Temperature measurement and examination of E to H transition in vacuum ICP plasma

In this paper, we first briefly describe the constructed Inductively Coupled Plasma Source device, ICP-13.56, which includes two vacuum and atmospheric pressure torches. Afterward, focusing on the vacuum-torch operation, we discuss the plasma temperature characterization and examine the phenomenon of E to H mode-transition during the variation of experiment parameters including the initial pressure and input RF power. Based on the spectroscopic measurements of argon gas at pressure 4 mbar and input RF power 400 W, the electron excitation temperature of 11636 °K was obtained using the Boltzmann line method. Additionally, we have calculated the absorbed power in terms of plasma density and gas pressure using equations governing electromagnetic fields in ICP plasma. According to these relations, behaviors of load characteristics have been analyzed and E to H mode transition has been identified.