Energy transfer mechanism and regulation methods of plasma plume in high-power laser welding

During laser welding, the generated plume interferes with laser energy transmission. Especially under high-power conditions, the absorption of laser energy by the plume is significantly enhanced, leading to difficulty in increasing penetration depth and the occurrence of power saturation.This paper reviews laser‑metal interaction, plume monitoring, and control methods.During laser welding, the evaporation flow of metal inside the keyhole and the ejected vapor outside the keyhole form a coupled dynamic system of internal and external energy.Because the keyhole is located inside the molten pool, direct observation is difficult.Current research, based on clarifying the non‑uniformity of metal evaporation flow inside the keyhole, focuses on the metal vapor‑plasma plume system ejected outside the keyhole.Through real‑time acquisition of optical, acoustic, and electrical signals, combined with multi‑dimensional characterization methods and neural networks, a mapping relationship among the welding process, plume dynamic behavior, and keyhole stability is established.The main means of plume control include the use of pulsed short‑wavelength lasers, regulation of the ambient medium, changing the ambient pressure or gas composition, and introducing highly ionized inert gases.Future research should focus on clarifying the influence mechanism of the plume inside the keyhole on laser energy, identifying key plume characteristic parameters that affect keyhole stability, and developing more efficient and flexible high‑density plume suppression devices, so as to promote the further development of high‑power laser welding technology.