Theoretical investigation of liquid metal MHD free surface flows for Alps

Free surface plasma facing components (PFCs) offer the potential to solve the lifetime issues limiting current solid surface designs for tokamak fusion reactors by eliminating the problems of erosion and thermal stresses accompanying solid surface designs. The moving PFC free surfaces provide the possibility of absorbing impurities and possibly helium for removal outside of the plasma chamber. Free surface PFCs may also offer more creative possibilities for heat removal and higher thermal conversion efficiencies for the entire system. Design requirements for PFCs include handling similar to 50% of the plasma heat flux and similar to 90% of the ion flux. Magnetohydrodynamic (MHD) liquid metal flows with free surfaces are discussed with reference to Advanced Limiter-divertor Plasma-facing Systems (ALPS) program. Specific MHD issues for the jet divertor are outlined. Results for the rivulet flow and for the thermocapillary, or Marangoni, flow in a jet are presented.