A study of the coupling position of the microwave plasma torch

The microwave plasma torch (MPT) possesses a configuration with three conce ntric metal tubes, The microwave energy is coupled into the plasma via a cy lindrical antenna that surrounds the intermediate tube. The effects of the antenna position on MPT discharge and performance of the plasma were studie d. An end-on viewed MPT was used in this research, and a pneumatic nebulize r was used for sampling. Four emission lines of Ar were studied to find the effect of the coupling position on the plasma background emission. At the same time, the signal intensities and the signal-background ratios of three elements(Al, Mg and V) were also studied, and RSD was investigated also. F rom the research, it could be found that the analytical performance was bet ter when the antenna position was lambda /4 than 3 lambda /4, except of a l ittle poorer repeatability. The structure of electromagnetic field of the M PT was discussed also.