title: Analysis of double-probe characteristics in low-frequency gas discharges and its improvement.
abstract: The double-probe has been used successfully in radio-frequency discharges. However, in low-frequency discharges, the double-probe I-V curve is so much seriously distorted by the strong plasma potential fluctuations that the I-V curve may lead to a large estimate error of plasma parameters. To suppress the distortion, we investigate the double-probe characteristics in low-frequency gas discharge based on an equivalent circuit model, taking both the plasma sheath and probe circuit into account. We discovered that there are two primary interferences to the I-V curve distortion: the voltage fluctuation between two probe tips caused by the filter difference voltage and the current peak at the negative edge of the plasma potential. Consequently, we propose a modified passive filter to reduce the two types of interference simultaneously. Experiments are conducted in a glow-discharge plasma (f = 30 kHz) to test the performance of the improved double probe. The results show that the electron density error is reduced from more than 100% to less than 10%. The proposed improved method is also suitable in cases where intensive potential fluctuations exist.
authors: School of Aerospace Science and Technology, Xidian University, Xi'an 710071, China.
authors: DongLin
authors: D
authors: Liu
authors: School of Aerospace Science and Technology, Xidian University, Xi'an 710071, China.
authors: XiaoPing
authors: X
authors: Li
authors: School of Aerospace Science and Technology, Xidian University, Xi'an 710071, China.
authors: Kai
authors: K
authors: Xie
authors: School of Aerospace Science and Technology, Xidian University, Xi'an 710071, China.
authors: ZhiWei
authors: Z
authors: Liu
authors: School of Aerospace Science and Technology, Xidian University, Xi'an 710071, China.
authors: MingXu
authors: M
authors: Shao