Magnetically-Guided Liquid Metal First Wall (MAGLIMFW) with a Built-in Automatic Disruption Mitigation System
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ORIGINAL RESEARCH
Magnetically-Guided Liquid Metal First Wall (MAGLIMFW) with a Builtin Automatic Disruption Mitigation System Michiya Shimada1 Accepted: 7 September 2020 Ó Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract An innovative approach is proposed for the protection of plasma-facing surface of blankets (solid first wall), which will also serve as an automatic disruption mitigation system. In a strong magnetic field, liquid metal is frozen in the magnetic field. This property enables liquid metal to flow along the field line. In a divertor configuration with a lower single-null, a second separatrix exists above the plasma. Toroidally-continuous liquid metal sheets, poured through a toroidal slot located radially outside the 2nd separatrix flux surface, move along the field line, absorbing heat and particles, reach the divertor at a glancing angle. At the current quench in a disruption, a toroidal current is induced automatically in the liquid metal surrounding the core plasma. The resultant j 9 B force pushes the liquid metal toward the core plasma, significantly mitigating the heat load and force on the first wall and the divertor. Use of magnetically-guided liquid metal FW would also eliminate the need of fine shaping and toroidal alignment of the first wall. Keywords Fusion reactor Plasma facing component Liquid metal First wall Disruption Wall conditioning
Introduction The plasma-facing components (PFC) of a fusion reactor must accommodate high heat fluxes from the plasma, large heat and electromagnetic loads during off-normal events, making the PFC design one of the most technically challenging issues for ITER [1] and even more challenging for DEMO due to fusion power and stored plasma and magnetic energy of DEMO being significantly higher than ITER. A scheme of liquid metal divertor is proposed, which takes full advantage of both liquid metal convection and conduction to remove heat from the divertor [2]. In the case of solid first walls, such as those made of tungsten, to prevent possible melting of leading edges, the requirement on shaping and alignment of first walls is very demanding, despite the large size and heavy weight of the blanket. Thermal and electromagnetic loads during unmitigated major disruptions and runaway electron generation in & Michiya Shimada [email protected] 1
particular impose a serious threat to the plasma-facing components. The disruption prediction system currently developed relies on a learning process on the machine itself; prediction systems imported from a different machine have shown only limited success [3] and failure of prediction of a major disruption during the learning process could lead to consequences in DEMO much more serious than in present machines, including extended downtime for repair, taking several months or perhaps even longer. In this paper, an innovative approach to the first wall system is proposed. Toroidally continuous liquid metal sheets injected from
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