Research Of Basic Parameters Diagnosis For Surface Wave Driven Plasma Column

Surface wave plasma has attracted abroad attentions. Recently a large number of surface wave plasmas experimental data have been accumulated, so their modeling is well advanced and they have found applications in various fields of research and technology. Surface waves can used to excite the plasma from a single end, one of them is by means of capacitively coupled low-pressure radio-frequency (RF) discharge. This surface wave driven plasma column can replace metal as the guiding medium in radio frequency antennas in certain applications, which is the fundamental part of plasma antenna.Based on the surface wave plasma column system in the laboratory, this paper discusses the mechanism of the power coupling in rf discharges, which creates and sustains the plasma column. Theoretically, the plasma density distribution of the surface wave plasma column has a linear profile in axial direction and the radial structure of the plasma density satisfies the 0-mode Bessel distribution. The result of numerical calculation, with the plasma diagnosis using microwave transmission and emission spectroscopy, showing that the density distribution in axial direction is closely correlated with the driven power,the collision frequency and the gas ionization threshold. The experiments to measure surface wave plasma column discharge impedance have been designed. A matching network is necessary to match the impedance of the generator to that of the discharge. In this case, the power transfer from the generator to the discharge is at peak efficiency and the reflected rf power is minimized. Refer to the method to work out the radiation impedance and loss impedance of metal antenna, plasma column discharge impedance is calculated in the simplest cases and compared with experimental results . It is showed that surface wave plasma column discharge impedance plays an important part in analyzing the efficiency of plasma source and diagnosing plasma parameters such as densities, temperatures. In this article, the propagation of the surface waves along plasma column is studied. The dispersion relation of surface wave along the plasma column with homogeneity is analyzed. The axial electric field distribution in column is calculated, and measured the wave phase and attenuation coefficients along the plasma column with double probe technique. A system of remote data acquisition based on labview and SQL database is introduced. A server PC is used for data storage and control of the instrument, while a client PC is used for data display. This technique can not only reduce the burden of server PC and improve the rate of data acquisition, but also complete the remote data measurement and control function.Through the investigation, we have established an elementary theory model of surface wave driven plasma column in our laboratory, and gotten a lot of experimental result of plasma parameter. These will be of great importance for further scientific and engineering work.