase distributions in both vertical and horizontal directions. Based on this feature, a polarization beam splitter with large splitting angle is designed and fabricated to demonstrate the capability and flexibility of the proposed Huygens metasurface. The numerical simulations and measurement results have a good match, indicating the good performance on independent controls of orthogonally polarized transmitted waves.

     

利用单摆测重力加速度时的最大摆角的再讨论

根据误差传递理论和误差合成方法确定了单摆测重力加速度时的最大摆角．     

BRST invariance and the conical pendulum

The Hamiltonian formulation of the BRST method for quantizing constrained systems developed recently by Nemeschanskyet al is applied to the well-known problem of the conical pendulum in classical mechanics. The similarity of the system to a gauge theory wherein the two constraints serve as generators of local Abelian gauge transformations is also pointed out. The definition of the physical states of the system as a gauge theory and also as a BRST invariant theory is then discussed in some detail.