Investigation of cascade type falling liquid film flow along first wall of laser-fusion reactor

To protect from high energy/particle fluxes caused by nuclear fusion reaction such as extremely high heat flux, X rays, Alpha particles and fuel debris to a first wall of an inertia fusion reactor, a 'cascade type' falling liquid film flow is proposed as a 'liquid wall' concept which is one of the reactor chamber cooling and wall protection schemes. We conducted the flow visualization experiment to investigate the feasibility of this liquid wall concept. According to the preliminary numerical simulation results based on the water as the working liquid, the cascade structure design must be improved. Therefore, we redesigned the cascade-type first-wall and performed the flow visualization again. The new cascade-type first-wall is consisted of a liquid reservoir having a free-surface maintaining a constant water-head located at the backside of the first wall, and connects to the slit composed of two plates: one of the plates is the first wall. We performed the POP (proof-of-principle) experiments. According to the POP experimental results of this new cascade-type liquid-first-wall concept, we confirmed that we could control the liquid flow rate and the thickness of the liquid film. (author)