Diagnostic study of atmospheric pressure inductively coupled plasma temperature field based on image and relative spectral line method

Abstract

Atmospheric pressure inductively coupled plasma (ICP) is widely applied in the production of high-purity coatings and powders. This paper innovatively presents a dual-band imaging ICP temperature diagnostic system that integrates visible light image processing technology and relative spectral line method. The system utilizes a dual-band imaging unit to simultaneously acquire monochromatic grayscale images of ICP at two different wavelengths using a single CCD camera. By establishing the correspondence between the emission intensity received by the emission spectrometer and the grayscale images recorded by the CCD camera, the two-dimensional (2D) electron excitation temperature (EET) field distribution of ICP is obtained by the relative spectral line method. The experimental results demonstrate that the maximum EET is located near to the center line of the RF-driven coil. Additionally, the EET in ICP decreases gradually from the center of the induction coil to the periphery. As the radio frequency (RF) power increases, the maximum EET also increases, and the high-temperature region expands. The accuracy of this method is validated by comparing it with the results obtained from the Boltzmann plot method. Therefore, this method can quickly obtain the transient EET field distribution of ICP, which is significant for optimizing the application of ICP in material processing.