Spatial distribution study of argon radio-frequency inductively coupled plasma in inverse hysteresis transition area

•The emission of plasma would present an abnormal hysteresis phenomenon at the pressure of 0.6 Pa.•The value of plasma parameters has a slight change at the same power in different modes.•The spatial distributions of plasma parameters are more homogenous in H mode than E mode.

Parameters of radio-frequency (rf) inductively coupled plasma (ICP) have been investigated with Langmuir probe and optical emission spectrum (OES) in this paper. Through the observation results of OES, we can finally get that inverse hysteresis phenomenon would occur when the air pressure is 0.6 Pa. The mode of plasma is demonstrated based on OES while spatial distribution of electron temperature Te, plasma density np and plasma potential Vp at the same power and pressure in inverse hysteresis transition area could be assured with Langmuir probe. The experiment results indicate that even though Te, np and Vp distribute more homogeneously in both axial and radial direction at the stage of H mode than E mode, the result shows no great difference of the data in both H mode and E mode.