Microwave Surface Wave Plasma Device And Antenna Optimization

Plasma is a common form of matter in space and it is the fourth state co-existing with the gas,liquid and solid state of matter which is also called plasma state.Plasma is electrically neutral as a whole which is usually composed of electrons,ions and neutral particles.With the improvement of science and technology,plasma research has been deeply applied in modern industrial,military and civilian.The development of a plasma source which is capable of producing high density and large scale uniform plasma has become the focus of research in this field,as the application needs of plasma processing such as large-scale integrated circuit processing,solar cell materials processing and large-scale flat panel display have increased.Compared with other types of plasma sources,surface wave plasma source can satisfy the need of high density,space uniformity and high chemical activity.In order to obtain uniform and high-density plasma,the surface wave discharge device adopted in this paper is based on the principle of surface wave discharge.Slot antenna was cut on the surface of the waveguide that electromagnetic energy could be coupled from the waveguide to the plasma through the slot antenna.Based on the working principle of surface wave plasma source,the main work of this paper is to build a set of surface wave plasma generator with corresponding probe diagnosis system.Then we designed and optimized the planar slot antenna and the new type slot antenna structure to obtain high-density and uniform large scale surface wave plasma.The specific work is as follows:(1)We used 2.45 GHz microwave power as energy source,selected rectangularvacuum chamber as vacuum system,built waveguide coupling system,air source system,water-cooling circulation system,diagnostic system and other modules.(2)We designed the planar slot antenna on the rectangular waveguide.Slots were cut on the surface of waveguide.Two types of slot antenna structures were designed and the plasma discharge could be tested after the antenna was completed.(3)On the basis of planar slot antenna,we put new type of slot antenna structures.Several ways of cutting slots were introduced and we gained the uniformity of surface wave plasma through simulation.(4)HFSS,a kind of high frequency electromagnetic simulation software,was used to build and simulate the planar slot antennas and new type of slot antennas.The coupling efficiency of the antenna was compared by simulating the variation of electric field,and then the uniformity of plasma under different antenna structures was compared.By comparing the superior performance of the antenna structure,we would choose the better slot antenna structure.(5)After verifying the performance of plasma source,plasma discharge was produced by the mixture of argon,ammonia and other inert gases.It was aimed to carry out the surface treatment experiment of cerium dioxide.According to the rate of synthesis of imine catalyzed by cerium dioxide,the optimal plasma discharge conditions were selected.