MHD problems in free liquid surfaces as plasma-facing materials in magnetically confined reactors

The development of solid plasma-facing components (PFCs) that can withstand high heat and particle fluxes during normal and abnormal events has proven to be a difficult task for future power-producing magnetically confined reactors. Solid PFC cannot be reliably used because of the large erosion losses during normal and off-normal events such as disruptions and their consequences. The use of liquid metal surfaces for protection of PFCs seems attractive but is not easily implemented. The ability to use liquids as PFC surfaces depends on their overall integrated interaction with the plasma as well as with the strong magnetic field in the reactor. The temperature of a flowing liquid surface governed by surface velocity should be low enough to avoid core plasma contamination by the metal vapor. A high liquid flow velocity, V , may also be necessary to overcome the force F /[J /B ], where J is current and B is magnetic field. In this study, MHD flow patterns of the liquid metal across the magnetic field (B /5 T) are investigated. The retarding force F /[J /B ] results in a rather high pressure drop required to move the liquid metal across the magnetic field. New twodimensional calculations of MHD effects and resulting pressure drop have been completed with the upgraded HEIGHTS software package. # 2002 Elsevier Science B.V. All rights reserved.