Liquid metal heat pipes for fusion application

Liquid metal heat pipes (HP) possess excellent heat transfer characteristics and are now widely used in space and atomic industries as very attractive fully autonomous devices. However, their application in magnetic field devices is restricted due to very scare data on the influence of magnetic field on heat transfer parameters of liquid metal HP. The main objective of the present experiments is to determine the maximum surface heat flux removed by HP in magnetic field. Specially designed tubular sodium heat pipe has the following features: capillary structure which consists of metallic felt in the evaporation zone and a perforated screen in the condensation zone; the structural material is niobium alloy. Experimental set-up consists of a vacuum chamber placed between the poles of an electromagnet which can ensure magnetic field strength up to 1.5 T in the vacuum chamber. The direction of the applied magnetic field is transverse to the liquid metal flow in the heat pipe. The set-up provides a possibility to incline the vacuum chamber up to 45 relative to the horizontal axes. The dependence of critical heat flux of the heat pipes as a function of magnetic field strength up to 1.5 T has been studied. The concept of fusion reactor plasma facing components cooled by liquid metal heat pipes is presented. (orig.)