Profile studies of lithium vapor under high-density plasma irradiation using embedded multichannel capillary porous structure

Faced with complex operational environments, liquid metal divertors are considered alternative solutions to traditional solid divertors. Experiments have been conducted using a self-designed embedded multichannel capillary porous structure (EM-CPS) for plasma irradiation of lithium (Li)-prefilled EM-CPS in the high-density linear plasma device (SCU-PSI). The optical image analysis of the interaction region between the plasma and Li vapor shows that the region is not a regular geometric shape and the point of strongest light emission appears 1–2 cm in front of the target rather than on its surface. The irregularity is due to the uneven distribution and density of the Li vapor, as well as the radial and axial attenuation of the plasma. As the plasma discharge parameters increase, the vapor profile initially expands globally and then contracts locally, with the point of the strongest light emission gradually moving towards the target surface. The spectral lines of Li 670.78 nm and Ar 763.51 nm in the interaction region are produced by de-excitation. These lines gradually decrease in intensity along the axial direction, which is close to the trend of light emission intensity that initially increases and then decreases along the same direction. These findings provide a reference for studying the interaction mechanism between plasma and liquid Li capillary porous structures in linear plasma devices and future tokamak.