真空弧氘离子源中杂质氕对束流品质的影响

分析了真空弧氘离子源中杂质的主要构成,并着重分析了杂质氕的成因及其对氘离子源性能的影响.对单次脉冲和低重复频率脉冲工作状态下的真空弧氘离子源进行了光谱诊断实验和核反应分析实验,结果表明,氘离子源等离子体中的确含有较多的杂质氕,可对氘离子源的引出束流品质产生较大的危害.并对如何减小杂质氕的影响提出了建议.     

基于磁偏转的真空弧离子源成分诊断

采用磁偏转的方法,对金属氢化物电极真空弧离子源放电产生的等离子体进行了成分诊断。采用了Ti D2电极材料进行放电,测量了在30-80 A弧流情况下的各离子的组分。实验结果表明,弧流越大时等离子体的密度越大,在现有引出结构下,由于等离子体发射面的凹凸变化导致测得的离子信号出现双峰。通过增加栅网可以减少等离子密度,双峰情况会有所减少。另外,随着弧流增大,氘所占比例会有所增加,弧流达到60 A以上氘含量增幅不明显。     

金属真空弧离子源引出强流离子束的数值模拟

为了引出更高强度、更高亮度的铀离子束,以满足重离子研究中心(Gesellschaft für SchwerionenforschungmbH,GSI)重离子同步加速器的需求,本文用三维的计算机程序KOBRA3-INP对金属真空弧离子源(Metalvapor vacuum arcion source,MEVVA)引出强流铀离子束在引出系统和后加速系统中的动力学特性进行了研究,讨论了离子源发射束流密度对引出束性能的影响.结果表明,束流损失主要发生在引出系统和后加速系统之间的漂移区;在假设漂移区束流被空间电荷中和的情况下,模拟结果和实验结果符合;在发射束流密度为180-230 mA/cm2范围内,经后加速的束流强度变化不大.     

MEVVA离子源凸形引出电极的研制

介绍了金属蒸气真空弧(Metal vaporvacuumarc,MEVVA)离子源的凸形引出电极的研制.研究表明,凸形引出电极可以完成离子束的强制发散功能,从而在较短的引出距离和较小的引出电极面积的条件下得到大的束斑和均匀可应用的束流分布.通过对几种不同的电极结构的比较研究,得到了满足应用要求的凸形引出电极.     

真空弧离子源的电阻触发工作方式

介绍了真空弧离子源的一种电阻触发工作方式。有别于典型金属蒸汽真空弧(Metal vapor vacuum arc,MEVVA)离子源的触发工作方式,该方式不需要高压触发脉冲发生器和高压隔离脉冲变压器,简化了电源系统。实验测量了采用电阻触法20-200A主弧电流下的引出离子流,结果表明离子流随主弧流增大。研究了不同阻值触发电阻的起弧情况,实验结果表明在一定电阻阻值范围内,触发电阻越大,触发越难成功。电阻增大使得触发时间增长,主弧上升沿变缓,但是对引出的离子流几乎没有影响。     

氘双等离子体离子源的进展

一、引言低能加速器型中子发生器利用D-T反应能产生单色的14MeV快中子。发生器对离子束的要求既可以是原子离子(即必须分析),也可以是混合束(即不经分析)。现在中子发生器大多采用磁分析,虽然设备复杂些,但还是有其优点的。在原先调试的基础上,我们又进行了束分析的调试,源的结构也做了一些改进,使源的性能有了进一步提高。     

真空弧离子源脉冲工作瞬间的放电行为

采用高速摄影和光谱诊断的方法研究了真空弧离子源脉冲工作瞬间的放电行为。拍摄了离子源放电瞬间吸氢电极上阴极斑的形成过程，分析了不同放电电流时阴极斑的发射光谱。实验结果表明，当脉冲工作电流为10^1—10^2A时，真空弧离子源放电区一般只有单个阴极斑，阴极斑的位置在同一次放电中的变化很小；较大的脉冲工作电流有利于提高阴极斑的温度，并最终导致氢离子浓度的增加，但也会使阴极材料的溅射更加严重，造成离子源等离子体品质下降。     

真空弧离子源引出束流在加速空间的分布

采用数码相机直接照相的方法来确定真空弧离子源引出束流在加速空间的分布。实验在动态真空实验系统中进行,系统真空度优于2×10-3 Pa。在离子源脉冲工作的条件下,采用数码相机拍摄到离子源引出束流在加速空间的积分图像,得到引出束流的幅亮度在拍摄平面上的相对分布,然后再通过Abel转换得到引出束流在加速空间的径向分布。实验结果表明:真空弧离子源引出束流近似高斯分布,离子源出口处的束流比靶入口处的束流强40%。     

磁过滤真空弧沉积中过滤管道的第二阳极作用研究

利用一台磁过滤真空弧沉积装置,初步研究了磁过滤管道对系统弧放电的影响。实验证明,磁过滤管道在阴极真空弧沉积中不仅起到消除大颗粒的作用,还作为阴极真空弧放电的第二阳极对弧放电产生影响。给出了磁过滤阴极真空弧放电的等效电路,并用此电路对磁过滤阴极真空弧放电中的部分实验现象进行了解释。     

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'.     

第二阳极作用改善阴极真空弧沉积中弧放电稳定性的研究

研究了阴极弧等离子体沉积中第二阳极现象改善弧放电稳定性的作用。结果表明：由于弧放电规模增大,等离子体电阻降低,第二阳极现象的存在可大幅度提高造成阴极弧放电不稳定的聚焦磁场阈值。     

冷阴极潘宁(Penning)离子源

图1是离子源桌上试验电气原理图。K_1、K_2为阴极;A为阳极;磁钢M_1外径30mm、高45mm;凹槽内径8mm、高8mm;引出极孔径9mm;加速间隙3mm。以下试验除特殊说明外,上述参数均保持不变。 (1)放电电流I_α与阳极内径D的关系当引出极电压V_t=20kV,阳极长度L=10mm时,D与放电电流I_α、靶流I_t、引出极电流I_t、束流引出效率η[(I_t/I_α)％]的关系见表1。     

Oxygen ion source with plasma cathode

An ion source with a plasma cathode has been developed for long lifetime use in ion implanters. In this ion source, a plasma cathode replaces the conventional metallic filament used in a Freeman-type ion source. This ion source consists of two compartments, namely a plasma generator and an ion source chambers interconnected by a tapered narrow duct. The pressure difference between the two parts, maintained by differential pumping, prevents the feed gas from flowing into the plasma generator. With any combination of an argon plasma cathode and a feed gas of either fluoride (AsF₅, PF₅) or oxygen, the lifetime was found to be more than 90 h with an extraction voltage of 40 kV and a correspoding ion current density of 20 mA/cm², and a considerable amount of As⁺, P⁺, O⁺, and O₂⁺ ions were observed in mass spectra.     

911A型中空阴极离子源的改进

对从丹麦进口的９１１Ａ型中空阴极离子源进行了重新设计，经多次出束调试及改进，离子源部件已基本国产化。气体束可达到１０＾－５Ａ；固体束最大可达到１０＾－６Ａ，一次填料可持续稳定地工作５ｈ左右。     

Study on a cold-cathode H- PIG-type ion source

A cold-cathode Penning Ion Gauge(PIG) type ion source as the internal ion source of an 11 MeV cyclotron is designed and tested at Institute of Fluid Physics.The design considerations and some testings are presented.Experimental results of Balmer-line-Emission show that the discharge characteristic,which is mainly determined by gas-flow rate,is not very sensitive to arc current and magnetic field in the operation ranges of the cyclotron.The arc power decreases and ascends while the gas-flow rate goes up from 0.5 SCCM to 20 SCCM.By improving the sealing design and reducing the machine tolerance of the source,the minimum power consumption reduces from 9 SCCM to 4 SCCM,thus having better energy efficiency and benefiting for the pumping system.Preliminary DC extractions show that H–microampere current ranges from several tens to hundreds under different operation conditions.Some problems during the experiments and future plan are discussed in the end.     

Deposition of metastable binary alloy thin films using sequential ion beams from a single ion source

A technique of producing metastable films by the sequential deposition of low energy ion beams of two different ion species from a single ion source system is described. A microprocessor controlled data acquisition and control system sequentially selects one ion species at a time. The selected ion species is deposited onto a substrate at a low energy which gives an almost unity sticking coefficient and a negligible sputtering coefficient. With this extreme low energy ion bombardment the atomic mixing process is governed mainly by the injected particle range distribution and to a lesser degree by collisional mixing. By selecting the optimum duty cycle of two sequential ion beams, the film composition can be programmable as growth proceeds. Some simulation results of the growth of binary Pb/Mg films are presented when atomic mixing theories are modified to represent film growth.