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We overview current experiments and accompanying theoretical studies in the area of MHD thermofluids in the US, which are aimed at characterization of MHD flows coupled with heat and mass transfer in fusion breeding blankets. We also outline recent upgrades of the experimental MHD facility at UCLA called MaPLE (Magnetohydrodynamic PbLi Experiment) and introduce near-future experimental plans. [ABSTRACT FROM AUTHOR]

Abstract: The paper summarizes results of experimental and theoretical studies related to the flow of liquids with a free surface and poor electrical and thermal conductivity, such as molten salts, under conditions relevant to fusion energy systems. These results have been obtained over last several years when developing the liquid wall concept as a part of the APEX project [M.A. Abdou, The APEX TEAM, On the exploration of innovative concepts for fusion chamber technology, Fusion Eng. Des. 54 (2001) 181–247]. As a theoretical tool a modified K–ε model of turbulence coupled with the Navier–Stokes equations written in the thin-shear-layer approximation is used for studying wavy, turbulent flows in a spanwise magnetic field. The experimental part covers current results for supercritical flows in regimes transitional from “weak” to “strong” turbulence, which are expected to occur in the reference liquid wall flows. The paper also describes on-going work on novel schemes of heat transfer promotion and current directions for direct numerical simulation. [Copyright &y& Elsevier]

Liquid wall concept has a significant place in the Advanced Power Extraction (APEX) study as a part of the US program on Nuclear Fusion. In the present paper, different approaches currently developed for modeling liquid wall magnetohydrodynamics and heat transfer in APEX have been presented. Turbulent flows of low-conductivity liquids, such as molten salts (Flibe), are analyzed using a two-equation turbulence model and Direct Numerical Simulation. The analysis of liquid metal flows under a strong reactor magnetic field is based on the magnetohydrodynamic equations for laminar flows. [ABSTRACT FROM AUTHOR]

GaInSn, a eutectic alloy, has been successfully used in the Magneto-Thermofluid Research Laboratory at the University of California-Los Angeles and at the Princeton Plasma Physics Laboratory for the past six years. This paper describes the handling and safety of GaInSn based on the experience gained in these institutions, augmented by observations from other researchers in the liquid metal experimental community. GaInSn is an alloy with benign properties and shows considerable potential in liquid metal experimental research and cooling applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] New MHD PbLi loop has been constructed and tested at UCLA. [•] Pressure diagnostics system has been developed and successfully tested. [•] Ultrasound Doppler velocimeter is tested as velocity diagnostics. [•] Experiments on pressure drop reduction have been performed. [•] Experiments on MHD flow in a duct with SiC flow channel insert are underway. [Copyright &y& Elsevier]

Abstract: This paper reports on experimental findings on liquid metal (LM) free surface flows crossing complex magnetic fields. The experiments involve jet and film flows using GaInSn and are conducted at the UCLA MTOR facility. The goal of this study is to understand the magnetohydrodynamics (MHD) features associated with such a free surface flow in a fusion-relevant magnetic field environment, and determine what LM free surface flow option is most suitable for lithium divertor particle pumping and surface heat removal applications in a near-term experimental plasma device, such as NSTX. Experimental findings indicate that a steady transverse magnetic field, even with gradients typical of NSTX outer divertor conditions, stabilizes a LM jet flow—reducing turbulent disturbances and delaying jet breakup. Important insights into the MHD behavior of liquid metal films under NSTX-like environments are also presented. It is possible to establish an uphill liquid metal film flow on a conducting substrate, although the MHD drag experienced by the flow could be strong and cause the flow to pile-up under simulated NSTX magnetic field conditions. The magnetic field changes the turbulent film flow so that wave structures range from 2D column-type surface disturbances at regions of high magnetic field, to ordinary hydrodynamic turbulence wave structures at regions of low field strength at the outboard. Plans for future work are also presented. [Copyright &y& Elsevier]