Central region design for a 10 MeV internal ion source cyclotron

Internal ion sources are widely adopted in commercial cyclotrons used for short-life isotopes produc-tion. Without beam manipulation provided by the external beam injection line, the central region of this type of cyclotron is more sensitive and should be carefully designed. A design study and beam dynamics simulation for the central region of a 10 MeV compact cyclotron is presented. The OPERA3D/TOSCA code was used to calculate the electric field from a parameterized three dimensional (3D) central region model. With iterative structure optimizations of the central region, the beam centering and vertical focusing is well controlled, and the RF phase acceptance is around 25° A c++ code for beam simulation in the central region was developed and tested.     

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.     

Investigation of Elliptical Gaussian Beam in Optical Disk System

1.IntroductionLaserdiodehasbeenx`idelyusedinfibrc-opticcommunicat:onandopticaldisk$yctems.LaserbeamIsradiationangle(fullangu1aratha1f-maximumintensitypoint)ismeasuredbothparllelandPerpendiculartothcjunctionp1anclgenera1ly.o//=6,~1o",oJ-=2o"~5O':Inerasableopticaldisksystemsasmagneto-optica1disksystems,thelaserbcamiscollimatedandshapedtobecircularsymInetricbeaminordcrtoaquireahighintensityandhighqualityscanningbeamiPot,butitsoptica1systemiscomplicatedandeasyaddingassocialaberration.usingaellip…     

Effect of imperfections of the radial component of a magnetic field on beam dynamics in medical cyclotron C235-V3

This paper presents numerical simulations and experimental results related to the effect of imperfections of the radial component of a magnetic field on the beam dynamics in the medical cyclotron C235-V3 of the Dimitrovgrad Proton Therapy Center. These imperfections in the region of the minimal axial betatron frequency lead to a transformation of coherent motion of the center of gravity of the beam to the incoherent motion of separate particles. The radial component increases the axial size of the beam by a factor of 2 at a radius of 20 cm, which produces additional losses of protons. To reduce undesirable actions of the radial component on the axial motion, the magnetic system in the central region has been optimized using two procedures: the positioning of shim correctors on sectors and selecting a special asymmetric arrangement of the upper and lower central plugs. This led to a twofold reduction in the axial size of the beam and a decrease in proton losses. Eventually, the beam transmission in C235-V3 has been increased to 72% without a limiting aperture diaphragm, which is commonly used in cyclotrons of this type. This makes it possible to reduce the irradiation dose of machine elements and increase the beam current at a deflector entrance of the cyclotron C235-V3 by a factor of 1.5 when compared to a serial C235 cyclotron.     

电子束在弯曲螺线管中的运动

 为研究HIRFL-CSR电子冷却装置中电子束穿过电子冷却装置中弯曲螺线管后电子横向能量的变化,用POISSON程序计算出弯曲螺线管的磁场分布,考虑了空间电荷效应,用数值方法模拟计算了电子在弯曲螺线管中的运动情况,得到了电子束横向能量变化最小时磁场各分量与电子束能量和弯曲螺线管几何尺寸之间的关系,并获得了电子束横向能量在束流截面的空间分布。     

30MeV医用回旋加速器气体靶束流线的研制

中国原子能科学研究院于1994年研究建成我国第一台医用强流回旋加速器CYCIAE-30及配套放射性同位素生产线, 目前为了增加气体靶以生产新品种医用同位素, 在原有束流输运线的基础上开展了束流输运系统的升级改造方案设计, 包括束流线的总体布局考虑和光学设计, 并根据束流光学设计的结果, 进行了新增束流线上电磁元件的设计. 在物理设计的基础上, 还进行了施工设计以及各分系统的加工、调试、安装, 并以物理设计得到的参数为依据进行了束流调试, 靶上得到的束斑与理论值有较好的符合, 满足设计要求.     

High frequency acceleration system of the DC-280 cyclotron

The radio-frequency (RF) accelerating system designed at the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research (FLNR JINR), for the DC-280 cyclotron is described. The cyclotron is intended to increase the capabilities and efficiency of experiments on the synthesis of superheavy elements and investigate their nuclear-physical and chemical properties. The DC-280 isochronous heavyion cyclotron will produce an accelerated beam of ions in the range from neon to uranium. The results of the preliminary and 3D numerical calculations of the main cavity of this system are reported. The preliminary calculations by the Coaxresonator software have allowed the geometry of the main cavity to be chosen. 3D numerical simulation has completely confirmed the correctness of the preliminary calculations. For example, the difference in frequency between the preliminary and 3D numerical calculations is no larger than 1%. The electric-field component maps obtained from the simulations are used to calculate the beam dynamics in the cyclotron.     

基于PIC方法的二维束流动力学模拟程序及其初步应用

为了深入研究强流负氢束在强流质子回旋加速器CYCIAE-100轴向注入线中的传输, 利用split-operator方法分解外场和束流自身的空间电荷场的作用. 对外 场利用单粒子跟踪技术, 采用一阶线性近似; 对空间电荷场采用PIC方法, 利用 快速傅里叶变换求解Poisson方程. 用FORTRAN95语言开发了一个基于面向对象技术的二维宏粒子传输计算程序CYCPIC2D, 本程序可以计算任意分布的强流束在输运线上的传输.最后给出了对CYCIAE-100注入线的模拟计算结果, 并和程序ORBIT, TRACE 3-D的结果进行比对验证, 结果表明: 空间电荷效应在此注入线上有较大的影响, 而且3个程序计算的不同中性化的结果基本上一致; 束流强度达到几十毫安时, 基于PIC方法的两个程序CYCPIC2D和ORBIT的计算结果完全吻合, 而线性近似程序TRACE 3-D有明显差异.     

电子束心的横向运动：Corkscrew

电子束心的横向运动：Ｃｏｒｋｓｃｒｅｗ施将君，李献文（中物院流体物理所，成都５２３信箱，６１０００３）摘要由于轴向引导磁场的存在，直线感应加速器中当束轴与磁轴有夹角时，束心要发生磁回旋运动。当电子束存在能散度时，束心的磁回旋运动演变成束心的ｃｏｒｋｓ...     

CYCIAE-100轴向注入线设计及中心区束流匹配

采用包含空间电荷效应的束流光学计算软件TRANSOPTR对CYCIAE-100回旋加速器轴向注入线进行设计,在综合考虑空间布局、元件选择、真空度、空间电荷效应、轴向磁场和造价等问题后,最终确定了轴向注入线的聚焦结构。将数值跟踪获得的真实磁场下螺旋偏转板传的输矩阵编写到TRANSOPTR程序中,从而实现了从离子源出口至偏转板出口的束流光学匹配。介绍了CYCIAE-100回旋加速器轴向注入线的设计思想、布局结构和束流光学计算结果,并给出了主要元件的设计结果。在确定中心区结构和对中轨道后,采用多粒子轨道跟踪的方法进行中心区束流匹配的研究,通过对数值模拟的结果进行椭圆拟合并结合解析公式计算得到注入点处匹配矩阵,为注入线的设计提供拟合条件。     

The physics design of magnet in 14 MeV cyclotron

The 14 MeV, 400 μA compact cyclotron is under construction at China Institute of Atomic Energy (CIAE). The design of main magnet and the result of beam dynamics in the cyclotron will be described in this paper, including the choice of main parameters of magnet, the method of shimming isochronous field in the compact cyclotron and optimization of the magnetic field in central region. The beam will be accelerated to 14.6 MeV by optimizing the magnet structure.

     

回旋加速器中的空间电荷效应和束晕

在考虑束团内粒子之间的空间电荷相互作用力的条件下,对日本理化研究所(RIKEN)现有的一台注入器(加速常数为K70的AVF型回旋加速器)中束团的演变过程进行了模拟计算.模拟结果表明,束团的形变、束晕现象同样发生在回旋加速器中,不过,其产生机制不同于直线加速器.它不是由共振和混沌引起,而是由于粒子的排斥运动和束团内粒子的涡流运动引起的.     

为IBA C70回旋加速器设计研制的采用Cusp场型H-离子源与产生He束的ECR离子源的双束轴向注入系统

At the moment,a 70MeV cyclotron is under construction by the IBA company.This cyclotron will be able to accelerate H~- beam from a multicusp source and with a beam intensity in the range of 10mA at the source extraction.A He~(1 2 ) beam is also required.This beam will be produced by a PANTECHNIK ECR ion source(SUPERNANOGAN)with an extracted current of 1 to 2mA.In this paper the studies and design of the two sources with a common axial injection in the cyclotron are described.     

The generation of Bessel beams at millimetre-wave frequencies by use of an axicon

An axicon is used to generate a Bessel beam at 90 GHz in the millimetre-wave region of the spectrum. The Bessel beam has a central intensity maximum of approximately 4 mm in diameter that is maintained over a propagation distance greater than 60 mm.     

Transverse shift of the transmitted beam of anon-uniformly polarized paraxial light beam at dielectric interfaces

This paper reports that the central position of the reflected and transmitted beams of a nonlinear polarized light beam at the interface between two media undergoes transverse shifts. It presents a solution to the problem of transverse shift of a non-uniformly polarized paraxial light beam transmitting through interfaces between two homogeneous media by using a two-form amplitude and an extension matrix to represent the vector angular spectrum of a three-dimensional （3D） light beam. It derives general formula for the transverse shift of the transmitted beam, and discusses the shift of a well-collimated beam transmitting through an interface between two homogeneous media and a thin dielectric slab.     

ELECTROSTATIC WAVE EXCITATION BY LITHIUM ION BEAM IN UPSTREAM RECION OF AMPTE LITHIUM RELEASES

It is shown that the electron cyclotron harmonic waves and the ion acoustic broad band obsefved in the transition region and the upstream region of the two AMPTE lithium releases can be explained ,by the interaction of the lithium ion beams and the solar wind plasmas.The cycloidal motion of the freshly produced lithium ion in the solaz wind magnetic and electric fields is essential for these wave excitations.Two simplified models in ion velocity distribution are used in the dispersion relation analysis,one is an orientating ion beam, the other is an ion beam ring (the hollow beam).It is shown that the electron cyclotron. harmonics can be effectively excited by both of these beams if they are very cold. Satisfactory consistence of the theory with the observed results is obtained for the harmonic excitations.The strong Iow frequency (much less than the electron cyclotron frequency) noices might be multioriginal.It is also proposed that the interaction of the lithium ion beam and the solar wind protons provides a suitable mechanism for exciting these broad bands.     

Experimental investigation of a 140 GHz gyrotron-backward wave oscillator

We report the experimental operation of a voltage tunable gyrotron backward wave oscillator (gyro-BWO) in the frequency range near 140 GHz. Voltage tunability is an important feature of the gyro-BWO for application as a fast tuning source for driving high power free electron lasers or cyclotron autoresonance maser amplifiers. The gyro-BWO operated in an overmoded cylindrical waveguide structure in the TE_1,2 mode. The electron beam source was a Pierce-wiggler gun producing an 80 kV, 6.2 A beam. Frequency tuning with voltage between 134 and 147 GHz was achieved in the TE_1,2 mode with constant magnetic field. However, this tuning was found to be discontinuous. Output powers of up to 2 kW and 2% efficiency were found, significantly below theoretical predictions for a cold beam. The theoretical beam velocity spread was modeled by a 3D beam transport code. The code results show that space charge forces, coupled with the wiggler-induced helical motion and the short cyclotron wavelength of the beam, produce large increases in velocity spread in the magnetic compression region. A beam with smaller velocity spread would be needed to make the gyro-BWO operate at the desired efficiency.     

Study on CYCIAE-100 radiation field and residual radioactivity

The accelerators should be properly designed to make the radiation field produced by beam loss satisfy the dose limits. The radiation field for high intensity H^－ cyclotron includes prompt radiation and residual radiation field. The induced radioactivity in accelerator components is the dominant source of occupational radiation exposure if the accelerator is well shielded. The source of radiation is the beam loss when cyclotron is operating. In this paper, the radiation field for CYCIAE-100 is calculated using Monte Carlo method and the radioactive contamination near stripping foil is studied. A method to reduce the dose equivalent rate of maintenance staff is also given.     

Study on using high injection voltage and spiral inflector in the central region of VEC

A feasibility study of using high injection voltage and spiral inflector in the present heavy ion central region of VEC is described. Conditions necessary for waist-to-waist transfer of the ion beam in the hole lens of main magnet have been obtained. The results of orbit studies of a variety of heavy ions indicate that a spiral inflector can be used in the central region.     

Discrete mathematical model of a sheet electron beam in a decaying magnetic field

A discrete model of a sheet electron beam is developed in a weakly relativistic approximation. A 3D simulation of the sheet electron beam with cyclotron rotation in an axially symmetric static magnetic field under time-periodic conditions of entry is performed. The velocity spread in the beam and the efficiency of converting the energy stored in the beam into DC power depending on the beam perveance are calculated.