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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 en sinβ with 1 • ≤ β ≤ 5 • , based on all of the experimental data, collapses into one line, which can be scaled as δ en sinβ ∼ 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.

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As a novel portable and robust broadband coherent light source, mid-infrared (MIR) Kerr microresonator-based frequency combs (microcombs) have prospective applications in the precision spectroscopy of molecules and biochemical sensing. The mature integrated silicon photonics platform is well suited for the MIR microcombs study because silicon has both large linear and nonlinear refractive index, but the transparency window of the platform is limited by the cladding material. Here, we numerically demonstrate the generation of a broadband MIR comb in a silicon microring resonator, harnessing the large-cross-section air-cladding waveguide to alleviate the absorption loss. The effects of higher order nonlinearities are also investigated, which show that the effect of five-photon absorption around the pump wavelength (4.78 µm) is negligible while an octave-spanning (3.5-8 µm) Raman-Kerr comb line can be obtained with the assistance of Raman effect and a quite pure Kerr frequency soliton comb can also be achieved at large detuning. The proposed structure can be compatible with the CMOS technology, thus can be a very promising solution to the MIR integrated photonics.