多靶强流铯溅射离子源的研制

多靶强流铯溅射离子源是多种加速器中常用的离子源之一,在科学研究和工业生产领域的应用十分广泛。但是,目前商业化应用的该种离子源由欧美几个国家垄断,国内还没有厂家能够生产。为了提高加速器运行和建造中的自主化水平,研制了一种多靶强流铯溅射离子源。该离子源主要由离子源腔、换靶装置、冷却系统、控制箱等组成,根据功能需求对其关键部件进行结构设计,采用了全新的伺服电机驱动换靶方式,提供靶位微调功能和远程控制模式,并使用Opera-3D软件模拟优化结构参数和束流光路。经过测试,该离子源在中国原子能科学研究院的400 kV小型加速器质谱(AMS)装置上应用情况良好,换靶定位精准,供束稳定,束流参数达到进口离子源的参数指标,实现了预期目标。     

强流离子源新型LaMo阴极实验研究

对从美国购进的强流离子源新型LaMo阴极的发射特性以及用于强流离子源阴极的放电性能进行了测试.实验结果表明了LaMo阴极是一种有效的热阴极发射体,且该阴极用于强流离子源时,离子源工作稳定,放电起弧正常,使用寿命大大延长(相对于LaB₆阴极).从实际应用来看,LaMo阴极确是强流离子源的一种有效的新型阴极.     

Asymptotic Analysis of the Steady-State Current Flow in a Uniform Multicathode-Spot Generated Vacuum-Arc Plasma Flow

The current distribution in a model multicathode-spot vacuum-arc generated uniform plasma flow is analyzed analytically by studying the asymptotic behavior of the magnetic transport equation in the limit of large electron-flow magnetic Reynolds number. It is found that the radial distribution of the axial current flow imposed at the cathode is maintained throughout most of the interelectrode region, and that a strong constriction of the current flow occurs in a narrow boundary layer adjacent to the anode surface. The results support the general trend observed in previous numerical solutions.     

ECR源低能强流高电荷态离子束四维发射度测量仪的研制

为全面研究ECR（Electron Cyclotron Resonance）离子源引出的高电荷态离子束流品质,获取ECR离子源引出离子束流的横向四维相空间分布,提高向加速器的注入效率,中国科学院近代物理研究所研制了一台高精度Pepper Pot型发射度测量仪PEMiL（Pepper pot Emittance Meter in Lanzhou）。根据使用需求,利用KBr晶体喷涂技术取代传统的CsI闪烁体成像技术,解决了束流光斑重叠效应,获得了边界清晰的束流图像;并开发了相应的数据处理分析程序,以分析处理得到的束流横向四维相空间分布。利用PEMiL获得了75 keV,170 eμA的O5+束流横向四维发射度。分析结果表明:PEMiL测量分析后的束流发射度结果可靠性高,荧光屏电荷累积效应造成的发射度差异不超过25%,PEMiL可作为ECR离子源引出离子束流品质诊断的有效装置。     

一台2.45GHz强流中子源

A 2.45GHz microwave-driven ion source is being used to provide 40mA of deuterium ion beam (peak current) for an RFQ accelerator as part of a neutron source system.We have also designed a 60kV electrostatic LEBT using computer simulations.In our experiment,we measured the hydrogen and deuterium ion beam currents as functions of discharge power,gas flow,and magnetic field strength.The required beam current was obtained using leas than 700W of net microwave power with a gas flow of less than 1.5sccm.From the rise time data,it was determined that in order to obtain a high percentage of atomic ions in the beam, the beam extraction should start after 1ms of switching on the microwave power.At steady state,the proton fraction was above 90%.     

强流ECR离子源引出系统研究

为了提高强流ECR 离子源的引出束流品质,分别设计了1# 和2# 引出系统,利用束流引出模拟软件PBGUNS 对1# 和2# 引出系统进行了质子束流引出与传输的模拟计算,结合实际测得的发射度数据分析引出系统,发现2# 引出系统比1# 引出系统引出束流品质高。对ECR 离子源引出系统的电势等位线分布等参数引起的球差进行了简单数学推导及MATLAB 绘图,并结合1# 和2# 引出系统束流相图模拟结果证明了球差会使引出束流品质有效发射度增长,通过适当加大电极孔径可改善束流聚焦情况,得到了束流光学聚焦较好的束流引出系统设计。To improve the quality of extracted ion beam from a high current ECR ion source, 1# and 2# extraction systems were designed and tested. The PBGUNS code was used to simulate the 1# and 2# extraction systems of proton ion beam. The emittance measurement results with the two different extraction systems were compared and analyzed with the simulation, the conclusion that more high quality beam extracted from 2# system than 1# system was got. The formula derivation of ECR ion source extraction system spherical aberration and MATLAB drawing was done by the analyzing on the distribution of extraction field equipotentials, effective emittance increasing caused by spherical berration was proved by 1# and 2# extraction systems beam phase space simulation result, beam focusing would be improved if electrode hole size increasing appropriately and a general concept on good optics focusing of ion beam extraction system was proposed finally.     

Measurement of the Intensity Distribution of a Hard X-Ray Radiation Source

Physics of Atomic Nuclei - The procedure of measurement of the brightness distribution of the hard X-ray source of the MIB-7.5 betatron with a penumbral aperture is detailed (i.e., a measurement...     

Design Calculation of a Improved ECR Ion Source

The design of a ECR ion source in a working mode with a ω_ecr resonance surfaces and a 2ω_rf enclosed surface is presented.The 0.8T axial mirror field and 0.8T radial hexapole field are introduced with detailed discussions.The computational results show that the axial length of the ω_ecr resonance surface in the improved ECR ion source is extended significantly compared with the original CAPRICE one and a closed 2ω_rf equigauss surface is also formed.The new topology of the magnetic field in the improved ECR ion source will largely raise the intensity of high charged ion on the basis of the analysis of ionization mechanism.     

Ion Beam Generation in a Vacuum Arc Ion Source with a Multicomponent Cathode

Russian Physics Journal - Vacuum arc ion sources are widely used for modifying the properties of various surfaces using ion implantation. The use of cathodes consisting of multicomponent compounds...     

第四代ECR离子源的主要概念(摘要)

To go beyond the present and planned third generation ECR ion sources operating at microwave frequencies between 20 and 30GHz to a fourth generation of sources operating above 50GHz offers new oppor- tunities and challenges.Based on the experimentally demonstrated frequency scaling,a doubling in operating frequency could provide more intense high charge state beams with higher charge states.The technical chal- lenges include the development of magnetic structures capable of producing 8T solenoid field and 4T sextupole fields,production and coupling of high power microwave power to heat the plasma,extraction of intense mul- tiple charge ion beams from a region of strong magnetic field and shielding of bremstrahlung from the hot electrons.In this paper,the status of high field superconducting magnets now under development for acceler- ator applications,gyrotrons for microwave power and other technical aspects that would be incorporated into a fourth generation ECR ion source are explored and applied to a conceptual design.     

Energetic Ion Effects on the Ion Saturation Current

The ion saturation current is very important in probe theory, which can be used to measure the electron temperature and the floating potential. In this work, the effects of energetic ions on the ion saturation current are studied via particle-in-cell simulations. It is found that the energetic ions and background ions can be treated separately as different species, and they satisfy their individual Bohm criterion at the sheath edge. It is shown that the energetic ions can significantly affect the ion saturation current if their concentration is greater than T_e/(γi2 T_(i2))~(1/2), where Te is the electron temperature, and γ_(i2) and T_(i2) represent the polytropic coefficient and temperature of energetic ions, respectively. As a result, the floating potential and the I V characteristic profile are strongly influenced by the energetic ions. When the energetic ion current dominates the ion saturation current, an analysis of the ion saturation current will yield the energetic ion temperature rather than the electron temperature.     

A Unidirectional Ion Source Discharge

An asymmetric axial plasma potential gradient would be useful for creating an efficient unidirectional ion source. A weak inhomogeneous axial magnetic field has been employed to enforce such plasma density and potential gradients. An alternative technique has been studied by computational methods and involves a differential vacuum pumping which introduces a strong axial dependence into the electron-gas ionization rate.     

High-Power Ion Beam Characteristics of a Magnetic Multi-Pole Line-Cusp Ion Source for the HL-2A Tokomak

A circular magnetic multi-pole line-cusp ion source with a nominal 45 keV 25 A hydrogen ion beam is developed for the neutraJ beam injector of the HL-2A tokomak. At present, this bucket ion source can produce a 40 keV 20 A hydrogen ion beam for less than lOOms on a test bed, and a 35 ke V 13A ion beam for 300ms on the injector of the HL-2A tokomak. The 1/e half-width of the ion beam power profile is about 6.0 ± 0.2 em at the positionof 3.26m downstream from ion source, and the corresponding divergence degree is nearly 1.1. The optimum perveance matched conditions were obtained experimentally, and were in good agreement with the values from experiential equation of Uhlemann et al. The maximum of optimum perveance reached 2.2 × 10^-6 A/V^1.5 for 38 keV beam energy. An ion beam with above 60% H^＋ species fraction can be achieved, which was measured by Ha light Doppler shift spectroscopy. According to research results, a neutral beam with a total power of more than 0.6 MW was successfully injected into the plasma of the HL-2A Tokomak in 2008.     

DECRIS-4离子源的初步测试结果

The ECR ion source DECRIS-4 has been designed and constructed at the FLNR JINR to be used as a second injector of heavy multiply charged ions for the U-400 cyclotron.The design of the magnetic structure of the source was based on the idea of the so-called"magnetic plateau".The axial magnetic field is formed by three independent solenoids enclosed in separated iron yokes.As a result the superposition of the coils and hexapole magnetic fields creates the enlarged resonance volume.The first experiments showed that the source was able to produce more than 300eμA of Ar~(8 ) when only 100W of microwave power was used. During the last experiment almost 500eμA of Ar~(8 ) was extracted with the same power.In this paper we will present the preliminary results with other gaseous ions,such as oxygen,krypton and xenon.     

光吸收定律的离子强度效应

本文推引出热力学摩尔吸光系数定义,并且比较了它与表观摩尔吸光系数的特点。采用作图法测出硫氰酸钒热力学吸光系数对数ｌｇε＾０＝１．５８（２０℃,Ｉ→０）。     

ECR离子源束流发射度的实验研究

利用最新自行研制的电扫描发射度探测系统, 在ECR离子源上进行了一系列关于ECR离子源引出束流发射度的研究. 这套电扫描发射度探测系统安装在中国科学院近代物理研究所(兰州)的LECR3试验平台的束运线上. 试验中, 通过测量相关参数, 研究了磁场、微波、掺气效应及负偏压效应等对引出束流发射度的影响. 利用实验所得的结果与关于ECR等离子体和离子源束流发射度的半经验理论, 分析推导了离子源各可调参数与ECR等离子体的直接关系, 这为分析探索ECR离子源的工作机制提供了一定的参考依据.     

Direction Finding of a Source in an Acoustic Waveguide and the Angular Resolution Limit

Acoustical Physics - A reduced-rank adaptive algorithm is constructed, which makes it possible to find sound sources directions using a horizontal array operating in a waveguide with inaccurately...