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A simple diagnostic tool for density measurements in plasma with a certain spatialresolution is proposed in this paper. It uses the emission characteristics of monopole antenna todetermine the dielectic property of plasma e = 1 - f_p~2/f_p~2, with the fp electron plasma frequencyrelated to plasma density. We immersed a monopole antenna probe into plasma and introduceda microwave signal via a network analyzer. When the emitted power is maximized, the reflectedpower 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 comparisonwith the amended Langmuir double-probe method, the monopole antenna probe is valuable. Inaddition, 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 determinate the dielectic property of plasma e = 1 - f_p ~ 2 / f_p ~ 2, with the fp electron plasma frequencyrelated to plasma density. Since the emitted power is maximized, the reflectedpower 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.