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.     

Magnet design and beam dynamics in computed fields for the DC-350 cyclotron

The DC-350 is an isochronous cyclotron designed in the Flerov Laboratory of Nuclear Reaction (FLNR). It is intended for accelerating ions with a mass-to-charge ratio A/Z within an interval of 5–10 and with an energy of 3–12 MeV/u at the extraction radius. These ion beams will be used in nuclear and applied physics experiments. The paper describes the results of a 3D magnet simulation. The cyclotron magnet and IM90 analiziting-bend magnet of the axial injection channel are studied here. The influence of correction coils on the cyclotron magnet is calculated. All magnet fields were calculated by MERMAID 3D code [1]. The text was submitted by the authors in English.     

Correction of vertical displacement of extracted beam during commissioning tests of the DC-110 cyclotron

The specialized DC-110 heavy ion cyclotron has been developed and created at the Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research for the BETA research and production complex in Dubna (Russia), which allows producing intense accelerated Ar, Kr, and Xe ion beams with a fixed energy of 2.5 MeV/nucleon. Commissioning works on the cyclotron complex, during which the design parameters were obtained, were carried out at the end of 2012. During commissioning of the accelerator, vertical displacement of the beam was found at the final acceleration radii and during its extraction. It is shown that the main cause of this displacement was the occurrence of a radial component of the magnetic field in the median plane of the magnet caused by asymmetry of the magnetic circuit. Vertical beam displacement was corrected by creating asymmetry of the current in the main electromagnet winding of the DC-110 cyclotron.     

A facility upgrade at Texas A&;M University for accelerated radioactive beams

The Cyclotron Institute at Texas A&M University is carrying out an upgrade project which will lead to accelerated radioactive ion beams at intermediate energies. The project involves recommissioning a K150 cyclotron for acceleration of stable beams which will be used to produce radioactive ions. Both light-ion and heavy-ion guides will be used to stop and transport the radioactive ions to a charge breeding electron cyclotron resonance ion source. Following charge breeding, highly-charged ions will be injected into the K500 cyclotron, accelerated and then transported to existing equipment to carry out experiments.     

DC-60 heavy ion cyclotron complex: The first beams and project parameters

The construction of the DC-60 Heavy Ion Cyclotron for the Interdisciplinary Scientific Research Complex (ISRC) in Astana started in early 2004. The cyclotron was manufactured and tested at the Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna. The main units were delivered to Astana and assembled in the ISRC building in the summer of 2006. The cyclotron was turned on in September, 2006. The first heavy ion beams in the whole A/Z and energy ranges were accelerated and extracted in December, 2006. The complex, based on the DC-60 cyclotron, is intended for applied and fundamental research using accelerated heavy ion beams ranging from Carbon to Xenon with energies in the range of 0.34–1.77 MeV/nucleon, as well as for experiments on the channel of low energy ion beams, where the ion extraction voltage supplied by the ECR source reaches 25 kV. The energy variation of the accelerated ions is accomplished by changing the ion charge. The possibility of smoothly tuning the ion energy by ±30% of its nominal value can be seen by changing the cyclotron magnetic field. Within the framework of commissioning the DC-60 cyclotron, a number of experiments were carried out with accelerating charged particle beams in the main points of the working diagram

The superconducting magnet system with a cryocooler for the ion source Decris-SC

A superconducting magnet system (SMS) for the multicharged ion source DECRIS-SC was designed and manufactured at the Joint Institute for Nuclear Research. Successful tests of the SMS were conducted in late 2003 and early 2004. The peculiarities of this system are stipulated by the use of a cryocooler 1 W in power for the cryostating of the magnet and also by the special configuration of the magnetic field demanded for the source of ions. Four coils ensure the induction of a magnetic field on the axes of the source of up to 3 T (the stopper ratio of ～6), which considerably extends the possibilities of the ion source from the point of view of producing intense highly charged ion beams. The problem of compensating the large forces of interaction between the coils and surrounding iron yoke in this magnet has been successfully solved, and a reliable suspension of the magnet in a cryostat realized. To compound the windings, which work in vacuum at indirect cryostating, prepreg (thermosetting fiberglass fabric impregnated with epoxide) is used. A new technology of superconducting magnet protection has been applied with the help of sectionalized windings, using passive elements of protection based on “cold” diodes and resistances. A new technology of active protection has also been applied, with normal zone detectors and heaters.     

Vacuum system of heavy ion cyclotron complex DC-60

The vacuum system of the heavy ion cyclotron complex DC-60 created at the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research for the interdisciplinary research complex (Astana, Kazakhstan) is described. The results of numerical simulation of transmission efficiency of accelerated ions in the course of recharging on residual gas, which determines the basic parameters of the designed vacuum system, are presented. As a result of successful implementation of the cyclotron complex DC-60 project, heavy ion beams were accelerated. The obtained parameters of the vacuum system agree completely with calculations, which were the basis of the project.     

IC-100 accelerator complex for scientific and applied research

Industrial production of nuclear filters has been implemented at the IC-100 cyclotron complex of the Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research. After the complete upgrade, the cyclotron was equipped with the superconducting ECR ion source and the system of external axial beam injection. The implantation complex was equipped with the special transportation channel with the beam scanning system and the setup for irradiation of polymer films. Intense beams of heavy ions Ne, Ar, Fe, Kr, Xe, I, and W with an energy of ～1 MeV/nucleon were obtained. the properties of irradiated crystals were studied, different polymer films were irradiated, and several thousands of square meters of track membranes with pore densities varying in a wide range were produced. Other scientific and applied problems can be solved at the cyclotron complex.     

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.     

不同磁路电子回旋共振离子源引出实验

空间推进所用的电子回旋共振离子源(ECRIS)应具有体积小、效率高的特点. 本文研究的ECRIS使用永磁体环产生磁场, 有效减小了体积, 该离子源利用微波在磁场中加热电子, 电子与中性气体发生电离碰撞产生等离子体. 磁场在微波加热电子的过程中起关键作用, 同时影响离子源内等离子体的约束和输运. 通过比较四种磁路结构离子源的离子电流引出特性来研究磁场对10 cm ECRIS性能的影响. 实验发现: 在使用氩气的条件下, 特定结构的离子源可引出160 mA的离子电流, 最高推进剂利用率达60%, 最小放电损耗为120 W·A^-1; 所有离子源均存在多个工作状态, 工作状态在微波功率、气体流量、引出电压变化时会发生突变. 离子源发生状态突变时的微波功率、气体流量的大小与离子源内磁体的位置有关. 通过比较不同离子源的引出离子束流、放电损耗、气体利用率、工作稳定性的差异, 归纳了磁场结构对此种ECRIS引出特性的影响规律, 分析了其中的机理. 实验结果表明: 保持输入微波功率、气体流量、引出电压不变时, 增大共振区的范围、减小共振区到栅极的距离, 离子源能引出更大的离子电流; 减小共振区到微波功率入口、气体入口的距离能降低维持离子源高状态所需的最小微波功率和最小气体流量, 提高气体利用率, 但会导致放电损耗增大. 研究结果有助于深化对此类离子源工作过程的认识, 为其设计和性能优化提供参考.     

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。     

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。     

Instability of Electromagnetic Ion Cyclotron Harmonic Waves in Plasmas

The stability of electromagnetic ion cyclotron harmonic waves propagating normal to an external magnetic field is studied for plasmas whose ions possess loss cone type velocity distributions. It is found that, if the ions are stationary, no instability develops except in the extreme case when the ratio of parallel to perpendicular "temperatures" of the ions is of the order mi/me, where mi and me are the ion and electron masses respectively. However, for the case of two counterstreaming ion beams in a neutralizing background of electrons, instability at zero frequency and near the first several ion cyclotron harmonics can occur if the streaming velocity is of the order of the electron thermal speed.     

Resistive electromagnetic ion cyclotron instability in counterstreaming plasmas

Obliquely propagating electromagnetic ion cyclotron waves are found to be unstable in a collisional, fully-ionized plasma consisting of two electron beams counterstreaming along an external magnetic field in a background of stationary ions.     

A Proposed Storage Ion Trap of an ‘In-Flight Capture’ Type for Precise Mass Measurement of Radioactive Nuclear Reaction Products and Fission Fragments

Data on nuclear masses provide a basis for creating and testing various nuclear models. A tandem system comprised of the U-400M cyclotron, the COMBAS magnetic separator and the mass spectrometric ion trap of an ‘in-flight capture’ type is considered as a complex for producing of the short-lived nuclei by heavy ions in fragmentation reactions and for precise mass measurement of this nuclei. The FLNR plan scientific and technical research includes a project DRIBs for producing accelerated beams of radioactive nuclear reaction products and photofission fragments. This project proposes also precise mass measurements with the help of ion trap. This revised version was published online in July 2006 with corrections to the Cover Date.     

兰州冷却环总体设计

兰州重离子冷却环CSR是兰州重离子加速器研究装置HRRFL的一项升级工程, 是一个双冷却储存环系统,由主环CSRm和实验环CSRe构成. 从HIRFL回旋加速器系统来的重离子束, 首先注入到主环CSRm中进行累积冷却, 然后加速到较高的能量引出打初级靶产生放射线次级束RIBs或高离化重离子束, 这些次级束再被送到验环CSRe储存起来以开展内靶实验.     

A Corrugated Mirror-Cyclotron Frequency Direct Conversion System (COMI-CYFER)

In this scheme the plasma escaping from a mirror machine is split into an array of long narrow beams by means of a grid of iron slabs. For proper shaping of the slabs, the increased mirror ratio at the iron causes acceptably low beam interception. After spherical expansion of the magnetic field containing the escaping plasma, the electrons are repelled by non-intercepting grids. A spatially alternating electric and/or magnetic field which follows is converted to an alternating or rotating force by the motion of the ions. At sufficiently low velocity, this force resonates with the cyclotron frequency and sweeps the ions to collector plates. With average ion energies of 293 keV an efficiency of 85% can be obtained in a system whose size is much smaller than other proposed direct conversion systems. For a 74% efficienicy, only 186 keV ions are required and the system becomes extraordinarily compact.     

CyclSyntWin software application for synthesis and optimization of cyclotron magnetic structures and magnets

The Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research in Dubna is developing and creating new cyclotrons. In the initial stage of development, it is necessary to analyze several variants of their magnetic structures in a relatively short time. Examined herein is the Laboratory’s developed CyclSyntWin software application which allows preliminary analysis of several variants and determination of the main physical and geometrical parameters of the cyclotron magnetic structure and magnet itself. The data obtained thereby can subsequently be used in 3D software applications, which substantially accelerates the final synthesis of the cyclotron magnetic structure and magnet. The CyclSyntWin application can be used to synthesize and optimize the magnetic structures of straight and spiral sector cyclotrons, close to azimuthally symmetric. The ratio of their air gaps in the valley and in the region of the sectors shouldn’t exceed 25 and the average magnetic field shouldn’t be more than 2 T.     

正电子发射成像回旋加速器磁铁设计与测试

中国工程物理研究院流体物理研究所目前正在建造一台医用11 MeV回旋加速器,该加速器磁铁采用小气隙、深谷结构以提供更高的平均磁场和更强的聚焦能力。为实现510-4的测量精度,自行研发了一套磁场点测装置,该装置可实现二维极坐标下的精确测量。经过多次磁场垫补,束流的相位偏移控制在9,一次谐波幅值控制在0.001 T以内,满足了磁铁的设计需求。在束流调试过程中,成功实现了质子束的引出,表明回旋加速器磁铁建造成功。此外,还对磁铁研制过程中出现的磁场缺陷及磁测误差进行了讨论。