부유 랑뮤어 탐침법에서 다양한 전압파형에 따른 플라즈마 전류고조파의 해석

Abstract

In this paper, it is shown that the measured plasma currents have specific harmonics depending on the types of the input voltage waveforms due to nonlinearity of the sheath in plasma. The applied voltage waveforms were sinusoidal, saw-tooth, square, and triangular, respectively in this experiment, and it revealed that the harmonics from both the plasma current waveforms and the stray currents had different characteristics against each applied voltage waveforms. These harmonics were analyzed using Fourier transform of various periodic functions and the results were discussed including circuit model analysis. It was also found that floating harmonic method by using the triangular waveform has a valuable potential to measure plasma parameters such as plasma density and electron temperature, and the plasma parameters obtained from our method were good agreements with the results from single Langmuir probe and sinusoidal floating harmonic methods.