A Preliminary Study of the Application of a Model Animal-Caenorhabidity elegans＇ Exposure to a Low-Energy Ion Irradiation System

Because of the lack of suitable animal models adapted to high vacuum stress in the low-energy ion implantation system, the bio-effects ion irradiation with an energy less than 50 keV on multi-cellular animal individuals have never been investigated so far. The nematode Caenorhabditis elegans has proved to be an excellent animal model used for the study of a broad spectrum of biological issues. The purpose of this work was to investigate the viability of this animal under ion irradiation. We studied the protection effects of glycerol and trehalose on the enhancement of nematodes＇ ability to bear the vacuum stress. The results showed that the survival of the nematodes was enhanced remarkably under long and slow desiccation, even without glycerol and trehalose. 159 glycerol showed a better anti-vacuum stress effect on the nematodes than trehalose did under short-time desiccation. Low-temperature pre-treatment or post-treatment of the samples had no obvious effect on the survival scored after argon ion irradiation. Moreover, little effect was induced by 15% glycerol- and vacuum-exposure on germ cell apoptosis, compared to the untreated control sample. It issuggested that such treatment would provide relatively low background for genotoxic evaluations with ion irradiation.     

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。     

小型腔式微波离子源的等离子体产生及引出特性

研制了一种用石英管制作的小型腔式微波离子源，该腔套在石英管的一端，封装两电极引出系统。该离子源利用腔激发起的表面波在石英管内产生等离子体柱。在微波频率为2．45GHz、输入功率为93W时，氮的引出离子流密度可高达91．7mA／cm2。这种表面波放电等离子体源具有体积小、结构简单，在宽的压强范围内能产生再生性好、工作十分稳定的等离子体柱（1012～1013cm-3）等特点。还给出了放电的自一致描述以及放电的电子密度与压强、等离子体柱半径和输入功率的关系。     

小型腔式微波离子源的表面波放电模型

研究了小型腔式微波离子源的表面波放电模型。当考虑了放电管几何参量及放电参量（如压强、气体流量、微波频率等）的影响时，对低气压下的等离子体柱轴向密度分布曲线和色散特性进行了较为系统的理论描述。数值计算结果发现，放电管参数γ＝１＋ｄ／Ｒ（ｄ为管厚，Ｒ为等离子体柱半径）、介电常数εｄ和气体流量及方向对密度分布曲线影响十分显著。ＡＳｏｌａ及ＳＤｖｌａｕｄ测得的表面波产生等离子体柱轴向密度分布与计算结果一致。用该理论模型预测了这种表面波离子源的放电结果。     

聚焦离子束系统中微波离子枪的束光学特性研究

通过实验和数值模拟研究了聚焦离子束系统中微波离子枪的离子束光学特性，该离子枪由微波等离子体源和Orloff-Swason引出透镜组成。该透镜除了广泛用于场致发射离子枪外，在等离子体源情况下，也能获得很好的离子束光学性能。