The Study Of The Micro Ion Source For FAIMS

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.