【作者】 刘坤；

【导师】 魏学业；

【作者基本信息】 北京交通大学 ， 交通信息工程及控制， 2010， 博士

【摘要】 为了能实现对化学战剂、爆炸物、毒品、大气、水有机污染物、工业有毒气体、人呼出气体等物质的快速检测与分析,我们课题组设计开发了具有自主知识产权的FAIMS系统,突破了国外对中国的技术封锁。本论文工作主要围绕适用于FAIMS系统的新型离子源展开。论文首先根据FAIMS系统的工作原理,分析得出了其对离子源的要求。选择了适合于本课题组FAIMS系统的两种离子化方法——电晕放电离子化和大气压辉光放电离子化。论文提出了一种适用于FAIMS系统的新型离子源。该离子源主要由内线电极、外筒电极和牵引电极组成,内、外电极半径分别是0.08mm和2 mm。筒壁电极上开有对称的4个槽,用于通入样品和牵引离子。利用有限元分析的方法仿真计算了该结构下的电场分布情况。发现在外壁上开口不会影响放电的电离区域,仅仅影响离子、电子在外围区域的漂移运动轨迹。论文分析了正负电晕放电的物理机理,分析了结构的精密度对离子源工作稳定性的影响。在此基础上,设计了一套机械装置,该装置通过精密的加工、装配保证了结构的精密度,获得了稳定的电晕放电。通过质谱实验发现丙酮、N,N—二甲基甲酰胺、苯胺、乙醇、乙酸乙酯、甲基磷酸二甲酯(DMMP)、甲醇、乙腈、苯甲醇、苯乙烯、正庚烷、甲酸、乙酸、苯酚等正、负电性物质都可以很好的被离子化。并分析了该离子源的离子化机理。通过静电计以及质谱仪实验分别从物理和化学角度对该离子源进行了稳定性分析,发现该离子源可以稳定的长时间工作。论文在原结构基础上进一步研究,实现了大气压辉光放电离子源。捕捉了从电晕放电向辉光放电的过渡过程。通过伏安特性曲线分析可以看出,在辉光放电状态下施加电压与放电电流成正电阻特性,电极间电压不随放电电流以及外部施加电压的增大而变化。这些特性与低气压下的辉光放电完全吻合。研究了转动温度和振动温度的计算方法,分析了转动谱线模拟的算法,计算了该离子源生成的等离子体的振动温度和转动温度。通过质谱实验发现,该大气压辉光放电离子源可以产生大量离子,实现了在大气环境下痕量物质的检测。通过对大气压下离子运动规律的研究,论文提出了一种适用于FAIMS系统的离子聚焦装置。并提出了一种离子空间分布的检测方法,实现了对离子空间分布的检测。通过仿真以及实验验证了该装置确有聚焦的作用。根据MEMS加工的特点以及沿面放电的理论,论文提出了一种可防止沿面放电的改进结构。并通过实验验证了其有效性。通过ICP、溅射和键合等工艺实现了该结构的MEMS离子源。更多还原

【Abstract】 In order to realized the rapid detection of chemical warfare agents, explosive, drugs, air, organic pollutants in the water, industrial toxic gases, expired gas of people, our studying team design and develop the FAIMS which has independent intellectual property and break through the foreign technical blockade. The dissertation focuses on the novel ion source for FAIMS.In this dissertation, the requirements to the ion source are obtained according to the analysis of working principle of the FAIMS. Then two kinds of ionization method are choosed for FAIMS--- corona discharge ionization and atmospheric glow discharge ionization.A novel kind of ion source for FAIMS is put forward in the dissertation and it is made up of inner line electrode, outer cylinder electrode and traction electrode. The radii of the inner and outer electrodes are 0.08mm and 2 mm, respectively. Four symmetrical slots are opened in the cylinder electrode for injection of samples and traction of ions. The electric field distribution of the ion source is calculated by finite element analysis method. And we find that the four slots only influent the drift trajectory of the ions and electorns in the outer region, not the ionization region.The physical mechanism of positive/negative corona diacharge and the influence of electrode precision on ion source working stability are analysed. On this basis, we design a suit of mechanism in order to make sure the precision by precious processing and assembly and obtain the stable corona discharge. The mass spectrum experiments show that the chemicals such as acetone, N,N-dimethyl formamide, aniline, ethanol, ethyl acetate,dimethyl methylphosphonate (DMMP), methanol, acetonitrile, benzylalcohol, styrene, n-Heptane, formic acid, acetic acid and phenol, can be ionized well. The stability experiments by the electrometer and mass spectrometer test the performance of the ion source in physics and chemistry and show that it can work stably for long time.Through further research on the basis of original structure, atmospheric glow discharge ion source is realized. The transition from corona to glow discharge is catched. The volt-ampere characteristics show that the discharge current is proportional to the applied voltage and the voltage between electrodes do not vary with discharge current and applied voltage in glow discharge mode. They are fully consistent with glow discharge characteristics under low pressure. The calculation methods of rotational temperature and vibrational temperature are studied. The simulation algorithm of rotational spectra is studied. The rotational temperature and vibrational temperature of the plasma generated by the ion source are calculated. The mass spectrum experiments show that the atmospheric glow discharge ion source can produce a large number of ions and realize the chemical detection in trace level under ambient conditions.The atmospheric ion motion law is studied and an ion focus device for FAIMS is put forward. A new detection method of ions distribution is put forward. The ions spatial distribution is detected. The simulations and experiments show that this ion focus device do have focusing effect.According to the MEMS characteristics and theory of surface discharge, an improved structure which can go against surface discharge is put forward. And it is proved by the experiment. The MEMS ion source is achieved by ICP, sputtering and bonding technology, etc.更多还原