Research On Discharge Simulation Of Inductively Coupled Plasma (ICP) Light Source

The inductively coupled plasma (ICP) lamps have been receiving increasing attention due to their high efficacy and long lifetime. This thesis mainly focuses on three popular types of ICP lamps:re-entrant cavity electrodeless lamp, external ferrite core electrodeless lamp and ferrite-free electrodeless lamp. We simulate the plasma parameters of the discharge and testify the model by experiment. The physical process and distribution of parameters are analyzed. Based on the models, the influences of different conditions on the efficiency of the discharge are investigated. And the characteristics of these three types of ICP lamps are compared.Firstly, a self-consistent model of re-entrant cavity electrodeless lamp with Ar-Hg mixtures discharge is developed. Intensities of mercury lines are measured to testify the model. The model includes the electromagnetic field profile and plasma collisional-radiative model. High energy levels of mercury are also taken into consideration. The simulation results show that the electron temperature and electron density decreases with the increase of the pressure of buffer gas. To get higher efficacy of the lamp, the optimum Argon pressure is between0.2Torr-0.4Torr.For ferrite core electrodeless lamp, due to the asymmetrical profile of the electric field, a2D model in rectangular coordinate is established. The profile of the electrical field is measured by single coil method. The distribution of73S1sate of mercury by simulation aligns well with the experiment results. Based on the model, we analyze the main production and loss mechanism of63P1state of mercury. And we also make a comparison of re-entrant cavity electrodeless lamp and external ferrite core electrodeless lamp. It is shown the distribution of plasma parameters on the cross section of the latter lamp is more uniform than the former one.To understand the characteristics of ferrite-free electrodeless lamp, we design a series of experiment to prove that the heat mechanism of the tube is not because of the coil, but the recombination of the plasma on the tube. Then, a self-consistent2D model is established to analyze the influence of frequency and the gas temperature. The simulation results demonstrate the population of63P1decreases when the gas temperature increases, but it isn’t sensitive to the frequency.