MEMS质谱仪研究综述

近年来,小体积、低功耗、价格低廉、使用方便的MEMS质谱仪成为了质谱领域的研究重点和热点。目前国外对MEMS质谱仪及其相关技术的研究已取得了一些成果,甚至研发出了较为完整MEMS质谱仪。但是整体而言,MEMS质谱仪的性能还很低,其研究主要还处于对其元件分别进行微型化的阶段。其中,MEMS离子源以对电喷雾离子源的研究为主;MEMS质量分析器以对离子阱的研究为主;MEMS离子检测器以对法拉第筒的研究为主。本文总结了MEMS质谱仪的最新成果,同时分析了可能面临的问题。     

Application of air ions for bacterial de-colonization in air filters contaminated by aerosolized bacteria

We aerosolized the Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis) bacteria and collected them on membrane filters. Then we generated air ions by applying a high voltage to a carbon fiber tip and applied them to the contaminated filters. The antibacterial efficiency was not significantly affected by the bacteria being Gram-positive or Gram-negative, however, negative ions showed a lower antibacterial efficiency than positive ions to both E. coli and S. epidermidis, even though the concentration of negative air ions was much higher than that of positive air ions. With a field emission scanning electron microscope (FE-SEM) images and fluorescence microscopy images using a LIVE/DEAD BacLight Bacterial Viability Kit, electrostatic disruption of the bacteria was found to be the dominant antibacterial effect.     

表面电离的计算与测量

通过对电离度和表面下离子流密度的计算以及对靶电流和负离子的测量，对诸如钽，铁，钨，镍，铼和铂等高功函数金属表面的电离效率进行比较研究后表明：铁作为一种普通金属同样是较好的电离材料，并对影响表面电离的温度，铯蒸汽压力以及表面功函数进行了讨论。     

860A型高强度溅射离子源的改进

球面电离器的采用使溅射区域缩小到直径～0.75mm;用3根远离溅射区的瓷柱取代原来绝缘阴极的瓷环,可使溅射电压在10kV以内稳定工作。这些改进措施使860A的部分负离子品种的流强提高了近300％,传输效率得以提高,从而为2×1.7MV串列加速器进行大注量高能离子注入改善了条件。     

静电放电机理、影响及离子发生器在电子设备静电防护上的应用研究

静电放电问题是困扰包括半导体晶圆,液晶面板,太阳能模块的生产和加工等众多电子、光电子行业的顽疾。被动防止静电放电需要在加工材料选择,工艺流程优化,生产环境温湿度控制等众多环节加以严格限制,其过程复杂,管控起来难度较大。主动预防静电放电的最佳方式就是采用在电子、光电子加工设备上安置离子发生器中来和电子、光电子器件上的多余电荷。离子发生器的性能特点,参数设置等对电子、光电子设备的静电放电控制起着至关重要的作用。     

溅射负离子源靶的制作与使用

研究制作了多种溅射负离子源靶,在2×1.7MV串列加速器上采用Middleton-Ⅶ型溅射负离子源引出了流强大、稳定的30多种元素的负离子束。探讨了靶的材料、形状和尺寸等因素对束流质量的影响,以及如何通过控制铯蒸汽、电离器电流、靶压和靶位等来改善束流的质量,提高靶及电离器的寿命,降低源体的污染等。     

Thoron (Rn) decay products removal in poorly ventilated environments using unipolar ionizers: Dosimetric implications

Ionizers are proven to be effective in reducing the activity concentration of radon/thoron decay products in workplace environments. However, limited studies have been conducted on understanding the mechanism of removal and the related size dependency. This study demonstrates the feasibility of reducing the activity concentrations in small chambers and in room environments up to a factor of about 7. Field experiments in an uncontrolled ventilation area such as a thorium oxalate storage shed have also shown promising results with a possible concentration reduction by a factor of 4. However, these reductions have been necessarily associated with an increase (3-5 times) in the unattached fraction of the decay products which is a significant contributor to the lung dose. Owing to this, aspersions have been cast on the capability of the ionizers in reducing the effective dose. An attempt has been made here to estimate the effective doses over a wide range of parameters such as the initial unattached fraction, activity reduction ratio and the change in the unattached fraction, which get altered due to the use of ionizers. The study proves that for realistically achievable activity reduction ratios of about 3-5 with the employment of ionizers, the inhalation dose in workplace environments can be reduced by a factor of at least 4, as indicated by model calculations.