Fig. 7. (a) Cross-sectional view of the parallel double-curling probe with single cylindrical plasma with distance of 1.0 mm from the antenna surface. (b) S₁₁ values of the parallel double-curling probe with various input electron densities (n_e,input). The f₀ indicates the resonance frequency without plasma and the dashed line indicates the trace of the resonance frequency (f_r). (c) The values of $f_r^2-f_0^2$ 2 over the n_e,input for four resonance frequencies of 0.87, 1.99, 2.10, and 2.75 GHz. The line graph is the curve fitting for the f₀ of 0.87 GHz (gray) and one of 2.75 GHz (magenta). (d) Output electron density (n_output) and difference in the input electron density values for two resonance frequencies of 0.87 and 2.75 GHz. Here, the discrepancy is defined as $\left|\left(n_{\text{output}}-n_{\text{input}}\right)\right|/n_{\text{input}}\times 100$ (%).

Applied Science and Convergence Technology 2023;32:127~133 https://doi.org/10.5757/ASCT.2023.32.5.127

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