极尖断面为折线的四极透镜磁性能研究

对传统双曲线极尖的四极透镜进行了磁性能分析。在此基础上，提出了极尖断面为折线的四极透镜结构。磁场的数值分析以及测量结果表明：该结构产生的场梯度均匀，且具有磁场集中、磁场梯度高、便于加工和安装的对称性控制等优点。该结构的四极透镜已用于ＣＹＣＩＡＥ－３０回旋加速器和ＨＩ－１３串列加速器束流输运线之中     

强聚焦圆柱形四极电透镜

在JM-400静电脉冲加速器中,安装在大三通闸阀后面的圆柱形四极电透镜具有强聚焦的功能,可以将φ30 mm平行离子束会聚成φ5 mm以下的束径。双元四极电透镜的透镜见图1。八个电极用1Cr 18 Ni 9 Ti制成,每个电极长60 mm,宽28 mm,用螺栓均匀地固定在绝缘壳体上。两组电极边缘相距24 mm。透镜绝缘壳体用螺栓同轴安装在铝合金外壳内,使其工作时保持真空。绝缘壳体是四极电透镜的关键零件,它要支撑八个电极构成内径φ40_0~(+1.0)mm的同轴     

磁四极透镜测量装置的研制

本文介绍一台测量磁四极透镜的磁中心和各次谐波的测试仪器和设备。它是采用旋转长线圈的方法来测量四极透镜孔径内场形分布,测量线圈长500 mm,线圈的旋转速度为     

1.2m迴旋加速器束流输运线性能的改进

四川大学1.2 m迴旋加速器的一条束流输运线是由磁四极透镜对、15°偏转磁铁、93°分析磁铁系统组成,如图1所示。我们采用的TRANSPORT-EM程序是一个运行在微型计算机IBM-PC/XT及其兼容     

三合透镜系统的腰腰传输图解法

一、引言众所周知,由两个极性相反的四极透镜所组成的双合透镜以及由三个极性相互交替的四极透镜所组成的三合透镜系统,可以在两个方向上实现聚焦,它们常常被用来聚焦束流或实现束流横向相空间的匹配。由于双合透镜在结构上比三合透镜简单,在束流输运系统中,一般多采用双合透镜系统。但是,三合透镜在x,y两方向较对称,如果要求所设计     

迴旋加速器引出管道离子光学系统的设计问题

本文讨论了偏转磁铁和磁四极透镜对的成象条件,并给出一些不同参数的偏转磁铁和磁四极透镜对的成象曲线。我们曾对离子光学系统的设计问题进行了一些调研,对离子光学系统上常用的元件,如偏转磁铁、磁四极透镜的性能,进行了一些计算,积累了一些数据资料。现将这些数据整理出来,供有关的同志参考。     

四极磁场中粒子束输运的非线性分析及模拟

为了提高粒子在四极磁场中输运轨迹计算的精度,基于李代数方法,分析和计算粒子束在四极磁场中空间电荷的非线性效应,得到二级近似下粒子坐标的映射公式,编写了粒子束在四极磁场中传输的模拟程序QML。用模拟程序对四极磁场中的传输进行了模拟计算,并对模拟结果进行了分析。模拟结果表明,在空间电荷的非线性效应的影响下相图产生了明显的扭曲,对粒子束包络曲线横向发散作用明显。     

直通道磁元件磁场测量

为使重离子束从注入器（ＳＦＣ）不经主加速器（ＳＳＣ）直接传输到实验终端。最近在兰州重离子研究装置（ＨＩＲＦＬ）上新建了直通管道系统。在该系统中有３台偏转磁铁和３台四极透镜。本文叙述了它们的测磁内容和方法，给出了激磁曲线、径向和轴向场分布、磁场梯度、等效长度等结果。结果表明：全部符合原设计要求，并有一定的余量。     

100 MeV回旋加速器中心区实验台架上注入线设计、加工及安装

100MeV回旋加速器中心区实验台架的注入能量为30keV，采用的横向聚焦元件包括1个螺线管透镜（S：Solenoid），1对四极磁铁（Q：Quadrupole）。注入线的设计有两种考虑，分别对应于不考虑和考虑聚束器的情况。两种设计的布局如图1所示。     

BRISOL谱仪关键技术研究

HI-13串列加速器升级工程在线同位素分离器（BRISOL）需对同质异位素进行分辨,谱仪设计质量分辨率为20 000,是很高的技术指标,对离子源、高压、分析磁铁、四极透镜等设备均有很大的挑战。本文详细介绍了BRISOL谱仪关键技术及其测试结果。能散对谱仪的质量分辨率影响较大,BRISOL谱仪设计采用异能大小铁结构消除能量色散。离子源采用表面离子源,并采用三电极引出系统,中间电极电压可调用以优化束流品质,优化后离子束RMS发射度好于3.8 πmm•mrad。分析磁铁采用表面线圈进行磁场垫补,垫补后积分场均匀性好于3.5×10^-5。为修正像差,大分析磁铁安装了β线圈和γ线圈,同时,在分析磁铁前后共设置了4台电六极透镜。     

四极磁铁比较测量

为了提供35块四极磁铁在800 MeV电子储存环上的编组排列的数据,研制了一台称为“四极铁比较测量”的测量系统。文章描写了该系统的测量原理和方法,并且给出了测量结果,最后对测量结果的误差进行了讨论。     

Experimental verification of an APF linac for a proton therapy facility

Alternating phase focusing (APF) is known as a beam focusing method; it was applied to an interdigital H-mode structure and successfully accelerated high current proton beams up to the desired energy for a medical synchrotron injector. A high-current APF linac was achieved by the optimal design of the cavity and the drift tubes themselves, as well as drift tube arrangement based on the co-iteration of a precise electromagnetic field and space charge beam dynamics.A proton injector for a medical accelerator complex was fabricated with the newly developed APF linac. The injector consists of an electron cyclotron resonance ion source, a radio-frequency quadrupole linac and the APF linac. The experimental results showed that over 10 mA proton beams were accelerated up to 7.4 MeV.     

Control of vacuum arc source cathode spots contraction motion by changing electromagnetic field

This paper investigates the magnetic field component impact on cathode spots motion trajectory and the mechanism of periodic contraction.Electromagnetic coils and permanent magnets were installed at the different sides of cathode surface,the photographs of cathode spots motion trajectory were captured by a camera.Increasing the number of magnets and decreasing the distance between magnets and cathode both lead to enhancing cathode spots motion velocity.Radii of cathode spots trajectory decrease gradually with the increasing of electromagnetic coil's current,from 40 mm at 0 A to 10 mm at 2.7 A.Parallel magnetic field component intensity influence the speed of cathode spots rotate motion,and perpendicular magnetic field component drives spots drift in the radial direction.Cathode spot's radial drift is controlled by changing the location of the ‘zero line' where perpendicular magnetic component shifts direction and the radius of cathode spots trajectory almost equal to ‘zero line'.     

谐波垫补原理及其在加速器常规磁铁设计与磁场垫补中的应用

加速器常规磁铁磁场质量评估通常表示为工作气隙好场区内高阶磁场占主磁场的相对含量,它通常要求在10^-4量级内。这些高阶磁场来源于磁极的有限长度与宽度和极面设计参数选择产生的若干过大的系统高阶磁场偏差及加工与材料的不理想等因素产生的若干过大的随机高阶磁场偏差。这些偏差均会导致磁场质量变坏。谐波垫补法针对每个过大的高阶磁场利用磁极形位改变对磁场的扰动效应产生一与现存过大高阶磁场大小相当但符号相反的高阶磁场,用来抵消现存的过大的高阶磁场,达到根本改善磁场质量的目的。本文分析了谐波垫补原理,并具体分析了它们在二极磁铁和四极磁铁设计与磁场垫补中的应用。     

Drift Collection Calorimetry Using a Combined Radiator and Field Shaping Structure of Lead Glass Tubing

A design for a drift collection calorimeter having a combined radiator and electric field shaping structure made of fused lead glass tubing is described. Reduction of a surface layer of lead oxide in a hydrogen oven is used to form a high resistance metallic layer on the interior of the tubes. This layer is used as a continuous voltage divider for drift field shaping. The EGS shower Monte Carlo code was used to model the performance of the proposed calorimeter. The effects of choice of the tube geometry, gas pressure and sampling scheme (digital vs. conventional) are discussed. The possibility of using this type of radiator/drift field structure in liquid argon is briefly considered.     

上海光源二期工程的垂直发射度研究

上海光源二期工程正在设计一个新的磁聚焦结构,它包含双斜插入件、超导二极铁以及超导扭摆器等新的元件。光谱亮度是表征同步辐射光源性能的一个重要参数,通过降低垂直发射度的方式来提高亮度是一种简便可行的方法。首先分别模拟和计算了各类磁铁准直误差对垂直发射度的影响,然后采用奇值分解法校正了误差引起的闭轨畸变,最后使用60个斜四极铁来校正垂直发射度。结果表明,在上海光源二期工程的磁铁准直公差与目前正在运行的上海光源相同的条件下,六极铁垂直准直误差对垂直发射度的影响最大;用60个斜四极铁来校正垂直发射度,能使耦合度保持在0.5%以下。     

BEPCⅡ超导插入四极磁体冷却流程的数值分析

按北京正负电子对撞机重大改造工程（BEPCⅡ）计划，为压缩束团尺寸、提高探测器的分辨率以及粒子识别能力，在南对撞区分别安装1对强聚焦超导插入四极磁体（SCQ）和1台超导螺线管探测器磁体（SSM）。本文针对1对超导插入四极磁体的冷却，采用数值模拟的方法给出了SCQ磁体分别采用超临界氦流和过冷氦流两种冷却方式下冷却流程的热力参数，通过对模拟结果的分析，给出了适合该超导插入四极磁体的冷却方式和正常运行的热力参数。还给出了该低温系统关键设备之一的过冷器的设计方法以及设计参数。      

Operation of the ATLAS muon drift-tube chambers at high background rates and in magnetic fields

In the ATLAS muon spectrometer, large drift-tube chambers are used for precision tracking. The chambers will be operated at a high neutron and /spl gamma/ background resulting in count rates of up to 500 Hz cm/sup -2/ corresponding to 300 kHz per tube. The spatial resolution of the drift tubes is degraded from 82 /spl mu/m without background to 108 /spl mu/m at 500 Hz cm/sup -2/ background count rate. Due to afterpulsing in the Ar/CO/sub 2/ gas mixture used in the drift tubes, ionizing radiation causes more than one hit in a tube within the maximum drift time of about 800 ns which is expected for magnetic field strengths around 1.2 T. In order to limit the count rate, the drift tubes are read out with an artificial dead time of 790 ns which causes an efficiency loss of 23% at a rate of 300 kHz per tube. The space-to-drift-time relationship of the tubes varies with background rate, temperature, and magnetic field strength. The mean magnetic field strength in a muon chamber is 0.4 T on the average, but may vary by up to 0.4 T within a chamber. The space-to-drift-time relationship must therefore be determined in short time intervals with an accuracy better than 20 /spl mu/m using muon tracks and applying corrections for measured magnetic field variations.     

Measurement and Research of Beam-Based Alignment With AC k-Modulation at HLS

A new beam-based alignment (BBA) measurement system with AC k-modulation module was developed recently at Hefei Light Source (HLS), which equipped the quadrupole magnets on the storage ring with a current shunt system which was able to vary the magnet current of a given quadrupole at a given frequency. The corresponding closed orbit oscillation amplitude measured for different beam positions in the quadrupole reached a minimum when the beam was centered in the quadrupole. Amplitude estimation algorithms of software lock-in amplifier and interpolated FFT were discussed. A V-shaped curve was used to determine the offset; a method using a parabola fit to determine the offset was also discussed. This BPM-to-quadrupole offset was determined at HLS with an accuracy of ~50 mum. The reproducibility of the beam based alignment using this technique is about 20 mum (RMS)     

磁四极透镜的Lie代数分析--三级近似

用Ｌｉｅ代数方法分析了带电粒子在四极透镜中的运动，得到六维相空间中粒子轨迹的三级近似解，并包含了运动的相对论效应。当需要时，还可以推展到更高级像差。