Analysis of double-probe characteristics in low-frequency gas discharges and its improvement

作者：Liu, DongLin^*; Li, XiaoPing; Xie, Kai; Liu, ZhiWei; Shao, MingXu

来源：Review of Scientific Instruments, 2015, 86(1): 013504.

DOI：10.1063/1.4906368

• LANGMUIR PROBE
• RF DISCHARGES
• PLASMA

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.

• 出版日期2015-1
• 单位西安电子科技大学