Balmer-alpha and Balmer-beta Stark line intensity profiles for high-power hydrogen inductively coupled plasmas

We compare Balmer-alpha (H_α) and Balmer-beta (H_β) emissions from high-power (1.0-6.0 kW) hydrogen inductively coupled plasmas (ICPs), and propose region I (0.0-2.0 kW), region Ⅱ (2.0-5.0 kW), and region Ⅲ (5.0-6.0 kW). In region I, both H_α emission intensity (I_α) and H_β emission intensity (I_β) increase with radio frequency (RF) power, which is explained by the corona model and Boltzmann's law, etc. However, in region Ⅱ, I_α almost remains constant while I_β rapidly achieves its maximum value. In region Ⅲ, I_α slightly increases with RF power, while I_β decreases with RF power, which deviates significantly from the theoretical explanation for the H_α and H_β emissions in region I. It is suggested that two strong electric fields are generated in high-power (2.0-6.0 kW) hydrogen ICPs: one is due to the external electric field of high-power RF discharge, and the other one is due to the micro electric field of the ions and electrons around the exited state hydrogen atoms in ICPs. Therefore, the strong Stark effect can play an important role in explaining the experimental results.