Experimental Investigation on MHD Instabilities of Free Surface Jet and Film Flow for Liquid Metal Divertor/Limiter Options

1 Introduction Recently, it is rising of the study of liquid metal free surface as the divertor, limiter and the first wall in a fusion device. Many special facilities are employed to investigate MHD-related issues of free surface jet and film flow, and many results are carried out on theory and experiments . But, there are still not enough experimental data to well understand magneto- hydrodynamics （MHD） instability. For theory, the greatest challenge is how to develop a modeling to expect and understand free surface MHD phenomenon, and for experiments is how to diagnose the flow state of liquid metal free surface flow in magnetic field.