An Investigation For The Characteristics Of Hollow Cathode Discharge

Hollow cathode discharge is a very especial discharge type which is different from normal and abnormal glow discharge and named after its specific cathode configuration. The application of the discharge in film production, illumination and display apparatus is extensive because of its special characteristics. In this thesis, some characteristics of hollow cathode discharge are investigated by means of fluid modeling, Langmuir probe diagnosis and etc.Numerical simulation technique as an effective method for the research of plasma is more and more popular recently. In this paper, a hollow cathode discharge was investigated by means of a two-dimensional fluid model. The distribution of the electric field, electron density, ion density and electron energy has been calculated. The characteristics of hollow cathode discharge, when its gas pressure at 0.25 - 1 torr, discharge voltage at 150 - 300 V and the diameter of cathode is 0.3 - 0.75 cm, is investigated. The results show that there exists a hollow cathode discharge effect in the discharge process and the major discharge is taken place at the bottom of cylindrical cathode. The electron energy is strength gradually along the radius of the cathode. Its value is 10eV in negative glow and more than thirty in cathode dark space. On the other hand the influences of cathode potential, gas pressure and dimension of the cathode on discharge characteristics were also investigated.In addition, probe diagnosis and optical emission spectroscopy (OES) method also be used to research the hollow cathode discharge in laboratory. Langmuir probe diagnosis method is the oldest and easiest method for diagnosing plasma. The thermal and non-thermal model has been used respectively when we processed the experiment data of probe current and probe voltage. The electron energy distribution function (EEDF) and electron temperature and density has been obtained, and the relationship between these variable and source voltage and gas pressure also be investigated. We can see that the magnitudes of results from these two methods have some different, but the change trends of it are similar. Also the results demonstrated that electron density is bigger when source voltage and gas pressure are bigger, and the change trend of electron temperature is not like this.Optical emission spectroscopy is a non-intrusive diagnostic technique, widely used to study different kinds of plasmas. We can obtain particle species and electron temperature used this method, and the reaction state of special particles also could be analyzed. In the present work, an optical emission spectroscopy technique was used to hollow cathode discharge in Nitrogen. It was observed that there are some high-energy (>10eV) electrons in the plasma. Because the irradiance of the bottom of the hollow cathode is most intense, so we think that the results from optical emission spectroscopy diagnosis correspond to the plasma center. We can see the outcome is similar to the result of numerical simulation.The outcome of this thesis is of some usefulness in the application of hollow cathode discharge in hard film production and the research of display apparatus and so on.