串列加速器358型双等离子体离子源改进及性能研究

为提高北京师范大学GIC4117型串列加速器358型双等离子体离子源束流强度及灯丝使用寿命,改进了离子源灯丝涂覆材料中Ba、Sr、Ca元素的占比、灯丝涂覆方法及离子源保护措施。讨论了在不同灯丝电流下,进气量、弧流、约束磁铁电流对离子源输出束流强度的影响。灯丝累积使用寿命达到200 h以上,靶室束流强度较原来采用860A溅射源提高约500倍。同时本文对358型双等离子体离子源调试过程中的异常断弧情况进行了分析和改进。     

用于蓝姆移动型极化离子源的低能强流双等源

建立了用于蓝姆移动型极化离子源的双等源和低能引出聚焦系统，实验比较了等离子体出口孔径和聚焦电极之间的距离对引出束的影响，并调整了离子源的运行参数。离子束的质子比可达６０％以上，满足了极化离子源的工作要求。约有４ｍＡ低能氢离子束（５５０ｅＶ）或氘离子束（１１００ｅＶ）进入铯蒸汽电荷交换管道，在极化源上使用低能强流双等源后，可获得２００ｎＡ左右的极化质子（或氘核）束。     

强流氘束引出系统与加速管束流匹配的研究

为增加传输通过加速管的束流强度,提高中子发生器的中子产额,采用Particle-in-cell(PIC)程序模拟研究了入射束强度在10～150 mA范围内,不同初始参数条件下D⁺₁束在加速管中的传输状态。结果表明,当入射束在加速管入口处的归一化发射度取0.25 πcm•mrad,Courant-Snyder参数α=-4、β=60 cm/rad时,50～100 mA D⁺₁束与加速管匹配良好。根据匹配参数,对双等离子体离子源的引出系统进行了优化,结果显示,在引出系统与加速管之间放置两个螺线管透镜和1个光阑,能有效去除D⁺₂、D⁺₃离子,实现100 mA D⁺₁束顺利传输通过加速管的目的。     

New Method of Large-Area DC Ion Beam Formation with Multiple Electron Beams, (I)

A study was made of the correlation between the focusing of an ion beam and the spatial distribution of the ion density in the source plasma, which determines the geometrical shape of the plasma boundary, using a duoplasmatron ion source. It was revealed that the focusing of the ion beams extracted from a gaseous plasma through a large-area single aperture is sensitively influenced by the concavity of the plasma boundary, which concavity varies with the radial density profile of the plasma ions at the plasma boundary.     

First results of negative ion extraction with Cs for CRAFT prototype negative beam source

In order to understand the physics and pre-study the engineering issues for radio frequency(RF)negative beam source, a prototype source with a single driver and three-electrode accelerator was developed. Recently, the beam source was tested on the RF source test facility with RF plasma generation, negative ion production and extraction. A magnetic filter system and a Cs injection system were employed to enhance the negative ion production. As a result, a long pulse of 105 s negative ion beam with current density of 153 A m-2 was repeatedly extracted successfully. The source pressure is 0.6 Pa and the ratio of co-extracted electron and negative ion current is around0.3. The details of design and experimental results of beam source were shown in this letter.     

Studies of an Expanded Plasma Front Duoplasmatron Ion Source

A new and more flexible ion source assembly has been built for continued study of a duoplasmatron with an expanded plasma front and a cylindrical Pierce-electrode extraction geometry. Studies of conditions necessary for the formation of an expanded plane plasma boundary are discussed, and progress toward the achievement of an aberration-free parallel beam of several hundred mA of protons is reviewed. Recent studies suggest that a duoplasmatron with an expanded plasma front and a diverging Pierce-electrode extraction geometry would produce significantly higher aberration-free beam currents than can be obtained with the present cylindrical geometry. The information necessary for the design of lens optics for matching such a source, or any source which produces a diverging aberration-free beam, to an accelerator or plasma containment device is provided in a convenient and comprehensive form by beam characteristic curves which give beam radius and divergence as functions of perveance at some convenient measuring plane close to the extractor for several fixed values of arc current. Data provided by a constant perveance experiment establish practical limits on obtainable beam current at the chosen design points on the characteristic curves.     

关于离子源供气气压稳定性的探讨

一、前言随着离子源应用范围的扩展,对其工作稳定性的要求也越来越高。为改善离子源的工作特性,必须维持放电参数的稳定。放电参数主要取决于放电电流、磁场和放电室气压。其中,气压的稳定性对放电等离子体密度、引出离子束流、质子比及离子电荷数的影响最为明显。由图1,2,3,4可见,在最佳气压下,离子密度、质子比、引出离子束流出现峰值,最佳值两侧则明显下降。通常,离子源都希望选在最佳气压下工作。因此,保持气压的稳定性十分重要。对于直流工作状态的离子源尤其如此。     

Hefei utility negative ions test equipment with RF source: commissioning and first results

In order to study the key technology and physics of RF driven negative ion source for neutral beam injector in China, the Hefei utility negative ions test equipment with RF source was developed at Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). Its negative ion source can be equipped with single or double RF drivers. There is a plasma expansion chamber with depth of 19 mm and an enhanced filter field. A three electrodes negative ion accelerator was employed to extract and accelerate the negative ions, which are plasma grid, extraction grid and ground grid. And there are several diagnostic tools for the plasma and beam parameters measurement. The characteristics of plasma generation, negative ion production and extraction were studied on the test equipment. The negative ion beam was extracted from the RF driven negative ion source for the first time. The detailed structure and main results are presented in this article.     

离子注入与离子束混合两用机

早在1979年,为了解决应用于高温高真空环境下的轴承的自润滑问题,我们就着手采用     

微波离子源聚焦离子束光学系统的研究

设计了一种微波离子源的聚焦离子束光学系统,分析计算了光学系统的束径。并数值模拟了由空间电荷作用造成的束径增宽效应,找出了影响束斑大小的主要因素和减小束径的方法。测试结果表明,在束能在２５ｋｅＶ时,束流为１４８ｎＡ,束径约为２０μｍ左右。