Optical System Design for Laser-Induced Fluorescence Study of Helium Atoms on the Linear Plasma Device

According to the characteristic spectral lines of helium atoms, an optical system for the laser-induced fluorescence study of helium atoms has been designed. The design includes a helium spectral scheme and a laser injection and fluorescence collection system. The diode laser generates a 667.8-nm laser, and the laser is injected into the linear plasma device through an optical fiber. The fluorescence collection system detects 501.6-nm fluorescence signals. Experiments were carried out on the linear plasma device during helium discharge, simulating the helium ash environment at the boundary of the fusion reactor. The fluorescence collection was realized, and the fluorescence signals showed an increasing trend with laser power. Atomic density calibration and study will be performed based on the collected signals in the next step.