Magnetohydrodynamic effects on liquid metal film flowing along an inclined plate relating to plasma facing components

The liquid metal film plasma facing component (PFC) is considered to be one of the most promising ways to realize a PFC capbable of operating for long periods. However, in the presence of a magnetic field, magnetohydrodynamic effects appearing in the liquid metal film flow directly influence the reliability of the flowing liquid metal limiter or divertor. In the present study, we consider the influence of flow rate, transverse magnetic field, and inclination angle, and conduct experiments on a liquid metal film flowing along an inclined conducting stainless steel plate. A laser profilometer (LP) and a high-speed camera are respectively adopted to obtain the local film thickness quantitatively, and its free surface structures qualitatively. We observe the magnetohydrodynamic effects of liquid metal film flow, such as the nonmonotonic change of film thickness, the reduction of film flow velocity, and the weakening of free surface waves in the direction of magnetic lines. Moreover, the film thickness increases with an increasing flow rate, whereas it decreases with an increasing inclination angle at a constant value of the magnetic field. When plotting the relative film thickening δ _en, and the reduction of flow velocity against the Stuart number N, we find that there is a critical N, N _cr ≈ 0.1, at which δ _en begins to increase dramatically. The δ _ensinβ with $1^{\circ }\le \beta \le 5^{\circ }$, based on all of the experimental data, collapses into one line, which can be scaled as δ _ensinβ ∼ N. The present experimental data and its scaling law may prove useful for estimating magnetohydrodynamic effects on liquid metal film flows when considering the design of liquid metal film PFCs. (paper)