Ion temperature and fluctuation in a large-diameter electron–cyclotron-resonance plasma

Abstract

Using high-resolution optical emission spectroscopy, Ar + ion temperature in a large-diameter electron cyclotron resonance (ECR) plasma was obtained from Doppler broadenings. It was found that the ion temperature depends on gas pressures and incident microwave powers. The ion temperature at low-pressures was considerably high. When the gas pressure was decreased from 13.0×10 −2 to 2.6×10 −2 Pa for the incident microwave power of 2.0 kW, the ion temperature increased from 0.03 to 0.56 eV. The amplitude of fluctuations observed in the ECR plasma also increased with decreasing the gas pressure and increasing the incident microwave power. These results suggest that there is a correlation between the ion temperature and fluctuations. The fluctuations were excited by the flute instability.