摘要
A simple diagnostic tool for density measurements in plasma with a certain spatial resolution is proposed in this paper. It uses the emission characteristics of monopole antenna to determine the dielectic property of plasma c = 1 - fp^2/f^2, with the fp electron plasma frequency related to plasma density. We immersed a inonopole antenna probe into plasma and introduced a microwave signal via a network analyzer. When the emitted power is maximized, the reflected power is minimized and there occurs a resonance. Since can be derived from the resonant frequency, this is actually a method to measure the absolute electron density. Validated by a comparison with the amended Langmuir double-probe method, the monopole antenna probe is valuable. In addition, it is free from the difficulties, such as fluctuation in plasma potential.
A simple diagnostic tool for density measurements in plasma with a certain spatial resolution is proposed in this paper. It uses the emission characteristics of monopole antenna to determine the dielectic property of plasma c = 1 - fp^2/f^2, with the fp electron plasma frequency related to plasma density. We immersed a inonopole antenna probe into plasma and introduced a microwave signal via a network analyzer. When the emitted power is maximized, the reflected power is minimized and there occurs a resonance. Since can be derived from the resonant frequency, this is actually a method to measure the absolute electron density. Validated by a comparison with the amended Langmuir double-probe method, the monopole antenna probe is valuable. In addition, it is free from the difficulties, such as fluctuation in plasma potential.
基金
supported by National Natural Science Foundation of China (Nos. 10705028,10835009)
National Basic Research Program of China (No. 2008CB717800)
