LAPECR2离子源在320kV高压平台上的试运行

The high charge state all permanent Electron Cyclotron Resonance Ion Source(ECRIS)LAPECR2 (Lanzhou All Permanent magnet ECR ion source No.2)has been successfully put on the 320kV HV platform at IMP and also has been connected with the successive LEBT system.This source is the largest and heaviest all permanent magnet ECRIS in the world.The maximum mirror field is 1.28T(without iron plug)and the effective plasma chamber volume is as large as (?)67mm×255mm.It was designed to be operated at 14.5GHz and aimed to produce medium charge state and high charge state gaseous and also metallic ion beams.The source has already successfully delivered some intense gaseous ion beams to successive experimental terminals.This paper will give a brief overview of the basic features of this permanent magnet ECRIS.Then commissioning results of this source on the platform,the design of the extraction system together with the successive LEBT system will be presented.     

6.4 GHz ECR ion source at VECC

The 6.4 GHz ECR ion source that was indigenously developed a few years ago has been operating continuously for injecting oxygen and neon beams to the cyclotron since 1997. VEC-ECR is a single stage high magnetic field ion source provided with a negatively biased electron repeller placed on the axis, near the injection mirror point. The supply of cold electrons and use of low mass mixing gas improve the stability of ECR plasma. Very recently, the effect of aluminum oxide coating on the copper plasma chamber wall has been studied. The plasma chamber wall was coated with aluminum by vacuum evaporation method and then exposed to oxygen gas to form aluminum oxide. It was noticed that the process substantially shifts the charge state distribution to the higher charge state with an enhancement of ion current by an order of magnitude. With the aluminized plasma chamber, the VEC-ECR can now produce 12 μA of O⁷⁺, 6.5 μA of Ar¹²⁺, 1.5 μA of Kr²⁰⁺ and 1.0 μA of Xe³¹⁺.     

A Newly Designed 14.5 GHz All Permanent ECR Ion Source in IMP

A new all permanent ECR (Electron Cyclotron Resonance) ion source LAPECR2 (Lanzhou All Permanent ECRIS No. 2) is now under developing in IMP. This source will be used to set up on thc IMP 400 HV (High Voltage) platform. This HV platform aims to deliver high ion beams from low charge state to very high charge state, so the rigorous requirement to this ECRIS is obvious. To satisfy this requirement, the ion source is designed to be a very large one, which has very large volumc plasma chamber, larger ECR length and mirror length, and very strong 3 -dimension magnetic field. The detail parameters, are shown in Table 1 listed below.     

VENUS离子源的最新结果(28GHz)

The nest generation, superconducting ECR ion source VENUS (Versatile ECR ion source for Nuclear Science) has operated with 28GHz since 2004,and has produced world record ion beam intesities. The VENUS project is focused on two main objectives. First, for the 88-Inch Cyclotron,VENUS will serve as the third injector soures boosting both the energy and itensity of beams available form the facility.Seconly,VENUS also serves as the prototype injector source for a high intensity heavy ion beam driver linac for a next generation radioactive ion beam facility, where the goal is to produce intense beams of medium to low charge states ions such as 240eμA of Xe 20 or 250eμA of U28 to 34 . These high intensity ion beam requerements present a challenge for the beam transport system since the total currents extracte from the ECR ion source reach several mA. Therefore in parallel to io beam develoments,we are also enhancing our ion beam diagnostics devices and are conducting an extensive ion beam simulation effort to improve the understanding of the ion beam ransprot form the VENUS ECR ion source. The paper will give an overview of recent experiments with the VENUS ECR ion source. Since the last ECR ion source workshop in Berkeley in 2004.we have installed a new plasma chamber,which includes X-ray shielding.This enables us to operate the source reliably at high power 28GHz operation.With this new chamber several high intensity beams(such as 2.4mA ofO6 ,600eμA of Ar9 ,etc.) have been produced. In addition, we have started the developent of high intensity uranium beams. For example, 200eμA of U33 and U34 have been produced so far. In respect to high charge state ions,leμA of Ar18 ,133eμA of Ar16 ,and 4.9eμA of U47 have been measured. In addition,ion beam profile meaurements are presented with ,and without the sextupole magnetic field energized. These expeerimental results are being compared with simulations using the WARP code.     

超导ECR离子源DECRIS-SC2

A new compact version of the"liquid He-free"superconducting Electron Cyclotron Resonance Ion Source,to be used as an injector for the U-400M cyclotron,is presently under construction at the FLNR in collaboration with LHE(JINR).The axial magnetic field of the source is created by the superconducting magnet,and the NdFeB hexapole is used for the radial plasma confinement.The microwave frequency of 14GHz will be used for ECR plasma heating.The DECRIS-SC2 superconducting magnet is designed for the induction of a magnetic field on the axis of the source of up to 1.4T(extraction side)and 1.9T(injection side) at nominal current of 75A.Cooling of the coils is carried out by CM cryocooler with cooling power of 1W at the temperature 4.5K.The basic design features of the superconducting magnet and of the ion source are presented.The main parts of the source are in production.The first beam test of the source is expected in the beginning of 2007.     

Simulation of electron behavior in PIG ion source for 9 MeV cyclotron

In this paper, we focus on a PIG source for producing intense H-ions inside a 9 MeV cyclotron. The properties of the PIG ion source were simulated for a variety of electric field distributions and magnetic field strengths using a CST particle studio. After analyzing the secondary electron emission (SEE) as a function of both magnetic and electric field strengths, we found that for the modeled PIG geometry, a magnetic field strength of 0.2 T provided the best results in terms of the number of secondary electrons. Furthermore, at 0.2 T, the number of secondary electrons proved to be greatest regardless of the cathode potential. Also, the modified PIG ion source with quartz insulation tubes was tested in a KIRAMS-13 cyclotron by varying the gas flow rate and arc current, respectively. The capacity of the designed ion source was also demonstrated by producing plasma inside the constructed 9 MeV cyclotron. As a result, the ion source is verified as being capable of producing an intense H^- beam and high ion beam current for the desired 9 MeV cyclotron. The simulation results provide experimental constraints for optimizing the strength of the plasma and final ion beam current at a target inside a cyclotron.     

高电荷态ECR离子源引出束流4D 发射度测量仪设计

为了进一步探究高电荷态电子回旋共振(ECR) 离子源引出束流品质和横向相空间耦合情况,根据中国科学院近代物理研究所高电荷态离子源引出束流发射度测量需求,针对束流流强为1 eμA∼1 emA,能量范围为10∼35 keV/q 的直流或脉冲高电荷态重离子束,设计了一台实时四维Pepper-pot 发射度测量仪。该Pepper-pot 型发射度测量仪具有响应时间快和工作范围宽等特点。针对强流重离子束诊断的特点,在结构与材料选择上做了设计与优化,并对获得图像的处理方法提出了具体的解决办法。For the purpose of on-line beam quality diagnostics and transverse emittance coupling investigation of the ion beams delivered by an Electron Cyclotron Resonance (ECR) ion source, a real-time 4D Pepper Pot type emittance scanner is under development at IMP(Institute of Moden Physics, Chinese Academy of Sciences). The high charge state ECR ion source at IMP could produce CW or pulsed heavy ion beam intensities in the range of 1 eμA∼1 emA with the kinetic energy of 10∼35 keV/q, which needs the design of the Pepper Pot scanner to be optimized accordingly. The Pepper Pot scanner has many features, such as very short response time and wide dynamic working range that the device could be applied. Since intense heavy ion beam bombardment is expected for this device, the structure and the material selection for the device is specially considered during the design, and a feasible solution to analyze the pictures acquired after the data acquisition is also made.     

磁场构型的影响及用于RIKEN的RIBF项目的新型ECR离子源

We measured the main plasma parameters(density of electron,temperature of electron and ion confinement time)and beam intensity of various heavy ions as a function of B_(min).The B_(min) strongly affects the field gradient at the resonance zone,consequently the plasma parameters and beam intensity are changed. Based on these experimental results,we started to construct new 18GHz ECRIS and make a detailed design of the 28GHz SC-ECRIS for RIKEN RI beam factory project.     

Surface enhancement of molecular ion H_2~+ yield in a 2.45-GHz electron–cyclotron resonance ion source

High current hydrogen molecular ion beam is obtained with a specially designed stainless steel liner permanent magnet2.45-GHz electron–cyclotron resonance(ECR) ion source(PMECR II) at Peking University(PKU). To further understand the physics of the hydrogen generation process inside a plasma chamber, theoretical and experimental investigations on the liner material of the plasma chamber in different running conditions are carried out. Several kinds of materials, stainless steel(SS), tantalum(Ta), quartz, and aluminum(Al) are selected in our study. Experimental results show that stainless steel and tantalum are much better than others in H~+_2 generation. During the experiment, an increasing trend in H~+_2 fraction is observed with stainless steel liner after O_2 discharge inside the ion source. Surface analyses show that the roughness change on the surface after O_2 discharge may be responsible for this phenomenon. After these studies, the pure current of H~+_2 ions can reach 42.3 mA with a fraction of 52.9%. More details are presented in this paper.     

Operation and Experiments on LECR3

LECR3 (Lanzhou Electron Cyclotron Resonance ion source No.3) which aims to produce intense highly charged ion beams for atomic physics research, was designed and constructed based on LECR2 (Lanzhou Electron Cyclotron Resonance ion source No.2) with high B mode. In year 2003, according to the arrangements of atomic physics research experiments and the ECR ion source research activities, ion beams of 14 elements were produced on LECR3. The elements include ^16O, ^40At, ^129Xe, ^63Cu, ^65Zn, ^56Fe, ^58Ni, ^26Mg, ^208Pb, ^35C1, ^37C1, ^28Si, ^84Kr and ^181Ta. Many of them were tested for the first time on LECR3 ion source.     

2 cm电子回旋共振离子推力器离子源中磁场对等离子体特性与壁面电流影响的数值模拟

电子回旋共振离子推力器(electron cyclotron resonance ion thruster,ECRIT)离子源内等离子体分布会影响束流引出,而磁场结构决定的ECR区与天线的相对位置共同影响了等离子体分布.在鞘层作用下,等离子体中的离子或电子被加速对壁面产生溅射,形成壁面离子或电子电流,造成壁面磨损和等离子体损失,因此研究壁面电流与等离子体特征十分重要.为此本文建立2 cm ECRIT的粒子PIC/MCC(particle-in-cell with Monte Carlo collision)仿真模型,数值模拟研究磁场结构对离子源内等离子体与壁面电流特性的影响.计算表明,当ECR区位于天线上游时,等离子体集中在天线上游和内外磁环间,栅极前离子密度最低,故离子源引出束流、磁环端面电流和天线壁面电流较低.ECR区位于天线下游时,天线和栅极上游附近的等离子体密度较高,故离子源引出束流、天线壁面电流和磁环端面电流较高.腔体壁面等离子体分布与电流受磁场影响最小.     

微型电子回旋共振离子推力器离子源结构优化实验研究

微型电子回旋共振(ECR)离子推力器可满足微小航天器空间探测的推进需求. 为此, 本文开展直径20 mm的微型ECR离子源结构优化实验研究. 根据放电室内静磁场和ECR谐振区的分布特点, 研究不同微波耦合输入位置对离子源性能的影响, 结果表明环形天线处在高于ECR谐振强度的强磁场区域时, 微波与等离子体实现无损耦合, 电子共振加热效果显著, 引出离子束流较大. 根据放电室电磁截止特性, 结合微波电场计算, 研究放电容积对离子源性能的影响, 实验表明过长或过短的腔体长度会导致引出离子束流下降甚至等离子体熄灭. 经优化后离子源性能测试表明, 在入射微波功率2.1 W、氩气流量14.9 μg/s下, 可引出离子束流5.4 mA, 气体放电损耗和利用率分别为389 W/A和15%.     

ECR离子源中的微波功率在线测量

 在中子发生器中采用ECR离子源是一种新技术。由于受结构的限制,ECR离子源不能像高频源离子源那样通过观察气体放电的颜色判断其工作状态,所以在运行中调节状态非常困难。解决这个问题的方法是：用定向耦合器加微波小功率计的方法在线测量ECR离子源的微波入射功率,通过微波入射功率可以直接得到ECR离子源引出离子束流的大小,从而推断微波信号源的放电过程是否正常,然后调整ECR离子源,最终使中子发生器工作在最佳状态。从ECR离子源后面的引出电极测得的最大束流为20 mA,且工作长时间稳定,当微波功率在160 W~500 W之间时,放电效果较好,离子束流随微波功率的增加而增加。     

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.     

An EBIS for charge state breeding in the SPES project

The ‘charge state breeder’, BRIC (breeding ion charge) is in construction at the INFN section of Bari (Italy). It is based on EBIS scheme and it is designed to accept radioactive ion beam (RIB) with charge state +1 in a slow injection mode. This experiment can be considered as a first step towards the design and construction of a charge breeder for the SPES project. The new feature of BRIC, with respect to the classical EBIS, is given by the insertion, in the ion chamber, of a rf-quadrupole aiming at filtering the unwanted masses and then making a more efficient containment of the wanted ions. In this paper, the breeder design, the simulation results of the electron and ion beam propagation and the construction problems of the device will be reported.     

A study of density in electron-cyclotron-resonance plasma

A theory is developed for the density profile of low temperature plasmas confined by applied magnetic field and an experiment of the electron-cyclotron-resonance (ECR) plasma is conducted to compare the theoretical prediction and experimental measurements. Due to a large electron mobility along the magnetic field, electrons move quickly out of the system, leaving ions behind and building a space charge potential, which leads to the ambipolar diffusion of ions. In a steady-state condition, the plasma generation by ionization of neutral molecules is in balance with plasma loss due to the diffusion, leading to the electron temperature equation, which is expressed in terms of the plasma size, chamber pressure, and the ionization energy and cross section of neutrals. The power balance condition leads to the plasma density equation, which is also expressed in terms of the electron temperature, the input microwave power and the chamber pressure. It is shown that the plasma density increases, reaches its peak and decreases, as the chamber pressure increases from a small value (0.1 mTorr). These simple expressions of electron temperature and density provide a scaling law of ECR plasma in terms of system parameters. After carrying out an experimental observation, it is concluded that the theoretical predictions of the electron temperature and plasma density agree remarkably well with experimental data     

单粒子态ECR离子源

介绍了一台2.45GHz电子回旋共振(ECR)单电荷离子源的磁场场形,以及它和总束流的关系.并且比较了国际上现有的几台同类型离子源的磁场场形.由此得出了关于2.45GHzECR离子源磁场场形的一些结论.     

Calculation of the charge composition of an ion beam from an E-Mevva source

The charge composition of an ion beam from an E-Mevva source is calculated within a model of sequential electron ionization of ions in a vacuum arc plasma. The effect of the plasma initial parameters on the charge composition of the ion beam is studied. Possible charge compositions for more than 30 elements omitted from this article are estimated. Also, the charge composition of the ions is calculated for the ultimate current density of the electron beam.     

Texas的14.5GHzECR离子源

A new plasma chamber for the Texas A&M 14.5GHz ECR ion source ECR2 has been recently installed and the beam analysis line has been recently upgraded with the replacement of the solenoid with a shorter Glaser lens.The source is now used along with the 6.4GHz ECRl for injection of beams into the K500 cyclotron.The new plasma chamber incorporates water-carrying copper tubes,each with an inner diameter of 0.7mm and all outer diameter of 1.8mm.interposed between the NbFeB permanent magnets and the aluminum plasma-chamber wall.The design allows for a much higher water flow and thus better cooling than the previous design,which used a thin,water-cooled liner.The source commissioning and operation is described.