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

Abstract

We compare Balmer-alpha (Hα) and Balmer-beta (Hβ) 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 Hα emission intensity (Iα) and Hβ emission intensity (Iβ) increase with radio frequency (RF) power, which is explained by the corona model and Boltzmann's law, etc. However, in region II, Iα almost remains constant while Iβ rapidly achieves its maximum value. In region III, Iα slightly increases with RF power, while Iβ decreases with RF power, which deviates significantly from the theoretical explanation for the Hα and Hβ 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.