中文摘要：

自行研制的等离子体针在大气压下通过介质阻挡放电产生的等离子体,再由喷嘴处安装的漏斗形装置聚焦形成针状等离子体.然后对针状等离子体的基本特性和杀Enterococcus faecalis（E.faecalis）菌进行了研究,E.faecalis菌是一种引起完善充填根管再感染的主要微生物.当等离子体针功率为5—28W时,对等离子体的温度进行了测量,表明它不同于其他热杀菌方式.通过改变等离子体针内电极末端注入的氧气量,发现适当的氧气量,不仅增加等离子体内含氧粒子的浓度而且对等离子体的长度影响也不明显.实验表明最佳参数为功率15W,0.1m3.h-1氦和2.5%氧气,间距12mm,处理时间30s.为了找出杀菌的关键粒子,进一步比较了大气压下的等离子体针的发射光谱与agar（琼脂）2mm下的光谱并找出关键粒子.

英文摘要：

A Plasma Needle using a dielectric barrier discharge reactor at atmospheric pressure with a funnel-shaped nozzle was designed and realized. The preliminary characteristics of the plume and applications in the sterilization of Streptococcus mutans （S.mutans）,which is the most important microorganism causing dental caries,were presented in this paper. The reactor produced a cold plasma plume with temperature not higher than 315K at 28W. The effect of oxygen,which was injected downstream in the plasma afterglow region through a steel tube,was studied using its spectrum. The results show that addition of 26 mL·min-1 O2 led to the transport of atomic O further without significant effects on the jet length. The experiments show the best parameters are 15W power,0.1m3·h-1 He with 2.5% O2 addition and separation of needle-to-sample 12mm. It is found that ultraviolet rays,O,OH and He radicals can reach and act with S.mutans. To find critical radicals which are related to sterilization,we compareed the probe spectrum at atmosphereic pressure with that in agar.